Modeling cell departure for shared buffer ATM switch

The framework of the performance analysis for a buffered Asynchronous Transfer Mode (ATM) switch usually consists of modeling the input traffic arrivals, the switching mechanism, and the cell departure process. The overall accuracy of the performance results relies on how accurately the cell departure process, especially for shared buffer switch is modelled. Unlike output buffer switches where there are at most one cell that can leave, multiple cells may depart from the shared buffer for shared buffer switches. Modeling the cell departure process is hence more complex for shared buffer switches. It is of practical interest and is challenging to find the appropriate probabilistic model to describe the cell departure process for shared buffer switches. This paper compares and verifies the accuracy of three models, including a new one called "Urn Model" proposed by us. These models are put under test in a performance evaluation of a shared buffer ATM switch, by using a discrete-time Markov chain. The numerical results are compared to the simulation, and they show that the Urn Model is a good compromise between accuracy and efficiency. This finding is significant because it helps speeding up running an analytical model of a large network in the other researches while providing satisfactory accuracy.