Adaptive Vegas: A solution of unfairness problem for TCP Vegas

Abstract

We study the unfairness problem for TCP Vegas. There are three sources to cause the unfairness for Vegas: α < β over-estimation of base RTT, and multiple congested gateways. To solve the unfairness caused by multiple congested gateways, we propose a new version of Vegas-Adaptive Vegas(A-Vegas) which assigns the value of parameters adaptively according to the number of congested gateways. Simulation shows that A-Vegas not only can solve the unfairness caused by multiple congested gateways, it also reduces the unfairness caused by over-estimation. We also introduce a new fairness index, RNBS (normal bandwidth sharing ratio), which indicates the ratio of the amount of bandwidth grabbed by a connection to the uniformly distributed bandwidth. © Springer-Verlag Berlin Heidelberg 2005.