In this paper we use an analytic fluid approach in order to analyze the dif
ferent features of both Vegas and Reno TCP versions. We then use simulation
s to confirm our analytic results. When the available bandwidth is high, in
deed Vegas can retransmit less than one-fifth as much data as Reno does, so
that the higher the available bandwidth is, the more efficient Vegas is. H
owever, under heavy congestion Vegas behaves like Reno and does not manage
to make efficient use of its new mechanism for congestion detection. The an
alytic results that we obtain are the evolution of the window size, round t
rip times and their averages, and the average throughput.