Delay analysis of a metropolitan area network

An approximation for the mean end-to-end packet delay in a two-level, ring-based metropolitan area network (MAN) is presented. The upper level of the MAN is a ring-based backbone network, and the lower level consists of a number of ring-based local area networks (LANs) connected via gateway to the backbone. Both levels are modeled using a single-server multiqueue system with nonexhaustive cyclic service and nonzero switchover times. The delay formula is derived assuming uniform routing of packets through the MAN and symmetric external traffic patterns. The two-level approximation utilizes Boxma and Meister´s (1987) one-level, nonexhaustive, asymmetric polling model. Comparisons with simulation results show the approximation to be accurate over a variety of network parameters