Analyzing the Impact of TCP Connections Variation on Transient Behavior of RED Gateway

Several gateway-based congestion control mechanism have been proposed to support an end-to-end congestion control mechanism of TCP (Transmission Control Protocol). One of promising gateway-based congestion control mechanisms is a RED (Random Early Detection) gateway. Although a number of researches on the steady state performance of the RED gateway have been performed, the transient behavior of the RED gateway has not been fully investigated. In this paper, we analyze the transient behavior of the RED gateway when the number of TCP connections changes. We model both TCP connections and the RED gateway as a single feedback system, and derive the number of packets in the RED gateway’s buffer when the number of TCP connections changes. Through numerical examples, we quantitatively show that the transient performance of the RED gateway is quite sensitive to the total number of TCP connections, the transmission capacity of the RED gateway, and propagation delay of TCP connections. We also show that control parameters of the RED gateway have little impact on the transient behavior of RED gateway. key words TCP (Transmission Control Protocol), RED (Random Early Detection) Gateway, Transient Behavior