Analysis and optimization of a partial buffer sharing scheme for ATM switch overload control

Cell loss probability is a critical performance criterion that will be encountered in satisfying the needs of ATM services. To enforce dynamic control on the finite buffer in an ATM switch, it is desirable that multiple loss priority classes can be supported to accommodate diverse connection-levels as well as cell-level loss requirements of users. However, very little work has appeared in literature in the study of controlling cell loss probabilities with multiple priority classes. In this paper we conduct a thorough analysis of a generalized space priority control scheme, the Partial Buffer Sharing scheme, to manage optimally the finite shared buffer system. We develop an analytical queuing model to characterize accurately the system, and present efficient optimization procedures that are capable of finding the optimal loss thresholds to maximize the system admissible load. We verify the optimization procedures, demonstrate the resource efficiency improvement and evaluate the impact of given traffic conditions and cell loss criteria by numerous numerical examples. The study produces a feasible and attractive means to support different grades of loss probabilities with a minimum hardware cost and also to provide a better control on the delay introduced during cell buffering.