AT&T completed field trials of its 10-gigabit symmetric passive optical network technology (XGS-PON) using a new platform and acronym for the software brains behind the operation: OSAM-HA (Open Source Access Manager Hardware Abstraction).
OSAM-HA (pronounced “awesome-HA”) replaced the previously entitled Virtual Optical Line Termination Hardware Abstraction (VOLTHA) software in the trial. OSAM is a vendor agnostic platform for managing broadband access network elements and services. It’s separate from vendor-specific access element management systems (EMS).
The trials were conducted in Atlanta and Dallas, both of which are headquarter locations for AT&T. The trials used a virtualized broadband network gateway (vBNG) to manage subscribers testing multi-gigabit Internet traffic of AT&T’s DirectTV Now video service.
Eddy Barker, assistant vice president for access architecture and design at AT&T, said the carrier was not ready yet to name vendors in the trial. The carrier did use white box solutions from a couple of manufacturers that were powered with merchant silicon.
“We would have liked to have used more vendors, but couldn’t use them all due to just a lack of volume on the trials,” Barker said.
A coexistence element was also used to manage gigabit PON (GPON) and XGS wavelengths on the same single fiber interface.
XGS-PON technology is a fixed wavelength symmetrical 10 Gb/s platform. Barker said that XGS-PON provides up to four-times greater downlink bandwidth and up to eight-times greater uplink bandwidth capacity compared with traditional GPON.
Barker said OSAM-HA allowed for abstraction of the virtual network functions (VNFs). It also acts as an interface between the abstracted infrastructure at the lower level and the Open Networking Automation Platform (ONAP) AT&T uses higher in the stack.
“It’s a pipeline between orchestration and ONAP down into these software-defined access functions,” Barker explained. “We sort of have an end-to-end control plane that goes between ONAP and the access portion of the network.”
Barker noted that due to the interlinking, the carrier could avoid duplicating actions at different operational layers.
“I don’t have to go and control or spin up VNFs down in the access control mechanism,” Barker said. “I can go up and can interlink up with ONAP, have it spin up the VNFs, have it turn up vLANs (virtual location area networks) to establish end-to-end infrastructure or provision Layer 3 gateways.”
This centralization of control using ONAP also allows the carrier to avoid creating “islands” of software-defined networking (SDN) and network functions virtualization (NFV) technologies.
AT&T has been working on VOLTHA since early 2016. The carrier eventually managed to attract interest from more than a dozen partners, including German telecom giant Deutsche Telekom. VOLTHA was migrated into the Open Networking Foundation (ONF) last October.
The platform provides a software framework – or “brain” – behind the XGS-PON access network in the cloud. Barker explained the software allows AT&T to take white and gray boxes from multiple vendors.
The VOLTHA software also supports the Central Office Re-Architected as a Data Center (CORD) Project plans for multi-vendor, multi-domain service support. VOLTHA provides isolation between a vendor agnostic PON management system and vendor-specific PON hardware devices.
Those efforts will now be pushed into OSAM-HA. Barker did explain that the name change is requiring some work within ONF to include the latest updates into the open source community workflow.
ONAP began as part of AT&T’s ECOMP platform before being merged with the similar Open-O project within the Linux Foundation. AT&T is looking to ONAP as a key component of its broader network virtualization plans.
“Ultimately, instead of deploying islands of technology that have SDN control, we want to orchestrate the entire end-to-end network through ONAP,” said Barker.
“It’s exciting for us to see more partnership in ONAP,” Barker said. “It’s positive to get as much of the community as possible into the work program. The broader it is, the more valuable it is.”
Barker did note it will be a challenge to manage different priorities from different companies, “but that’s sort of a natural impact you are going to get. Ultimately, what we all contribute into ONAP is going to be 80 percent the same. There will just be some natural variation once we get to that point.”
With the latest trials complete, Barker said AT&T would be looking this year to solidify the OSAM-HA platform so that it can be used by the carrier’s operations teams.
“We are focused this year on getting that infrastructure to market so we can realize the vision we started out with in terms of greater software control and avoid any gaps in that implementation,” Barker said. “We want to make it as easy as possible for our operations teams to implement so we can take advantage of our work.”