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LOCAL AREA NETWORK (LAN) SIMULATOR
By PONG SlEW SEONG
~LAYSlt
~ fS ~
~ ~ ~ -J ~
Vtv Mp~ esis Dikemukakan Kepada
Fakulti K(Il1rnteraan Univorsiti Malaysia Sarawak Sebagai M(mwnuhi Sebabagian Daripada Syarat
P(mganug(rahan Sarjana Muda Kejuruteraan 1 )ongan PpujIall (I(jurutoraan Elektronik Dan Tpekomunikasi)
2000
IV
LOCAL AREA NETWORK (LAN) SIMULATOR
By PONG SlEW SEONG
~LAYSlt
0 ~ fS ~ ~ ~ -J ~ bull bull vJvJMp~
esis Dikemukakan Kepada Fakulti K(Il1rnteraan Univorsiti Malaysia Sarawak S(bll~ai Mprrwnuhi Sebahugian Daripada Syarat
P(mganug(rahan Sarjana Muda Kejuruteraan 1 )(mgan PpujIall (I(jurutoraan Elektronik Dan Tpekomunikasi)
2000
IV
Dedicated to
My beloved people
v
I
Dedicated to
My beloved people
v
ACKNOWLEDGEMENTS
[irst of all I would like to dedicate this thesis projeet to my family mnmhcm
(spnciaHy ()r giving me support encouragement and eoncern during the pnriod
of my study Also to my girl friend Lee Gaik Fong for giving me motivation and
morale support
I would aJso like to express my gratitude to my supervisor Mr Ng Liang Yew
ror giving any soft of guidance and advise to make this thesis project a success
Moreovt~r thanks to Lam Hon Kit a senior and good friend of mine for providing
important materials on the thesis report writing
Not forgotten thanks to my thesis project partner Goh Beng Huat who
dpv(gt]ops the Loeal Area Network (LAN) Simulation program with me
Finally J would like to thanks the Faculty of Engineering under the leadership
Ill Dr Moham(J(1 Kadim as Dean for allowing me to usp all kind of n~sourees
lailahln
V]
I
ACKNOWLEDGEMENTS
[irst of all I would like to dedicate this thesis projeet to my family mnmhcm
(spnciaHy ()r giving me support encouragement and eoncern during the pnriod
of my study Also to my girl friend Lee Gaik Fong for giving me motivation and
morale support
I would aJso like to express my gratitude to my supervisor Mr Ng Liang Yew
ror giving any soft of guidance and advise to make this thesis project a success
Moreovt~r thanks to Lam Hon Kit a senior and good friend of mine for providing
important materials on the thesis report writing
Not forgotten thanks to my thesis project partner Goh Beng Huat who
dpv(gt]ops the Loeal Area Network (LAN) Simulation program with me
Finally J would like to thanks the Faculty of Engineering under the leadership
Ill Dr Moham(J(1 Kadim as Dean for allowing me to usp all kind of n~sourees
lailahln
V]
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
Jn order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if the program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
I
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
J n order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if IIw program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
pi
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisis keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V111
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisi8 keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V 111
TABLE OF CONTENTS
Pagn
Tlwsis Submis8ion Form
Approval II
j)mlaratioll III
J)(~dication v
Aeknowledgment VI
Abstract vii
Abstrak Vlll
Table of Contents IX
List of Figures xiv
1 CHAPTER 1 INTRODUCTION
1 ] Jn trod uetiOJl
1t Ohjpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application 4
~1i LOlal Arpa N(twork j(~quirmnents 4
IX
I
Tlwsis Submis8ion Form
Approval
j)mlaratioll
J)(~dication
Aeknowledgment
Abstract
Abstrak
Table of Contents
List of Figures
TABLE OF CONTENTS
1 CHAPTER 1 INTRODUCTION
1 ] J n trod uetiOJl
1 t Objpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application
~1i LOlal ArPil N(twork j(~quirmnents
IX
Pagn
II
III
v
VI
vii
Vlll
IX
xiv
4
4
7
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ IAHal Jrc~a Network Toehnology
~~ J Opon Systnm lntereonnndion (OS) Modol H
~~~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMACD Opf)ration ] ]
~222 CSMJICD Function 12
2228 CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management JG
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
~228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
22212 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Baseband Media Access Unit
2221 G Nonpersistent and pmiddotPersistent CSMACD
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
I
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ I AHal Jrc~a Network Tochnology 7
~~ J Opon Systmll lntnreonnndion (OS) Model H
~2~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMJCD Opf)ration ] ]
2222 CSMJICD Function 12
~22a CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management ]6
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
2228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
~2~12 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Basfband Media Access Unit 2fi
2221 G Nonpersistent and pmiddotPersistent CSMACD 2G
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
Dedicated to
My beloved people
v
I
Dedicated to
My beloved people
v
ACKNOWLEDGEMENTS
[irst of all I would like to dedicate this thesis projeet to my family mnmhcm
(spnciaHy ()r giving me support encouragement and eoncern during the pnriod
of my study Also to my girl friend Lee Gaik Fong for giving me motivation and
morale support
I would aJso like to express my gratitude to my supervisor Mr Ng Liang Yew
ror giving any soft of guidance and advise to make this thesis project a success
Moreovt~r thanks to Lam Hon Kit a senior and good friend of mine for providing
important materials on the thesis report writing
Not forgotten thanks to my thesis project partner Goh Beng Huat who
dpv(gt]ops the Loeal Area Network (LAN) Simulation program with me
