Editing Wormhole switching (section)

== Usage ==

Wormhole techniques are primarily used in [[multiprocessor]] systems, notably [[Connection Machine|hypercube]]s. In a hypercube computer each [[Central processing unit|CPU]] is attached to several neighbours in a fixed pattern, which reduces the number of hops from one CPU to another. Each CPU is given a number (typically only [[8-bit]] to [[16-bit]]), which is its network address, and packets to CPUs are sent with this number in the header. When the packet arrives at an intermediate router for forwarding, the router examines the header (very quickly), sets up a circuit to the next router, and then bows out of the conversation. This reduces latency (delay) noticeably compared to [[store and forward|store-and-forward]] switching that waits for the whole packet before forwarding. More recently, wormhole flow control has found its way to applications in [[Network on a chip|network-on-chip]] systems (NOCs), of which multi-core processors are one flavor. Here, many processor cores, or on a lower level, even functional units can be connected in a network on a single [[Integrated Circuit|IC]] package. As wire delays and many other non-scalable constraints on linked processing elements become the dominating factor for design, engineers are looking to simplify organized interconnection networks, in which flow control methods play an important role.

The [[IEEE 1355]] and [[SpaceWire]] technologies use wormhole.