A CPN model of the MAC layer

This paper describes the design and validation of a CPN (Coloured Petri Net) model for the MAC layer based on the IEEE 802.3 standard. The main purpose of this system is to teach the TE students at this university how Coloured Petri Nets can be used in the modeling and analysis of real systems (especially those based on concurrency), allowing them to extract net modeling and analysis techniques. Furthermore, it also aims to introduce Design/CPN as an adequate tool for the edition, simulation and validation of CPN models. A bus LAN has been modelled. The model comprises a set of stations (each of them with the MAC layer implemented inside it) and a common channel which connects them all . By means of this model it is aimed to analyse how the MAC layer allocates use of the shared communication medium among the competing nodes. The basic idea is to make the stations transmit packets in bursts to the common noisy channel using the CSMA/CD access method and analyse how they adquire the medium and recuperate from colli sions. This access method where several stations may try to transmit their packets concurrently creates the perfect environment for the use of Coloured Petri Nets because of the natural way they include concurrency in their structure.