Finally J would like to thanks the Faculty of Engineering under the leadership
Ill Dr Moham(J(1 Kadim as Dean for allowing me to usp all kind of n~sourees
lailahln
V]
I
ACKNOWLEDGEMENTS
[irst of all I would like to dedicate this thesis projeet to my family mnmhcm
(spnciaHy ()r giving me support encouragement and eoncern during the pnriod
of my study Also to my girl friend Lee Gaik Fong for giving me motivation and
morale support
I would aJso like to express my gratitude to my supervisor Mr Ng Liang Yew
ror giving any soft of guidance and advise to make this thesis project a success
Moreovt~r thanks to Lam Hon Kit a senior and good friend of mine for providing
important materials on the thesis report writing
Not forgotten thanks to my thesis project partner Goh Beng Huat who
dpv(gt]ops the Loeal Area Network (LAN) Simulation program with me
Finally J would like to thanks the Faculty of Engineering under the leadership
Ill Dr Moham(J(1 Kadim as Dean for allowing me to usp all kind of n~sourees
lailahln
V]
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
Jn order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if the program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
I
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
J n order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if IIw program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
pi
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisis keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V111
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisi8 keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V 111
TABLE OF CONTENTS
Pagn
Tlwsis Submis8ion Form
Approval II
j)mlaratioll III
J)(~dication v
Aeknowledgment VI
Abstract vii
Abstrak Vlll
Table of Contents IX
List of Figures xiv
1 CHAPTER 1 INTRODUCTION
1 ] Jn trod uetiOJl
1t Ohjpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application 4
~1i LOlal Arpa N(twork j(~quirmnents 4
IX
I
Tlwsis Submis8ion Form
Approval
j)mlaratioll
J)(~dication
Aeknowledgment
Abstract
Abstrak
Table of Contents
List of Figures
TABLE OF CONTENTS
1 CHAPTER 1 INTRODUCTION
1 ] J n trod uetiOJl
1 t Objpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application
~1i LOlal ArPil N(twork j(~quirmnents
IX
Pagn
II
III
v
VI
vii
Vlll
IX
xiv
4
4
7
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ IAHal Jrc~a Network Toehnology
~~ J Opon Systnm lntereonnndion (OS) Modol H
~~~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMACD Opf)ration ] ]
~222 CSMJICD Function 12
2228 CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management JG
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
~228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
22212 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Baseband Media Access Unit
2221 G Nonpersistent and pmiddotPersistent CSMACD
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
I
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ I AHal Jrc~a Network Tochnology 7
~~ J Opon Systmll lntnreonnndion (OS) Model H
~2~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMJCD Opf)ration ] ]
2222 CSMJICD Function 12
~22a CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management ]6
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
2228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
~2~12 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Basfband Media Access Unit 2fi
2221 G Nonpersistent and pmiddotPersistent CSMACD 2G
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
ACKNOWLEDGEMENTS
[irst of all I would like to dedicate this thesis projeet to my family mnmhcm
(spnciaHy ()r giving me support encouragement and eoncern during the pnriod
of my study Also to my girl friend Lee Gaik Fong for giving me motivation and
morale support
I would aJso like to express my gratitude to my supervisor Mr Ng Liang Yew
ror giving any soft of guidance and advise to make this thesis project a success
Moreovt~r thanks to Lam Hon Kit a senior and good friend of mine for providing
important materials on the thesis report writing
Not forgotten thanks to my thesis project partner Goh Beng Huat who
dpv(gt]ops the Loeal Area Network (LAN) Simulation program with me
Finally J would like to thanks the Faculty of Engineering under the leadership
Ill Dr Moham(J(1 Kadim as Dean for allowing me to usp all kind of n~sourees
lailahln
V]
I
ACKNOWLEDGEMENTS
[irst of all I would like to dedicate this thesis projeet to my family mnmhcm
(spnciaHy ()r giving me support encouragement and eoncern during the pnriod
of my study Also to my girl friend Lee Gaik Fong for giving me motivation and
morale support
I would aJso like to express my gratitude to my supervisor Mr Ng Liang Yew
ror giving any soft of guidance and advise to make this thesis project a success
Moreovt~r thanks to Lam Hon Kit a senior and good friend of mine for providing
important materials on the thesis report writing
Not forgotten thanks to my thesis project partner Goh Beng Huat who
dpv(gt]ops the Loeal Area Network (LAN) Simulation program with me
Finally J would like to thanks the Faculty of Engineering under the leadership
Ill Dr Moham(J(1 Kadim as Dean for allowing me to usp all kind of n~sourees
lailahln
V]
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
Jn order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if the program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
I
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
J n order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if IIw program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
pi
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisis keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V111
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisi8 keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V 111
