Optimal buffer management policies for shared-buffer ATM switches

Shared-buffer ATM switches can have severe cell loss under asymmetrical or heavy loading conditions, which makes buffer management essential. In this paper, we study the shared buffer system under the class of all work-conserving pushout policies and derive the properties of the optimal policy, which gives the least-average expected total cell loss probability. In a 2 x 2 system with independent identically distributed Bernoulli arrivals, we show that the optimal policy can be characterized by a single threshold. In the case of correlated arrivals, modeled by a Discrete Batch Markovian Arrival Process, the optimal policy has multiple thresholds, one for each phase of the arrival process. For the N x N shared buffer ATM switch, we are unable to prove optimality of any policy, but study the system via simulations. We provide a dynamic buffer management policy and compare its performance with that of static threshold-type policies.