An Investigation of Application Level Performance in ATM Networks

The goal of this paper is to investigate the relation that exists between the performance guarantees provided by a network, and what users of the network ultimately get. There are many different performance measures that may be of interest, but our focus is on the relation that exists between packet losses in the network and message losses experienced by the application. This investigation is carried out in the context of an ATM network where network packets are of fixed size (cells), and we concentrate mostly on the impact of one key parameter, the application peak transmission rate. As we shall see, varying this parameter for a given source while keeping network cell losses constant can translate into significant variations in the loss probability of application messages. In the paper, we develop and solve an analytical model that permits us to identify and evaluate this behavior. Based on the results available from this model, we then develop a set of {\em guidelines} that applications can use to determine which performance guarantees to require from the network, in order to ensure the appropriate level of service. In general, the ability to express performance in terms that are meaningful to applications is likely to play a major role in the acceptance and use of high speed networks. This paper attempts to take one step in this direction, and hopes to motivate further work in this important area.