I am a computer science under graduation student, and was going through some Go Back N ARQ (Computer Networking) videos on YouTube, and got a doubt in a question, which according to me should have a different answer than what the instructor on the video is arriving at (given that no other comment in the comments section of the video raises the same doubt, I am pretty sure I have had some problem in understanding the protocol). I would be greatful for any help. The question goes as follows:
Given a connection oriented communication between two hosts that are following the Go back N protocol, with
sender's window = 3, and assuming that every
5th packet transmitted by the sender is lost (no acknowledgements are lost), what are the total number of transmissions required by the sender host? Assume that the packets to be sent are numbered
The sequence of transmissions by the sender that I am getting is (final answer = 16):
1,2,3; 4,5,6; 5,6,7; 8,9,10; 8,9,10; 10
Meanwhile, the instructor in the video gets it like this (final answer = 18):
I would appreciate if someone could point out where I am going wrong in understanding the protocol. Thanks!