Protocol performance using image protocols

Abstract

Performance analyses of data communication systems do not always rely on a detailed analysis of the underlying protocols. Those analyses which do, usually rely on an analysis of the protocol state transition graph. These graphs tend to become very large for nontrivial protocols and the analyses correspondingly complex. Image protocols are a recent approach to reduce the complexity of communication protocol analysis. The method allows for the construction of an image protocol which is generally sma.ller than the original protocol and its analysis therefore less complex. An image protocol system is said to be faithful if it preserves the safety and liveness properties \ of the original protocol system. In this paper we show that an image protocol is also faithful as far as its performance is concerned, a result which simplifies performance studies of the protocol considerably. An example which illustrates the principles involved is included.