TCP Westwood+

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TCP Westwood+ is a sender-side only modification of the TCP Reno protocol stack that optimizes the performance of TCP congestion control over both wireline and wireless networks. TCPW is based on end-to-end bandwidth estimation to set congestion window and slow start threshold after a congestion episode, that is, after three duplicate acknowledgments or a timeout. The bandwidth is estimated by properly low-pass filtering the rate of returning acknowledgment packets. The rationale of this strategy is simple: in contrast with TCP Reno, which blindly halves the congestion window after three duplicate ACKs, TCP Westwood+ adaptively sets a slow start threshold and a congestion window which takes into account the bandwidth used at the time congestion is experienced. TCP Westwood significantly increases fairness wrt TCP (new) Reno in wired networks and throughput over wireless links.

TCP Westwood+ is now in the Linux 2.6 distribution.

Essential papers on Westwood

Linux 2.6 implementation of Westwood+ TCP at www.kernel.org

ns-2 implementation of Westwood+ TCP

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