It is an imaginary box that covers the sequence numbers of the data frame which can be in transit. Send (sliding) window for Go-Back-N ARQīasically, the range which is in the concern of the sender is known as the send sliding window for the Go-Back-N ARQ. With the help of the Go-Back-N ARQ protocol the efficiency in the transmission increases. With the help of Go-Back-N ARQ, there is a reduction in the waiting time of the sender. This protocol is used to send more than one frame at a time. Using the Go-Back-N ARQ protocol leads to the retransmission of the lost frames after the expiry of the timeout timer. In case if the sender does not receive any acknowledgement then the entire window of the frame will be retransmitted in that case. In case if the receiver receives the out of order frame then it simply discards all the frames. In that case, the receiver sends the independent acknowledgement for that frame. In case after the expiry of the acknowledgement timer, suppose there is only one frame that is left to be acknowledged.

By discarding silently we mean that: “Simply rejecting the frame and not taking any action for the frame'. Thus receiver silently discards the corrupted frame. If the receiver receives a corrupted frame, then it silently discards that corrupted frame and the correct frame is retransmitted by the sender after the timeout timer expires. It is important to note that the new acknowledgement timer only starts after the receiving of a new frame, it does not start after the expiry of the old acknowledgement timer. When the timer expires then the receiver sends the cumulative acknowledgement for all the frames that are unacknowledged by the receiver at that moment. This protocol makes the use of cumulative acknowledgements means here the receiver maintains an acknowledgement timer whenever the receiver receives a new frame from the sender then it starts a new acknowledgement timer. In Go-Back-N ARQ, the size of the sender is N and the size of the receiver window is always 1. This protocol is a practical approach to the sliding window. The sender keeps a copy of each frame until the arrival of acknowledgement. Go-Back-N ARQ is mainly a specific instance of Automatic Repeat Request (ARQ) protocol where the sending process continues to send a number of frames as specified by the window size even without receiving an acknowledgement (ACK) packet from the receiver.

In this tutorial, we will be covering the Go-Back-N Automatic Repeat Request protocol for Noisey channels in the data link layer.

Stop and wait arq protocol program in c