Computation of Blocking Probability for Large Circuit Switched Networks

The ever-growing Internet and the mounting evidence to the important role of circuit switching motivate the need for an accurate and scalable means for performance evaluation of large circuit switched networks. Previous work has shown that the Erlang Fixed Point Approximation (EFPA) achieves accurate results for such networks where the number of channels (circuits) per link is large. However, a conventional application of EFPA for large networks is computationally prohibitive. In cases where the EFPA solution is unattainable, we propose, in this paper, to use an asymptotic approximation, which we call A-EFPA, for the link blocking probability and demonstrate savings of many orders of magnitudes in computation time for blocking probability approximation in realistically sized networks with large number of circuits per link. We demonstrate for NSFNet and Internet2 accurate calculations of the blocking probability using simulations, EFPA and A-EFPA, where each of these three methods is used for a different range of parameter values.