CorWave hits 3200-km transmission distance

Corvis introduced its CorWave family of products at this year's SUPERCOMM in Atlanta, raising many eyebrows and lots of interest from telecommunications industry customers and suppliers. The Columbia, MD-based upstart, headed by David Huber, founder of CIENA Corp., launched its network platform as the "first all-optical network."

Corvis combines the three capabilities it says are required for next-generation Internet backbones: all-optical switching, transport, and network management into a transparent all-optical mesh. The mesh can be organized into any number of logical architectures, according to Corvis, which permit flexibility to support different traffic and protection requirements in large networks.

The Corvis all-optical mesh increases bandwidth and optical distance with its optical-transport equipment called Corvis Optical Network Gateway 160 and the Corvis Optical Amplifier 3200. The Corvis Optical Router 2400 provides all-optical switching at 2.4 Tbits/sec. The CorManager, a software solution that provides network operators complete control over the mesh network from remote terminals and interactive software, rounds out the product suite.

Carriers can allocate wavelengths to optimize network efficiency and minimize interference, while enjoying smoother migration paths from ring-based topologies to mesh topologies. According to the company, this move can result in a 60% gain in network capacity using existing fiber. Corvis sees its products as a new approach to network design that enables carriers to build a single, unified network to carry such traffic as Internet protocol (IP)/Asynchronous Transfer Mode (ATM), video, and voice, rather than overlay or stack networks devoted to single-traffic types.

A major benefit of the Corvis network approach is its ability to transmit up to 3200 km without electrical regeneration. For long-distance networks, this equates to a substantial reduction in cost by eliminating expensive electrical-generator sites along the network. Optical transparency at network nodes eliminates combinations of discrete network elements such as wavelength-division multiplexing (WDM) terminals, Synchronous Optical Network (SONET) add/drop multiplexers, and electrical crossconnects. Another benefit is reduced provisioning time for coast-to-coast routes-from weeks to minutes--resulting in lower operating costs and faster investment returns to carriers.

Mathew Steinberg of Ryan, Hankin & Kent, a South San Francisco-based industry forecast and analysis firm, says the capability to transmit up to 3200 km without regeneration is impressive. To achieve that distance, four key elements of the network architecture must be addressed. For instance, to achieve higher bit rates, more power per channel is required. Amplifier spacing must be close, or cost savings could be reduced by the need for more amplifier locations. The type of fiber used in existing fiber plants could also affect network characteristics. As in all long-distance networks, forward error correction must be addressed, although it is unlikely to be a limiting factor.

The ease with which Corvis can address these concerns under differing circumstances will likely determine the success of the CorWave platform. Corvis' achievements are drawing attention from some big names in the telecommunications industry, such as Williams Communications Group and Cisco Systems. Williams believes Corvis is poised to shake up the marketplace by creating a fundamental shift that "will give competitive carriers access to tremendous bandwidth and operational flexibility." Cisco states, "Corvis' dramatic innovations in transmission distance, channel count, and optical switching will assist network operators in building cost-effective IP networks."

"When [Corvis] begins shipping, it will be the only company, at this point, shipping OC-48 at 25-GHz spacing," says RHK's Steinberg. "It's doing a lot of good work in that area. People do, however, need to be aware of what circumstances the Corvis system can be optimized."

Does Corvis truly possess the world's "first all-optical network?" It may depend on your definition. For Steinberg, "all-optical" means having an optical signal from the ingress point of the network to the egress point, without any optical-to-electrical conversion in the network.

"I like Mat's [Steinberg] definition because I'm a purist when it comes to definitions," says Corvis's Huber. "But even using Mat's definition, it is an all-optical network as long as the total reach is less than 3200 km...and we're not claiming to go more than that. The point is, you can make a national network out of this with very little regeneration. You have to poke out of the optical cloud if you're going to go further, but as long as you're within the 3200 km, you can make it all-optical."

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