Understanding TCP Vegas: A Duality Model
We view congestion control as a distributed primal--dual algorithm carried out by sources and links over a network to solve a global optimization problem. We describe a multilink multisource model of the TCP Vegas congestion control mechanism. The model provides a fundamental understanding of delay, fairness and loss properties of TCP Vegas. It implies that Vegas stabilizes around a weighted proportionally fair allocation of network capacity when there is sufficient buffering in the network. It clarifies the mechanism through which persistent congestion may arise and its consequences, and suggests how we might use REM active queue management to prevent it. We present simulation results that validate our conclusions.
© 2002 ACM, Inc. Received February 2001; Revised January 2002; Accepted January 2002. Partial and preliminary results have appeared in LOW, S. H., PETERSON, L., AND WANG, L. 2001. Understanding Vegas: A duality model. In Proceedings of ACM SIGMETRICS (June). ACM, New York. S. H. Low acknowledges the support of the Australian Research Council through Grant A49930405, National Science Foundation (NSF) through Grant ANI-0113425, and the Caltech Lee Center for Advanced Networking. L. L. Peterson acknowledges the support of NSF through Grant ANI-9906704 and DARPA through contract F30602-00-2-0561. We are grateful to Sanjeewa Athuraliya, Nick Maxemchuk, and the anonymous reviewers for their helpful comments.