darpa adds startup to monet project

By STEPHEN HARDY

The Defense Advanced Research Projects Agency (darpa) has added a new member to the Multiwavelength Optical Networking Technology (monet) program. The agency awarded a $2.5 million contract to Tellium Inc. (Oceanport, NJ) for the provision of a three-node unidirectional path switched ring in Washington, DC, that will feature wavelength-division multiplexing (wdm) and optical crossconnect technology. The contract is the first Tellium has received since it spun out of Bell Communications Research (Bellcore--Morristown, NJ) last year.

darpa launched the monet project to develop and demonstrate optical networking for government and commercial applications. Original monet team members include at&t, Bell Atlantic, Bellcore, BellSouth, Lucent Technologies, and sbc/tri. As originally envisioned, the project was to include a testbed network in New Jersey that included wdm and optical crossconnects, as well as an optical-ring network in the metropolitan Washington, DC, area. The two networks were to be connected by a long-distance fiber-optic link.

However, according to Tellium`s Farooque Mesiya, president and chief executive, and Richard Barcus, vice president, marketing and product management, darpa wanted to further demonstrate multivendor interoperability and the incorporation of commercial equipment into the program. At the same time, the dedicated long-distance link was dropped from the program. These factors opened the door for a competitive award for a new ring in the Washington, DC, area to complement the network already under contract to Lucent. Tellium won the award, and will now supply both its newly unveiled Aurora4816 optical crossconnect and its forthcoming MetroExpress32 wdm transport system.

Each of the three nodes will have a 16 ¥ 16 optical crossconnect and two wdm systems, according to Mesiya. Tellium will begin delivering the equipment this summer, with service on the ring scheduled to begin early next year. The two Washington rings will connect with each other, Mesiya says. The networks also may expand by another node or two, he says. Bell Atlantic (New York City) will provide the fiber for the rings, while Bellcore will develop the network management system.

Crossconnects provide the gateway

The monet work will provide a platform for the new company to demonstrate both its products and its vision of optical networking. Like the optical networking philosophy espoused by the Cisco and ciena partnership (see related story on page 1), Tellium foresees that carriers will begin to revamp their network topologies in light of the increasing amount of data traffic now being carried by their infrastructures. These new data-centric architectures will see high-speed data pipelines plugging directly into the optical layer at OC-48c (2.4-Gbit/sec) speeds. Unlike ciena and Cisco, however, Mesiya sees the optical crossconnect as the gateway to the optical layer.

"We believe that the optical crossconnect as we view it, which is as a managed network element, will become an important element of the architecture of future optical networks," explains Mesiya. "And we believe that other people also will eventually be offering it. Because I think if you want to bring the survivability function into the optical layer, then you`ll need a network element like that."

As the Tellium principals envision future optical networking, the optical crossconnect will assume many of the restoration and management functions now performed by Synchronous Optical Network (sonet) multiplexers and related digital crossconnect equipment. Current sonet-based backbone networks require OC-48 (2.5-Gbit/sec) channels to be broken down to DS-3 (44.736-Mbit/sec) or DS-1 (1.544-Mbit/sec) signals for grooming and provisioning by very large digital crossconnect systems. According to Mesiya, carriers could install optical crossconnects for restoration and to handle pass-through traffic at their original high speeds and pair the optical equipment with comparatively smaller digital crossconnects for local signal grooming and provisioning. Mesiya estimates that the average savings at a point of presence with this configuration would be $250,000 if 50% of the traffic were to be pass-through signals. In addition to providing cost and space savings, optical crossconnects could provide wavelength provisioning, protection and restoration at the optical layer, and eventually wavelength conversion among traffic from multivendor transmission equipment.

However, Mesiya agrees with Cisco and ciena that sonet equipment such as add/drop multiplexers (adms) will not drop out of the network completely. Such systems will surrender their central role, though. "As most of the growth is occurring in the data side, the traditional role of sonet adm per se, or the multiplexing function of sonet adm, is sort of disappearing from the backbone and core networks of the [incumbent local exchange carriers] and [interexchange carriers] and it is going to the edge of the network. So you`re going to see most of the sonet multiplexing function being performed in the edge of the network," Mesiya says.

"Low-speed, dial-up data and all your voice traffic still have some pretty good growth that the network operators have to accommodate," agrees Barcus. "The sonet multiplexing hierarchy is a good, efficient way to do that."

In addition, the Tellium equipment monitors sonet overhead bits to help maintain network performance. The combination of the use of sonet overhead and the accommodation of traffic sifted through existing sonet adm infrastructures means the optical crossconnects will provide a comfortable migration path to optical networking for established carriers, Mesiya says. q