Operators Hang Big Hopes on ROADMs
Next-Generation ROADM News Analysis Craig Matsumoto, Editor-in-Chief, Light Reading 9/9/2010
The products and architectures to create that network were the subject of yesterday's Light Reading Webinar, "The Need for Next-Generation ROADM Networks."
The technologies, some of which are still emerging, add up to a more flexible optical network, one that can be remotely reconfigured on the fly. The goal is to keep traffic in the optical domain for as long as possible, said Webinar speaker Glenn Wellbrock, director of backbone architectures for Verizon Communications Inc. (NYSE: VZ).
Lower-layer transport tends to be less expensive, so a network that takes better advantage of the optical layer, as opposed to switching and routing, could have lower capital and operational costs. Moreover, now that ROADMs are ensconced in the network, operators find themselves wishing the devices could be more automated -- a dream that, admittedly, isn't new.
"Full reconfigurability has been on the operator wish list from day one, the early part of this decade, but it's taken time for the technology to mature to the point to make this actually possible in the network," Heavy Reading analyst Sterling Perrin said in his introductory remarks.
Operators want ROADMs to be colorless (delivering any wavelength to any port), directionless (allowing ports to send traffic in any direction on the network), and contentionless (allowing wavelengths to get reused by different ports in a node). Speakers on the Webinar outlined those requirements, which are apparently abbreviated as CDC these days.
Wellbrock also discussed gridless -- or, more properly, flexible-bandwidth -- ROADMs. The idea here is to mix wavelengths that use different widths of spectrum (some on a 50GHz grid and some on a 100GHz grid, for instance) or could handle wavelengths that don't conform to the International Telecommunication Union (ITU) grid at all. (See ROADMs Get Ready to Go Off-Grid.)
To make CDC and gridless ROADMs work, though, network management systems would have to step up, Wellbrock said. These optical capabilities open the possibility of accidentally sending the same wavelength down the same path twice, or of asking for a wavelength that would eat more spectrum than a fiber can spare.
"The network element's going to have to tell me no even if I hit the button three times," Wellbrock said.
A replay of "The Need for Next-Generation ROADM Networks" will be available on the Webinar archives page starting early next week, through September 2011.
For the next few months, you can also follow this topic at our Next-Generation ROADM Briefing Center at http://www.lightreading.com/roadm.
— Craig Matsumoto, West Coast Editor, Light Reading