2001: TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms.

Modern implementations of TCP contain four intertwined algorithms that have never been fully documented as Internet standards: slow start, congestion avoidance, fast retransmit, and fast recovery. [2] and [3] provide some details on these algorithms, [4] provides examples of the algorithms in action, and [5] provides the source code for the 4.4BSD implementation. RFC 1122 requires that a TCP must implement slow start and congestion avoidance (Section 4.2.2.15 of [1]), citing [2] as the reference, but fast retransmit and fast recovery were implemented after RFC 1122. The purpose of this document is to document these four algorithms for the Internet.