# Routing protocols¶

1. Consider the network represented in the figure below. Assume that the network is using a distance vector protocol as its routing protocol. When the network boots, which of the following distance vectors correspond to the first vector that each router sends ? We assume that the link weights are configured on the routers as shown in the figure. We consider a basic version of distance routing without split horizon and without poisoning. What are all the correct distance vectors among the choices below ? Router R1 sends [ R1=0, R2=1, R3=1]

Router R2 sends [ R2=0, R1=1, R3=3, R4=1]

Router R3 sends [ R3=0, R1=1, R2=3]

Router R4 sends [ R4=0, R2=1, R3=3, R4=1]

Router R4 sends [ R4=0 ]
Router R3 sends [ R3=0 ]
Router R2 sends [ R2=0 ]
Router R1 sends [ R1=0 ]
1. Consider the same network as in the previous question. The network has been running for several hours. Among the following answers, what are the distance vectors that are produced by the routers at that time ?

Router R1 sends [ R1=0, R2=1, R3=1]

Router R2 sends [ R2=0, R1=1, R3=2, R4=1]

Router R3 sends [ R3=0, R1=1, R2=3]

Router R4 sends [ R4=0, R2=1, R3=3, R1=2]

Router R4 sends [ R4=0 ]

Router R3 sends [ R3=0 ]

Router R2 sends [ R2=0 ]

Router R1 sends [ R1=0 ]

1. Consider the network shown in the figure below. Among the link state packets shown below, which corresponds to link state packets that could be transmitted by the nodes of this network ? Select all the valid answers.

Router R1 sends LSP : R1-0 [R2:1] [R3:1] [R4:1]
Router R2 sends LSP : R2-0 [R1:1] [R3:3] [R4:1]
Router R3 sends LSP : R3-0 [R1:1] [R2:3]
Router R4 sends LSP : R4-0 [R1:1] [R2:1]

Router R3 sends LSP : R3-0 [R1:1] [R2:3] [R4:3]

Router R4 sends LSP : R4-0 [R1:1] [R2:1] [R3:3]