IEEE 802 - HSNold.hsn.or.kr/workshop/hsn2005/document/session5/5_2.pdf · 2014-04-03 · IEEE 802.3...
Transcript of IEEE 802 - HSNold.hsn.or.kr/workshop/hsn2005/document/session5/5_2.pdf · 2014-04-03 · IEEE 802.3...
1394
• Computer 연결• CE
– all digiCam– Only way to connect DTV/STB/Cam
• New Market– A/V Receiver
• Networking 1394 bus– 아직은 수요가 없다. – 집에 2대 이상의 DTV가 설치될 경우에는 수요가 창출될 것이다.
Current Solutions
• 1394b/c–100/800 Mbps on UTP–No Product yet.–Not Ethernet
• 802.15.3, 802.11e WLAN–Limited range–QoS Issues–How to connect devices..
Gibson Guitar’s MAGIC• “Guitar maker preps digital network platform”,EE Times,
January 28, 2003• “Guitars tune into digital sounds”, BBC News, Feb. 11, 2003.
Why not legacy Ethernet
• Non-deterministic delays at–Ethernet MAC–Switches–Protocol stacks
• jitter• No native time synchronisation
802.1p 스위치의 Jitter 문제점
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
Real-timeCODECsource
125usec
1 2Async frame 3 4
1 2 3 4
1 2 3 4 1 2 3 4sync frame
Tx
1 2 3 4 1 2 3 4Real-time CODEC sink
delayed sync frames
Starvation/Overbooking
1 2 3 4 1 2 3
4
1 2Async frame 3 4
1 2 3 4 1 2 3 4sync frame source #1
Tx
1 2 3 4 1 2 3 4sync frame source #2
1 2 3 4 1 2 3 4
buffer overflow
starvation
다단 연결시 문제점
Sync Frame의 Jitter
VBR source
CBR source #1
1
1
1
1
1
1
2
1
3
2
1
CBR source #2 CBR source #3
Typical worst-case switch latency
(example)• 100 Mbps • switch latency = 10us. • real time packet length = 200 bytes• 5 other real time stations------• Worst case switch latency of a realtime packet :
– 16 us : transmission time of a real time packet. – 10 us : minimum switch latency. – 122 us : worst case latency for transmitting an async
frame– 80 us : 5 real time packets already in the same priority
queue. – Total : 228 us.
Two types of real-time
• Hard real-time system :– fails if the timing requirements are not met– (예) Industrial control, networking in a car
• Soft real-time system :– can tolerate some deadline overruns, as long
as– the mean latency time is smaller than the
deadline– (예) DVD-player, streaming media
Real-time in terms of deadline
time
processing time
deadline
deadline
..V
actionevent
•a missed hard deadline can have serious consequences.
Real-time in terms of Jitter
•All RT systems have a certain level of jitter (a variance on actual timing). •In a RT system, jitter should be measurable so system performance can be guaranteed.
time
processing time
..V
event
processing time
processing time
Jitter boundary
TDMA Railroad
•Every train (frame) runs on a schedule•Space is reserved•No spacing between cars (no variable back-off / wait)•Arrival times are guaranteed (latency, jitter)•Space assigned long term or for a single trip (Isochronous, asynchronous) •No collisions, hidden nodes, Traffic Jams – fully managed system
Industrial Ethernet의 종류
All provide sub-microsecond synchronisationaccuracy of distributed clocks over Ethernet.
PROFInet
• a fieldbus standard for automation systems• built on IEEE 802.3• 종류
– PROFInet V1: response time of 10-100 ms– PROFInet-SRT (soft realtime): cycle time of 5-10 ms – PROFInet-IRT : hard-RT with sub-microsecond
synchronisation / cylce=250usec
• 특징– 1 ms cycle time– 1 µs jitter accuracy, and guaranteed determinism – Using full-duplex switched fast Ethernet– Special ASIC사용– allows both RT and non-RT traffic to co-exist on one
network
노래자랑…
전화기
arami
전화망
반주기
라디오
mixer FM
arami
IP전화기
All IP 망 (e.g. BcN)
반주기
IP radio
mixer AudioCast
in addition …HDTV Video…
Solutions
• Simple Network Time Protocol (SNTP) – 123 UDP port 사용.
