Routing and Router 1d Learns
5. (10 pts) Consider the network shown below. Suppose AS3 and AS2 are running OSPF for their intra-AS routing protocol. Suppose AS1 and AS4 are running RIP for their intra-AS routing protocol. Suppose eBGP and iBGP are used for the inter-AS routing protocol. Initially, suppose there is no physical link between AS2 and AS4.
* Router 3c learns about subnet with prefix x from which routing protocol: OSPF, RIP, eBGP, or iBGP? eBGP * Router 1d learns about subnet with prefix x from which routing protocol? iBGP * Once router 1d learns about x it will put an entry (x,I) in its forwarding table. Will I be l1 or l2 for this entry? Explain your answer briefly. I1, the interface with least cost path to 1c the gateway * Now suppose that there is a physical link between AS2 and AS4, shown by the dashed line. Suppose router 1d learns that x is accessible via AS2 as well as via AS3. Will I be set to l1 or l2? Explain your answer briefly. I2, both has equal AS-PATH length, but I2 has the closest next hop router * Now suppose that there is another AS, called AS5, which lies on the path between AS2 and AS4 ( not shown in diagram). Suppose router 1d learns that x is accessible via AS2, AS5, AS4 as well as via AS3, AS4. Will I be set to l1 or l2? Explain your answer briefly. I1, begins with the path that has the shortest AS-PATH
6. (7 pts) Consider the topology shown below. Suppose that each link has unit cost. Suppose node X is chosen as the center in a center-based multicast routing algorithm. Assuming that each attached router uses its least-cost path to node X to send join messages to X, draw the resulting center-based routing tree. Is the resulting tree a minimum-cost tree? Justify your
* Router 3c learns about subnet with prefix x from which routing protocol: OSPF, RIP, eBGP, or iBGP? eBGP * Router 1d learns about subnet with prefix x from which routing protocol? iBGP * Once router 1d learns about x it will put an entry (x,I) in its forwarding table. Will I be l1 or l2 for this entry? Explain your answer briefly. I1, the interface with least cost path to 1c the gateway * Now suppose that there is a physical link between AS2 and AS4, shown by the dashed line. Suppose router 1d learns that x is accessible via AS2 as well as via AS3. Will I be set to l1 or l2? Explain your answer briefly. I2, both has equal AS-PATH length, but I2 has the closest next hop router * Now suppose that there is another AS, called AS5, which lies on the path between AS2 and AS4 ( not shown in diagram). Suppose router 1d learns that x is accessible via AS2, AS5, AS4 as well as via AS3, AS4. Will I be set to l1 or l2? Explain your answer briefly. I1, begins with the path that has the shortest AS-PATH
6. (7 pts) Consider the topology shown below. Suppose that each link has unit cost. Suppose node X is chosen as the center in a center-based multicast routing algorithm. Assuming that each attached router uses its least-cost path to node X to send join messages to X, draw the resulting center-based routing tree. Is the resulting tree a minimum-cost tree? Justify your