Efforts toward 25 Gigabit Ethernet specs stall at IEEE plenary

As described in a Lightwave webcast March 25, major data center operators and their technology suppliers who hoped to create specifications for 25 Gigabit Ethernet found disappointment at last week’s IEEE plenary meetings in Beijing. A proposal to create a study group toward development of a 25 Gigabit Ethernet MAC did not reach a vote when the proposal failed to generate enough support, a source told Lightwave.

The interest in 25 Gigabit Ethernet has grown out of the 4x25-Gbps approaches within the IEEE’s 100 Gigabit Ethernet PMDs. A 25-Gbps interface might be useful as an interim step between 10 Gigabit Ethernet and 100 Gigabit Ethernet and would lead to such products as 100 Gigabit Ethernet cables with 25-Gbps breakouts for connections between servers and top of rack switches. Breakouts of 4x10G leveraging 40 Gigabit Ethernet have found success in the market, according to an IEEE webpage created in the run up to the plenary.

Data center operators such as Microsoft were said to be very interested in development of such an interface. However, sources told Lightwave at OFC that some members of the IEEE community were concerned that a 25 Gigabit Ethernet development effort would deflect resources from ongoing specification work to create lower-cost 100 Gigabit Ethernet interfaces and 400 Gigabit Ethernet technology. (The 400 Gigabit Ethernet effort took steps toward achieving Task Force status at the Beijing plenary.) The advent of 25 Gigabit Ethernet products also might slow adoption of 100 Gigabit Ethernet technology, some were said to believe.

Brad Booth, principal engineer at Microsoft, made the 25 Gigabit Ethernet call for interest presentation at the plenary. Contacted by Lightwave, Booth deferred a discussion of the presentation until next week; however, a lukewarm response from the audience led Booth to not seek a vote to create a study group, according to Lightwave’s source.

The stumble in Beijing probably won’t daunt 25G proponents, however. An industry-driven multi-source agreement (MSA) is a likely next step, the source predicts.

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