Answer Happy

Ⓒ Problem 5 (13 points): Routing protocol Consider a network with 8 routers in the right figure. The routers run OSPF routing protocol and re-calculate the routing table for every re- ceived routing update message. All links have a cost of 1. When a router has to choose between two or more equal-cost paths to a given destina- tion, it breaks the tie by picking the next hop with the lowest node ID (in alphabetic order). Assume that, (F (H) • Initially (T=0) the routing tables of all routers are empty. • Propagation delay across each link is 50 msec. • All routers send their first routing update message to its neighbors at time T=0. • Ignore processing, queuing, and transmission delays. 1) Assume there is no failure and no packet lost, how long does it take for router E to build and finalize its routing table (get the correct shortest paths to all other routers) Please explain your answer 2) After all routers have finalized their routing tables, router E fails. Fill the forwarding tables of router G before the failure and after the failure. Leave the next hop filed blank if the destination is no long reachable. Assume that router G received all the update messages from all other routers. Please explain your answer. Destination Next hop Destination Next hop A A B с D E F H BUDEFI H A B E