Driving the Open ROADM: How AT&T is Redesigning the Optical Network

March 22, 2016
By Andre Fuetsch

It might seem like you can’t get any faster than a network that runs on light. Sounds sci-fi, right? And it is. But we have to make cutting-edge optical tech even better to stay ahead of demand. Data traffic on our wireless network grew more than 150,000% between 2007 and 2015. It’s not stopping. Everything from the Internet of Things to virtual reality to 4K video will drive the next surge.

I’m at the Optical Fiber Conference in Anaheim, Calif., today to talk about how we’re pushing optical into the next generation. It involves key concepts we’ve talked about before on this blog: software control and open hardware.

We’re applying those concepts to a special type of network switch called a ROADM (pronounced road-em), or Reconfigurable Optical Add/Drop Multiplexer. These are the hardware devices that manage and route data traffic that comes in over high-capacity fiber optic lines.

First, software control.

In most ROADMs today, there are particular “lanes” dedicated to each wavelength of laser light that comes into the switch. You can’t easily move signals to less congested lanes if traffic gets heavy on the original path. That’s where software control comes in.

Software-controlled ROADMs can automatically detect and adjust bandwidth. They can move traffic to different lanes as needed. These software-controlled ROADMs can turn capacity up or down, route around trouble and come back online quickly when there’s a failure. This isn’t just talk. We’ve already built a nationwide, software-controlled optical network. We think it’s the largest optical network of its kind in the world.

Second, open hardware.

Ideally, we’d virtualize these ROADM devices like we’re doing with other hardware on our network. But the laws of physics still apply. You’re working with lasers: a physical medium. So you need a physical device that can accept and reroute those signals.

However, we can do the next best thing. We can make the specs for these ROADMs openly available.

A small number of specialized hardware manufacturers design and build these proprietary ROADMs today. That limits the pace of innovation. There’s also very little interoperability between equipment from different vendors.

That slows us down and reduces our ability to deliver the best experience to customers. In a major metro area like Chicago or Dallas, for example, we’ve generally had to rely on a single vendor’s equipment to manage all optical traffic in that area. You can’t mix and match according to capability or price.

That needs to change.

That’s why we’re launching a group called Open ROADM (www.openroadm.org). Together, we’ll build and publish open standards for ROADMs. The first set of standards is already available on the website. We recently held an event with our founding member companies where we successfully tested this prototype open and interoperable hardware. We encourage more companies to join this effort. We’ve done a lot of research and development on ROADM technology, and we want to share that expertise. But we also want to collaborate with the innovators and traditional vendors who can bring their own ideas. We’re accelerating our ability to serve our customers.

It turns out, even light can sometimes can get a little faster. 

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