Message delay analysis of the DQDB subnetwork based on an approximate node model

The analytical evaluation of the message delay in an approximate DQDB network model is investigated. The authors extend the results obtained by C. Bisdikian (1990), which assumes that each network node can queue at most one packet, to the case of node queues each holding an entire message containing l packets, via some unobvious reselection of model definitions. Corresponding to the single-packet waiting time analysis, they obtain an expression for the number of requests queued ahead of an arriving message, from which an expression for the average message delay can be derived. One conclusion drawn from the analysis is that the average steady-state message delay is linear in sufficiently large l. Furthermore, the analytical results can provide an upper bound on the mean message delay for variable message size, and explain some observations of earlier simulation studies