FCoE

(Fibre Channel Over Ethernet) A protocol for transmitting Fibre Channel frames over 10G Ethernet. FCoE replaces the bottom Fibre Channel (FC) layers F0 and F1 with Enhanced Ethernet layers, enabling the same network port on a server to carry Fibre Channel frames to an FC storage device and Ethernet frames to the local network.

Enhanced Ethernet
Rather than regular Ethernet adapters, FCoE requires Enhanced Ethernet adapters on all nodes that support FCoE, and these adapters are called "converged network adapters" (CNAs). Regular Ethernet can lose packets under heavy congestion, but Enhanced Ethernet prevents packet loss by providing flow control. The FC to Ethernet conversion also takes place in the FCoE engine within the CNA. See Fibre Channel.

Typical FCoE Topology

Both IP traffic for the LAN and FC traffic for the SAN (storage network) ride over the same FCoE-based Ethernet port. Although a CNA may have two 10G Ethernet ports, they exist for redundancy, not to separate IP from FC traffic. Both the server and switch perform the FC to Ethernet and Ethernet to FC conversion in their respective CNAs.

The FCoE Frame

Each Fibre Channel (FC) frame is encapsulated within an FCoE frame, which becomes the payload of the Ethernet frame.