Priority broadcast and multi-cast for unbuffered multi-stage networks

Abstract

A dual priority switching apparatus for making input port to output port connections on a requested basis quickly and dynamically, in a standard mode from any one of the input ports to a fixed number of subsets of multiple output ports simultaneously, or in a broadcast mode from any one of the input ports to all output ports simultaneously. The apparatus permits multiple broadcasts to be queued at the individual switching apparatus which resolves the broadcast contention on a synchronous priority driven basis that permits one broadcast to follow the other at the earliest possible moment and the quickest possible speed. The apparatus permits multiple multi-cast operations to occur simultaneously within the network. The multi-cast function permits subsets of nodes assigned to the same tasks to communicate among themselves without involving other nodes that are not in its own subset. Hardware circuitry detects and corrects deadlock conditions in the multi-stage network. The hardware circuitry detects all the different types of deadlock conditions automatically and issues correction indications to the network paths involved. The network deadlock is thereby eliminated, and the two broadcasts or multi-casts involved continue their operation in a rearranged sequence that will not cause deadlock.