A basic principle of modelling is to try and reduce the detail in the model. This has to be done in the context of having the model accurately portraying the essential aspects that are of interest to the system. The detail in the model should only really represent the detail of the data that is available to us. Each component of the system is modelled separately and then the resulting model is the combination of these. The main interest of the modelling is for performance and so the elements that are modelled effect the performance of the system.
Individual elements are the source models and the network elements.
There are also other elements modelled such as customer behaviour and performance measures. The source models are discussed in detail in Section 2.3 . The network elements include the ATM cell structure, the ATM Adaptation Layers of interest, the control measures in the ATM user-network interface, the policing methods, various link rates and standards as well as buffers and multiplexors. The result that are expected from the models is to be able to build computer simulation models. These models can then be used to investigate the performance of proposed systems and compare them to each other.