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Coming soon: Ethernet 40/100G spec

Posted: 09 Dec 2008 ?? ?Print Version ?Bookmark and Share

Keywords:Ethernet? 100GbE standard? network?

The IEEE 802.3ba group is on track to deliver a first cut of the 40 and 100Gbit/s Ethernet standard by March next year. Despite the economic downturn and technical challenges ahead, companies are already gearing up to implement the specification in progress.

At a Nov. 10 meeting in Dallas, the task force received more than 600 comments on its preliminary draft now out for review. The group expects to resolve the comments and have its first technically complete draft out for a vote by the working group in March.

"We're on track at least to get to the next phase," said John D'Ambrosia, a components scientist at Force10 Networks who is chairing the effort. "We are working on cleaning up the document, and there aren't massive changes being made," he added.

The spec supports a wide range of uses spanning 40Gbit/s backplanes to 40km multimode fibre links at 100Gbits/s. It includes 40- and 100Gbit/s links for 10m copper cables.

NetLogic Microsystems recently announced a PHY chip for the spec. A group of companies conducted a 100Gbit/s demo in June.

"A lot of companies are doing evaluation now for what they can do with current and new systems," said D'Ambrosia. "The Internet exchanges and backbones are where you will see changes first," he added.

Telecom carriers were among the first to push for the standard, driven by the need to expand core networks in part to accommodate rising traffic from video and social networking. For example, the Amsterdam Internet exchange reported traffic increased since July 2008 from 300 to 528Gbit/s, D'Ambrosia said.

"The point is bandwidth is growing, customers need a road map and there is a lot of pressure on chip vendors to have solutions," he said.

Some proponents see the 40Gbit/s work serving large aggregation switches in data centers. "For those people, going to 40G will reduce a lot of cables," he said.

The shift won't be easy. Initial products are expected to gang multiple 10Gbit channels, raising multiplexing the thermal issues. "These are engineering problems and they are getting worked out," D'Ambrosia said.

Eventually, vendors are expected to move to 20-25Gbit channels which will create new hurdles in signal integrity and require new connector designs. The Optical Internetworking Forum has launched a program to define interfaces at 20G and beyond.

The 40- and 100G designs will need new levels of equalization, although the spec plans to leverage work done for 10Gbit backplanes in feed forward and decision feedback techniques. The new data rates will also raise issues in crosstalk and test procedures as well.

"These are engineering problems, not show stoppers," said D'Ambrosia.

- Rick Merritt
EE Times

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