Queueing strategies for multicast packet switching

The authors consider multicast packet switching where an input may send the same packet to many outputs within an ATM (asynchronous transfer mode) time slot. A host of multicast queuing disciplines can be exercised. Assuming only independent HOL (head of line) service to an output from slot to slot, the delay performance and saturation throughput are derived. The accuracy of the assumption for different disciplines is examined via extensive simulation. It is shown that the FCFS (first come, first serve) HOL service discipline not only has almost completely identical results for simulation versus analysis, but also provides the best saturation throughput, fairness, and delay performance among all disciplines considered. The analysis shows that implementing packet priorities can significantly improve delay performance. It is concluded that offering priority according to age in the queue is a worthwhile feature for multicast (as well as unicast) packet switches