Packet timed token service discipline: a scheduling algorithm based on the dual-class paradigm for providing QoS in integrated services networks

Integrated services networks face the challenge of managing several traffic classes at the same time. Service disciplines devised for integrated services networks therefore need to be flexible, i.e. able to provide different types of service, in order to accommodate different traffic classes efficiently. In this paper we focus on the integration of rate-guaranteed and best-effort traffic, and we argue that service disciplines based on the generalized processor sharing paradigm, which schedule flows according to their weights, lack the flexibility needed to efficiently manage both classes at the same time. We propose that a different service paradigm, the dual-class paradigm, which considers the two traffic classes at the same time, be used as a reference to devise flexible and efficient service disciplines for integrated services networks. We then present and analyze an innovative packet timed token service discipline, which approximates a dual-class paradigm at a low computational complexity. PTTSD properties are described analytically: we derive minimum rate guarantees for rate-guaranteed traffic and propose rules to select the system parameters in order to achieve pre-specified guarantees. Finally, we show some of the PTTSD properties by means of simulation. (C) 2002 Elsevier Science B.V. All rights reserved