Deadlock avoidance for switches based on wormhole networks

We consider the use of wormhole routed networks as internal interconnects of switches. The interconnection of two wormhole networks that are free from deadlocks does not necessarily produce a deadlock free network. This is problematic when wormhole networks are used as switch-internal fabrics, because it severely restricts the possibilities for coupling the switches together. This paper presents a theory that can be effectively used to control this phenomenon caused by aggregated dependencies. We show that all aggregated dependencies can be removed from wormhole networks by careful inclusion of a limited number of virtual channels