Topology and traffic scenarios for ATM network simulation

Efficient routing of traffic in any sort of network is obviously dependent on the topology of the network and the volume, distribution and mix of traffic. The paper considers the likely topology of future ATM networks and the mix of traffic that they will carry. It proposes an arrangement which can be used, when simulating ATM network routing algorithms. The particular interest is in the routing overhead of flooded status information which is used to calculate or discover optimal routes. The experimental topology used in the study is a flat, sparsely connected mesh of 43 nodes based on a segment of the BT network to the south and east of London. Since the network exists and serves a "real" user community, it is possible to make reasoned estimates of the magnitude and mix of the offered load using population and behavioural statistics. Three different traffic scenarios are considered. These are telephone, audio-visual and data traffic and each traffic class are carried in a separate overlay (virtual path) network which supports the appropriate quality of service. Simulation is used to predict the variation in the pattern and volume of traffic, and subsequently the generation of routing status update messages.