• IEEE1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems– Precision Time Protocol (PTP)사용
SNTP time updates
0 T1 = 1
T2 =1 2
T3 = 2 3
3 T
T2,T3
4 =4
Propagation Delay = {(T4 -T1)-(T3-T2)}/2 = {(4-1)-(2-1)}/2 = 1Offset = {(T2 -T1)+(T3-T4)}/2 = {(1-1)-(2-4)}/2 = +1
Who stamps the time?
• Timing accuracy depends on where the time stamping is performed and network latency variations.
• Time stamping can be performed in – SNTP/NTP application layer
• millisec
– Ethernet driver level (software)• 10~100microsec
– Ethernet data link/physical layer (hardware)• <1 microsec
RSE MAC개념
1
2
3
4
1
1
2
3
4
2 3 4 1 2 3 4
cycle=125usec
Sync-E MUX
a max 15K bytes FIFOfor Sync-E frame
4 4
4 4
max 1522bytes
Cycle and Frame Format
Ethernet Header22bytes
Sync Header32bytes
Sync Data Slot192*32bit = 768 bytes
HCS4bytes
FCS4bytes
Iso Version4 bits
Sync1 bit
Frame Couterin the cycle 1 byte
Reserved19 bits
Cycle Couter4 bytes
Data Slot Validity24 bytes
WLAN/PCF, WPAN MAC의문제점
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
Real-timeCODEC
Sync-e #2 timimg(best-case)
125usec
1
1
2
2
Async frame 3
3
4
4
delayed cycle start
shortened asynch duration
target cycle start time
1 2 3 4 1 2 3 4sync frame
RE Applications
• Networked Audio– Both compressed and uncompressed streams– Issue : Room to room phasing
• Video Distribution– Primarily compressed streams– High Definition (HDTV) Satellite/Cable
Receivers– HD Digital Video Recorders– Issue : Lip-sync with networked audio
Issues• Backward compatibility
– 100Mbps를 수용할 것인가?– HDX를 수용할 것인가?– 토폴로지는?
• Time-sensitive requirements – Jitter bound– Latency bound– Timing master
• User Requirements– Plug & Play without
interruption– Easy– Low cost
• BW management– Admission Control– Slot reservation procedure– Slot reuse– Slot interchange– Sync/Async Ratio
• Market– 802.1p와의 경쟁– 1394와의 경쟁– Home backbone ? device
interconnection?– BcN? Sonet? – Industrial Ethernet?– Ubiquitous Ethernet?
How to coexist with legacy Ethernet backbone?
class 2switch
class 1 NIClegacy NIC
legacyswitch
legacy switchclass 1 NIC
legacy switch
prioritized?
100Mbps RSE
Cycle = 125usec– For 1Gbps : 10% of Asynch traffic : OK– For 100Mbps : 123.36/125 = 98.688%
해결책 : – 동기 프레임 길이 축소– 비동기 프레임 분할 전송– 사이클 구간 확장 : n * 125usec
Interconnected Network
hub
class 1
class 1+
class 2
class 1
hub
class 1
class 1
class 0 : Legacy Hub/Repeater/Switch/NICclass 1 : a device without switching capabilityclass 1+ : a class 1 device with timing master capabilityclass 2 : a device with switching capability
Time-sensitive requirements
• Bounded jitter and latency• End point synchronization
–Network Timing should be deterministic
Admission Control
• Bandwidth allocation–Non-interfering streams–Guaranteed BW
• Allocate slots with GMRP?• Request/Relase BW procedure
PoE
• Power over Ethernet(PoE)–15.4W, 48V Rev2의 경우 40W제공 가능
• Digital Camcoder:3W~20W• Ethernet Speaker: 5~40W• LCD Monitor : 30W• Elec Guitar• Elec Keyboard : 10~20W
802.1p/RE Comparison:(Simulation Result)
(a)802.1P((a)802.1P(ρρSS=0.1,=0.1, ρρAA=0.1=0.1))
0 10000 20000 30000 40000 50000
10
12
14
16
18
20
22
24
26
28
30
T A (u
sec)
Time (usec)
0 10000 20000 30000 40000 50000
10
12
14
16
18
20
22
24
26
28
30
T A (u
sec)
Time (usec) 0 10000 20000 30000 40000 50000
10
15
20
25
30
T A (u
sec)
Time (usec)(a)802.1P((a)802.1P(ρρSS=0.5,=0.5, ρρAA=0.4=0.4)) ((a)Synca)Sync--EE (Zero Jitter)(Zero Jitter)
