NESSY: AN OBJECT-ORIENTED NETWORK SIMULATION TOOL

This paper describes NESSY (NEtwork Simulation SYstem). This software tool aims to deal with the main problems in the area of performance evaluation simulation tool for communication networks. The tool provides an object oriented methodology in order to represent network components. The assembly of these components is then used for building a network model. Furthermore, the tool relies on a formal model to describe these basic components. They are described with a dedicated language derived from the ESTELLE FDT (Formal Description Technique). These descriptions form objects which have good properties to model all kinds of network components, to be reusable and modular. The final simulation model is made by composition of instances of various object classes. One peculiarity of this tool is the full flexibility between the simulation and the model to reduce the prototyping time. This is of great interest for example when transient phenomena are under study. 1