PERFORMANCE EVALUATION OF A WORST-CASE MODEL OF THE METARING MAC PROTOCOL WITH GLOBAL FAIRNESS

The MetaRing is a Medium Access Control (MAC) protocol for high-speed LANs and MANs. The MetaRing MAC protocol offers its users synchronous, and asynchronous types of services and can operate under two basic ac cess control modes: buffer insertion for variable size packets, and sl otted for fixed length packets (i.e., cells). The latter mode of opera tion is considered in this paper, which only reports performance resul ts of an analysis related to the asynchronous type of service. In this paper we propose and solve a specific worst-case model that enables u s to calculate quantiles of the queue length distribution at cell depa rture time as a function of the offered load, and for three different arrival processes: Poisson, Batch Poisson (B-Poisson), and Batch Marko v Modulated Poisson Process (BMMPP). The model proposed is a discrete time discrete state Markov chain of M/G/1-Type, and hence we used a ma trix analytic methodology to solve it. Exploitation of the structure o f the blocks belonging to the transition probability matrix considerab ly reduces the computational costs. Our results show that the more rea listic the arrival process is, the longer the tail of the queue length distribution.