Analysis of a Window-Based Flow Control Mechanism Based on TCP Vegas in Heterogeneous Network Environment

Keiichi TAKAGAKI  Hiroyuki OHSAKI  Masayuki MURATA  

IEICE TRANSACTIONS on Communications   Vol.E85-B   No.1   pp.89-97
Publication Date: 2002/01/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Internet Technology II -- Traffic Control and Performance Evaluation in the Internet)
TCP Vegas,  control theory,  fairness,  stability,  transient performance,  

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A feedback-based congestion control mechanism is essential to realize an efficient data transfer service in packed-switched networks. TCP (Transmission Control Protocol) is a feedback-based 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 TCP Reno. In previous studies, performance analysis of a window-based flow control mechanism based on TCP Vegas only 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.