So I spent a day at Cisco last Friday for a cram training session on Cisco’s new Nexus range of switches, aside from some very impressive features of the switches by way of flexibility, speeds and feeds (12 Terrabits per seconds capability of you’re interested) and some very cool virtualisation features in the switches; one thing that came up was FCoE (Fibre Channel over Ethernet) which effectively encapsulates a Fibre Channel frame into an Ethernet frame with no extra frills, no additional clunky IP protocols.. keep it simple, keep it quick, as opposed to iSCSI which is used to carry SCSI commands and provide block level storage connectivity over TCP/IP which is prone to packet loss. FCoE uses something coined enhanced Ethernet and something called priority flow control where packets are embedded with Class of Service (CoS) value.. where packets with a certain CoS value (namely FCoE packets) utilize no drop, reliable behavior and other packets use the familiar ‘Best Effort’ Policy as traditional Ethernet does. This means that Ethernet can be a viable medium to carry fibre channel traffic within the data center, where iSCSI is not. Don’t get me wrong, iSCSI still has its place, FCoE is currently only supported over 10GbE and it will be a while until many organizations adopt 10 GbE fully.
Currently FCoE is geared more to the datacenter, the idea being that less cabling is required within the datacenter rack as both storage connectivity and standard IP traffic can be delivered through one form of connectivity; no need for NICs and FC HBA’s… Converged Network Adapters or CNA’s are the new flavour (basically a NIC which supports FCoE). This means that server build times are reduced, doubling up on switching infrastructure to support FC and IP traffic is no more, cabling is reduced and everything is generally tidier.
There are still arguements against FCoE.. to site one example from the blog Etherealmind.com and the flip coin of the arguement from a Cisco Chappy Dante Malagrino (see here for his response to the previous link), so its not to the taste of all…
Have a dig into it and make your own judgements.
Some good sites of reference :