TABLE OF CONTENTS
Pagn
Tlwsis Submis8ion Form
Approval II
j)mlaratioll III
J)(~dication v
Aeknowledgment VI
Abstract vii
Abstrak Vlll
Table of Contents IX
List of Figures xiv
1 CHAPTER 1 INTRODUCTION
1 ] Jn trod uetiOJl
1t Ohjpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application 4
~1i LOlal Arpa N(twork j(~quirmnents 4
IX
I
Tlwsis Submis8ion Form
Approval
j)mlaratioll
J)(~dication
Aeknowledgment
Abstract
Abstrak
Table of Contents
List of Figures
TABLE OF CONTENTS
1 CHAPTER 1 INTRODUCTION
1 ] J n trod uetiOJl
1 t Objpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application
~1i LOlal ArPil N(twork j(~quirmnents
IX
Pagn
II
III
v
VI
vii
Vlll
IX
xiv
4
4
7
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ IAHal Jrc~a Network Toehnology
~~ J Opon Systnm lntereonnndion (OS) Modol H
~~~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMACD Opf)ration ] ]
~222 CSMJICD Function 12
2228 CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management JG
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
~228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
22212 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Baseband Media Access Unit
2221 G Nonpersistent and pmiddotPersistent CSMACD
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
I
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ I AHal Jrc~a Network Tochnology 7
~~ J Opon Systmll lntnreonnndion (OS) Model H
~2~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMJCD Opf)ration ] ]
2222 CSMJICD Function 12
~22a CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management ]6
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
2228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
~2~12 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Basfband Media Access Unit 2fi
2221 G Nonpersistent and pmiddotPersistent CSMACD 2G
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
Jn order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if the program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
I
ABSTRACT
Tlw cone(~pt of Local Area Network (LAN) Simulator is to provid(- a m(~an~ to
study the dynamic behavior of local an~a network system without building the
real prototype which is time and cost consuming
J n order to develop the simulator it is important to understand the
functionality and operation of each topology For different type of LAN there
arc~ differ(mt parameters events and assumptions to be considered These will
determine the level of detail with which the simulation program will do Next
the seJected variables as well as other parameters required are related to the
system
At this point the next step is to determine if the computer program executes
tlH simulatIon as intended Typically this phase requires analysis of stop
outputs aud ov(~rall results to see if the proper actions are oCGurring as
mtcraquoHled
Tlw final portion of implementation is composed of running the simulation and
sP(~ing if IIw program capable of meeting th(~ performanee f(~quif(lnwnts of tlw
ljN
VII
pi
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisis keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V111
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisi8 keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V 111
TABLE OF CONTENTS
Pagn
Tlwsis Submis8ion Form
Approval II
j)mlaratioll III
J)(~dication v
Aeknowledgment VI
Abstract vii
Abstrak Vlll
Table of Contents IX
List of Figures xiv
1 CHAPTER 1 INTRODUCTION
1 ] Jn trod uetiOJl
1t Ohjpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application 4
~1i LOlal Arpa N(twork j(~quirmnents 4
IX
I
Tlwsis Submis8ion Form
Approval
j)mlaratioll
J)(~dication
Aeknowledgment
Abstract
Abstrak
Table of Contents
List of Figures
TABLE OF CONTENTS
1 CHAPTER 1 INTRODUCTION
1 ] J n trod uetiOJl
1 t Objpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application
~1i LOlal ArPil N(twork j(~quirmnents
IX
Pagn
II
III
v
VI
vii
Vlll
IX
xiv
4
4
7
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ IAHal Jrc~a Network Toehnology
~~ J Opon Systnm lntereonnndion (OS) Modol H
~~~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMACD Opf)ration ] ]
~222 CSMJICD Function 12
2228 CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management JG
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
~228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
22212 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Baseband Media Access Unit
2221 G Nonpersistent and pmiddotPersistent CSMACD
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
I
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ I AHal Jrc~a Network Tochnology 7
~~ J Opon Systmll lntnreonnndion (OS) Model H
~2~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMJCD Opf)ration ] ]
2222 CSMJICD Function 12
~22a CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management ]6
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
2228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
~2~12 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Basfband Media Access Unit 2fi
2221 G Nonpersistent and pmiddotPersistent CSMACD 2G
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
pi
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisis keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V111
ABSTRAI
Konsop Loeal Area Nf)twork (LAN) Simulator mpmiJeri sumhangan knpada
pembelajaran tingkahlaku dinamik mengenai sisLem local area network tan]lltJ
melihatkan pemhinaan prototaip eli samping pembaziran masa dan kewangan
Pemahaman kepada setiap fungsi dan operasi adaJah penting untuk
menghasilkan simulator ini Pelbagai jenis LAN memerlukan pertimhangan
dalam peJbagai jenis parameter perkara dan tanggapan Dengan itu ia dapa1
