dwdm offerings compete for metro applications

Nov. 1, 1997

dwdm offerings compete for metro applications

By STEPHEN HARDY

From startups to well-established competitors, fiber-optic equipment manufacturers across the board--with, perhaps, one notable exception--have decreed that the next big application for dense wavelength-division multiplexing (dwdm) will be short-haul and metropolitan-area networks. Nearly every supplier in this field believes these new offerings have arrived ahead of market demand. The question is by how much.

The David amid a legion of Goliaths is Cambrian Systems Corp., Kanata, ON, Canada. Cambrian, a Newbridge company, says that its new optera system provides ring protection switching with both bit-rate and protocol independence. According to Don Smith, president of Cambrian, optera will provide 2.5 Gbits/sec over each of 32 wavelengths, for a total capacity of 80 Gbits/sec. The system will support such protocols as OC-3 (155-Mbits/sec), OC-12 (622-Mbits/sec), OC-48 (2.5 Gbits/sec), 100BT, Synchronous Optical Network (Sonet), and Gigabit Ethernet, he says. Applications include point-to-point, mesh, and ring configurations. The unit will support a 30-km ring with no optical amplification. A Telecommunications Management Network (tmn)-based system with a Web-browser-based graphical user interface provides operational oversight.

Cambrian`s bid for market acceptance should receive a boost from its big brother, Newbridge Networks Corp., also in Kanata. Newbridge will use the optera system as part of an Asynchronous Transfer Mode (atm)-based Distributed Service Delivery offering it will provide using the Siemens/Newbridge MainStreetXpress product line. Combining the optera with the MainStreetXpress 36170 Multiservices Switch, Siemens, of Munich, Germany, and Newbridge say the new offering will deliver services such as frame relay, private line, cell relay, and Internet protocol (IP) without the need for Sonet multiplexers.

Cambrian will have to move nimbly in the metro arena if it is to avoid being trampled by the rush of fiber-optic giants who have suddenly made this a very crowded market. For example, Lucent unveiled its Metro Optical Line System (ols) at roughly the same time as Cambrian introduced the optera. Available this month, the Metro ols also provides a wide range of interfaces, including OC-3, OC-12, and OC-48 Sonet as well as "any data rate or format" in the 150- to 750-Mbit/sec range, including ibm`s Escon networking interface. A new Broadband Optical Translator Unit provides this protocol transparency. The unit will support up to 16 wavelengths over 132 km. It can operate in such configurations as ring, linear, and add/drop. Lucent plans to offer an optional optical protection switching feature for the ols next year.

Meanwhile, ciena Corp., Linthicum, MD, announced two dwdm products for short-distance applications. The MultiWave Firefly addresses short-haul point-to-point public network applications, while the MultiWave Metro will be targeted at metropolitan area networks. The MultiWave Metro will be applicable to ring, mesh, and point-to-point applications and will accommodate 16 wavelengths. Depending on the number of nodes involved, it will support a ring 60 km in circumference, according to Steve Chaddick, the company`s senior vice president of products and technology. Like the Cambrian and Lucent offerings, ciena`s product will simultaneously accommodate a variety of traffic, including Sonet/Synchronous Digital Hierarchy (at OC-12 and OC-48 for the former and stm-4 and stm-16 for the latter), atm, and fast IP. The unit, which will be available during the second half of 1998, will enable traffic to be added or dropped around the ring.

Another industry heavyweight, Alcatel Network Systems, Richardson, TX, also has a metro product in the wings. Called the optinex Local Exchange Terminal, the system is part of the company`s new optinex optical networking product line. The system will handle up to 16 channels of OC-48 and OC-192 (10-Gbit/sec) traffic for a maximum of 160 Gbits/sec on a single fiber. It will transmit up to 80 km without amplifiers and carries tmn interfaces for network management.

For its part, adc Telecommunications Inc., Minneapolis, MN, has a 16-channel dwdm system in prototype that company sources say could also be used in metropolitan networks. The system uses fused biconic taper technology and fiber Bragg gratings to minimize insertion loss. The modular system will be capable of upgrade in 8-channel increments to cover the 32-channel International Telecommunication Union grid, and will provide add/drop capability as required. adc sources predict the system will be available by the end of this year.

Fujitsu Network Communications Inc., Richardson, TX, also has a dwdm system on the drawing board, with a target delivery date of the second quarter of 1998. The system, says a company source, will accommodate up to 32 wavelengths of OC-48 or OC-192 in any combination. The system will be scalable from one wavelength to the full complement of 32. It will work with both conventional singlemode and non-zero dispersion-shifted fiber in both long-haul and metropolitan applications.

These new offerings join the T-31 omds16, which Pirelli Telecom Systems Group, Lexington, SC, introduced in June of this year (see photo on page 1). Described as an optical multiplex carrier system, the unit combines wdm and optical amplifier technology to transmit 16 channels up to 55 mi. It accommodates speeds from 140 Mbits/sec to 2.5 Gbits/sec.

Market pull?

The big question, of course, is whether local exchange carriers see a reason to buy this equipment--and if so, when. Scott Grout, Sonet product marketing and management vice president at Lucent, told a group of reporters at the recent National Fiber Optic Engineers Conference (nfoec) in San Diego, CA, that he felt the Metro ols was leading the market by about 6 to 12 months. However, he feels that three factors will drive local exchange carriers to adopt the technology. First, carriers in the metropolitan market can`t afford to install new fiber to meet increasing bandwidth demands. Many of these carriers, says Grout, also would like to avoid adding Sonet capabilities to their metro networks--making an optical protection capability an attractive feature in dwdm systems. Finally, Grout feels the addition of dwdm equipment does not represent a big investment for the carriers.

Investment may be an important point for potential customers. "Local exchange carriers increasingly are faced with problems associated with fiber exhaust," said John Ryan, principal at research firm Ryan Hankin Kent, San Francisco, CA, in a press release circulated by ciena. "Until now, dwdm has not been an option because the price points of products designed for long-distance applications have been prohibitive when applied on shorter links. Our analysis now shows that dwdm can be economical at lower speeds and over shorter distances."

Meanwhile, ciena`s Shadduck agrees that while the metro market is generally ready for dwdm, it might take six months to accurately measure the demand. The quick acceptance of asymmetric digital subscriber line would put pressure on carriers to upgrade their metropolitan backbones quickly, he says, further speeding the requirement for dwdm. He also noted that short-haul dwdm configurations might prove popular in Europe, where major traffic centers are relatively close together.

However, not everyone is ready to jump into the metro dwdm pool. For example, Nortel, St. Laurent, QC, Canada, is conspicuous by its absence in that market. Queried at nfoec, Brian McFadden, assistant vice president, high-capacity applications, Sonet networks, said that the company has already demonstrated its abilities in this area through a project sponsored by the Defense Advanced Research Projects Agency. However, he said Nortel doesn`t believe the demand required to launch a product is currently forthcoming. He also said that certain management, operations, and scalability issues remain to be addressed before dwdm is ready to fully penetrate the metropolitan marketplace. q

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