AT&T has put the VOLTHA 1.0 (Virtual Optical Line Termination Hardware Abstraction) software-defined access specification into the Open Networking Foundation (ONF), providing a framework to have XGS-PON access in the cloud.
The service provider said that the use of open hardware and software designs allows it to accelerate the speed of innovation and get services to customers faster.
VOLTHA is the first major open source software release that provides the “brain” for XGS-PON technology. Additionally, it reflects AT&T’s move toward open source software and SDN/NFV frameworks.
Eddy Barker, AVP of technology design and architecture for AT&T, told FierceTelecom that VOLTHA is a flexible environment that allows service providers to use elements that are most relevant to their own specific needs.
“VOLTHA is hardware abstraction aspect of what we’re trying to put in place,” Barker said. “It can be part of CORD as a turnkey configuration of an SDN and NFV platform end-to-end platform with orchestration.”
Barker added that VOLTHA carriers like AT&T “are piece parting out CORD where we have got certain parts of our own Domain 2 structure, our own cloud, our own Layer-2 fabric into our own solution set.”
To develop the VOLTHA concept, AT&T worked closely with Open Networking Foundation (ONF) and the vendor community. The goal is to align with other service providers across to develop future versions of VOLTHA.
But supporting FTTH is just one element that VOLTHA can support.
In the second release, VOLTHA will create a foundation to merge all services on a single network, including 5G wireless infrastructure.
“When we get to the second release of VOLTHA, we’ll take what we have been doing for FTTP which supports GPON, XGS-PON and NG-PON2, and make it work across other access technologies whether it is Gfast and 5G wireless technology,” Barker said. “We want to standardize how we control these access technologies and make it generic is the goal of this whole effort.”
For AT&T, VOLTHA is another necessary tool to fulfill its vision of a software-defined network (SDN) which employs network function virtualization (NFV). By the end of 2017, AT&T set a goal to have 55% of its networks virtualized and 75% of our traffic on our software-defined network by 2020.
Reducing costs, driving operational efficiency
By implementing VOLTHA in its last mile network, AT&T can reduce the costs of the network electronics needed to support a FTTH service.
“Fiber to the premises has a lot of aspects,” Barker said. “What this effort does is it influences the electronic piece of it and this allows us to drive down to the costs of capital, substitute more freely with competition and transition to different variations of the technology more quickly,” Barker said.
Besides reducing capital costs, AT&T sees an opportunity to use VOLTHA and other software-based infrastructure elements to improve operational efficiency.
“On the operations side, which is the big part of SDN, is to simplify the effort of operations management, including provisioning automation and orchestration,” Barker said. “We’re trying to build a broader end-to-end SDN-based ecosystem that does not require near as many people to operate it, provision it, and troubleshoot it.”
For AT&T, the ultimate cost of any network it builds is based on how much capacity it needs to support.
However, traffic growth does not always mean more revenues for AT&T or any provider, which makes controlling costs even a more compelling issue.
“We all know traffic is a very different growth pace than revenues for service providers,” Barker said. “If we could contain and hold down our operations costs in the business more in line with the revenue growth it’s a better business model for and more competitive pricing for ultimately the end-customer.”
Vendor interop is key
Like SDN-related efforts such as ECOMP, AT&T sees VOLTHA as an effort that benefit the broader telecom provider community.
On the hardware side, AT&T submitted seven hardware specifications for the next-generation access network into the Open Compute Project (OCP). These specifications are open to the hardware supplier community for anyone to build and commoditize.
While moving towards an open source environment is the direction AT&T sees as the best path to have a more agile and efficient network, the service provider admits vendors were initially skeptical.
“When we first started, it was a tough sell for the incumbent OEMs in routing and access,” Barker said. “A lot of it early on some of those companies said they had a lot of intellectual property and I think through time you have to show companies you’re committed to your target architecture direction.”
But the transition to software will still require a broad set of solutions that vendors across the silicon and hardware spheres will need to support.
“Open source is for collaboration for lowering the cost of software and capabilities, but we’re still going to need an ecosystem that’s made up of hardware suppliers and have vendors that take open source software and hardened it and scale it,” Barker said. “We’re going to need that integration to bring things together, but there may be parts of the ecosystem that can be secret sauce.”
Another issue is vendor platform interoperability.
Overall, interoperability in various technology iterations has developed in different ways over time, and next-gen PON will be no different.
AT&T’s VOLTHA and Verizon’s Open OMCI for NG-PON2 are examples of ensuring platforms can interoperate with one another.
“In each technology area, you have seen interop mature at different paces,” Barker said. “Some come out of the gate effective and other ones come out of the gate and there’s a proprietary piece that prohibits interop and it’s up to service providers to make sure we keep a level playing field to ensure interop stays forward.”