Fibre Channel

Fibre Channel is a gigabit speed network technology primarily used for Storage Networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards (INCITS), an American National Standard Institute (ANSI) accredited standards committee. It started for use primarily in the supercomputer field, but has become the standard connection type for storage area networks in enterprise storage. Despite its name, Fibre Channel signaling can run on both twisted-pair copper wire and fiber optic cables.

History

Fibre Channel started in 1988, ANSI standard approval in 1994, as a way to simplify the HIPPI system then in use for similar roles. HIPPI used a massive 50-pair cable and gigantic connectors, and had limited cable lengths. Fibre Channel was primarily interested in simplifying the connections and increasing the lengths, as opposed to increasing speeds. Later it broadened its focus to address SCSI disk storage, providing higher speeds and far greater numbers of connected devices.

It also added support for any number of "upper layer" protocols, including SCSI, ATM, and IP, with SCSI being the predominant usage.

Fibre Channel topologies

There are three major Fibre Channel topologies,

Point-to-Point (FC-P2P). Two devices are connected back to back. This is the simplest topology, with limited connectivity.

Arbitrated Loop (FC-AL). In this design, all devices are in a loop or ring, similar to token ring networking. Adding or removing a device from the loop causes all activity on the loop to be interrupted. The failure of one device causes a break in the ring. Fibre Channel hubs exist to connect multiple devices together, or a simple point-to-point connection can be made. An arbitrated loop with two devices degenerates to point-to-point topology.

Switched Fabric (FC-SW). All devices are connected to Fibre Channel switches, similar conceptually to modern Ethernet implementations. The switches manage the state of the fabric, providing optimized interconnections and also security.

Fibre Channel layers

Fibre Channel is a layered protocol. It consists of 5 layers, namely:

FC0 The physical layer, which includes cables, fiber optics, etc.
FC1 The data link layer, which implements the 8b/10b encoding and decoding of signals.
FC2 The network layer, defined by the FC-PI-2 standard, consists of the core of FC.
FC3 A thin layer that implements auxilary functions that span across multiple ports on a Fibre Channel device.
FC4 Application layers, or upper-layer protocol encapsulation. This layer is responsible for encapsulation of various upper layers over FC.

FC0, FC1, and FC2 are also known as FC-PH, the physical layers of fibre channel.

Fibre Channel products are available at 1 Gbit/s, 2 Gbit/s and 4 Gbit/s. A 10 Gbit/s standard has been ratified, but no products are available yet based on that standard. An 8 Gbit/s standard is being developed. Products based on the 1, 2, 4 and 8 Gbit/s standards should be interoperable; the 10 Gbit/s standard, however, requires a complete changeover.

Industry support

ATTO Technology provides Fibre Channel connectivity and bridging solutions.
Brocade provides Director (large) and desktop (small) class Fibre Channel switches
Cisco provides Director (large) and desktop (small) class Fibre Channel switches
DataDirect Networks provides Fibre Channel storage systems powering many of the top Super Computers.
Engenio provides Fibre Channel ASICs, HBAs, drivers, and controller technology for FC-switched FC-AL storage arrays.
QLOGIC provides Fibre Channel ASICs, HBAs, drivers, and Fibre Channel switch technology used to create 2 and 4 Gbit/s budget conscious SAN fabrics.

Fibre Channel RFCs

RFC 4044 - Fibre Channel Management MIB
RFC 2837 - Definitions of Managed Objects for the Fabric Element in Fibre Channel Standard
RFC 2625 - IP and ARP over Fibre Channel

External links