Fairness and stability of congestion control mechanisms of TCP

In this paper, we focus on fairness and stability of the congestion control mechanisms adopted in several versions of TCP by investigating their time- transient behaviors through an analytic approach. In addition to TCP Tahoe and TCP Reno, we also consider TCP Vegas which has been recently proposed f or higher throughput, and enhanced TCP Vegas, which is proposed in this pap er for fairness enhancements. We consider the homogeneous case, where two c onnections have the equivalent propagation delays, and the heterogeneous ca se, where each connection has different propagation delay. We show that TCP Tahoe and TCP Reno can achieve fairness among connections in the homogeneo us case, but cannot in the heterogeneous case. We also show that TCP Vegas can provide almost fair service among connection, but there is some unfairn ess caused by the essential nature of TCP Vegas. Finally, we explain the ef fectiveness of our enhanced TCP Vegas in terms of fairness and throughput.