Admission Control of Multi-Class Traffic with Service Priorities in High-Speed Networks.pdf

Queueing Systems 27 (1997) 79–97 79 Admission control of multi-class traffic with service priorities in high-speed networks ? V.G. Kulkarni and N. Gautam Department of Operations Research, University of North Carolina, Chapel Hill, NC 27599-3180, USA E-mail: {vg kulkarni;gautam}@unc.edu Received 29 November 1995; revised 15 June 1997 We consider a fluid model of a system that handles multiple classes of traffic. The delay and cell-loss requirements of the different classes of traffic are generally widely different and are achieved by assigning different buffers for different classes, and serving them in a strict priority order. We use results from the effective bandwidth of the output processes (see Chang and Thomas (1995)) to derive simple and asymptotically exact call-admission policies for such a system to guarantee the cell-loss requirements for the different classes assuming that each source produces a single class traffic. We compare the admission-control policies developed here with the approximate policy studied by Elwalid and Mitra (1995) for the case of two-class traffic. Keywords: quality-of-service, fluid-flow models, effective bandwidth, multi-priority traffic, Chernoff dominant eigenvalue 1. Introduction The concept of effective bandwidth and its use in the admission control for the statistical multiplexing of bursty sources is now well-documented and accepted (see Gibbens and Hunt [11], Kesidis et al. [12], Elwalid and Mitra [8], Choudhury et al. [3], Whitt [18], etc.). In the emerging high-speed networks using asynchronous transfer mode (ATM), each traffic-source is described by its stochastic characteristics, and is assured a quality of service (QoS), as measured by cell-loss probability, delay, delay- jitter, etc. The effective bandwidth is a number associated with a traffic-source such that if the sum of the effective bandwidths of all the sources multiplexed onto a buffer is less than the output rate of that buffer, then the QoS is satisfied for