Unified Computing system (UCS) takes advantage of extensions made to the Ethernet protocol called as Data Center Ethernet (DCE). DCE provides for lossless transmission of traffic over Ethernet, which is very important for Fibre Channel traffic. The Fibre Channel traffic in UCS is encapsulated in a Fibre Channel over Ethernet (FCoE) frame, and when the traffic reaches the SAN network this FCoE encapsulation is removed. The server blades as well as the OS running on them see the adapter to carry the Fibre Channel traffic as a normal HBA and the Fibre Channel traffic is passed to this adapter. In UCS the converged network adapters perform the function of both NIC and HBA. When the traffic leaves the blade, it gets FCoE encapsulated and is passed to the UCS 6100/6200 series fabric interconnect. The UCS 6100/6200 series fabric interconnect makes the switching decision and as required removes the FCoE encapsulation and passes the original Fibre Channel frame to the SAN network.
The hardware and software components in the UCS support the unified fabric of Cisco, which allows multiple types of data center traffic over a single physical Ethernet network. This Data Center Ethernet (DCE) technology reduces the amount of cabling, management, and cost with the combination of the host bus adapters (HBAs) and network interface cards (NICs) into a single adapter called the Converged Network Adapter (CNA). This adapter can carry LAN and SAN traffic on the same cable.
The FCoE protocol maps Fibre Channel natively over Ethernet and is independent of the Ethernet forwarding scheme. FCoE transports native Fibre Channel frames over an Ethernet infrastructure, allow¬ing existing Fibre Channel management modes to stay intact.
The FCoE encapsulation is completely transparent to the host OS and the Fibre Channel SAN. This FCoE encapsulation exists only between the converged network adapter on the blade to the fabric interconnect. The encapsulation is removed when the traffic is passed to the Fibre Channel SAN. In this entire process the original Fibre Channel frame is not altered in any way.
Refer to the following document to configure FCoE on UCS.