Design and Analysis of Hybrid Packet Schedulers

This paper addresses the problem of scheduling variable-size packets from large number of distinct traffic flows. Although the problem of fair packet scheduling in computer networks has received thorough theoretical consideration, practical high-speed packet scheduling systems remain elementary. The disparity arises because algorithms with theoretically favorable delay and fairness characteristics have unacceptably high computational cost, while algorithms of low complexity have substantially inferior properties. A variety of hybrid scheduling methods have been proposed as a compromise, but we argue that existing hybrid algorithms are either impractical, or do not provide full spectrum of required features. We then formally define requirements for a packet scheduler and propose a hybrid scheduling algorithm which guarantees these requirements. We develop a theoretical framework to prove that our algorithm indeed provides all the properties claimed.