The scheme is described in terms of processor to processor communication for simplicity. It is understood that the destination devices are not necessarily the same as the source ones, nor need there be the same number of destinations as sources. In the sorters and the merger the smaller numbers come out towards the top of the diagram. A low priority number implies high priority. Zero is the highest priority.
Every processor emits a message every message interval.
The following discussion examines a single message wave. The first sorting net orders the messages by destination address, and within a given destination by priority number. Thus the upper inputs of the merger receive a list of messages, grouped by destination, with the highest priority message to each processor heading its group. The lower inputs of the merger receive N dummy messages, exactly one for each destination processor. Merging these dummies with the sorted list of real messages results in a list still grouped by destination, with each group headed by a dummy, by virtue of its high priority, followed immediately by the highest priority real message, if any, for the destination.