PERFORMANCE STUDY OF MULTISTAGE ATM SWITCHES USING AN ACCURATE MODEL OF THE BEHAVIOR OF BLOCKED CELLS

Most of the existing analytical models for multistage ATM switching fa bric are not accurate in the presence of a non-uniform traffic at the input of the switch. In this paper, we discuss the issues in modeling a multistage ATM switching fabric, and investigate the effect of indep endence assumptions in two previous analytical models. A highly accura te 4-state Markov chain model for evaluating the performance of ATM sw itching fabrics based on multistage switches with 2x2 finite output-bu ffered SEs is proposed. The proposed model correctly reflects the corr elation of cell movements between two subsequent cycles and states of the buffers of two adjacent stages. By comparing the results obtained from the proposed model, existing models and simulations, it has been shown that the proposed model is much more accurate than existing mode ls in the presence of a non-uniform traffic in the switch. The results From the existing models are unsatisfactory in the presence of an inc reased blocking in the su itch arising from a non-uniform traffic in t he switch. On the contrary, the proposed model is very robust even und er severe blocking in the switch.