1. Network Layer CS176A Ramya Raghavendra

2. Routing table [Q1] Destination Address Range Link Interface 10000000 00000000 00000000 00000000 Through0 10000000 11111111 11111111 11111111 10000010 00000000 00000000 00000000 Through1 10000010 00000000 11111111 11111111 10000010 00000001 00000000 00000000 Through2 10000010 11111111 11111111 11111111 Otherwise 3

3. Subnetting [Q2] A B C D E F

4. Subnetting 21497254/23 11010110 01100001 11111110 00000000 9 N bits – 2 n addresses : 8 bits – 256 etc Each router: subnet (A,B or C) + 2 of (D, E, F) Longest Prefix matching (Examples) –11010110 01100001 11111111 : A –11010110 01100001 11111110 0000000 : D

5. NAT Translation Table [Q3] NAT translation table WAN sideLAN side 138.76.29.7,5000192.168.0.1,4000 138.76.29.7,5001192.168.0.1,4001 138.76.29.7,5002192.168.0.2,4000 138.76.29.7,5003192.168.0.2,4001

6. Dijkstra’s Algorithm Have some fun: http://www-b2.is.tokushima-u.ac.jp/~ikeda/suuri/dijkstra/Dijkstra.shtml

7. Link State Routing [Q6] u 5 6

8. Reverse Path Forwarding [Q7] Controlled flooding Router receives a broadcast packet Checks if the packet came on the “shortest unicast link” to the source –Path used to send a unicast packet to source If so, forwards it on all other links Else discards it

9. Illustration of RPF

10. Questions on Extra Credit? - Is it easy? Yes Email me! ramya@cs.ucsb.edu