Multicasting in Irregular Networks with Cut-Through Switches Using Tree-Based Multidestination Worms

Multidestination message passing has been proposed as a mechanism to achieve efficient multicast in regular direct and indirect networks. The application of this technique to parallel systems based on irregular networks has, however, not been studied. In this paper we pro- pose two schemes for performing multicast using multidestination worms on irregular networks and examine the extent to which multidestination message passing can improve multicast performance. For each of the schemes we propose solutions for the associated problems such as, meth- ods for encoding and decoding multidestination headers, alterations to the setup algorithm run by the switches, logic to perform header manip- ulation, etc. We perform extensive simulations to evaluate our schemes under a variety of changing parameters: software startup overhead per message, system size, switch size, message length, and degree of connec- tivity. Our results establish that even a very naive multicasting algorithm using multidestination message passing can result in considerable perfor- mance gains over the best unicast based multicasting schemes.