Over the last year or so, I’ve had the opportunity to speak with a number of customers about the emerging Fibre Channel over Ethernet standard. The idea of converging Ethernet and Fibre Channel sounds instantly appealing, but the realities of large scale implementations have many caveats with them. Last week Gartner published a paper on FCoE titled “Myth: Single FCoE Data Center Network = Fewer Ports, Less Complexity and Lower Costs”.
Given the release of this paper, I thought it would be a good time for me to share some thoughts on FCoE as well. From my experience, not all customers are aware of some important considerations when evaluating deployments of FCoE. In no particular order.,.
1. While FCoE can converge ports at the server edge, the total bandwidth remains the same. So as you go to aggregation and core, the number of ports required to run 8Gb FC or 10Gb Ethernet will likely remain roughly the same or greater. Replacing relatively inexpensive lossy Ethernet switches with 10Gb lossless ones may actually increase costs substantially.
2. FCoE is literally Fibre Channel running on top of enhanced Ethernet, so both protocols need to be managed. This may reduce expected management savings.
3. For IT organizations with both a LAN and SAN team, FCoE will likely add a new dependence of the SAN team onto the LAN team. This could slow down IT change events as more teams are involved in routine provisioning and maintenance operations.
4. FCoE requires lossless Ethernet to operate properly. Most switches deployed in customer data centers today lack the hardware to support this. As a result, implementing FCoE will typically require a large-scale replacement of switch hardware. Most SAN arrays do not support FCoE natively and would also need to be replaced to support end-to-end FCoE.
5. The lossless Ethernet (DCB) that FCoE is dependent on is not yet ratified by the IEEE. One new protocol for congestion notification across multiple hops (QCN) requires new silicon to fully implement. Even the newer FCoE enabled switches lack the necessary silicon hardware to support QCN, so full implementations will require next generation switches.
FCoE is an interesting concept, but multi-hop FCoE is a bit premature. The standards that take this from a concept to a reality are being fleshed out as we speak by the IEEE DCB Workgroup. For more information on the status of DCB, see: http://www.ieee802.org/1/pages/dcbridges.html.