5. Modeling

5.1 OSI reference model

The integration of services implies the implementation of different types of connection in the network, and consequently the use of complex signaling. Describing and specifying such a wide range of functions calls for a rigorous approach, using appropriate modeling methods and tools.

ISDN standardization is based on the OSI (Open System Interconnection) reference model, as well as on specially developed characterization methods.

The reference model includes :

• defining the concepts and terminology to be used to describe communications between open systems;

• the breakdown of these communications into seven functional layers to which...