ATM simulation with CLASS

The paper describes an efficient, versatile and extensible software tool for the analysis of the quality of connectionless services in ATM networks. The tool is named CLASS for ConnectionLess ATM Services Simulator. CLASS is a time-driven, slotted, synchronous simulator, entirely written in standard C language. CLASS allows the performance analysis of ATM networks adopting the viewpoint of both the end-user, and the network manager; the measured performance parameters include the cell and message loss probabilities and the cell and message delay jitters. The investigation of the impact of shaping and policing techniques, and of the use of connectionless servers on the network performance is also supported. With CLASS, the network synthetic workload can be modeled choosing from a variety of traffic generators ranging from simple Poisson traffic sources to sources modelling the traffic produced when higher level protocols, like TCP, access the ATM services.