FCoE: Fibre Channel over Ethernet

The pitch

10Gbps Ethernet made room for storage and data traffic on one wire, so FCoE encapsulates FCP in an Ethernet header.

The consolidation math per server: native FC needs 4 adapters, 4 cables, and 4 switches (2 Ethernet + 2 FC); FCoE needs 2 of each.

QoS guarantees the storage traffic its bandwidth, and FC’s reliability and performance carry over.

How it works

Above the wire nothing changes: WWPNs, FLOGI/PLOGI/PRLI, zoning, masking, all identical to native FC.

One physical port must carry two personalities, so the CNA (Converged Network Adapter) virtualizes into a vNIC with a MAC for data traffic and a vHBA with a WWPN for storage traffic.

Data and storage ride separate VLANs (see VLANs).

Keeping it lossless

FCP assumes a lossless network; Ethernet drops frames and lets TCP retransmit. Not good enough.

PFC (Priority Flow Control) provides lossless delivery hop by hop, which means every NIC and switch on the initiator-to-target path must be FCoE capable.