Effective bandwidths in a priority queueing system with leaky bucket regulated traffic sources
Résumé
A new admission control algorithm is proposed in this paper for traffic streams controlled by a dual leaky bucket enforcing on the one hand, the peak rate with a stringent tolerance, and on the other hand, the mean rate with a given a bucket size. The proposed algorithm relies on a model, which stochastically dominates the theoretical system composed of deterministic worst case traffic sources multiplexed in a finite capacity queue. Assuming that there are N source types characterized by the traffic parameter sets (_i,_i,_i), i = 1, , N, this dominating model is the M^[X]/M/1/K system, where input batch Poisson process is the superposition of N batch Poisson processes; the ith batch Poisson process is composed of batches of size _i arriving at rate _i/_i. We derive effective bandwidths for both the M^[X]/M/1/K system with heterogeneous traffic and the M^[X]/M/1/K system including a head of line priority level. In the former case, the effective bandwidth obtained by using the M^[X]/M/1/K system is compared with other effective bandwidths, which have been proposed earlier in the literature for ATM networks. It turns out that the proposed effective bandwidth definition leads to similar results but has the advantage of yielding admissibility regions delimited by hyper-planes. In the latter case, for the numerical values considered for the bucket sizes and the buffer capacities- , the effective bandwidths, which rely on exact upper bounds, are very close to those obtained by using the so-called reduced service rate approximation. This rigorously justifies a posteriori that approximation.