Abstracr-One of TCP's critical tasks is to determine which packets are lost in the network, as a hasis for control actions (flow control and packet retransmission}. Modern TCP implementations use two mechanisms: timeout, and fast retransmit. Detection via timeout is necessarily a timeconsuming operation; fast retransmit, while much quicker, is only effective for a small fraction of packet losses. In this paper we consider the problem of packet loss detection in TCP more generally. We concentrate on the fact that TCP's control actions are necessarily triggered by inference of packet loss, rather than conclusive knowledge, This suggests that one might analyze TCP's packet loss detection in a standard inferencing framework based on probability of detection and probability of false alarm This paper makes two contributions to that end: First, we study an example of more general packet loss inference, namely optima1 Bayesian packet loss detection based on mund trip time. We show that fnr long-lived flows, it is frequently possible to achieve high detection probability and low false alarm probability based on measured round trip time. Second, we construct an analytic performance model that incorporates general packet loss inference into TCP. We show that for realistic detection and false alarm prohabilities (as are achievahle via our Bayesian detector) and for moderate packet loss rates, the use of more general packet loss inference in TCP can improve throughput by as much as 25%. 1826 0-7803-8%8-9/05/s20.0D (C)2005 IEEII. K. Pentikousis, "TCP in wired-cum-wireless environments." , "The eifel algorithm: making tcp robust against spurious retransmissions." SlGCOMM C o m p~. E Wang and Y. Zhang. "Improving tcp performance over mobile ad-hoc networks with out-of-order detection and response," in Proceedings of the 3rd ACM internntional symposium on Mobile ad hoc networking & computing. ACM Press, 2002. pp. 217-225.
The packet loss detector used in this paper adopts the ideas of a Bayesian packet loss detector for TCP REF .
Bayesian packet loss detection for TCP
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.
Computer Science