Performance Enhancement for TCP Vegas in Slow Start Phase over a Satellite link

Space Communication Protocol Standard-Transport Protocol (SCPS-TP) is an acceleration protocol, used to improve the performance of TCP protocol over satellite links. Because of the everyday improvements in satellite communication technology, the amount of bandwidth offered by satellite links is growing more and more. The issue of using this growing bandwidth by SCPS-TP as efficient as possible is an open research area. TCP-Vegas is the congestion control mechanism used by SCPS-TP. The performance of TCP-Vegas is under utilized in Slow Start phase of the connection, when being used over satellite links with high bandwidth and high round trip delay. In this paper we discuss the performance of TCP-Vegas in Slow Start phase and propose a new pacing method to solve the problem. Also, we suggest using ssthresh to avoid premature exit from Slow Start phase. In this research we use NS2 simulation environment to investigate the performance of these solutions.