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 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.