Specification and analysis of the FDDI MAC protocol using systems of communicating machines

Abstract

A model designed for the specification of communication protocols called systems of communicating machines is used to specify the FDDI token ring protocol, and to analyse its safety and ‘liveness’ properties. This model specifies each node as a finite state machine which has a set of local variables. With each transition is an enabling predicate and action. The predicates determine whether transitions may be taken, and actions alter the variable values as the transition executes. Communication between nodes is through shared variables. Our contributions include the specification of the basic FDDI protocol using a formal description technique; the use of this specification to analyse the safety and liveness properties of the network; the extension of the formal model to include the timing of transitions; and confirmation of the timing properties of the protocol.