Evaluating the Eifel Algorithm for TCP in a GPRS network
In Proceedings of European Wireless, February 2002, Florence, Italy. (Invited paper).
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Large and sudden variations in packet transmission delays are often
unavoidable in GPRS. This may cause spurious timeouts in TCP. Spurious
timeouts affect TCP performance in two ways: (1) the TCP sender
unnecessarily reduces its load, and (2) the TCP sender is forced into a
go-back-N retransmission mode. The Eifel algorithm avoids these
consequences. We evaluate the performance of the Eifel algorithm for TCP
Reno, NewReno and SACK in a simulated GPRS network. We use throughput and
goodput as equally important performance metrics. In all our simulations,
we find that the Eifel algorithm improves goodput; in some cases by up to
20 percent. When complemented with an efficient loss recovery scheme (SACK
or NewReno), we find that the Eifel algorithm also improves bulk data
download times in all our simulations; in some cases by up to 12 percent.