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: A large network switch has switch elements distributed across several chassis separated by perhaps several hundred meters. A generated sync pulse arrives at different switch elements at different times, creating skew. The latency of data through the network switch is set to match the frame period of SONET frames. SONET frames are adjusted at the ingress ports to align the data pointer to the beginning of the frame. The frame is divided along row boundaries into separate cell-packets that are routed across the switch fabric to the egress port. The packets are held in a buffer at the egress port until the next frame begins with the next sync pulse. Upon receiving the next sync pulse, the frame is transmitted. No pointer adjustment is needed by the egress port. A row number is used as a sequence number for the cell-packet to allow the egress port to re-order the cell-packets when transmitting the frame. Since no pointer manipulation is needed at the egress port, pointer management is simplified.

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.