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Fibre Channel over Ethernet (FCoE)

FCoE stands for Fibre Channel over Ethernet (FCoE). It solves the problem of organizations having to run parallel network infrastructures for their local area networks (LANs) and their storage area networks (SANs). As a result, they have to operate separate switches, host bus adapters (HBAs), network interface cards (NICs) and cables for each of these networks. Even utilizing a virtualization solution like VMware can actually increase the number of network adapters required to carry traffic out of the servers.

With so many NICs, HBAs, switches and cables to deal with, both capital and operational costs to run a data center can increase significantly. FCoE represents a way to drastically reduce the number of cards, switches, adapters and assorted cabling by running LANs and SANs over the same infrastructure. According to analyst firm Enterprise Strategy Group (ESG), FCoE works out considerably cheaper to deploy than traditional networks due to reduced hardware costs.

To look at it another way, FCoE is a standard for using the Fibre Channel (FC) protocol (which is the mainstay of the SAN) over Ethernet networks (the mainstay of the computer networks, both wired and wireless). FCoE provides a way to transport FC SAN traffic over Ethernet, eliminating the need for a separate storage network.

Fibre Channel meets Ethernet

To understand FCoE, it is important to grasp the two key definitions that form the term – Fibre Channel and Ethernet.

Fibre Channel (FC) is a serial data transfer protocol and standard for high-speed enterprise-grade storage networking. It supports data rates up to 10 Gbps and delivers storage data over fast optical networks. Basically, FC is the language through which storage devices such as HBAs, switches and controllers can communicate.

Ethernet is an architecture developed almost 40 years ago for LANs. In its early days, it supported up to 10 megabits per second (Mbps). However, more recently this has been extended to 1 Gbps, 10 Gbps and more. Ethernet is essentially a transfer medium enabling data to travel along cables or wirelessly in units known as frames.

FCoE Vendors

There are a large number of storage and networking vendors offering FCoE products. Chief among them are the likes of Cisco, EMC, NetApp, QLogic, Emulex, Brocade, IBM, Dell, HP and Oracle.

FCoE Technology

FCoE is basically a way to map Fibre Channel over full duplex Ethernet networks based on the Institute of Electrical and Electronic Engineers (IEEE) 802.3 standard. As well as consolidating I/O, it is an effective way of reducing complexity by eliminating the necessity of establishing and running parallel networks for storage and networking.

The technology can be deployed in a "Top-of-the-Rack" configuration: An FCoE-enabled switch sits on the top of the rack and takes the place of a Fibre Channel switch and an Ethernet switch. This configuration would assume the use of Converged Network Adapters (CNAs) or a universal LAN on Motherboard (LOM) that is capable of supporting FCoE.

If warranted, redundant connections can be established using at least two FCoE connections for each server to the top-of-the-rack FCoE switch. This would take the place of 2 FC and 2 Ethernet connections per server for redundancy purposes. The top of the rack switch would then send the Ethernet traffic to the LAN and the Fibre Channel traffic to the SAN.

As well as top-of-rack switches, FCoE is also available in other formats, such as blades that plug into the storage backbone. And at the server level, CNAs for FCoE can replace FC HBAs and Ethernet NICs, along with associated cabling. Both protocols can be supported on the same port. In terms of the overall network stack, FCoE routes Fibre Channel traffic at the link layer, and also uses Ethernet to transmit the FC protocol.

Overall, the move toward FCoE is seen as part of an overall trend toward network convergence. In recent times, we have seen convergence in such areas as voice and data. Formerly, telecom utilized one network to carry phone lines and another line for computerized data traffic. This has converged using Voice over Internet Protocol (VoIP) as a means of cutting down on network clutter and unifying traffic.

The same basic trend is now beginning to take effect in storage, where more and more hardware can accommodate converged networks. Servers, for example, are available with universal connectivity adaptors that are able to handle almost any Ethernet-based protocol either via chips on the motherboard or through adapter cards. Eventually, storage networks may converge completely with Ethernet. But for now, both converged and dedicated storage networks remain widely.

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