Discuss the below:
Q: Consider a selective-reject ARQ system with a window size of 3.
a) Circle (or shade or bold) the sender window after frames 0 through 3 have been sent and ACK 2 has been received
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0
b) Circle (or shade or bold) the sender windows after frames 4 through 6 have been transmitted, ACK 5 and NAK 5 are received.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0
c) After a) and b) have occurred, which frames need to be resent?
d) After a) and b) have occurred, which frames have been acknowledged?