Details of the architecture will remain under wraps until Monterey undertakes field trials later this year. But product line manager Stevan Plote said this past week at a DesignCon panel on wavelength-division multiplexing (WDM) that his company's system will use a hybrid electronic/optic switch to route data flows at the optical layer.

That decision reflects an apparently growing sentiment that all-optical switches may not be the most practical means for achieving optical signaling.

H. Michael Zadikian, vice president of marketing at Monterey, said in an interview before DesignCon kicked off that the breakthrough behind his company's architecture was the decision to replace the ring topology commonly used in time-division-multiplexed (TDM) Sonet networks with an any-to-any mesh. By placing network intelligence in the optical domain, Monterey's architecture will handle bandwidth provisioning and end-to-end path restoration in less than 50 ms. Use of a mesh topology will save 30 to 60 percent of the necessary restoration bandwidth, Plote predicted.

Warp borrows aspects of the ATM Forum's Private Network-Network Interface (PNNI) protocols and of the Open Shortest Path First data-routing protocols, adapting them to the optical domain. Monterey's Wavelength Router will connect to multiple dense-WDM terminals, linking passive WDM equipment to high-speed Internet Protocol routers, Asynchronous-Transfer-Mode switches, and Sonet add/drop multiplexers and cross-connects.

Monterey will not seek to displace Sonet equipment already in carrier networks; rather, it will look to move that equipment further out to the edge and establish the Wavelength Router, the backbone network arbitrator and aggregator. The primary market for the optical router will be the new breed of interexchange carriers that serve as "bandwidth brokers," such as Williams Co., Level 3 Communications Inc. and Qwest Communications International Inc.

Monterey, which recently relocated to Richardson, Texas from the Bay Area, is hardly the only company to have moved beyond passive dense-WDM equipment. Companies ranging from Alcatel and Lucent to small startups are expected to announce post-WDM equipment plans at the Optical Fibers Conference. And Tellium Inc. — whose chairman, Farooque Mesiya, was also on the DesignCon WDM panel — has developed optical cross-connect systems that eliminate the need for Sonet-layer digital cross-connects in a network.

While the new optical data equipment does not use micromechanical or lithium-niobate components that truly switch an optical signal, Mesiya argued that a true optical switch may be largely irrelevant for practical networks that wish to turn to optical signaling.

"It's not even clear that it is desirable to have an all-optical switch, since you need to extract certain bytes from the network, such as B1 and J0, in order to verify connectivity," Mesiya said. "If you are going to make that opto-electronic conversion anyway, what point does the all-optical switch serve?"

By contrast, Mesiya and Monterey's Plote said, systems that can route and add/drop data flows as combined wavelengths can assume many of the network-protection duties of the Sonet layer, perhaps allowing most TDM Sonet equipment to be moved out of the long-haul backbone. Plote predicted that Sonet systems will move to the network-access edges, as optical routing and cross-connect systems without a Sonet layer move into the network core.

Territorial spat
Meanwhile, the access networks at the edge of the broadband backbones are becoming disputed territory for Sonet and WDM. DesignCon WDM panelist James Chitkowski, senior vice president of sales and marketing at Osicom Technologies Inc., made a viable case for using WDM channelization in metropolitan-area rings, where "the time-to-market is literally 24 hours" for provisioning new services. Osicom's GigaMux can provide moderate-density WDM over fiber rings using various protocols.

Many companies already have demonstrated WDM over Gigabit Ethernet within metropolitan rings. Chitkowski suggested that WDM's protocol agnosticism could make even such storage protocols as Escon and Fibre Channel fair game for WDM channelization in the future.

Other newcomers are sticking with Sonet, albeit with a few new wrinkles, for the metropolitan area. Startups Atmosphere Networks Inc. and Omnia Communications Inc. launched architectures in the past year that link ATM virtual path technology with Sonet framing structures.

This month, optical startup Cerent Corp. (Petaluma, Calif.) is expected to introduce a packet-over-Sonet architecture that makes use of Sonet line rates and framing, without the time-division multiplexing of traditional Sonet hierarchies.