Consider the following modified stop-and-wait protocol for a noisy channel where
ID: 3723065 • Letter: C
Question
Consider the following modified stop-and-wait protocol for a noisy channel where the highlighted lines are commented. The protocol assumes a sender sending frames to a receiver. What may go wrong with this protocol? Justify your answer.Void sender3 (void){seq_nr next_frame_to_send; frame s; packet buffer;event_type event;next_frame_to_send = 0; from_network_layer(&buffer);while(true){s.info = buffer;s.seq = next_frame_to_send; to_physical_layer(&s);start_timer(s.seq); wait_for_event(&event); if (event == frame_arrival){from_physical_layer(&s);//if (s.ack == next_frame_to_send){stop_timer(s.ack);from_network_layer(&buffer);inc(next_frame_to_send);//} }}}
Explanation / Answer
Generally stop and protocols work as:
one is STOP until acknowledgement get from sender/receiver, it means, it is not complete the entire process, it will stop some amount time i.e., until TIMEOUT, upto that time it will WAIT for the acknowledgement. for that, 0 and 1 acknowledgements are to be enough. the solution also like that but the acknowledgements continusly incrementing i.e., 0,1,2,3,4,5,6,7,8, etc..
After some days, it will go uncountable acknowledgements. It is the big problem. So that we have Stop and Wait ARQ, GO-BACK N, SELECTIVE REPEAT protocols.