The Eifel Retransmission Timer
Appears in ACM Computer Communications Review, Vol. 30, No. 3, July 2000.
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We analyze two alternative retransmission timers for the Transmission
Control Protocol (TCP). We first study the retransmission timer of TCP-Lite
which is considered to be the current de facto standard for TCP implementations.
After revealing four major problems of TCP-Lite’s retransmission timer,
we propose a new retransmission timer, named the Eifel-Xmit-Timer, that
eliminates those problems. The strength of our work lies in its hybrid
analysis methodology. We develop models of both retransmission timers for
the class of network-limited TCP bulk data transfers in steady state. Using
those models, we predict the problems of TCP-Lite’s retransmission timer
and develop the Eifel-Xmit-Timer. We then validate our model-based analysis
through measurements in a real network that yield the same results.