A queueing analysis of the performance of DQDB

A queueing model for the DQDB protocol with a single priority level is presented and analyzed. The state of a node is defined by the number of requests in the distributed queue prior to, and post generation of a segment. It is shown that the number of states that a node can be in, is finite and position dependent. Moreover, it is shown that the request rate and the network traffic that a node perceives at any particular moment are highly dependent on its state. An iterative technique is presented to calculate the request rate and network traffic for all the nodes in a DQDB network by carefully modeling the relationship between adjacent nodes. The node average waiting time and average throughput are analyzed as functions of the node position and state in the network. Our results illustrate the effect of the various parameters on the waiting time and throughput. Comparisons with simulation and existing analytical results are presented.