Corner-First Tree-based Region Broadcasting in Mesh Networks

In direct interconnection networks, the collective communication operation one to all, which is usually referred to as broadcasting, can be generalized to allow one source node to send a message to a rectangular region of nodes, rather than to all nodes. Most of the proposed routing algorithms for direct mesh and torus networks use a broadcast tree of unicast messages. The minimum spanning tree-based region broadcasting is not deadlock free, unless the network is partitioned into many virtual sub-networks, where the number of virtual channels grows exponentially with the dimension of the network [3]. This paper proposes two versions of the minimum spanning tree regionbroadcasting algorithm that are based on the idea of starting always at a corner of a region. The first algorithm uses always a fixed corner, while the second one uses the nearest corner. The two proposed algorithms are deadlock free and use virtual cut through for buffering blocked packets. Both broadcast algorithms can be safely mixed with unicast routing algorithms.