In a Go-Back-N (GBN) protocol, the sender is allowed to transmit multiple packets
(when available) without waiting for an acknowledgment, but is constrained to have no
more than some maximum allowable number, N, of unacknowledged packets in the
pipeline. We describe the GBN protocol in some detail in this section. But before reading on, you are encouraged to play with the GBN applet (an awesome applet!) at the
companion Web site.