Consider a go$-$back$-$N protocol with cumulative acknowledgements that uses sequence

numbers $0-3$ and has a window size of $2.$ Assume that the sender transmits four packets P$0,$

P$1,$ P$2$ and P$3$ and that P$1$ is discarded before it reaches the receiver. No other packets or acks

are lost. The beginning of this scenario is shown at below, with the timeout interval shown.

A$)$ Complete the diagram to show all the acknowledgements and all packet transmissions

and retransmissions.

B$)$ Label all packets and acknowledgements with their sequence numbers. Continue the

scenario until all four packets have been delivered and acknowledged.