Estimation of the variances of TCP/RED using stochastic differential equation

Abstract

By using the stochastic differential equation (SDE), a model is built to describe the system behavior, especially the queue length behavior, of TCP/RED (transmission control protocol with random early detection) on a single bottleneck network. Then, not only the static equilibrium point of the system is calculated, but also its variance is estimated. After calculating the variance of the queue length in the router, the authors show how such random oscillation affects the maximum connection number that the link admits while keeping low dropping probability, and how this relation is influenced by other network parameters. This model can be applied to the case where only homogeneous TCP flows exist, as well as where TCP and UDP (user data protocol) flows coexist. The simulations by NS-2 show that our deductive method is effective.

On the Use of Feedback Control in the Design of Computing System Components

“…Adopting the computer science jargon, such systems modify themselves so as to better respond to varying operating conditions, such as workload , network throughput , services offered , etc. The subject is of interest also for the control community, where many of the involved adaptations have been formulated as modifications of tunable system parameters based on the desired and actual system behaviour—that is, feedback control problems for which dynamic models in the system‐theoretical sense can be applied .…”