Modelling and Verification of End-to-End Transport Protocols

Abstract End-to-end transport protocols are a fundamental concept in networking. Its situation within the protocol hierarchy as well as its main functions are first reviewed. A formal representation model, particularly well adapted to this kind of protocols, but useful also for other protocol types, is then introduced. The separation of the protocol automation in two distinct finite state automata and the splitting of the state set of one of these automata in a set of user partial states and a set of network partial states are main features of this model. A modelling methodology allowing a straightforward application of the model to any end-to-end transport protocol is also described. A second part of the paper is concerned with the validation of the control functions of protocols. A method for detection of deadlock situations is presented. This method consists of determining all possible deadlock situations and then of testing whether these situations may be reached by the protocol. Some results of the verification of the Cyclades transport protocol are also reproduced.