TCP Vegas revisited

The innovative techniques of TCP Vegas have been the subject of much debate in recent years. Several studies have reported that TCP Vegas provides better performance than TCP Reno. However, the question of which of the new techniques are responsible for the impressive performance gains remains unanswered so far. This paper presents a detailed performance evaluation of TCP Vegas. By decomposing TCP Vegas into the various novel mechanisms proposed and assessing the effect of each of these mechanisms on performance, we show that the reported performance gains are achieved primarily by TCP Vegas´s new techniques for slow start and congestion recovery. TCP Vegas´s innovative congestion avoidance mechanism is shown to have only a minor influence on throughput. Furthermore, we find that the congestion avoidance mechanism exhibits fairness problems even if all competing connections operate with the same round trip time