Adaptive access control of multiple traffic classes in ATM networks

An admission control and bandwidth allocation strategy is applied to several traffic classes entering an ATM (asynchronous transfer mode) network through a statistical multiplexer. At the call level, incoming virtual calls are either accepted or refused on the basis of a class-selective control rule designed to maintain a certain grade of service. Each class is assigned a buffer partition and a virtual capacity share, which affect the parameters of the acceptance controller. Buffer space is assigned statically with an offline procedure; on the other hand, bandwidth shares are periodically recomputed online at the cell level, by means of the (parametric) constrained minimization of a cost function, which takes cell loss probability and refused traffic into account. These quantities are computed by observing the number of refused, accepted, and active (i.e., possibly generating bursts) calls within the previous decision interval, and are assumed to be slowly varying with respect to the cell dynamics. In turn, the results of the optimization are used to adaptively adjust the parameters of the access controller.