---------------------------------------------------------------------------- Mohamed G. Gouda CS 356 Spring 2019 Homework 3 ---------------------------------------------------------------------------- Consider an AS that has: 3 routers A, B, C, and 6 subnetworks u, v, w, x, y, z Router A is attached to subnetworks u, w, x Router B is attached to subnetworks v, x, y, z Router C is attached to subnetworks w, z Assume that subnetwork z is down. Assume also that the routers in this AS use the OSPF protocol to route packets within this AS. Describe the local states, global states, and routing tables for the three routers in this AS. -------------------------------------------------------------------------- Solutions: -------------------------------------------------------------------------- Local state of A: Router A is attached to u, w, x Local state of B: Router B is attached to v, x, y, z and z is down Local state of C: Router C is attached to w, z and z is down Global state of A: It has A, B, C and u, v, w, x, y, z and z is down Global state of B: It is the same as that of A Global state of C: It is the same as that of A Routing table of A: -------------------- | u | A | -------------------- | v | B | -------------------- | w | A | -------------------- | x | A | -------------------- | y | B | -------------------- | z | none, down | -------------------- Routing table of B: -------------------- | u | A | -------------------- | v | B | -------------------- | w | A | -------------------- | x | B | -------------------- | y | B | -------------------- | z | none, down | -------------------- Routing table of C: -------------------- | u | A | -------------------- | v | A | -------------------- | w | C | -------------------- | x | A | -------------------- | y | A | -------------------- | z | none, down | --------------------