Day 1

Network Fundamental(OSI 7 Layer, IP Subnetting, Route Summary)

Johnson Liujohnsonl@juniper.net Sep. 29, 2011

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OSI ,,,, ,

OSI

OSI

OSI ,,

OSI ,,

OSI

OSI ( ,,)

(Encapsulation)

()

(De-Encapsulation)

()

(Unicast)

(One-to-One)

(Broadcast)

(One-to-All)

(Multicast)

(One-to-Many)

()224.0.0.0~239.255.255.255

TCP/IPTCP/IP Transmission Control Protocol / Internet Protocol (TCP/IP) ARPANET Sun MainframeMainframe TCP/IP Request For Comment (RFC) RFC TCP/IP TCP/IP Internet TCP/IP WWWE-MAILFTPDNS

TCP/IP vs OSI

Application Application

TransportInternetData Link

Transport

Internet

Network Access Physical

(Reliable) vs. (Best-Effort)

TCP

OSITCP/IP (Acknowledgement)

UDP

OSITCP/IP (Overhead) (Best-effort)

()

(Three-Way Handshake)

CTL = TCP1/

TCP(Sliding Windowing)

IP Address ?IPIP Address () (Host) ID: - -

Network . Host

IP

IP Class

IP (Private IP Address)

10.0.0.0 to 10.255.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255

(Subnet Mask)IPIP (Network IP)(Network Number) IP AddressSubnet MaskAND IPIP(Network IP) IP Address Subnet Mask AND Network IP 192.10.10.195 255.255.255.192 --------------------192.10.10.192 1100 0000.0000 1010.0000 1010.1100 0101 1111 1111. 1111 1111.1111 1111.1100 0000 --------------------------------------------------------1100 0000.0000 1010.0000 1010.1100 0000

(Subnet Mask)IP (Network Bits)

(host) IP 2n-2n=Host bitsNetwork IP & Broadcast IP2172.16.0.0/16 172.16.0.0/20 Network bits=20 Host bits=(32 20)=12 Host IP=(232-20)-2=212-2=4094

2nn= Network bitsNetwork bits( Host bitsNetwork bits)192.168.0.0/24 192.168.0.0/27 Network bits=27 Host bitsNetwork bits=27-24=3 =(227-24)=8

1. IP Public or Private IP 2. IP Boundary( 192.168.0.0/26, 192.168.0.64/25 192.168.0.0/25, 192.168.0.128/26)

3. Public or Private IPIP (IP 2n-2n=Host Bits) 4. IPNetworkBroadcast IP () IPBroadcast IPNetwork IPIP (: 192.168.0.0/25Broadcast IP192.168.0.128/25IP 192.168.0.127)

()Juniper 192.168.0.0/22(192.168.0.0/24 ~ 192.168.3.0/24)(1)A35IP (2)B100IP (3)C8IP

IP (1)B100IP (2)A35IP (3)C8IP

(Host Bits) (1)B100IP ((27)-2)=126>100>((26)-2)=62 (2)A35IP ((26)-2)=62>35>((25)-2)=30 (3)C8IP ((24)-2)=14>8>((23)-2)=6

() IP (1)BHost Bits7 Network Bits(32-7)=25 1111 1111.1111 1111.1111 1111.1000 0000(/25) IP27=128IP27-2=126 192.168.0.0/25 (Network IP:192.168.0.0, Broadcast IP:192.168.0.127) (2)AHost Bits6 Network Bits(32-6)=26 1111 1111.1111 1111.1111 1111.1100 0000(/26) IP26=64IP26-2=62 192.168.0.128/26 (Network IP:192.168.0.128, Broadcast IP:192.168.0.191)

(3)CHost Bits4 Network Bits(32-4)=28 1111 1111.1111 1111.1111 1111.1111 0000(/28) IP24=16IP24-2=14 192.168.0.192/28 (Network IP:192.168.0.192, Broadcast IP:192.168.0.207)

(Direct connected) (Default route) 10.0.0.0 0.0.0.0 20.0.0.0/0 (Static routing)

(Dynamic routing)

()AS3462 AS9416

IGP Interior Gateway Protocol(IGP) RIP OSPF IS-IS Exterior Gateway Protocol(EGP) EGP BGP

EGP

IGP

() Distance Vector Flat Network Design Full Updates Periodic Updates EX: RIP(Hop Count)

Link State Hierarchical Network Design(Area) Incremental Updates Trigger Updates Neighbors relationship SPF Algorithm Link-State Advertisement(LSA)/Link-State Packet(LSP) EX: OSPF(Cost)IS-IS(Metric)