memastikan tahap kejituan program yang beroperasi tersebut berLanding
dengan sistem sebenar Sehubungan dengan itu pemilihan pembolehubah
parameter yang lain yang berhubungkait dengan sistem tersebut juga
diperlukan
Langkah spterusnya adalah untuk memastikan pengoperasian program
komputer tprseLut Penganahsisan untuk setiap keputusan yang sebenarnya
adalah diperlukan dalam jleringkat tersebut
Poringkat terakhir implltgtmfmtasi terdiri daripada perIaksanaan serta
mpnganalisi8 keupayaan program dalam menghasilkan tugm~an yung
dlj)Crlukan oJ(h LAN
V 111
TABLE OF CONTENTS
Pagn
Tlwsis Submis8ion Form
Approval II
j)mlaratioll III
J)(~dication v
Aeknowledgment VI
Abstract vii
Abstrak Vlll
Table of Contents IX
List of Figures xiv
1 CHAPTER 1 INTRODUCTION
1 ] Jn trod uetiOJl
1t Ohjpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application 4
~1i LOlal Arpa N(twork j(~quirmnents 4
IX
I
Tlwsis Submis8ion Form
Approval
j)mlaratioll
J)(~dication
Aeknowledgment
Abstract
Abstrak
Table of Contents
List of Figures
TABLE OF CONTENTS
1 CHAPTER 1 INTRODUCTION
1 ] J n trod uetiOJl
1 t Objpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application
~1i LOlal ArPil N(twork j(~quirmnents
IX
Pagn
II
III
v
VI
vii
Vlll
IX
xiv
4
4
7
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ IAHal Jrc~a Network Toehnology
~~ J Opon Systnm lntereonnndion (OS) Modol H
~~~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMACD Opf)ration ] ]
~222 CSMJICD Function 12
2228 CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management JG
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
~228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
22212 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Baseband Media Access Unit
2221 G Nonpersistent and pmiddotPersistent CSMACD
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
I
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ I AHal Jrc~a Network Tochnology 7
~~ J Opon Systmll lntnreonnndion (OS) Model H
~2~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMJCD Opf)ration ] ]
2222 CSMJICD Function 12
~22a CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management ]6
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
2228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
~2~12 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Basfband Media Access Unit 2fi
2221 G Nonpersistent and pmiddotPersistent CSMACD 2G
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
TABLE OF CONTENTS
Pagn
Tlwsis Submis8ion Form
Approval II
j)mlaratioll III
J)(~dication v
Aeknowledgment VI
Abstract vii
Abstrak Vlll
Table of Contents IX
List of Figures xiv
1 CHAPTER 1 INTRODUCTION
1 ] Jn trod uetiOJl
1t Ohjpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application 4
~1i LOlal Arpa N(twork j(~quirmnents 4
IX
I
Tlwsis Submis8ion Form
Approval
j)mlaratioll
J)(~dication
Aeknowledgment
Abstract
Abstrak
Table of Contents
List of Figures
TABLE OF CONTENTS
1 CHAPTER 1 INTRODUCTION
1 ] J n trod uetiOJl
1 t Objpehves
11 lntroduetion to LAN Simulator (LanSim)
2 CHAPTER 2 LITERATURE REVIEW - LOCAL AREA NEfiTORK
t] Local Arpa Nptwork (LAN) Concepts
tll Local Ana Nptwork Definitioll
~ 1~ Local Arta Ndwork Application
~1i LOlal ArPil N(twork j(~quirmnents
IX
Pagn
II
III
v
VI
vii
Vlll
IX
xiv
4
4
7
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ IAHal Jrc~a Network Toehnology
~~ J Opon Systnm lntereonnndion (OS) Modol H
~~~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMACD Opf)ration ] ]
~222 CSMJICD Function 12
2228 CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management JG
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
~228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
22212 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Baseband Media Access Unit
2221 G Nonpersistent and pmiddotPersistent CSMACD
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
I
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ I AHal Jrc~a Network Tochnology 7
~~ J Opon Systmll lntnreonnndion (OS) Model H
~2~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMJCD Opf)ration ] ]
2222 CSMJICD Function 12
~22a CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management ]6
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
2228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
~2~12 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Basfband Media Access Unit 2fi
2221 G Nonpersistent and pmiddotPersistent CSMACD 2G
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
7
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ IAHal Jrc~a Network Toehnology
~~ J Opon Systnm lntereonnndion (OS) Modol H
~~~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMACD Opf)ration ] ]
~222 CSMJICD Function 12
2228 CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management JG
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
~228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
22212 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Baseband Media Access Unit
2221 G Nonpersistent and pmiddotPersistent CSMACD
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
I
~ J t1 Local rnll N(~tw()rk Charadorislie
~~ I AHal Jrc~a Network Tochnology 7
~~ J Opon Systmll lntnreonnndion (OS) Model H
~2~ Carrt(~r Snns(~ MultipJ8 AecBSs with Collision Dntflction (CSMACD) 1 1
~2~] CSMJCD Opf)ration ] ]
2222 CSMJICD Function 12
~22a CSMACD Transmission Frame ]4
2224 CSMAlCD MBdia Access Management ]6
2225 Collimiddotion Detection
2226 Backoff After Collision 17
2227 CSMACD Physical Layer Standards 18
2228 Physical Signaling Functions 20
2229 Physical Signaling Interface 2]
22210 Thr MACPLS Interface 21
22211 The PLSPMA Interface 22
~2~12 Attachment Unit Interface
222] 8 Baseband Medium Attachment Unit
222J 4 Basfband Media Access Unit 2fi
