System vendors offer thoughts on ROADM components

By Meghan Fuller Hanna -- System vendors say they are anxious to meet with their ROADM component suppliers at next week's OFC/NFOEC.

By Meghan Fuller Hanna -- System vendors say they are anxious to meet with their reconfigurable optical add/drop multiplexer (search for ROADM) component and subsystem suppliers at next week's OFC/NFOEC Conference in San Diego. In particular, they will be trolling the show floor looking for component technology that will enable colorless capability and directionless switching.

Most ROADMs today are colored, meaning particular ports are still associated with particular wavelengths. Operators must manually connect the fiber at the end points for service turn up. As such, a number of operational benefits could be attained from removing this restriction. In a colorless configuration, any wavelength could be connected into any client port on the ROADM, enabling operators to pre-fiber transponders.

"If you're trying to do fully software-provisioned services whereby you don't even have to touch the end points when you turn up the service, you could have it all pre-fibered," explains Paul Morkel, senior director of business management, carrier WDM, at ADVA Optical Networking (search for ADVA Optical Networking). "Then you set the wavelength at the time you need the service, and you decide which wavelength you want to use at that time." In that case, he says, you really need to have colorless capabilities.

"And that's where a 20-degree wavelength selective switch [search for WSS] is very interesting," he continues. "Because the wavelength-selective switch ports themselves are colorless, you can use those not only for network connections but also for the client connections."

"You will need a WSS with a higher port count than the currently available device," agrees Ram Orenstein, associate vice president of product line management in ECI Telecom's (search for ECI Telecom) Optics Division. He believes such higher density subsystems are on the roadmap of leading component vendors and should be available in the next two to three years.

Hand in hand with colorless capability is the need for directional or directionless switching, which Cisco Systems (search for Cisco) claims to have been the first to develop in both hardware and software. Directionless switching is the ability to connect any client port or interface to any network port in a two-degree or multi-degree ROADM.

Russ Esmacher, manager of technical marketing for Cisco's Optical Transport Business Unit, argues that a colorless configuration without directionless switching is "completely useless. Great, I have the ability to have colorless, agnostic ports," he says. "Too bad I'm assigned to direction north. I need that to go out to the west, and I need to change that without moving any cables."

System vendors like Cisco are now relying on the component vendors to deliver the requisite port density to enable these new features. "We're waiting for it," reports Esmacher. "We have the architecture built and the software going for it. We just need better density. When we sit down and talk to our [component] vendors, these are the things we ask them about, very strongly."

There is good news, says ADVA's Morkel: "Wavelength-selective switching is a platform that is capable of doing more than has been implemented in the first generation of ROADM," he contends.

System vendors like Cisco are also looking to develop edge ROADMs, which will give network operators the key benefits of ROADM--including single-channel granularity and auto-power balancing--in a smaller, less expensive chassis. But, again, they'll need help from their component suppliers to achieve the requisite performance and price points for widespread deployment at the edge. Esmacher confirms that Cisco "has definitely been pointing [component vendors] to the edge. Hopefully, they will follow."

"We definitely want to see miniaturization," Esmacher reports. "That's something we desperately need at the edge and at the metro core. What takes me three slots today, I'd love to do in one slot tomorrow. So we are pushing heavily on our vendors for miniaturization."

Moreover, Esmacher says he could challenge the component vendors to develop hardened products. "Traditionally, metro and long haul are in nice carrier hotels or in environmentally controlled huts," he notes. "At the edge, that might not be the case. So we actually have to start having them look toward the ability to harden some of their packages."

For his part, Esmacher says the ROADM market, once new and exciting, is starting to feel "like old hat. So what do you do with it?" he muses. "You make it smaller, better, cheaper. We're definitely going to find out [next week] where the industry is. It's a good time for us to meet with all our suppliers face-to-face at OFC," he says.

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