In class we discussed sliding window protocols in which packets are numbered with 2n sequence numbers that range from 0 to 2n 1 for some n.

In class we discussed sliding window protocols in which packets are numbered with 2n sequence numbers that range from 0 to 2n 1 for some n. We identified limitations on the use of sequence numbers for both Go-Back-N and Selective Repeat, as discussed below.

(a) For Go-Back-N, the receive window size is 1, and the maximum send window size is 2n 1 sequence numbers (one less than the total number of sequence numbers). For example, with n = 2, the maximum send window size is 22 1 = 3. Draw a timing diagram for n = 2 illustrating a situation where a send window size of 2n = 4 can cause the protocol to fail.

(b) For Selective Repeat, the receive window size is 2n1, and the maximum send window size is also 2n1 (half the total number of sequence numbers). Draw a timing diagram for n = 2 illustrating a situation where a send window size of 2n 1 = 3 can cause the protocol to fail.