2221 G Nonpersistent and pmiddotPersistent CSMACD 2G
228 Star Tupology 2G
2211 Star Op(ration 2(i
22iL2 Star Limitatioll
221~ Star P(r(lflnanCe
x
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
30
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion 2
i] 1 LAN Il(~rJ()rm anC8 Considerations 2
B] 1] Communication Capacity iiO
81] B Network Stability ii]
ii] 1~ Protocol Efficiency
8 ] 14 N(~twork Reliability 32
8115 Component Limitations 32
8116 BouJeneck Analysis 32
31] 7 Fault Tolerance 33
82 Analytical Models 33
33 Simulation Models 33
331 Characteristics of Simulation Models 34
3311 ContinuouslDiscrete Models 34
3312 Deterministic Stochastic Models 34
B313 TimeEvent Based Models 3G
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
STA11STI CS
41 1n troductioll H)
42 Poisson Dislrihutioll Hl
43 Generation of Random Number8
XI
I
3 CHAPTER 3 LJTERATURE REVIEW - SIMULATJON MODEL OF
LAN
L I 1 nLrorludion
i] 1 LAN I l(~rJ()rm anC8 Considerations
B] 1] Communication Capacity
ii] 1~ Protocol Efficiency
81] B Network Stability
8 ] 14 N(~twork Reliability
8115 Component Limitations
8116 BouJeneck Analysis
31] 7 Fault Tolerance
82 Analytical Models
33 Simulation Models
331 Characteristics of Simulation Models
3311 ContinuouslDiscrete Models
3312 Deterministic Stochastic Models
B313 TimeEvent Based Models
3middott 14 l-lardwareSoftware Models
4 CHAPTER 4 LITERATURE REVIEW - PROBABILITY AND
ST A 11 STI CS
41 1 n troductioll
42 Poisson Dislrihutioll
43 Generation of Random Number8
XI
2
2
iiO
30
ii]
32
32
32
33
33
33
34
34
34
3G
H)
Hl
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 Introdudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction G8
G2 Assumptions 70
63 Input and Output Variables 71
GA Description of lhe Simulation Program 73
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction Sri
72 Program Interface 85
71 Program Documentation HH
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
I
) CHAPTER 5 IMPLEMENTATION - SIMULATION PROGRAM
DOCUMENTATION (CSMAlCD)
ri 1 I ntrodudion
ri~ Assumptiomi
ria Input and Output Variables
riA D(~seription of the Simulation Program
6 CHAPTER 6 IMPLEMENTATION SIMULATION PROGRAM
DOCUMENTATION (STAR)
GI lntroduction
G2 Assumptions
63 Input and Output Variables
GA Description of l he Simulation Program
7 CHAPTER 7 PROGRAM DOCUMENTATION AND
IMPLEMENTATION
7] Introduction
72 Program Interface
71 Program Documentation
7a] Testlnput Function
7middot~2 rr~stlllt(~gerlilput FunctioIl
7Ll Network Topology Layout Frame
7BmiddotLl Ring Topology
7t32 Bus Topulogy
Xli
G8
70
71
73
Sri
85
HH
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
7333 Star Topology J7
7334 Open Saved Form 100
74 Program Implementation 110
741 Simulation Results For Token Passing Bus ]]0
742 Simulation Results For Token Passing Ring ]11
743 Simulation Results For CSMAJCD 112
744 Simulation Results For Star 110
75 Performance Comparison 114
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation 116
82 Conclusion 117
Bibliography and References 118
xm
I
7333 Star Topology
7334 Open Saved Form
74 Program Implementation
741 Simulation Results For Token Passing Bus
742 Simulation Results For Token Passing Ring
743 Simulation Results For CSMAJCD
744 Simulation Results For Star
75 Performance Comparison
8 CHAPTER 8= RECOMMENDATION AND CONCLUSION
81 Recommendation
82 Conclusion
Bibliography and References
xm
J7
100
110
]]0
]11
112
110
114
116
117
118
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
Fijiur8 Numher
Fijiurn ]
Figurp 2
Figure 3
Figure 4
Figure 5
Fijiure G
Figure 7
Figure 8
Fig-urp 9
LIST OF PICTURES
Pajip
CSMNCD Simulation Flowchart 4 ]
Star Simulation Flowchart 69
LanSim Interface 86
Simulation Example 87
Progresses Bar 88
Ring Topology Layout Frame 91
Bus Topology Layout Frame H5
Star Topology Layout Frame 98
Open Records Form 100
XIV
I
LIST OF PICTURES
Fijiur8 Numher Pajip
Fijiurn ] CSMNCD Simulation Flowchart 4 ]
Figurp 2 Star Simulation Flowchart 69
Figure 3 LanSim Interface 86
Figure 4 Simulation Example 87
Figure 5 Progresses Bar 88
Fijiure G Ring Topology Layout Frame 91
Figure 7 Bus Topology Layout Frame H5
Figure 8 Star Topology Layout Frame 98
Fig-urp 9 Open Records Form 100
XIV
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
I
CHAPTER 1
INTRODUCTION
11 Introduction
Over the past the way of information transmitting has changed
dramatically The developments of powerful and high-speed computer and
its peripherals such as modem and network interface card have made the
globalization of information sharing a reality In the newer personal
computer and workstation world data distribution no longer a
time-consuming inconvenient and human factor dependent process The
increasing of interconnection between personal computers workstations and
other digital devices are making it possible for communication links to carry
more and faster signals As a result internetworking particularly via local
area networks (LANs) has become a trend in business industry SCience
education merucine and entertainment
12 Objectives
The overa]] objeetive of this thesis project is to develop eomputpound~r software
that is capable of simulating a local area nt~twork before installing tlH
n(ltwork
t
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
The objectiV(~R of this thesis include
bull To study (literately) local area network especially Token Hing
Token Bus Star and CSMACD modeling and Rimulation
methodology and Microsoft Visual Basic 60
bull To develop the simulation program uRing MicrOloft Visual Hasie
60
bull To fine-tune the simulation program by comparing it to otber
similar simulation program
bull To debug the program by repeating testing it
13 Introduction to Local Area Network Simulation Program (LanSim)
