TCP mechanisms for Diff-Serv Architecture
Report ID: TR-605-99Author: Fang, Wenjia / Peterson, Larry
Date: 1999-09-00
Pages: 12
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Abstract:
Work on Diff-Serv has demonstrated that it is possible to create differentiations in throughput among TCP connections during periods of network congestions. However, the effectiveness of such schemes is limited by the impreciseness and biases in TCP's window-based congestion control algorithm. More precisely, TCP's window-opens mechanism has an intrinsic bias agains long RTT connections, and its window-close mechanism adapts to the perceived network congestion optimal point only, which is not sufficient to meet the underlying premise of Diff-Serv architcture. In response to these two weaknesses, this paper proposes a set of new mechanisms for TCP's congestion control algorithm that are specifically tailored to the Diff-Serv architecture. While preserving TCP's ``linear increase and multiplicative decrease" principle, these mechanisms make TCP more robust and precise in adjusting its sending rate to network congestion, as well as to a pre-defined service profile. Simulations and testbed implementations are used to qualitatively demonstrate the results. The results show that combined with Diff-Serv mechanisms in routers, the mechanisms in endhosts can allocate resource among TCP connections in a fair, precise and differentiated manner. The paper also discusses incremental deployment issues and proposes a deployment strategy for the proposed mechanisms.