Congestion-Avoidance in the Internet and Control Engineering

Professor Christopher V. Hollot

Department of Electrical and Computer Engineering

University of Massachusetts - Amherst

In the past decade the world has seen an explosion in Internet activity and with it has come increased expectations for performance. At the heart of this information exchange is the transmission control protocol (TCP) and active queue management (AQM) routers which work together to help prevent network congestion. This talk is concerned with the design of congestion avoidance algorithms and is based on a recently-developed fluid-flow model that expresses TCP in the language of control engineers. Using this model we first relate key network parameters such as load, link capacity and round-trip-time to the AQM feedback control problem. We then analyze the RED (Random Early Detection) router, the prevailing AQM scheme-of-choice, and, finally, argue that a classical PI (proportional-integral) router is a favorable alternative.

Friday, March 23, 2001

3:30 - 5:00 p.m.

1500 EECS