LanSim is a computer program written in Microsoft Visual Basic 60 that
runs on Microsoft Windows 9598 or any operating systems that able to run
Microsoft Visual Basic 60 LanSim is intended for local area network
designers who want to analyze the performance of their designs using
simulation LanSim able to simulate four types local area network which
are Token Bus Token Ring Star and CSMAlCD The average delay
collision rate throughput and utilization will be calculated based on various
parameters specified in the program such as cable types station number
and queue size
LanSim is implementing the concept of software models that are diserele
stochastic and event based
2
pa ZNiJ
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
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CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively close together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolved ill developing standards for computing communication electrical eBllIleeriJlI mid dlctwllIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
CHAPTER 2
LlTERATURE REVIEW - LOCAL AREA NETWORK (LAN)
21 Local Area Network (LAN) Concepts
211 Local Area Network Definition
The IEEE] defines a LAN as follows
A data communication system allowing a number of independent devices
to communicate directly with wch other within a moderately sized
geographic area over a physical communications channel of moderate
data rates
According to the definition above
bull LAN allows a number of independent devices to communicate
directly with each other usmg peer-to-peer communieati(ln~
where all communication devices have similar status in the
system
bull The communication takes place within a moderated sized
geographic area such as single building or to a group of buildings
that are relatively dose together
I Inslitull of Electrical and Electronics Engineers (IEEE) is the largest professional enginLocring group lllvolvcd ill developing standards for computing communication electrical eBllIleeriJlI mid dlcIWIlIlS
~ COllul1unicatioll between two equullayers in the OS1 modeL
3
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
~------------------------shybull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
3(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 to 10 Mbps8 (Joday extend up to speeds of 100
11bps or higher)
bull Cpogra)lhie distances spanning at most 1 Km (Today longPI
diRtanccs are spanned by one LAN mci often by intermiddot LAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
bull Communieation takeR place OVN a phYRical eommunieationH
(hanned
bull LAN RupportR a moderate data rat(~
212 Local Area Network Application
LAN can be used for many different applications Ruch al
bull Shared access to data any computer on the network able to
a(cess or URe data that is stored on another compu ter
bull Printer sharing - print jobs created on one computer can be sent
to computer that attaches a printer
bull Cooperative processing - able to allow an application runs partly
on a local machine and partly on a mainframe taking the
advantage of the best features of each
213 Local Area Network Requirements
LAN requirements as originally stated by the developers of Ethernet are
as follow
bull DatH rates of 1 10 10 Mbps8 (Joday extend up to speeds of 100
Ilbps or higher)
bull Cpographie distances spanning al most 1 Km (Today longPI
diRtances are spanned by one LAN mei often by inlermiddotLAN
eon nection)
bull bi1iI~ 10 support severa] hundred independent devi(es
Abbrciatioll l() mc~abils pcr sccond
4
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
------------------------------shybull Simplieity or use of the sjmph~st posHibk TTweilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeterifticf-
bull Minimal dependence on any e(mtra)jtA~d eomponent or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
mtwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Easy infltallation of a small system with graceful growth as the
flyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
rs th( physical path thai is used to earry inHlrmation in an
eleetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twislndpair cable IS used for analog- signals transmission
l)(~(mlS( of its limitation In the speed of trHnllmiRsioll (mxi1l1
5
bull Simplicity or use of the sjmph~llt pollHibk TTwcilanism thal hHV(
HlP n~qujred functionality and pnrf(lrmanee
bull Hdiahility Hnd good error ehnraeteriflicll
bull Minimal dependence on any e(mtra)jtA~d component or control
bull Irriei(ml use of hared fesourees particularly th(~ communication
olttwork itself
bull Stability under high load
bull Pair access to the system by all devices
bull Eally inlltallation of a small system with graceful growth as the
fyslem evolves
bull Ease of reconfiguration and maintenance
bull Low cost
214 Local Area Network Characteristics
There are four important characteristics in describing the architecture of
11 particular local area network implementation These characteristics
can be wed to compare one type of local area network wi th another
There are
bull Transmission Medium
r ll th( physical path thai ill used to earry inHlrmation in an
eieetromag-netie form between transmitter to the re(eiv(~r
Commonly used media are twisted-wire-pair wir( coaxial (~lbl(
11( optieal fiber
Twilllndpair cable IS used for analog- signals transmission
l)(~(mlll( of its limitation In the speed of trHnllmiRsioll (mxial
5
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
en hIe provideH 11 iiuhHtnntial performance improvemenl over
twiHtt~d pair 1t haH higher capacity can HUPllOrt a larg(~r numher
of devic()H and can Hpan gnmter diHtanecH Optical fjh(~r
demonHtrateH the biggeHt capacity hy using light or infrared rays
