Efficient broadcast and multicast on multistage interconnection networks using multiport encoding

This paper proposes a new approach for implementing fast multicast and broadcast in multistage interconnection networks (MINs) with multiport encoded multidestination worms. For a MIN with k×k switches and n stages such worms use n header flits each. One flit is used for each stage of the network and it indicates the output ports to which a multicast message must be replicated. A single multiport encoded worm has the capability to cover a large number of destinations with a single communication startup. A switch architecture is proposed for implementing multidestination worms without deadlock. Grouping algorithms of varying complexity are presented to derive the associated multiport encoded worms for a multicast to an arbitrary set of destinations. Using these worms a multinomial tree-based scheme is proposed to implement the multicast. This approach significantly reduces broadcast/multicast latency compared to schemes using unicast messages. Simulation studies indicate that improvement in broadcast/multicast latency up to a factor of 4 is feasible using the new approach. Interestingly, this approach is able to implement multicast with reduced latency as the number of destinations increases beyond a certain number