This paper analyzes the algorithm used for estimating retransmission timeouts in connection-oriented IP-based transport protocols, such as the Transmission Control Protocol (TCP) and the Stream Control Transmission Protocol (SCTP). The estimation algorithm uses historical values of the round-trip time to estimate future round-trip delays, and so creates a maximum waiting time before triggering retransmission attempts. The purpose of the analysis is to question / validate some of the fundamental

more »

... assumptions used in the estimation algorithm. The conclusion of the analysis is that the algorithm is somewhat mismatched to the dynamics of the current Internet. Alternative algorithms are discussed, and potential modifications are presented. Impact of the suggested alternative algorithm on the well-known selective acknowledgement and fast retransmit mechanisms is discussed.