Running Fibre Channel over Ethernet
FCoE has no enemies and is desired by everyone
By Chris Mellor, Techworld | Published: 00:15, 01 November 2007
Emulex has demonstrated Fibre Channel running over Ethernet (FCoE) at Storage Networking World in Frankfurt.
This is an opening public salvo in a revolution that seems to have no enemies at all. HBA vendors, SAN switch vendors, server vendors, storage array vendors; they all welcome FCoE.
New converged enhanced Ethernet
The new way of carrying Fibre Channel has come about because a datacentre-class converged enhanced Ethernet (CEE) standard is being developed. It will operate at 10 Gbit/s and be more reliable than current Ethernet. CEE will not drop packets or frames of data, being termed loss-less, and will have better flow control.
Currently the way of using Ethernet for storage networking is to layer TCP/IP onto the Ethernet protocols, as iSCSI does, and compensate for its 'lossy' characteristic by having TCP/IP retransmit packets that fail to travel from the source to the target. With CEE there is no need for this and the Fibre Channel protocol can be mapped directly onto Ethernet for the first time.
The flow control can be viewed as being analogous to flow control on a motorway (highway) with traffic lights controlling traffic on the on-ramps.
Joe Gervais, a senior marketing director at Emulex, expects an FCoE standard to come into being in 12 to 18 months time: "It's moving very, very quickly." Both Cisco and Brocade were invited to submit proposals to IEEE for a standard, 802.1au. Tom Hammond-Doel, vice chair of the Fibre Channel Industry Association (FCIA) said there was a 90 percent overlap between them. The standard is being created by working out the other ten percent, much of it relating to the precise frame format.
Hammond-Doel said that the FCIA and the T11 standards committee reached a consensus on the frame format in August this year. The FCI expects a stable FCoE standard in the first half of 2008 with OEM seed qualifications starting in the second half of the year. Shippable FCoE product can be expected in 2009.
He points out that FCoE is not routable; there is no TCP/IP which could accomplish this, and that, therefore, FCoE is restricted to Ethernet LANs. To send Fibre Channel long distance you would need FCIP, Fibre Channel over IP, which complements FCoE.
