Abstract: Multicast is performed in a packet-based network switch having a switch fabric of store-and-forward switch nodes. Congestion and blocking at an ingress port is avoided because packet replication is performed at random nodes dispersed throughout the switch fabric. Each multicast packet inserted into the switch fabric by the ingress port is sent to a randomly-selected node. The random node replicates the multicast packet into many unicast packets that are routed to egress ports. A SONET frame can be divided into several multicast packets that are dispersed to different random nodes before replication, thus dispersing congestion. Replication can be delayed until the next SONET frame to prevent latency build up from propagation delays in the switch fabric. Alternately, the SONET payload envelope pointer can be advanced by the propagation delay. Lookup tables at the random nodes can include a list of destinations so that all the destination addresses do not have to be stored in each multicast packet header.

Abstract: An interconnection network routes packets among switches connected in a multi-dimensional network of links. Each packet contains a header with an address of a source switch connected to an input port that receives the packet, and a destination switch connected to an output port that transmits the packet. Each packet header also contains a random address of a random switch in the network. The packet is first routed from the source switch toward the random switch. Then a phase flag in the header is cleared by the random switch, and the packet is routed toward the destination switch. If a faulty link or switch is encountered, and no known routes are available to the destination, the phase flag is again set and another random address generated. The packet is then routed to a new random switch, bypassing the fault.