Analysis of a two-stage queue with application to DATAKIT(TM) trunk module.

Multi-stage queueing mechanisms with quantum service are used in various computer and communication systems to guarantee small delays to short jobs without apriori knowing the service requirement of any job. In this memorandum we analyze the efficacy of one such scheme (a two stage first-in-first-out and round robin) in discriminating between short and long jobs. S. Morgan used this as an approximate model of the trunk model in DATAKIT and evaluated the mean delays for three different types of jobs for a specified traffic mix. We extend his results to obtain the distribution of the delay for short jobs, the cycle time in the round robin queue for long jobs and the number of messages in the first-in-first-out and the round robin queues.