Overload control in finite-buffer multiclass message systems

Abstract

A finite-capacity message system which handles several traffic types with different priority classes is considered. An overload control scheme is proposed which aims to maintain a strategic reserve of buffers for the higher priority traffic classes. Associated with each traffic class are two thresholds: ablocking threshold and aresume threshold. At the epoch when the buffer occupancy level reaches a blocking threshold, the priority class associated with that threshold is blocked. Similarly, at the epoch when the buffer occupancy level decreases to a resume threshold, the admission of the priority class associated with that threshold is resumed. The scheme is analyzed by means of the Green's function method, and closed-form results are obtained for the mean delay of admitted messages, the blocking probability for each priority class, and the ergodic state probabilities.