AT&T today is releasing a major hardware abstraction framework for XGS-PON into the Open Networking Foundation, laying further groundwork for software-defined networking control of a common access architecture.

The release of VOLTHA 1.0 -- which is pronounced Volt-HA and stands for Virtual Optical Line Terminal Hardware Abstraction -- is a follow-on to hardware specifications AT&T Inc. (NYSE: T) already submitted to the Open Compute Project and continues the work of the network operator and its vendor and carrier partners to define the access architecture of the future. It is currently operating in AT&T's Labs and will be in two field trials -- in Atlanta and Dallas -- by year's end. (See AT&T Embracing Software-Defined Access).

That future architecture needs to support any media -- fiber, copper or wireless -- and must be software-defined and multivendor, breaking down the current system of managing each access vendor's gear with its own element management and network management systems. As explained by Eddy Barker, AVP for technology design and architecture at AT&T, VOLTHA 1.0 goes a long way in this direction.

"What VOLTHA does is allow us to abstract out those common commands that should work with any kind of standard equipment -- some that is software VNFs, [virtual network functions] some is physical hardware," he told Light Reading in an interview. "It essentially allows us to go out and talk to that equipment with its interface type. What this is allowing us to do is create the ecosystem that gives us a software infrastructure layer that is common, and it is open source, although commercialized."

Currently VOLTHA 1.0 has the capability of talking to gear from seven different OLT makers to support XGS-PON, he says. VOLTHA can take in standard generic command structures and adapt them to specific silicon in a white box it controls, as well as any software applications.

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The longer-term view involves a totally SDN-controlled architecture, linked to the Open Network Automation Platform (ONAP) for orchestration, with access, metro and long-haul networks engaged on an end-to-end basis. What this hardware abstraction framework specifically addresses is a key piece of the access network, which will become more important as 5G comes to market and connecting more diverse cellsites becomes a priority.

AT&T has been working with CORD and the ON.lab (now merged into the Open Networking Foundation ) on virtualizing pieces of the access network from some time, and Barker stresses that many partners, both vendors and other network operators, have been engaged in this work as well.

"This first instantiation is based on FTTP and OLTs, hence the name VOLTHA ," he says. "But it is based upon trying to control any type of access. And so ultimately, the goal is to have a system that can send out standard command structures that provision or trouble shoot or collect data."

It would enable AT&T or other operators to mix and match not just gear from multiple vendors but ultimately different types of access media on a common infrastructure. The intent is to be able to support any type of service -- business, residential or wireless backhaul -- on a common access architecture.

"Once it is released to the community, we can essentially load VOLTHA with an ONOS SDN controller and use the same commands and hit OLTs from seven different manufacturers' white and gray boxes -- and they will also hear the same command structure and respond to it," Barker says. This more generic approach will speed up the time-to-market for new features and new equipment and "will eventually have an interface up to ONAP, to put together that end-to-end ecosystem so we can start to recognize that operational savings through reducing the complexity and orchestrating more of how we manage our networks."

AT&T will also be announcing this with Deutsche Telekom AG (NYSE: DT) later this month at the Broadband World Forum in Berlin, Barker says.

— Carol Wilson, Editor-at-Large, Light Reading