High Capacity Packet Switches

This talk describes a broadband digital switch intended for future visual and data communication needs. It provides arbitrary amounts of receive and transmit per user bandwidth (in fixed increments) for either bursty or continuous signals. In addition to the traditional one-to-one connection, the switch provides simultaneous reception of information from separate sources, simultaneous transmission of different information to separate destinations and broadcast transmission to separate destinations. The switch is constructed out of self-routing, non-blocking interconnection networks. Bursty data (variable length packets) and continuous data are reformatted into small, synchronized, fixed length "switch packets" which are used to route the networks. At the switch input, unused switch packets are discarded by a concentrator network. A sort-to-copy and a copy network are used to provide the broadcast mechanism. A sort-to-destination and an expander network route the switch packets to their destinations. The use of multiple channels per user allows the variety of interconnections. For n user channels, the sorting networks have O (n(log sub 2 n)sup 2) elements each; the other networks have O (nlog sub 2 n). Chip fabrication & packaging issues will be discussed.