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Performance Analysis and Modeling
Full Paper
A Fluid-based Analysis of a Network of AQM Routers Supporting TCP Flows with an Application to RED
Vishal Misra (University of Massachusetts, Amherst)
Wei-Bo Gong (University of Massachusetts, Amherst)
Don Towsley (University of Massachusetts, Amherst)
In this paper we use jump process driven Stochastic Differential Equations to model the interactions of a set of TCP flows and RED routers in a network setting. When expected behavior as a function of time is of interest, e.g., average queue length, loss rate, we show how the SDEs can be transformed into a set of ODEs which can be easily solved numerically. Our results show excellent agreement with those of similar networks simulated using the well known ns-simulator. Our model enables us to get an in-depth understanding of the RED algorithm. Using the tools developed in this paper, we present a critical analysis of the RED algorithm. We explain the role played by the RED configuration parameters in the behavior of the algorithm in a network and present guidelines for choosing those parameters. Our technique has straightforward extensions to other active queue management algorithms. We believe this modeling/solution methodolgy has a great potential in analyzing and understanding various network congestion control algorithms.