Myrinet physically consists of two fibre optic cables, upstream and downstream, connected to the host computers with a single connector. Machines are connected together via low-overhead routers and switches, as opposed to connecting one machine directly to another. Myrinet includes a number a fault-tollerance features, mostly backed by the switches. These include flow control, error control, and "heartbeat" monitoring on every link. The first generation provided 512 Mbit/s data rates in both directions, and later versions supported 1.28 Gbit/s and 2 Gbit/s.
Myrinet's throughput is close to the theoretical maximum of the physical layer. On the latest 2.0 Gbit/s links Myranet often runs at 1.98 Gbit/s of sustained throughput, considerably better than what Ethernet offers, from 0.6 and 1.9 Gbit/s depending on load.