4. Two hosts, one on East (host A) and one on the west coast (host B) of the USA are exchanging data. Suppose A is sending a large file to B. The file is split into packets of size 8000bits. The hosts are using a stop-and-wait protocol. Therefore A has to wait for an Ack before sending the next packet. They are connected by 1Gbps link. Assume that the round trip delay between them is 30ms. Thus the packet leaves A, reaches B and then an acknowledgement leaves B and reaches A. This round-trip takes 30ms.

4.1 Calculate the throughput and link utilization.

4.2 To improve utilization, the hosts decide to use a sliding window protocol. So they agree to send a bunch of packets which the receiver can acknowledge by sending one acknowledge packet. Assume a full duplex connection (i.e. A and B and simultaneous exchange data with each other).  If sliding window size is 50 packets then what happens to throughput and utilization?

4.3 What should be the sliding window size for the link utilization to be 100%?