Consider Figure 4.31. Suppose there is another router w, connected to router y and z. The costs of all links are given as follows: c(x, y) = 4, c(x, z) = 50, c(y, w) = 1, e(2, w) = I, c(y, z) = 3. Suppose that poisoned reverse is used in the distance- vector routing algorithm.
a) When the distance vector routing is stabilized, router w, y, and z inform their distances to x to each other. What distance values do they tell each other?
b) Now suppose that the link cost between x and y increases to 60. Will there be a count-to infinity problem even if poisoned reverse is used? Why or why not? If there is a count-to infinity problem, then how many iterations are needed for the distance-vector routing to reach a stable state again? Justify your answer.
c) How do you modify c(y, z) such that there is no count-to-infinity problem at all if c(y, x) changes from 4 to 60?