PAPER Special Issue on Traffic Control and Performance Evaluation in Internet Analysis of a Window-Based Flow Control Mechanism based on TCP Vegas in Heterogeneous Network Environment

A feedback-based congestion control mechanism is essential to realize an efficient data transfer services in packed-switched networks. TCP (Transmission Control Protocol) is a feedbackbased congestion control mechanism, and has been widely used in the current Internet. An improved version of TCP called TCP Vegas has been proposed and studied in the literature. It can achieve better performance than the current TCP Reno. In previous studies, only performance analysis of a window-based flow control mechanism based on TCP Vegas for a simple network topology has been performed. In this paper, we extend the analysis to a generic network topology where each connection is allowed to have a different propagation delay and to traverse multiple bottleneck links. We first derive equilibrium values of window sizes of TCP connections and the number of packets waiting in a router’s buffer. We also derive throughput of each TCP connection in steady state, and investigate the effect of control parameters of TCP Vegas on fairness among TCP connections. We then present several numerical examples, showing how control parameters of TCP Vegas should be configured for achieving both stability and better transient performance. key words: TCP (Transmission Control Protocol), TCP Vegas, control theory, fairness, stability, transient performanc