Question

5.0. Suppose P, Q and R are ISPs with respective CIDR address blocks (with bytes in decimal) 51.0.0.0/8, 52.0.0.0/8 and 53.0.0.0/8. P then has customers A and B, to which it assigns address blocks as follows:

A: 51.10.0.0/16

B: 51.23.0.0/16

Q has customers C and D and assigns them address blocks as follows:

C: 52.14.0.0/16

D: 52.15.0.0/16

(a).♢ Give forwarding tables for P, Q and R assuming they connect to each other and to each of their own customers.

(b). Now suppose A switches from provider P to provider Q, and takes its address block with it. Give the changes to the forwarding tables for P, Q and R; the longest-match rule will be needed to resolve conflicts.

Answer 1

(a)

(b)