New frontier for DWDM: Some RHCs hot on DWDM for their networks, others more wary

Despite a continued evolution that has included hundreds of additional channels and terabit-sized capacity, dense wavelength division multiplexing is a relatively mature technology in the long-haul environment.

Long-haul carriers have been deploying WDM since the advent of two- and four-channel systems in the late 1980s. Long-distance service providers and long-haul fiber network operators have long been able to reap financial benefits from expanding network capacity without laying new fiber along congested routes.

But the story has been very different for Bell regional holding companies, which are just now beginning to consider deploying DWDM systems in their networks. Some have made sparing use of DWDM in internal networks, but none has adopted the technology at nearly the level of its long-distance counterparts.

That is rapidly changing, however. The incumbent short-haul carriers have kept an eye on the progress of DWDM all along, and now they are beginning to see openings in their networks for the technology.

Bell Atlantic could be characterized as the most aggressive incumbent in terms of DWDM deployment. At an Institute for International Research DWDM conference last month, Bob Gallo, a member of Bell Atlantic's technical staff on outside plant transmission and future technologies, discussed trials that Bell Atlantic has conducted and plans for impending field deployments.

Within two weeks, Bell Atlantic announced a network upgrade that includes DWDM equipment from Ciena Corp. and Lucent Technologies, the first such announcement from an RHC.

But the contracts do not represent a wholesale switch to DWDM over other capacity-enhancing measures, said Carolyn Golematis, integrated network planning director for Bell Atlantic. Instead, the technology will be used on routes where cost studies have shown that DWDM deployment is more effective than laying new fiber or upgrading to OC-192 transmission (see figure). It will be deployed over relatively long spans in the network, generally between Bell Atlantic switching centers.

"We're looking at seven- to 10-mile span lengths, and determining the growth that's expected in those spans," Golematis said. "If we need quite a few fibers, we're better off laying the fiber."

But Bell Atlantic still is in the early stages of serious deployment. Neither vendor has completed testing-Lucent is on its way to the lab, and Ciena is preparing to go to field trials.

Mathew Steinberg, optical networking director for Ryan Hankin Kent, described Bell Atlantic as the first RHC to "write a big check" for DWDM systems. The other Bell companies all have examined requests for proposals for systems, but they have not yet decided to shell out the capital.

"If you look at the [DWDM] systems that are available today, you have to look at [deployment decisions] on a case-by-case basis," Steinberg said. And its not an easy decision. When comparing DWDM and alternative measures, "they all may make sense," he said.

Although Bell Atlantic sees a need for DWDM in its network, that doesn't mean the rest will necessarily follow soon. For incumbent LECs with large installed network bases, the issue of fiber exhaust is just now reaching a critical mass. And because DWDM offers no value-added applications to date, some incumbents have seen no need to deploy.

SBC Communications is still quite bearish on deploying DWDM. A spokesman confirmed that SBC is in the middle of an RFP but said the company is looking for evidence of economic feasibility.

At the IIR's DWDM forum, SBC presented a very different view of DWDM than Bell Atlantic. Although DWDM will be an important technology in the short haul-first for capacity and fiber relief, then for optical networking-at this time, SBC can't find an economically compelling reason to deploy, an SBC official said.

"There seems to be something missing," said Glenn Estes, technology vice president for SBC Technology Resources Inc., which is conducting SBC's DWDM evaluation program. "There's not the killer app that there was in the long-distance business."

The lack of an obvious application, combined with what SBC considers the still-too-high cost of DWDM in metro environments, will likely keep DWDM out of SBC's networks for now, Estes said.

"It's either going to have to be a killer app, or it's going to have to be better in price," he said.

BellSouth's stance falls somewhere between Bell Atlantic and SBC. BellSouth has used DWDM in its corporate network for several years but is compiling an RFP to be issued in June or July for broader deployment. The company has been lab-testing one vendor's equipment to in preparation for issuing the RFP, said Ken Cook, BellSouth's infrastructure planning group manager. "It's a technology evaluation as opposed to a product evaluation," he said.

Still, BellSouth plans to move quickly once the RFP is issued.

"It's highly possible we could see deployments this year," said John Spencer, transport systems engineering manager for BellSouth. "Much depends on how the responses to the RFP look."

U S West also has been lab-testing equipment, and it has already issued an RFP.

"We were getting unsolicited proposals with prices that made [DWDM] more appealing," said John Boe, director of network strategies and technology selection for U S West.

Price, applicability and the inability to provision DWDM into legacy systems have been the major barriers to metro deployment, Boe said. Now that price is coming down, Boe echoed the opinion that DWDM's initial application will be to provide capacity on long interoffice spans.

But for continued growth, DWDM must eventually provide revenue-enhancing applications, he said. "You can rate different types of services, offer different wavelengths, as soon as the price stabilizes and [DWDM] access matures," Boe said.

The vision of DWDM as a differentiated service tool is universal, BellSouth's Spencer said. "We all have a vision of working toward a platform that would allow us to do optical networking," he said.

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As local network operators begin to consider dense wavelength division multiplexing seriously, vendors are beginning to focus on applications targeted at local networks. Two have laid out their plans to expand DWDM's role from virtual fiber creator to service provisioning tool.

Ericsson is developing Erion, an optical networking system with DWDM rings and survivable point-to-point connections. Alcatel recently announced so-called optical gateways that are designed to aggregate individual wavelengths carrying low bandwidths into the multi-gigabit wavelengths that traverse long-haul networks.

These rather similar solutions are both aimed at giving short-haul carriers the building blocks for optical networks and, in Alcatel's case, end-to-end wavelength provisioning.

"Carriers are ambiguous about how they want to use [DWDM]," said Tim Krause, senior business development director for Alcatel's optical networks division. His company has received everything from requests for information to requests for quotations from every incumbent local exchange carrier and most major competitive LECs, he said. "The real interest in the technology is what it's going to do in large metro deployments," he said.

Ericsson's Erion system will include DWDM rings that incorporate survivability at the optical layer rather than the Sonet layer. It also will multiplex up to four traffic streams onto a single wavelength, reducing the need for additional channels and the costly lasers required to deliver them.

"The idea is a system that's able to carry multiple speeds and multiple traffic streams on a single wavelength," said Jose Maria Daza, business development vice president for Ericsson's transport and cable networks business. It's designed to "bring a different dimension to optical networking."