Switched fabric

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Switched fabric, switching fabric, or just fabric, is a network topology where network nodes connect with each other via one or more network switches (particularly via crossbar switches, hence the name). The term is popular in telecommunication, Fibre Channel storage area networks and other high-speed networks, including InfiniBand. The term is in contrast to a broadcast medium, such as early forms of Ethernet. Switched fabrics can offer better total throughput than broadcast networks, because traffic is spread across multiple physical links.

Similarly, some modern computers use a switched fabric, such as PCI Express, HyperTransport, or QuickPath, instead of a bus. Again, the advantage of the switched fabric is performance.

Switched fabric in Fibre Channel

Example topology of a Fibre Channel switched fabric network

In the Fibre Channel switched fabric topology (called FC-SW), devices are connected to each other through one or more Fibre Channel switches. This topology allows the connection of up to the theoretical maximum of 16 million devices, limited only by the available address space (224). Multiple switches in a fabric usually form a mesh network, with devices being on the "edges" ("leaves") of the mesh. While this topology has the best scalability properties of the three FC topologies, it is also the most expensive, the only one requiring a costly fibre channel switch.

Visibility among nodes in a fabric is typically controlled with zoning.

Most Fibre Channel network designs employ two separate fabrics for redundancy. The two fabrics share the edge nodes (devices), but are otherwise unconnected. One of the advantages of this topology is capability of failover, meaning that in case one link breaks or a switch is out of order, datagrams can use the second fabric.

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