The status of FCoE

Learn about the two major sets of proposed standards that will enable FCoE in data centers – one that defines mapping of Fibre Channel frames and the other that defines Ethernet enhancements -- and how close to final status they are.

You've been hearing about Fibre Channel over Ethernet (FCoE) for more than two years. So what's its status? The answer to that question is a bit complicated. First of all, it's not just one proposed standard; it's two major sets that, applied together, are designed to enable FCoE in data centers. Second, the two sets are at different steps in their process within different standards bodies.

One set of standards -- the fifth version of the Fibre Channel Backbone standard (FC-BB-5) -- defines how to map Fibre Channel frames to run over networks where the physical and the link layer are not Fibre Channel. Its development rested with the T11 technical committee, which is responsible for Fibre Channel interfaces, within the International Committee for IT Standards (INCITS).

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The other set of standards, known as Data Center Bridging (DCB), applies to the Ethernet enhancements necessary to ensure that FCoE traffic can be transported without packet loss and that bandwidth can be effectively shared between FCoE and Ethernet LAN traffic. DCB falls under the purview the Institute of Electrical and Electronics Engineers (IEEE).

Of the two sets of proposed standards, FC-BB-5 is closer to finalization. The T11 technical committee in June approved FC-BB-5 for submission to INCITS for public review and further processing. INCITS is accredited by, and operates under rules approved by, the American National Standards Institute (ANSI), so the final processing steps are designed to result in an ANSI standard.

Under an ideal scenario, the draft standard -- which is now known as INCITS 462-200x -- could move to final-approval status in early 2010, according to Lynn Barra, director of INCITS Standards Operations.

Meanwhile, products claiming to support FCoE have been on the market for months. Bob Laliberte, a senior analyst at Enterprise Strategy Group Inc., said, "Essentially, it's a de facto standard, and no changes need to be made to the hardware that's being shipped today," such as converged network adapters and switches.

On the enhanced Ethernet side, the proposed standards are moving along, but their status isn't as close to finalization as FC-BB-5/INCITS 462-200x. Active projects within the DCB Task Group of the IEEE 802.1 Working Group include Congestion Notification (802.1Qau), Enhanced Transmission Selection (802.1Qaz) and Priority-based Flow Control (802.1Qbb).

Of the trio, Congestion Notification is the farthest along in the standards process. A sponsor ballot is due to end on Nov. 29, but if any concerns or comments surface, they need to be addressed. Recirculation ballots are not uncommon, further extending the time frame.

"It's usually pretty stable at this point, but we won't know for sure until the end of the month," said Patricia Thaler, who chairs the DCB Task Group.

The 802.1Qau proposed standard will allow any point in the network that is experiencing congestion to send notifications to the congestion sources so they can slow the transmission rates. Thaler estimated finalization could happen some time between March and September 2010, with the timing contingent, in part, on when various groups meet.

A draft of Priority-based Flow Control is also up for a vote this month, but the ballot is at an earlier stage in the process, by the 802.1 working group. If interested parties have issues with a proposed standard, they typically raise them at this stage.

Priority-based Flow Control provides the ability to pause traffic, based on its priority, while allowing other traffic to flow. Thaler expressed hopes that the proposed standard will go to sponsor ballot following a March 2010 meeting, with finalization in September or December.

Enhanced Transmission Selection is expected to finish in the same time frame, since parts of Priority-based Flow Control are dependent on it. The 802.1Qaz proposed standard provides a standard way to manage bandwidth allocation to different classes of traffic, so each gets a share.

Another standard, known as Media Access Control Frame for Priority-based Flow Control (802.3bd), defining the frame that is sent for priority flow control, is also in the works. Thaler said she hopes that one will also be done by December 2010.

While some industry analysts advise that IT organizations wait until the standards reach completed status before investing in FCoE equipment, vendors and other analysts disagree. "There's nothing that will be added that will alter the products that are already shipping because we know from the development of standards what is going to be done," claimed Ahmad Zamer, a senior product manager for new technology protocols at Brocade Communications Systems Inc. "This is basically like building a 10-story building. You already built your ninth floor. You know where the 10th floor is going to go in the building."

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