Optical/IP Networks

Optisphere Claims Record in DWDM Trial

Optisphere Networks Inc., a subsidiary of Siemens AG (Frankfurt: SIE), announced today that it's transmitted multimedia traffic at 3.2 Tbit/s over a single fiber in a live network trial of DWDM (dense wavelength-division multiplexing) at WorldCom Inc. (Nasdaq: WCOM).

The trial announced today is just half the speed of a trial Optisphere conducted last year in a lab in Munich (see Siemens Claims Speed Record). That demonstration appears to have set a new DWDM speed record -- 7.04 Tbit/s over one strand of fiber.

The difference between Munich and this trial, Optisphere says, is that this one was based on real products and was conducted in a live carrier network instead of in a lab.

"There were some aspects of the Munich trial that could be included in actual products, but a lot of what was there won't be commercial for quite some time," says Stephan Rettenberger, director of product line management at Optisphere.

He says a key distinction between what Optisphere did in Munich and what it's doing in its prototypes at WorldCom is that instead of interleaving wavelengths in two directions, it ran all wavelengths in the same direction.

Optisphere set up the trial using a prototype version of its TransXpress Infinity DWDM Platform, which contains DWDM amplifiers and separate transponders that generate line rates. In the trial, the platform issued 80 wavelengths carrying 40-Gbit/s apiece -- 40 in the C band frequency range and 40 in the L band frequency. The wavelengths were spaced 100 GHz apart and run together in one direction over a span of about 250 kilometers. The signal was amplified every 80 kilometers or so, Optisphere says.

Optisphere insists this is a record -- the first time a carrier has trialed a 3.2-Tbit/s DWDM transmission system in a live network.

This claim appears to be true, based on information available at press time. Up to now, field trials have topped out at 1.6 Tbit/s. AT&T Corp. (NYSE: T), for instance, reportedly has been testing a 1.6-Tbit/s platform called the Spectralwave 160 from NEC Corp. (Nasdaq: NIPNY) since last fall. Time Warner Telecom Inc. (Nasdaq: TWTC) has been trialing the similarly equipped Wavestar OLS 1.6T from Lucent Technologies Inc. (NYSE: LU). So far, none of these carriers or vendors has reported tests above 1.6 Tbit/s in field trials with these nascent products.

The announcement isn't a total triumph for Optisphere. For one thing, it can't yet offer the product commercially. The company says a version of TransXpress Infinity capable of handling up to 160 channels at 10 Gbit/s will be shipping in the second quarter of 2001. By the end of the year, Optisphere hopes to ship the commercial version of the platform used in the WorldCom trial.

Also, despite the hoopla, WorldCom hasn't made any commitment to this box. Instead, the carrier says the trial with Optisphere is just one of several it's conducted with a range of optical vendors as part of a multi-step procurement program for optical gear capable of handling terabit-speed data traffic. Still, Optisphere's chances with WorldCom seem good, since the carrier already uses an earlier version of TransXpress Infinity DWDM.

-- Mary Jander, senior editor, Light Reading http://www.lightreading.com

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