Analysis and Simulation of WF²Q+ Based Schedulers: Comparisons and Compliance with Theoretical Bounds

Abstract

The statistical multiplexing of non-fixed-size packet flows with heterogeneous requirements onto a single network interface of a router gave rise to a number of different scheduling mechanisms. These algorithms attempts to work as close as possible to the ideal “fluid model”. One of the most effective proposals is the Worst-case Fair Weighted Fair Queueing (WF ² Q); this pays its optimality with a great computational complexity and has been followed by more “operative” derivatives: the WF²Q+ and S-SPFQ. The former has not been specified with a univocal algorithm, thus leaving space for a number of implementations: this article aims to analyse and compare the different algorithms coming out from the WF²Q concept at both theoretical and “practical” level (by means of simulations). To this purpose, an on-purpose discrete-event simulator for packet schedulers has been implemented at the University of Pisa. The simulations also allowed to verify to what extent the operative versions of WF²Q fulfill to the WF²Q theoretical properties.