CALL ADMISSION CONTROL AND BANDWIDTH ALLOCATION IN A MULTISERVICE DQDB NETWORK

We consider a DQDB network carrying both isochronous and asynchronous traffic flows. Different classes of isochronous traffic are distinguis hed, according to their speed and originating user site, and their dyn amics is modelled by continuous time Markov chains; the asynchronous p acket traffic is represented by a single class. The allocation of slot s in each frame to the various traffic classes is dynamically decided by means of two control levels: a distributed one, acting on the admis sion of isochronous connection requests independently for each class; and a centralized one, periodically adjusting two sets of parameters t hat affect the admission control functions. One such set represents up per bounds on the number of slots that may be assigned to each isochro nous traffic class, i.e. its maximum capacity; the remaining bandwidth is shared by the asynchronous packets by means of the distributed que ue algorithm. The capacity assignment is performed by minimizing a cos t function that takes into account call blocking probabilities and pac ket delay. The control problem, which is characterized by multiple tim e scales, is discretized with respect to events occurring in an equiva lent overall embedded Markov chain. Simulation results show the effect iveness of the method in ensuring quality of service requirements.