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Optical/IP

100-Gig? 40-Gig? Yes, Says Cisco

NEW YORK -- Packet-Optical Transport Evolution 2012 -- Rather than choosing 400Gbit/s or 1Tbit/s as the next standard speed grade, it might be better to have variable port speeds, a Cisco Systems Inc. (Nasdaq: CSCO) keynoter said here.

It's almost certainly not going to happen. But Cisco is floating the idea and verbally trying it out with some customers, says Bill Gartner, vice president of the company's Converged Optical and Routing business unit.

Gartner brought up the idea during a keynote and again in a late-afternoon panel here Thursday. He's not aware of anybody actually working on the media access control (MAC) devices necessary to do this -- and those customers he's mentioned it to seem to like the idea, he told Light Reading after the Packet Optical Transport Evolution conference.

Gartner's group inside Cisco is a manifestation of the greater trend that the conference is all about, namely, the converging of the packet and optical layers. As equipment starts to follow that trend, service providers have to contend with the corresponding human convergence: getting router and transport groups to talk to one another.

That's been happening inside Gartner's group and has been enlightening to both sides, he said.

"One of my experiences is that organizations tend to form around architectures," he said. "I had a college professor who said he could open up an automobile, look at the engine, and he could draw the org chart for the company that built that engine."

Among the operational benefits of combining network layers would be the ability to adjust to demand more quickly. Future capacity usage is "unknowable" for service providers, Gartner said. Collapsing layers together could give carriers more flexibility to react to changes in demand.

Vendors will have to think about how to manage the different scales of the optical and electrical sides, he said, and this is where that flexible port speed comes in. Optical interfaces have reached 100Gbit/s with 1Tbit/s reaching the early phases of planning. But services still come in increments of 1Gbit/s or smaller. How do you get all those 1Gbit/s services out of a 1Tbit/s link?

"Maybe what's next in order to match what's happening in the electrical and the optical layer is not 400Gbit/s or 1Tbit/s, but maybe it's a port that can grow from 25Gbit/s to 50Gbit/s to 75Gbit/s," Gartner said. "That would imply some level of flexible MAC scheme that doesn't exist today."

A flexible port speed would be analogous to what's happening with flexible-grid ROADMs, which allow wavelengths to span different amounts of bandwidth, he noted.

But the "doesn't exist" part is key. For now, the industry will have to eye a plain speed jump to 400Gbit/s or 1Tbit/s, Gartner later noted in an afternoon panel about 1Tbit/s possibilities. But he thinks a variable transport rate, driven by a standardized flexible MAC, is the right answer in the long term.

— Craig Matsumoto, Managing Editor, Light Reading

obaut 12/5/2012 | 5:32:39 PM
re: 100-Gig? 40-Gig? Yes, Says Cisco

Is this similar to ODUflex / G.HAO ITU-T standard, or something beyond these capabilities?

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