On The Optimality Of All To All Broadcast In k ary n dimensional Tori

All-to-all broadcast is a collective communication in a network with the constraint that every node must send to each other certain piece of its data. This paper addresses the problem of optimal all-port all-to-all broadcast in multidimensional tori. The optimality criteria considered are the minimum exchange steps, no duplicated data in the sense that only new data are conveyed to receivers and the balance of the communication links-load. It is proved that under these constraints, an optimal broadcast is not feasible in any multidimensional torus. Then, the tori which are capable of optimal broadcasts are characterized. Keywords-MIMD computers; distributed memory ; interconnection network; multidimensional torus; all-to-all broadcast; NODUP; store-and-forward routing; message combining; ε-optimality.