imLead of electrical signalH I t is not Rusceptible to noise) or
eleetrieal iJuctuations which makeH optical fiber the bCHt choiee
of future network medium
bull Transmission Technique
Determines how the physical medium is used for communication
common techniques are baseband and broadband transmiHsion
Baseband signaling means that the signal is not modulated for
transmission The entire frequency spectrum is used to form the
signal which is transmitted bidirectionaDy on broadcast systems
such as bus Baseband networks are limited in transmission
distance due to signal attenuation
Broadband signaling means information is frequency modulated
onto analog carrier waves This allows information from multiple
sources to be transmitted simultaneously
bull NNwork Topology identifies the shape the cabling takes when il
is used to interconneet the network devices common jopolo~ies
are bus ring mesh and star
bull AccesR Control Method - deseribes the method hy which
communicating stations eontrol their aeeCHH to the IransmiHsion
medium commonly used methods are token passing CSllA1CD
and eireuit switching
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
--------------------22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(veJop(~d and reported
J n fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA) l-persistent pshy
lWrsiftent nonpersistent
bull Carrier Sense Multiple Aeceff with ollision Detection
laquoSJ1AJ(D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CD-ltP)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo StlV( U- DCR)
7
22 Local Areu Network Technology
Simf II7() rlt~k(~ardl(~k on LAN technol()~y hav(~ Hpurred hy incrnasin~
rfquirNnnntk fhr mHOUf(lt~ Hharing in multiple flr()((~SHOr environments
Jsp(~ciall)- arh~r tile introduetion of Ethernet by Xerox Corporationk Palo
li~J HI~s(~arlth Center networks using a numb(~r of tOJlologies and prototoJs
have been d(velop(~d and reported
In fogtJli h~ of the prolifera tion of LAN prod uets the vast majori ty of LANs
conform to one of three topologies and one of a handful of medium-ac(css
control protocols summarized as follow
1 Ring Topology
Controlled Access
bull Token
bull Slotted
bull Bufferffiegister Insertion
2 Bus Topology
Controlled Access
bull Token
bull Multilevel Multiple Access (rvILM)
Handom Aecesf
bull Carrier Sense Multiple Access (CSMA)
lWrsiftent nonpersistent
l-persistent p-
bull Carrier Sense Multiple Acceff with ollision Detection
laquo SJ1AJ( D)
bull CSMAJCD with Dynamic Priori tie (CSJlA1CDmiddot(P)
bull CSJv1lCD with Determinifogttic Contention JpsoJutioll
laquo SrlV( U-DCR)
7
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
11 11~llrid Topolo)
bull rin~ - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topoloy
ngnals encoding interface and medium
11 11~llrid Topolo)
bull [in - Star
bull Hin~ Hm
bull Hus - StJlr
bull CSMACD - Token Hing
bull CSMACD - Token Bus
This report (~mJlhasi7e on Star Topology and Carrier Sense Multiple Access
with ColliHion Detection (CSMAJCD) meanwhile fe)r Token Ring and Token
HUH please refer to report prepared by Goh Beng Huat (00] 756)
221 Open System Interconnection (OSI) Model
OSI iH a set of protocols defined by International Standard Organization
(lSO) that allowH any two different systems to communicate regardless
of their architecture
The OSI model comprise of seven ordered layers physical (layer 1) data
lInk (Iay(r 2) network (layer 8) transport (layer 4) Hession (layer fi)
preHentalion (layer G) and application (layer 7)
I Physical Layer
The ph~si(al layer is responsible for the transmission of lgtil
strpam aCTOHS a particular physieal transmission medium It
involves a connection between two machineH thai allow electrical
Hlgnals 10 be exchanged between them SpeeifiC responsibilities
iud ude Jill( configuration data transmission mode topo loy
ngnals encoding interface and medium
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisgion
medium H is concerned with error free trangmission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rcgponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( servJ(c
quality i8 maintained and for notifying the users if jl lS not
Specifie responsible include endow-end m~~ssage delivery HerV1C(shy
t I )ata Link Layer
The lt1al link layer IH n~HJlonHihlc fClr providing reliable clal
tranHmiHHion from one nodc to another and filr RhieJding higher
layerH from any concernR about the physical transmisHion
medium H is concerned with error free tramimission of frames of
data Specific responsibilities of the data link layer include Nodeshy
to-node delivery addressing access control flow control error
handling and synchronization
1 Network Layer
The network layer IS concerned with routing data from one
network node to another It is responsible for establishing
maintaining and terminating the network connection between
two users and for transferring data along that connection There
can be only one network connection between two given users
although there can be many possible routes from which to choose
when the particular connection is established Specific
rCHponsibilities include source-to-destination delivery logical
addressing routing address transformation and multiplexing
4 Transport Layer
The transport layer IS responsible for providing data transfer
between two users at an agreed on level of quality When a
connection is established betweell two users the transport lavet
if rCRponsible for selecting a partieular da8s of servicc to be u8pd
for monitoring transmission to ensure the appropria ( scrvJ(c
quality i8 maintained and for notifying the users if it lS not
Specifie responsible include endow-end m~~Hsage delivery HerV1C(-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
point addreHsing R(~gmentati()n and reaHHemhly and mnnection
