I am trying to understand the working of Go-Back N using this website:- http://www.ccs-labs.org/teaching/rn/animations/gbn_sr/
Here, suppose we are sending frames 1,2,3,4,5,6 (window size 4) and in the current window we have frames 1,2,3,4. Now suppose ACK 4 is lost then according to the website none of frames in the current window are re-transmitted.
According to my understanding, frames 3,4,5,6 (of current window) must be re-transmitted.
Where am I going wrong?