Traffic congestion analysis of the public switched network

This paper presents a model for performing traffic congestion analyses of the entire public switched-voice network (PSN) in periods of network stress. The model considers the assets of the local exchange carriers and the three major interexchange carriers - AT&T, MCI, and Sprint. These assets include over 20,000 telecommunications switches interconnected by approximately 50,000 trunk groups. Off-the-shelf network analysis packages and call-by-call simulators cannot model such a network within practical computing limits. The TAMI model (Traffic Analysis by Method of Iteration) was developed to address this need. It was designed specifically for the size and structure of the PSN. Central to the model is the way it uses nested iterations of the traffic loading process to determine steady state convergence of trunk group blockages and switch overloads. These results are combined to measure the performance of the network with a single parameter-traffic-weighted average end office-to-end office blockage. TAMI was designed as a crisis analysis tool. It readily accepts different network stress scenarios. It models special handling of limited amounts of priority traffic. Glare and switch matching loss are considered, as well as the effects of network management controls