Understanding TCP Vegas: Theory and Practice*

Abstract:

*An updated version can be found in TR-628-00

This paper presents a model of the TCP Vegas congestion control mechanism
as a distributed optimization algorithm. Doing so has three important benefits.
First, it helps us gain a fundamental understanding of why TCP Vegas works,
and an appreciation of its limitations. Second, it allows us to prove that
Vegas stabilizes at a weighted proportionally fair allocation of network
capacity when there is sufficient buffering in the network. Third, it suggest
how we might use explicit feedback to allow each Vegas source to determine
the optimal sending rate when there is insufficient buffering in the network.
In addition to presenting the model and exploring these three issues, the
paper presents simulation results that validate our conclusions.