Efficient software multicast in wormhole-routed unidirectional multistage networks

A system-level multicast service, in which the same message is delivered from a source node to an arbitrary number of destination nodes, is fundamental in supporting collective communication primitives including the application-level broadcast, reduction, and barrier synchronization. This paper addresses how to efficiently implement multicast services in wormhole-routed unidirectional multistage interconnection networks (MINs), in the absence of hardware multicast support, by exploiting the properties of the switching technology. We show that the known topologically equivalent delta-class MINs have different capabilities in supporting software multicast. An optimal multicast algorithm is proposed for cube and omega networks. We also show that optimal multicast algorithms may not exist for baseline and butterfly networks. This papers addresses these properties and gives the performance via simulation.