Unicast-based Multicast Communication in Wormhole-routed Networks

Multicast communication, in which the same message is delivered from a source node to an arbitrary number of destination nodes, is being increasingly demanded in parallel computing. System supported multicast services can potentially ooer improved performance, increased functionality, and simpliied programming, and may in turn be used to support various higher-level operations for data movement and global process control. This paper presents eecient algorithms to implement multicast communication in wormhole-routed direct networks, in the absence of hardware multicast support, by exploiting the properties of the switching technology. Minimum-time multicast algorithms are presented for n-dimensional meshes and hypercubes that use deterministic, dimension-ordered routing of unicast messages. Both algorithms can deliver a multi-cast message to m ? 1 destinations in dlog 2 me message passing steps, while avoiding contention among the constituent unicast messages. Performance results of implementations on a 64-node nCUBE-2 hypercube and a 168-node Symult 2010 2D mesh are given.