((ρρSS=0.1,0.5 =0.1,0.5 ρρAA=0.1,0.4=0.1,0.4))
동기동기 패킷의패킷의 시스템시스템 지연지연 시간시간
Result
0 10000 20000 30000 40000 50000-20
0
20
40
60
80
100
120
140
160
180
200
T A (u
sec)
Time (usec)0 10000 20000 30000 40000 50000
-20
0
20
40
60
80
100
120
140
160
180
200
T A (u
sec)
Time (usec)
0 10000 20000 30000 40000 50000
-20
0
20
40
60
80
100
120
140
160
180
200
T A (u
sec)
Time (usec)
(a) IEEE 802.1p(a) IEEE 802.1p (b) Sync(b) Sync--E (NoneE (None--ZeroZero--Jitter)Jitter) (C) Sync(C) Sync--E (ZeroE (Zero--Jitter)Jitter)
비동기비동기 패킷의패킷의 시스템시스템 지연지연 시간시간 비교비교( ( ρρSS=0.5 , =0.5 , ρρAA=0.4=0.4))
QSS의 기능• ATM/Frame Relay
convergence on IP/MPLS• Per-Flow Traffic Shaping :
for low-jitter guaranteed rate service
• Macro" and "micro" QoS:supporting both aggregate and per flow QoS
• CAC for Premium IP service
구조 비교
MPLS Switch
Flow Classfication,CAC,
Shaping,Scheduling
Transport&
Applications
MPLS Switch
Flow Classfication,CAC,
Shaping,Scheduling
Transport&
Applications
IPIP
MPLS over(ATM)/(SONET)
MPLS over Ethernet MPLS over Ethernet
Legacy 802.1p Ethernet(non-zero jitter, unbounded delay)
Slotted Ethernet(Zero-jitter, Zero-loss)
Legacy 802.1p Ethernet(jitter, loss)
기존 QSS Sync-E based QSS
QoS-enabled Networks
ACCESSNETWORK
(EPON)
ACCESSNETWORK
(EPON)
Backbone
METROMETRO
SWITCHROUTER
HOMELIVING ROOM
BED ROOM
SWITCH
R
R
R
SWITCHSWITCH
PVR
video, audio,data streams over a single Ethernet
Summary and Suggestions• Ethernet :
– Cheap, mature tech, everyone knows..• Ethernet can provide Strict QoS Services
– TDM Superframe or Token-based• Many Issues to be solved
– Synchronization, Segmentation,…– Admission control, OAM– New Chips, Switches, – Interface to PSTN?
• Broad applications– Home Networking, and link to even SONET– Industrial Networking
Real-time Ethernets• Iso_Ethernet• Rtnet
– Token passing over Ethernet– Software based
• Rether– Token passing over Ethernet– Real-Time Ethernet for PLC Networks– Software based
• Vtnet : virtual token net– Software
• Synchronous Ethernet– Gibson Guitar Co. and Pioneer– MAGIC
Iso_ethernet
125usec Cycle•P-Channel : 10Mbps Asynch Ethernet•B/D channels : As you known…•M-channel: A full-duplex 96 kbit/s. physical layer control and status informations
Ethernet Switches for Military Applications
• Reliable operation from –40 to +85 °C
• Tested for vibration and harsh conditions
• Special technology for military apps.
• Easily adapted to special requirements
Reservation Procedure• Listener must confirm resources available along entire path to destination– sends “join request” control packet to talker with amount of bandwidth
needed (in bytes/cycle)– intermediate bridges make reservation, update delay count and pass on
control packet– if resources not available, packet is stamped as “unavailable”, but still sent to
talker– talker returns “join response” packet to listener with status status includes
resource available (or not), and delay• Obviously, various timeouts and disconnects affect this• Additional listeners also send “join” request – but this time an intermediate bridge can respond if it is already routing the
stream• Listener sends “leave” when done– only gets to talker if this is the last listener, bridges intercept all others• Talker is required to send one packet every cycle– may be zero length– if missing for more than “x” cycles, can be used to take down the connection