Modeling TCP Sack steady state performance in lossy networks

Modeling TCP performance is an important issue which has attracted research over the past two decades. Most literatures are to measure the steady state throughput of TCP Reno, however, few existing literatures are on modeling the throughput of the other important TCP variant, TCP Selective Acknowledgment (Sack). In this paper, an analytic model for the TCP Sack steady state throughput is proposed as a function of round trip time and packet loss rate. The presented model not only captures the behavior of fast recovery mechanism of Sack which is the main difference with Reno but also takes unsuccessful retransmission timeout in consideration. Those results simulated by ns2 show that our model can capture steady state TCP Sack throughput more accurately than existing TCP Sack model.