Myrinet

Myrinet, ANSI/VITA 26-1998, is a high-speed local area networking system designed by Myricom to be used as an interconnect between multiple machines to form computer clusters. Myrinet has much less protocol overhead than standards such as Ethernet, and therefore provides better throughput, less interference, and less latency while using the host CPU. Although it can be used as a traditional networking system, Myrinet is often used directly by programs that "know" about it, thereby bypassing a call into the operating system.

Myrinet physically consists of two fibre optic cables, upstream and downstream, connected to the host computers with a single connector. Machines are connected via low-overhead routers and switches, as opposed to connecting one machine directly to another. Myrinet includes a number of fault-tolerance features, mostly backed by the switches. These include flow control, error control, and "heartbeat" monitoring on every link. The newest, "fourth-generation" Myrinet, called Myri-10G, supports a 10 Gbit/s data rate and is inter-operable with 10 Gigabit Ethernet on PHY, the physical layer (cables, connectors, distances, signaling). Myri-10G started shipping at the end of 2006. (Source: Wikipedia)

For more information, see the section about Myrinet in the Overview of Recent Supercomputers.