As part of going "all in" with SDN and NFV, AT&T is on an "aggressive schedule" to make the optical transport layer more flexible, according to Andre Fuetsch, the carrier's senior vice president of architecture and design.

"We want to start pushing NFV down the stack. We want to push it to Layer 1," Fuetsch said during a keynote panel at the Open Networking Summit (ONS) on Tuesday.

The optical network has been getting more flexible with each new generation of a component called the reconfigurable optical add-drop multiplexer (ROADM). Crudely put, a ROADM is a traffic flow's onramp to the optical network, carried on one of dozens of wavelengths traveling down any given optical fiber. ROADMs are starting to allow more flexibility regarding which wavelength can be added onto the fiber and when, creating more degrees of freedom and opening more possibilities for automation.

But that's not enough. "If you look at that technology today, frankly, there's a lot of complexity. Closed proprietary silos," Fuetsch said. "We want to break that apart."

(Shameless plug: AT&T's Martin Birk plans to discuss this more on Wednesday afternoon, during an ONS panel on transport SDN that I'll be moderating.)

Many carriers are interested in the possibilities of transport SDN. In fact, Tuesday's two other carrier keynoters brought it up. SK Telecom is working on a proof-of-concept in that area, said Kang-Won Lee, senior vice president of R&D, although he didn't go into detail about it.

Yukio Ito of NTT Communications talked about his company's Transport Network Controller, a software that talks to OpenFlow switches, microwave devices, packet transport network devices, and optical networking gear. It's run by a network management program based on the ONOS network operating system and Odenos, an open source orchestration framework that Ito said is being added to ONOS.