Consider a network with three routers P, Q, R shown in the figure below. All the links have cost of unity.

The routers exchange distance vector routing information and have converged on the routing tables, after which the link Q-R fails. Assume that P and Q send out routing updates at random times, each at the same average rate. The probability of a routing loop formation (rounded off to one decimal place) between P and Q, leading to count-to-infinity problem, is _____________

Consider a source computer (S) transmitting a file of size 10⁶ bits to a destination computer (D) over a network of two routers (R₁ and R₂) and three links (L₁, L₂, and L₃). L₁ connects S to R₁; L₂ connects R₁ to R₂; and L₃ connects R₂ to D. Let each link be of length 100 km. Assume signals travel over each line at a speed of 10⁸ meters per second. Assume that the link bandwidth on each link is 1 Mbps. Let the file be broken down into 1000 packets each of size 1000 bits. Find the total sum of transmission and propagation delays in transmitting the file from S to D?

Consider a network with five nodes, N1 to N5, as shown below.

The network uses a Distance Vector Routing protocol. Once the routes have stabilized, the distance vectors at different nodes are as following

N1 : ( 0, 1, 7, 8, 4 )
N2 : ( 1, 0, 6, 7, 3 )
N3 : ( 7, 6, 0, 2, 6 )
N4 : ( 8, 7, 2, 0, 4 )
N5 : ( 4, 3, 6, 4, 0 )

Each distance vector is the distance of the best known path at that instance to nodes, N1 to N5, where the distance to itself is 0. Also, all links are symmetric and the cost is identical in both directions. In each round, all nodes exchange their distance vectors with their respective neighbors. Then all nodes update their distance vectors. In between two rounds, any change in cost of a link will cause the two incident nodes to change only that entry in their distance vectors

After the update in the previous question, the link N1-N2 goes down. N2 will reflect this change immediately in its distance vector as cost, $$\infty $$. After the NEXT ROUND of update, what will be the cost to N1 in the distance vector of N3?

Consider a network with five nodes, N1 to N5, as shown below.

The network uses a Distance Vector Routing protocol. Once the routes have stabilized, the distance vectors at different nodes are as following

N1 : ( 0, 1, 7, 8, 4 )
N2 : ( 1, 0, 6, 7, 3 )
N3 : ( 7, 6, 0, 2, 6 )
N4 : ( 8, 7, 2, 0, 4 )
N5 : ( 4, 3, 6, 4, 0 )

Each distance vector is the distance of the best known path at that instance to nodes, N1 to N5, where the distance to itself is 0. Also, all links are symmetric and the cost is identical in both directions. In each round, all nodes exchange their distance vectors with their respective neighbors. Then all nodes update their distance vectors. In between two rounds, any change in cost of a link will cause the two incident nodes to change only that entry in their distance vectors

The cost of link N2 - N3 reduces to 2 in (both directions). After the next round of updates, what will be the new distance vector at node, N3?