Essex Demos 40-Gig Alternative
The demo, in a hotel suite near Baltimore’s convention center, featured Essex’s “HyperFine” widget, a 16-channel multiplexer with 6.25 GHz channel spacing.
The channel spacing is pretty wild. 100 GHz spacing is more normal in today’s networks, and while plenty of vendors are talking about much tighter spacings, most of it is still under development. Ciena Corp. (Nasdaq: CIEN), for instance, has demonstrated 12.5 GHz spacing but doesn't expect to offer it commercially for a couple of years.
On the other hand, this demo comes nowhere close to what Essex was bragging about seven months ago, when it was claiming that it could cram as many as 4,000 channels into a single fiber, using 1 GHz spacing (see Essex Claims 4000-Channel DWDM). Give it another seven months and it might be talking about the same sort of spacing as Ciena, eh?
Essex says it isn’t like that. It’s just that it’s taken a long hard look at the potential benefits of tight channel spacings and concluded that 6.25 GHz spacings will offer the best opportunity for its technology to dovetail with existing DWDM equipment, according to Michael Piacenza, Essex's VP of business development.
Analysts, however, say it’s a classic case of a technology in search of a problem to solve. Essex “needs to find an application where high channel counts has a real benefit in the network," notes Mark Storm, optical networks program leader at Frost & Sullivan. "It's definitely thought provoking, because it affects how systems vendors architect something." Traditionally, tighter channel spacings have been deployed as a means of boosting overall system capacity. But things seemed to have reached an impasse on that front. In next-generation systems, tight channel spacings must be traded off against higher bit rates, leaving systems architects with the complicated question of which is the most cost-effective combination.
Essex is proposing that lots of slow channels will offer the best solution. It plans to use its HyperFine to multiplex 16 OC48 (2.5 GHz) channels together. This would deliver the equivalent of a single OC768 (40 Gbit/s) on the 100 GHz ITU grid.
Piacenza offers several reasons why he thinks carriers and systems vendors should consider this approach. For a start, slow channels travel farther without errors. "Fifty percent of fiber in the ground could not support OC768 data rates," he contends.
Second, he claims that it will simplify equipment at the edge of the network. Individual customers use bandwidth in tiny chunks, which are then aggregated before being moved to a switch, where they have to be unpacked. By using OC48 rather than OC192 or OC768, there is much less packing and unpacking to do at each node in the network.
Last, most carriers use OC48 extensively in their networks, so Essex's product would slot in without requiring them to throw away much of their existing investment.
Of course, it's early days. First, Essex has to convince everyone that its product works, and today's demonstration is the first step in that direction. The company says it is putting together four prototype devices, which it will deliver in August. One will go to a major DWDM components vendor, another to a test equipment vendor -- the HyperFine widget can be designed as a 50MHz filter, which would be great for making an accurate spectrum analyser -- and another to a systems integrator. The final prototype may end up with a long-haul carrier, but that hasn't been confirmed.
"I think everyone in the industry will scrutinize [HyperFine], to try and work out what they can do with it," says Storm.
— Pauline Rigby, Senior Editor, Light Reading
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