What is Fibre Channel over Ethernet (FCoE)?

Fibre Channel over Ethernet (FCoE) and Internet Small Computer System Interface (iSCSI) are essentially the abilities to combine two different worlds:

• Storage Area Network (SAN) – Dedicated network for enterprise storage management
• Ethernet – For traditional TCP/IP traffic

In this post, we will discuss FCoE.

Generally organizations use separate infrastructure for Ethernet and SAN. For example, you use LAN switch for the Ethernet traffic and SAN switch for SAN storage. As a system admin you need to manage SAN and Ethernet infrastructures separately.

However, with the introduction of FCoE things changed. Now FCoE allows you to send and receive FC frames over standard Ethernet. It’s economical because now you use the same existing infrastructure for “TCP-IP” as well “SAN” traffic.

For the implementation of FCoE, you need to use the FCoE switches (in SAN fabric) and Converged Network Adapter (CNA) from the server (TCP/IP) side.

Little bit about CNA here…

Traditionally, in a server, we have “NICs to handle Ethernet” traffic and “HBAs for SAN” traffic. However, a CNA combines the both – NIC and HBA, and the data flows from the CNA on the servers to the FCoE switches in your SAN fabric, and ultimately to the storage and applications.

FCoE, though uses Ethernet, does not uses TCP or IP (unlike iSCSI, which is also Ethernet based and it does use TCP-IP). FCoE uses a new Ether Type definition (Data Center Ethernet).

FCoE needs lossless Ethernet and it preserves the FC specification/constructs while running on Ethernet. Secondly, to operate FCoE, you also need jumbo frame support.