Question

In a sliding window protocol with a window size of 4, using Go-Back-N ARQ, if frame 3 (out of frames 0-7, using 3-bit sequence numbers) is lost during transmission but frames 4, 5, and 6 arrive successfully at the receiver, what does the receiver do?

Q: Answer-In a sliding window protocol with a window size of 4, using Go-Back-N ARQ, if frame 3 (out of frames...

Go-Back-N ARQ receivers only accept frames in the exact expected sequence order any out-of-order frame like 4, 5, 6 arriving after 3 was lost is discarded, even though they were correctly received. Once the sender detects frame 3 wasnt acknowledged via timeout or a duplicate ACK for the last in-order frame, it must go back and retransmit frame 3 AND all subsequent frames in the window 4, 5, 6 unlike Selective Repeat ARQ, which would buffer 4, 5, 6 and only request retransmission of frame 3 itself.