cDRⅢ stration Provider is given 201.10.0.0/21 Provider 201.10.0.0/22201.10.4.0/24 201.10.5.0/24 201.10.60/23 9-26-06 Lecture 9: IP Packets
9-26-06 Lecture 9: IP Packets 11 CIDR Illustration Provider is given 201.10.0.0/21 201.10.0.0/22 201.10.4.0/24 201.10.5.0/24 201.10.6.0/23 Provider
CIDR Implications ongest prefix match 201.100.0/21 201.1060/23 Provider 1 Provider 2 201.1000/22201.104.0/24201.10.50/24201.10.60/23 or Provider2 address 9-26-06 Lecture 9: IP Packets 12
9-26-06 Lecture 9: IP Packets 12 CIDR Implications • Longest prefix match!! 201.10.0.0/21 201.10.0.0/22 201.10.4.0/24 201.10.5.0/24 201.10.6.0/23 or Provider 2 address Provider 1 Provider 2 201.10.6.0/23
Outline CIDR IP addressing Forwarding examples ·| P Packet format 9-26-06 Lecture 9: IP Packets 13
9-26-06 Lecture 9: IP Packets 13 Outline • CIDR IP addressing • Forwarding examples • IP Packet Format
Host Routing Table Example Des七 ination Gateway Genmask 工face 128.2.209.1000.0.0.0 255.255.255.255eth0 128.2.0.0 0.0.0.0 255.255.0.0 etho 127.0.0.0 0.0.0.0 255.0.0.0 1 0.0.0.0 128.2.254.36 0.0.0.0 etho ·From“ netstat-rn Host 128.2. 209. 100 when plugged into CS ethernet Dest 128.2.209.100> routing to same machine Dest 128.2.0.0> other hosts on same ethernet Dest 127.0.0.0> special loopback address ·Dest00.0.0→ default route to rest of internet Main CS router: gigrouter net cs. cmu. edu (128.2. 254. 36) 9-26-06 Lecture 9: IP Packets 14
9-26-06 Lecture 9: IP Packets 14 Host Routing Table Example • From “netstat –rn” • Host 128.2.209.100 when plugged into CS ethernet • Dest 128.2.209.100 → routing to same machine • Dest 128.2.0.0 → other hosts on same ethernet • Dest 127.0.0.0 → special loopback address • Dest 0.0.0.0 → default route to rest of Internet • Main CS router: gigrouter.net.cs.cmu.edu (128.2.254.36) Destination Gateway Genmask Iface 128.2.209.100 0.0.0.0 255.255.255.255 eth0 128.2.0.0 0.0.0.0 255.255.0.0 eth0 127.0.0.0 0.0.0.0 255.0.0.0 lo 0.0.0.0 128.2.254.36 0.0.0.0 eth0