con trol
fl S(~Hsi()n llycr
The s(ssion layer focuHcs on providing Hervic(~s UHed to organize
and H~nehronize the dialog that takes place between URers md t~
manage the data exchange A primary concern of the session
layer is controlling when users can send and receive based on
whether they can send and receive concurrently or aJternately
Specific reHponsibilities of the layer include session management
synchronization dialog control and graceful close
(- PreHentalion Layer
The presentation layer is responsible for the presentation of
information in a way that is meaningful to network users This
may include character code translation data conversion or data
compression and expansion
7 Application Layer
The application layer provides a means for application proceHses
to access the system interconnection facilities in order to
exchang-e information This includes services used to establish
and terminate the connections between users and to monitor and
manage the systems being interconnected and the various
resource I hey employ
10
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
I
222 Carrier Sense Multiple Access with Collision Detection
(CSMAlCD)
A Ilwdia mcess control (MAC) suhlaYI~r operaU~s below he level or the
log-iell I link eon trol sublayer and provides Herviee wit At the MAC levld
thrl~p sl~mdards have been dcfinl~d by IEEE Project 802 ThpH(~
standards luldrcsFJ three different approaehel to controlling aeeClH i~) the
phYRical transmission medium CSMAJCD token bus and token ring AlJ
these interface to the same LLC4 standard
2221 CSMAlCD Operation
CSMACD is the most commonly used access method for local area
network that employs a bus or tree topology It is used as the IviAC
method in Ethernet
With CSMAlCD a transmitting station fIrst listens to the transmission
medium to determine whether or not another station is currently
transmitting a message If the transmission medium is Quiet the
station transmits When two or more stations all have message tn send
the may a11 listen at exactly the same time and then send their messaw
sim ultaneously resulting in a collision Receiving stations ignore the
garbled transmission and the transmitting stations immediately stop
transmitting as soon as they detect the collision Fo1lowing 11 collision
ewh transmitting station waits for a random period of time and thml
atJempts t) transmit again
The logiu link control (LLC) sublayer ofthe IEEE 802 architeclure provides scrvices II till laver lll il ill thl same manlier thaI a conventional data link protocol proide~ in II wide area mtwork
II
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallcl functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1clc passing the frame up to the LL(
subla~er
12
I
2222 CSMAlCD Function
Ttw IEEE CSMACD ftmdard derinr~s a mCH]cd thilf eompfls(s SIX
funr~ti()nr- thrc~c of funct1om are aSHocialA)d with transmittin~ data and
tllr pnrallel functions m) eoncernmJ with reeeivin~ datH The data
c)ncapsulationdc)eapsulation mltl mc~dia aeeer-s management functions
am peric)rmed by the media access control sublayer itself 1hp data
cmeodin~decoding function if performed by the physical layer which
opcmtes below the MAC layer
bull Data EncapsulationlDecapsulation
Data encapsulation apices too sending station and provides for
adding information lo the beginning and end of the data unit to
be transmitted after the transmission frame is received from
logical link control This information is used to perform the
following tasks
o Synchronize the receiving station with the signal
o Delimit the start and end of the frame
o Identify the addresses of the sending and f(~CelVmg
stations
o Detect transmission errors
When frame is received A data decapsulation function in the
receiving station is respomible for recognizing the ctestinatioll
address delermining if il matches the station- addn)ss
per10rming error ehecking and then removing til(- control
information that waH added by the dHa encapsulation function in
the Hending Htation be1cHc passing the frame up to the LL(
subla~er
12
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
- fong siew seongpdf
-
p
bull M(dia JCC(~SS Mnnllgemcnt
In a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
bull M(dia JCC(~SS Mnnllgemcnt
I n a s(mding station th(~ media aee(~ss mnnagpm()nt funetion IS
responsihl(~ liJr determining whethnr the transmisfolion medium IS
availahle for use and for initiating trammission when it if This
fundion also determinr)f the aetions W be taken when a col1ision
is detect~~d and when to attempt r()tnmfolmifolfoljon In a r(~eeiving
station media access management performl-i vaJidi ty chech on a
frame before passing it on to data decapsulation function
bull Data Encoding
Data encoding performed in the physicaJ layer is responsible for
translating the bits being transmitted into the proper electrical
signals to be sent across the transmission medium For
CSMAlCD Manchester phase encoding is used to translate the
bit I-itream into electrical signals When the signal is received
da ta decoding translates it back from the electrical signal into the
bit Htream those signals represent The data encoding function is
also responsible for listening to the transmission medium and for
notifying media access management whether the carrier is free or
bUHY and whether a collision has been detected
In addition to datn encodingdecoding the physical layer includes
functions related to attaching a station to ltI particular ph~skal
trammiRsion medium These functions are generally performed in
11 ph~sicaUy separHte device called a medium attachment ulli
that lS lIspd to connect a network station to th( physieaJ
transmiHsioll eable
13
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