Fibre Channel over Ethernet (FCoE) is a

computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...

technology that encapsulates

Fibre Channel Fibre Channel (FC) is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data. Fibre Channel is primarily used to connect computer data storage to Server (computing), servers in storage area networks (SAN) in ...

frames over

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

networks. This allows Fibre Channel to use

10 Gigabit Ethernet 10 Gigabit Ethernet (abbreviated 10GE, 10GbE, or 10 GigE) is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. It was first defined by the IEEE 802.3ae-2002 standard. Unlik ...

networks (or higher speeds) while preserving the Fibre Channel protocol. The specification was part of the

International Committee for Information Technology Standards The InterNational Committee for Information Technology Standards (INCITS), (pronounced "insights"), is an ANSI-accredited standards development organization composed of Information technology developers. It was formerly known as the X3 and NCIT ...

T11 FC-BB-5 standard published in 2009. FCoE did not see widespread adoption. Storage FCoE

Functionality

FCoE transports Fibre Channel directly over

while being independent of the Ethernet forwarding scheme. The FCoE protocol specification replaces the FC0 and FC1 layers of the Fibre Channel stack with Ethernet. By retaining the native Fibre Channel constructs, FCoE was meant to integrate with existing Fibre Channel networks and management software. Traditionally, data centers used both Ethernet for TCP/IP networks and Fibre Channel for SANs, each having different and mostly incompatible interfaces/connections and interconnects/wiring and thus requires separate cabling/wiring and interconnects such as switching hardware for each. With the advent of FCoE, SANs that would have traditionally used Fibre Channel is consolidated with Ethernet and becomes another network protocol running on the Ethernet fabric, alongside traditional traffic such as IP. FCoE operates on top of the

data link layer The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer p ...

in the

OSI model The Open Systems Interconnection (OSI) model is a reference model developed by the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems inter ...

which contrasts with most other well-known protocols that may use Ethernet, such as (for a storage-related example)

iSCSI Internet Small Computer Systems Interface or iSCSI ( ) is an Internet Protocol-based storage networking standard for linking data storage facilities. iSCSI provides block-level access to storage devices by carrying SCSI commands over a TCP/IP ...

, which runs on top of TCP over IP. As a consequence, FCoE is not routable at the IP layer and will not work across routed IP networks such as the Internet. Since classical Ethernet had no priority-based flow control, unlike Fibre Channel, FCoE required enhancements to the Ethernet standard to support a priority-based flow control mechanism (to reduce frame loss from congestion). The IEEE standards body added priorities in the data center bridging (dcb) Task Group. Fibre Channel required three primary extensions to deliver the capabilities of Fibre Channel over Ethernet networks: * Encapsulation of native Fibre Channel frames into Ethernet Frames. * Extensions to the Ethernet protocol itself to enable an Ethernet fabric in which frames are not routinely lost during periods of congestion. * Mapping between Fibre Channel N_port IDs (aka FCIDs) and Ethernet MAC addresses. Computers can connect to FCoE with converged network adapters (CNAs), which contain both Fibre Channel host bus adapter (HBA) and Ethernet

network interface controller A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter and physical network interface) is a computer hardware component that connects a computer to a computer network. Early network interface ...

(NIC) functionality on the same physical card. CNAs have one or more physical Ethernet ports. FCoE encapsulation can be done in software with a conventional Ethernet network interface card, however FCoE CNAs offload (from the CPU) the low level frame processing and SCSI protocol functions traditionally performed by Fibre Channel host bus adapters.

Application

The main application of FCoE is in data center

storage area network A storage area network (SAN) or storage network is a computer network which provides access to consolidated, block device, block-level data storage. SANs are primarily used to access Computer data storage, data storage devices, such as disk ...

s (SANs). FCoE has particular application in data centers due to the cabling reduction it makes possible, as well as in server virtualization applications, which often require many physical I/O connections per server. With FCoE, network (IP) and storage (SAN) data traffic can be consolidated using a single network. This consolidation can: * reduce the number of network interface cards required to connect to disparate storage and IP networks * reduce the number of cables and switches * reduce power and cooling costs

Frame format

FCoE is encapsulated over Ethernet with the use of a dedicated

Ethertype EtherType is a two- octet field in an Ethernet frame. It is used to indicate which protocol is encapsulated in the payload of the frame and is used at the receiving end by the data link layer to determine how the payload is processed. The same ...

, 0x8906. A single 4-bit field (version) satisfies the

IEEE The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) organization, 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines. The IEEE ...

sub-type requirements. The 802.1Q tag is optional but may be necessary in a given implementation. The SOF (start of frame) and EOF (end of frame) are encoded as specified in . Reserved bits are present to guarantee that the FCoE frame meets the minimum length requirement of Ethernet. Inside the encapsulated Fibre Channel frame, the frame header is retained so as to allow connecting to a storage network by passing on the Fibre Channel frame directly after de-encapsulation. The FIP (FCoE Initialization Protocol) is an integral part of FCoE. Its main goal is to discover and initialize FCoE capable entities connected to an Ethernet cloud. FIP uses a dedicated

of 0x8914.

Timeline

In October 2003, Azul Technology developed early version and applied for a patent. In April 2007, the FCoE standardization activity started. In October 2007, the first public end-to-end FCoE demo occurred at Storage Network World including adapters from QLogic, switches from Nuova Systems, and storage from NetApp (none of the companies involved made any product announcements at the time). In April 2008, an early implementor was Nuova Systems, a subsidiary of

Cisco Systems Cisco Systems, Inc. (using the trademark Cisco) is an American multinational corporation, multinational digital communications technology conglomerate (company), conglomerate corporation headquartered in San Jose, California. Cisco develops, m ...

, which announced a switch. Brocade Communications Systems also announced support in 2008. After the

Great Recession The Great Recession was a period of market decline in economies around the world that occurred from late 2007 to mid-2009.

, any new technology had a hard time getting established. In June 2009, the FCoE technology that had been defined as part of the

(INCITS) T11 FC-BB-5 standard was forwarded to ANSI for publication. In May 2010, the FC-BB-5 standard was published as ANSI/INCITS 462-2010. Some additional work was done in the INCITS. Data center switches from Force10 and Dell PowerConnect supported FCoE and in June 2013, Dell Networking, which is the new

brand A brand is a name, term, design, symbol or any other feature that distinguishes one seller's goods or service from those of other sellers. Brands are used in business, marketing, and advertising for recognition and, importantly, to create and ...

-name for all networking portfolio of Dell, introduced the S5000 series which can be a fully native FCoE switch with the option to include a native fibre channel module, allowing you to connect the S5000 directly to an FC SAN environment.Dell Networkin
S-Series switches overview
visited 26 May 2013

References

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External links