Preemptive Retransmission - Improving the Performance of Short-Lived TCP Connections

A.J. Tarr and B.V. Ghita (UK)


Networking, TCP Congestion Control Mechanisms, Short-Lived TCP Connections


This paper presents a method of improving the performance of TCP (Transfer Command Protocol) based shortlived connections, such as web transfers. The characteristics (throughput and round trip time) experienced while communicating to a selection of Internet sites were examined, revealing that path constancy can be observed over extended periods of time. The research identified a temporal correlation between the three-way handshake and subsequent measurements of the RTT; by using this correlation, the algorithm is able to detect the signs of a packet loss and retransmit the affected segment before a standard implementation of TCP is able to recover the lost segment. Following the proposal of the algorithm, simulations were performed to study the performance of the proposed algorithm. In summary, during these simulations it was found that use of the Preemptive Retransmission algorithm provided enhanced performance, with the average duration of a connection 8% shorter than when compared to TCP Reno.

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