On the Petrinet modelling of medium access protocols

The authors deal with the modelling and performance analysis of a medium-access protocol used in token-ring networks. The model is based on the advanced Petri net (APN) proposed by the authors (1987) and by K.S. Sivananden (1988). A brief overview of the APN is given. It is shown that the APN is a versatile modelling and analysis tool, as it incorporates such features as coloured tokens, source and sink places and transitions with flexible firing rules and finite firing times. A local-area network (LAN) of four stations, with token-ring topology is considered. It is shown that all aspects of the medium-access protocol can be readily and effectively modelled by the APN. Analysis of the net is undertaken for performance evaluation. Such an evaluation has been made possible due to the availability of appropriate analysis techniques with the APN