A Framework for Alternate Queueing: Towards Traffic Management by PC-UNIX Based Routers

Queueing is an essential element of traffic management, but the only queueing discipline used in traditional UNIX systems is simple FIFO queueing. This paper describes ALTQ, a queueing framework that allows the use of a set of queueing disciplines. We investigate the issues involved in designing a generic queueing framework as well as the issues involved in implementing various queueing disciplines. ALTQ is implemented as simple extension to the FreeBSD kernel including minor fixes to the device drivers. Several queueing disciplines including CBQ, RED, and WFQ are implemented onto the framework to demonstrate the design of ALTQ. The traffic management performance of a PC is presented to show the feasibility of traffic management by PC-UNIX based routers.