CIS 3210 Lecture Notes - Lecture 19: Selective Repeat Arq, Bitstream

• School: University of Guelph
• Department: Computing and Information Science
• Course: CIS 3210
• Professor: Xiaodong Lin

Document Summary

The n sized window is xed, you can not send out more than n without receiving an acknowledgement. When you receive an ack the window moves over to the right to introduce more sequence numbers that have not been used. If the timer (which is on the older non acked packet) times out, then all unacked packets are retransmitted. Only receives one ack for many sent out packets. Ack-only: always send the ack for correctly-received packet with the highest in-order sequence # Discard this packet, but still send and ack. Has a single timer, for the oldest sent out packet and not for each individual packets. The receiver has the more di cult job in this algorithm. The receiver must keep track of the received packets and the responses sent or not yet sent. If the packet is received out of order, must bu er it to wait for the packets from before it.