Migrating to the metro: All-optical wavelength routers move into new territory

As demand for high-bandwidth metro networks increases, the need for cost-effective - yet high-capacity - metro wavelength routers also increases. While earlier generations of metro networking equipment often was too expensive for many carriers, new all-optical solutions offer increased capacity, more protection options and the ability to multiplex multiple signals onto a single wavelength at a lower price.

Toward that end, Sorrento Networks unveiled its TeraMatrix all-optical wavelength switch router. The device uses a switching technology based on multiprotocol label switching (MPLS) to intelligently route signals and protection paths from ATM switches and IP routers. That capability eliminates the need for Sonet equipment.

With MPLS capabilities, the TeraMatrix also can operate as a pure optical add/drop multiplexer for ring and mesh networks, eliminating the need for electrical conversion in the metro. With Sorrento's software, a carrier can migrate in stages, from Sonet rings to point-to-point wave division multiplexing (WDM), to WDM rings, to an optical mesh architecture with dynamic add/drop capabilities, said Baksheesh Ghuman, vice president of marketing for Sorrento.

The company plans to test the equipment later this summer and already has developed a customer base that wants an affordable, scalable system, Ghuman said. "Up until now, what [equipment providers] offered was a fragmented [DWDM] system not meant to act as network," he said. With access, transport and management capabilities, TeraMatrix allows carriers to have an end-to-end solution, he said.

Growth in the overall metro market has been quite slow, which Ghuman attributes to costly, inflexible equipment. A modular, scalable product is more reasonable than buying a whole system, he said. "Customers are looking for solutions that don't require them to spend big money."

Sycamore Networks also is moving into the all-optical metro space with its SN 8000 MC, a metro version of its long-haul SN 8000 transport platform. Sycamore designed the system by adding a few key elements to address different types of markets, said Bill McCullen, director of product marketing for transport products at Sycamore. The company added lower-cost lasers and amplifiers and single-wave add/drop cassettes, which allow a carrier to modulate wavelengths throughout the network. "Each node can be customized with specific wavelengths being add/dropped at each node," McCullen said.

While Sorrento developed a switch specifically for the metro area, Sycamore modified its long-haul solution to fit the metro space. Both market approaches are equally valid as long as the solution is cost-effective, said Andy McCormick, senior analyst of optical communications for The Aberdeen Group.

Cost is a key factor for metro rollouts. The second and third generations of metro transport optics are priced significantly less than the first systems from Ciena, Lucent Technologies and Nortel Networks, McCormick said. The newer systems can cost between $20,000 and $40,000, compared with $150,000 and above for the older systems.

Still, the systems are not economical unless they have optical interfaces for ATM switches and IP routers and can interconnect with Sonet equipment, McCormick said. "But these systems are less applicable if a carrier already has Sonet boxes. They won't need a DWDM box unless it's in a high-traffic area," he added.

In addition, with Metromedia Fiber Network and Level 3 Communications laying more fiber and pricing that fiber affordably, it could be cheaper for a carrier to lease more fiber than buy an expensive box, McCormick said. "They could buy a lower-end Sonet box and light new fiber rather than spend $40,000 on a DWDM box."

All the available options are likely to propel the optical metro market. By the second half of this year, equipment providers will see more customer wins, McCormick said. "And by 2001, I think it will jump up."