SDI Seminar

Speaker: Hui Zhang, CMU

Integrated Traffic Management Based on Accurate and Practical Fair Queueing Algorithms

Date: May 9, 1996

Abstract: In this talk, I will focus on the question: how many service classes should be supported by ISN and how can they be integrated in one network? I will first argue that all useful services in the future ISN can be supported if link bandwidth can be split instantaneously among multiple sessions. Since this is not possible in a packet system, where only one traffic stream can utilize link bandwidth at any give time and an entire packet must be transmitted before the next packet can be served, we want to design packet algorithms that accurately approximate the behavior of instantaneously bandwidth splitting. In this literature, this class of packet algorithms are called Fair Queueing.

I will discuss limitations of existing Fair Queueing algorithms and give some intuition on why it is difficult to design accurate and practical Fair Queueing algorithms. I will then present an algorithm called Worst-case Fair Weighted Fair Queueing (WF^2Q, pronounced "W F squared Q") developed by me and Jon Bennett of FORE Systems. I will show that this algorithm can be used as the basic building block to support various services in integrated services networks. FORE system has done an ATM implementation of WF^2Q that can operate at 622 Mbps. We plan to have an IP implementation (which needs to support variable packet length) on the Netstar GigaRouter in the context of vBNS and DartNet testbed networks.