3. (i) Consider the data transfer between two hosts A and B, with the stop-and-wait protocol, rdt3.0. A is located on the West Coast of the United States and B is located on the East Coast. The speed-of- light round trip propagation delay between A and B, RTT, is approximately 30 milliseconds. Suppose that A and B are connected by a channel with a transmission rate, R, of 1Gbps. Given the packet size, L, of 1500 bytes, determine the channel utilization.

(ii) Following the problem (i), consider the pipelined technique instead of stop-and-wait protocol. How big would the window size have to be for the channel utilization to be greater than 98%?

(iii) What does the receive window (rwnd) field in a TCP segment indicate?

(iv) Why are the flow control and congestion control needed?