Consider two full-duplex point-to-point links connecting host A, B, and C. This distance of the link between A and B is 2000 miles, and the distance of the link between B and C is 500 miles. The propagation delay is 10 sec/mile for both links. The link between A and B has a bandwidth of 100 kbps (you are not given the bandwidth for the link between B and C but will calculate it below). All data frames are 1000 bits long, but ACK frames are separate frames of -2- negligible length. Between A and B a sliding-window protocol with window size of 3 is used, and Between B and C, a stop-and-wait protocol is used. Assume that there are no errors on the links. Notice that there is a reliable transmission protocol used on each link instead of an end-to-end reliable transmission protocol.

(a) What throughput (in bits per second) can be achieved on the link between A and B? (Ignore the link from B to C for this part).

(b) Frames are generated at node A and are relayed to node C by node B. Determine the minimum bandwidth in bits per sec required between nodes B and C so that the buffers of node B are not flooded. Hint: in order not to flood the buffers of B, the throughput entering node B must be less than or equal to the throughput leaving node B.

(c) For link A-B, the sliding window protocol with a window size of 3 limits the throughput. What is the smallest window size that should be used to maximize the throughput on the link between A and B? What problem occurs if this window size is used for the A-B link?