IEEE will write 40, 100 Gbit/s Ethernet specs

Engineers struck a consensus this week to pave a road map to both 40 and 100 Gbit/second options for Ethernet networking. The IEEE is expected to set up an official task group to start writing specifications for the data rates starting in March. In meeting in San Francisco, the IEEE Higher Speed Study Group decided […]

Engineers struck a consensus this week to pave a road map to both 40 and 100 Gbit/second options for Ethernet networking. The IEEE is expected to set up an official task group to start writing specifications for the data rates starting in March.

In meeting in San Francisco, the IEEE Higher Speed Study Group decided to support one effort that will draft specifications for 40 and 100 Gbit/s Ethernet. The 100 Gbit/s spec will include versions at 40 and 10 kilometers over single mode fibre, 100 meters over multimode fibre and 10 meters over copper cables.

The 40 Gbit/s proposal mainly backed by companies making data center equipment was the more controversial part of the decision. Just days ago, telecom and networking engineers were at loggerheads over the idea of 40 Gbit/s Ethernet.

Telecom engineers insisted the speed should be made compatible with existing 40 Gbit/s optical transport networks. Networking engineers did not want to see the 40 Gbit/s speed grade at all, fearing it might fragment the market for high speed routers and switches, many of which do not have to link directly to optical transport nets.

In the end, all sides agreed to support three flavors of a 40 Gbit/s standard. They include a version extending 100 meters over multimode fibre, 10 meters over copper cable and one meter over a backplane. In its documents, the group said the 40 Gbit/s spec will "provide appropriate support for the optical transport network."

"I think the wording leaves the door open to a number of ways to accomplish that goal," said Robert Hays, a strategic marketing manager for Ethernet products at Intel who was one of the backers of the 40 Gbit/s proposal. "I think one of the fears some people had going into this was that the 40 Gbit/s proposal would be too restrictive," he added.

In side discussions at the San Francisco meeting, engineers were able to assure themselves that no one group of companies would bear an undue burden making sure 40 Gbits/s Ethernet is compatible with the optical transport networks. Hays added.

"I think everyone felt good about this because we came to an agreement that met most people's needs," Hays said.

Specifically, engineers agreed informally they will work through groups such as the Ethernet Alliance to educate the market about the different market roles they see for 40 and 100G products. The Alliance is already drafting a white paper on the subject.

The 40G speeds mainly will be directed for use inside or between servers and switches and may not be needed until 2011 or later. The 100G products mainly will link switches in data centers and backbone networks and will be needed much sooner, said Dan Dove, a consultant and former long time employee of Hewlett-Packard's networking division who was active in the IEEE effort.

Dove said networking engineers will work to make sure the final specs do not prevent chip makers from designing silicon that can support both speeds. "We don't want to get into a situation where we have to have double the silicon and twice as many systems," Dove said.

More info: EETimes

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