Deadlock-Free Multicasting in Irregular Networks

A deadlock-free multicast scheme called prefix multicasting in irregular networks is studied. In prefix routing, a compact routing table is associated with each node (processor). Basically, each outgoing channel of a node is assigned a special label and an outgoing channel is selected if its label is a prefix of the label of the destination node. Node and channel labeling in an irregular network is based on a pre-defined spanning tree which may or may not be minimum. The routing process follows a two-phase process of going up and then down along the spanning tree, with a possible cross channel between two branches of the tree between two phases. It is shown that proposed routing scheme is deadlockand livelock-free. The approach is extended to multicasting in which the multicast packet is first forwarded up the tree to the longest common prefix (LCP) of destinations in the multicast. The packet is then treated as a multi-head worm that can split at branches of the spanning tree as the packet is sent down the tree. ∗This work was supported in part by NSF grants CCR 9900646, ANI 0093936, EIA 0130806.