Congestion Avoidance and Control

This paper asks how TCP can keep a busy network useful when delay, packet loss, and retransmission tempt every sender to add even more traffic. Read it to see how acknowledgements become a clock, how slow start fills an empty path without a full-window burst, and why a congestion signal should make the sender retreat quickly before probing capacity again.

Reading focus: How ACK spacing carries the bottleneck's packet rhythm back to the sender, so one departing packet can clock one replacement into the network. Why slow start begins with one packet and grows from returned evidence instead of dumping a complete receiver window into an empty path. How additive increase, multiplicative decrease, RTT-variation estimation, and exponential timeout backoff interrupt the positive feedback behind congestion collapse.

SIGCOMM 1988. Van Jacobson. 35 min read, easy difficulty.