Network protocols from a formal aspect
Dávid Ákos
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Pannon Egyetem
Csatári János
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Szegedi Tudományegyetem
Beleznay Péter
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Fast Lane Kft
Network protocols have all the characteristics of large and complex software systems. For this reason they are organized into hierarchical layers (e.g. ISO/OSI reference model) built on one another. The layered structure enables the independent definition of specific communication functions, and the separate development of these, based on different standards. A protocol belonging to a specific layer operates like some kind of a black box that provides services to the layer above, communicates with entities of the same layer, while uses services provided by the layer below. The actual protocol consists of the communication rules of the given layer, and the services (service specification) provided to the layer above. The description of the entities of the protocol together with the service specification is referred to as protocol specification. As protocol specifications with informal techniques and natural languages became insufficient, formal methods have been placed into the focus. One of the advantages of using formal specifications is that they can be strictly analyzed from the aspects of completeness and consistency.