Fibre Channel over Ethernet (FCoE)
A converged protocol that carries Fibre Channel storage frames directly inside Ethernet frames, so storage and data traffic share one network, without IP and so without IP routing.
Fibre Channel over Ethernet encapsulates Fibre Channel frames, the protocol of traditional storage area networks, directly inside Ethernet frames. It was standardised by the INCITS T11 committee in its FC-BB-5 standard. The aim is consolidation: one set of adapters, cables and switches carries both data and storage traffic. It needs Ethernet extended with lossless data centre bridging features, because Fibre Channel expects no dropped frames.
FCoE is a commonly cited example of converged protocols, and the comparison most likely to matter is with iSCSI. iSCSI carries storage commands over TCP/IP, so it can be routed. FCoE runs at layer 2 with no IP header, so it cannot be routed across IP networks. Security follows from the convergence: storage traffic now shares a physical network with everything else, so separating it logically, for example with a dedicated VLAN and Fibre Channel zoning, becomes a key control. Carrying frames inside Ethernet adds no confidentiality of its own, so encryption, where it is needed, has to come from elsewhere.
Exam relevance: questions in this area tend to turn on the difference between FCoE and iSCSI. Storage over Ethernet without IP points to FCoE; storage over routable TCP/IP points to iSCSI. Candidates are also expected to see that converging networks makes segmentation more important, not less.