ROADM platforms gain momentum: DWDM vendors drop price points, expand offerings.

America's Network, April 1, 2004 by Peter Lambert

To build a network once, then provision it as many times as required. It seems a small thing for service providers to ask.

Yet it has been too much to ask in metropolitan area networks, where setting up and tearing down high-capacity optical wavelength connections for business service transport has been hamstrung by the exorbitant costs of manual configuration.

In short, carriers have been starved for provisionable dense wavelength division multiplexing (DWDM) in their metro and access networks but unable to swallow the costs.

That dilemma is about to change.

By all accounts, a new wave of DWDM vendors, led in particular by Movaz Networks Inc., Photuris Corp. and Tropic Networks Inc., has all but solved the challenge. They are delivering working reconfigurable optical add/drop multiplexing (ROADM) products at affordable price points. Movaz characterizes the cost of ROADM as "a small premium" with a typical return counted in months. Photuris claims there is no real premium at all.

In any case, the price may now be called irresistible, says Michael Howard, principal analyst for Infonetics Research. He adds that prices will drop further over the next two years with help from leading DWDM and synchronous optical network Sonet/SDH equipment suppliers such as Cisco Systems Inc., Lucent Technologies Inc. and Nortel Networks Ltd., as well as ECI Telecom Ltd.'s Lightscape division, Internet Photonics Inc., Lumentis AB and Photonic Bridges Inc.

OUT OF THE BLOCKS

For ROADM, the momentum begins now.

Photuris claims the first ROADM platform delivering live traffic for a Texas A&M University inter-office network, as well as a place in three RBOC labs.

Lucent was impressed enough with Movaz Networks' RAYstar wavelength switching platform and RAYtracer management system to enter a DWDM and ROADM co-development deal with Movaz in late February.

Tropic Networks' Wavelength Tracker technology for identification and management of every wavelength traveling throughout an optical network across its TRX-24000 metro-optical transport platform has drawn more than $80 million in funding and former Global Crossing chief Robert Annunziata as its chairman.

Further, according to Photuris and Infonetics, RBOCs have issued one request for proposals (RFP) and one request for information (RFIs), with a second RFI expected later this year; several competitive local exchange carriers have issued RFPs; and one inter-exchange carrier plans an RFI this spring.

DEMAND AND SUPPLY

What these service providers are after is the ability to open a workstation window to provision an end-to-end connection for a Gigabit Ethernet, storage area network (SAN) or any other high-speed service to travel 50 to 1,000 kilometers, office to office. In a manner analogous to virtual private network (VPN) configuration, they want to click on the end-points and go.

Current DWDM technology does not afford this luxury. Instead it requires manual configuration of each inter-office service connection, not only at the ingress and egress end-points of the service, but at each of a dozen or more add/drop nodes between. Consequently, notes Ashish Vengsarkar, vice president of product marketing and co-founder of Photuris, provisioning a new high-speed, inter-office connection forces carriers to stack one expensive Sonet/SDH ring atop another.

This, he and others point out, is not building a network once and provisioning it ad infinitum; it is building a new network every time service mixes change and available connections become exhausted--two events becoming increasingly common in inter-office networks.

"The metro core or metro regional, inter-office network is where the traffic is very unpredictable," Vengsarkar says. "You forecast a certain amount of traffic then throw out the forecast as real traffic evolves, which requires reconfiguration. This is where the first big impact will be."

Using emerging generic multi-protocol label switching (G-MPLS) control plane standards, ROADM maps wavelengths from metro access through metro core. Eventually, it could take over all grooming of traffic above OC-3 (155-megabit-per-second) speeds and push the Sonet ADM's traditional job of grooming sub-wavelength DS-1 and DS-3 traffic out of the core toward the customer.

NO FORKLIFT

Advocates characterize ROADM as a Sonet enhancement, not a replacement. "What we do replace is the method of deploying Sonet, such as the stacking of Sonet rings," Vengsarkar explains. "We replace it with the stacking of 32 wavelengths on a single pair of fibers."

Multiple benefits may accrue in stages. First ROADM equalizes signal loss across all wavelengths, reducing the need for costly signal boosting equipment. Then, as customers demand service connections to support SAN and other applications from office to office, reconfigurability "comes essentially for free," says Movaz chief technology officer Zouheir Manzourati. "If the node requires no add/drop, we don't charge for add/drop functionality at that node."

Further, ROADM employs switching fabrics that can multiply fiber ring flexibility beyond east-west ring ins and outs to an integrated wavelength selectable switch (IWSS) mesh of multiple directions at each node, relieving carriers of unnecessary optical-to-electrical-to-optical conversion of pass-through traffic.