Fibre Channel

Fibre Channel. It is a high-speed network technology primarily used for storage area networking, providing lossless, in-order delivery of raw block data. Developed to overcome limitations in earlier SCSI and HIPPI interfaces, it connects data storage to servers in data centers. The technology is standardized by the International Committee for Information Technology Standards within the T11 Technical Committee.

Overview

Initially standardized in 1994, it emerged as a solution for high-performance computing environments like those at Lawrence Livermore National Laboratory and Los Alamos National Laboratory. It forms the backbone of most enterprise storage area network infrastructures, enabling features like storage virtualization and disaster recovery. Major adopters include financial institutions such as Goldman Sachs and technology firms like IBM and Hewlett-Packard. Its protocol suite maps SCSI commands over a dedicated network fabric.

Technical details

Speeds have evolved from 1 Gigabit per second to 128 Gbit/s in modern implementations, as defined by the Fibre Channel Physical Layer standards. It uses optical fiber cabling predominantly, though copper cable variants exist for shorter distances. Key operational characteristics include its credit-based flow control mechanism, which prevents frame loss, and its use of World Wide Names for addressing. The maximum frame payload is 2112 bytes, and it supports various service classes for different traffic types.

Topologies

Three primary interconnect schemes are defined. The point-to-point topology directly links two devices, such as a server and a storage array. The arbitrated loop topology, largely obsolete, connected devices in a logical ring, sharing bandwidth. The switched fabric topology, the most prevalent, uses Fibre Channel switches or director switches to create a network, allowing many simultaneous connections. This fabric can be scaled using protocols like Fabric Shortest Path First for routing.

Layers and protocols

Its architecture is defined by a five-layer model, similar to the OSI model. The physical layer (FC-0) defines media and connectors. The transmission protocol layer (FC-1) handles 8b/10b encoding and error control. The signaling protocol layer (FC-2) is the core, managing framing, flow control, and service classes. The common services layer (FC-3) provides functions like striping. The protocol mapping layer (FC-4) interfaces with upper-level protocols like SCSI (FCP), IBM's System Network Architecture, and Internet Protocol (FCIP). Fibre Channel over Ethernet is a related convergence protocol.

Products and market

The market has long been dominated by companies like Broadcom Inc. (via its Emulex and QLogic acquisitions), Cisco Systems, and Brocade Communications Systems. Key products include host bus adapters, Fibre Channel switches, and director switches. Major storage array vendors integrating the technology include Dell EMC, NetApp, Hewlett-Packard Enterprise, and Hitachi Data Systems. The technology faces competition but remains entrenched in core enterprise applications, with a significant installed base.

Comparison with other technologies

Compared to iSCSI, which runs SCSI over TCP/IP networks, it offers lower latency and deterministic performance, making it preferred for tier-one applications. Serial Attached SCSI is a point-to-point protocol for direct-attached storage, lacking the networking capabilities. InfiniBand, used in high-performance computing clusters like at the Texas Advanced Computing Center, offers higher throughput but different design goals. Fibre Channel over Ethernet attempts to converge the protocol with mainstream Ethernet networks, championed by the Fibre Channel Industry Association. NVMe over Fabrics is an emerging competitor for flash memory-based storage.