AT&T has arguably been the most aggressive telecom operator when it comes to transitioning its network toward greater software control. This has led to the operator being proactive in both developing telecom-specific SDN platforms as well as partnering with numerous software and open source groups to tailor already established platforms for telecom use. This has also positioned the carrier to be among the first to launch commercial 5G services.

The carrier initiated that SDN push with the Supplier Domain Program it launched in 2009. That program was a high-level move to realign its equipment purchasing pipelines and pare down the total number of vendor partners it worked with from around 150 down to around 40.

That effort gained steam with the 2.0 version of that program, which launched in 2013. AT&T said its Domain 2.0 focus was on separating hardware and software functionality, separating network control plane and forwarding planes, and improving management of functionality in the software layer. That includes using SDN and NFV technologies.

Shortly after the Domain 2.0 launch, the carrier laid out an aggressive timeline to have 75 percent of its network operations that could be controlled by software to be so by 2020. AT&T CTO Andre Fuetsch recently told SDxCentral that the carrier was at 63 percent control of network operations that could be virtualized, pushing toward its goal of 65 percent control by year-end.

“Sixty-three percent represents how we’ve enabled our networking capabilities. Now, we’re in the process of migrating our traffic to take advantage of those capabilities,” Fuetsch said.

Amy Wheelus, vice president of Network Cloud at the carrier, told SDxCentral that “the last 10 percent will be hard.” She explained that this was because as the carrier moved deeper into the software conversion it was becoming harder to replace the legacy equipment.

Most of AT&T’s SDN work today is focused on its Network Cloud platform, which was formerly known as the AT&T Integrated Cloud (AIC). That platform encompasses the hardware and software that supports all of the carrier’s applications and SDN services.

AT&T runs its ECOMP platform on top of the Network Cloud. ECOMP enables the carrier’s physical assets – like routers – to be implemented with software. Using the Network Cloud as a base, these components can interact with each other and with external applications or virtual network functions (VNFs).

AT&T last year moved a version of ECOMP into the open source community where it was merged with a similar platform from China Mobile to create ONAP. That platform has since been adopted by a number of large telecom operators as the basis for their own network transformation efforts.

One level deeper into Network Cloud is the AirShip platform that Wheelus described as the carrier’s “undercloud platform.” This open source project was developed with SK Telecom, Intel, and the OpenStack Foundation. That move evolved out of past work between the organizations as part of the OpenStack Helm project that launched last year.

The initial focus of Airship is the implementation of a declarative platform to introduce OpenStack on Kubernetes (OOK) and the lifecycle management of the resulting cloud. Basically, Airship allows operators to manage cloud sites at every stage from creation through minor and major updates, including configuration changes and OpenStack upgrades. It does this through a unified, declarative, fully containerized, and cloud-native platform.

All three of these efforts are being used by the carrier to power its 5G network plans. “5G is our first use case,” Wheelus said, explaining that the carrier has virtualized its 5G core that is now riding on its Network Cloud and being provisioned by Airship.

AT&T will launch commercial mobile 5G services in a dozen markets by year-end.

AT&T’s work with ONAP also underscores the carrier’s open source efforts. In fact, Wheelus explained that AT&T was an “open source-first shop,” adding that it had to go down the route of open source software to meet its growing software needs.

“We don’t want to carry the technical debt,” Wheelus said, noting that the carrier’s involvement with the open source ecosystem is not something she expected to have even started. “If you asked me five years ago if I would be talking about open source I would have said you were crazy,” she added.

AT&T’s embrace of the open source community was echoed by Wheelus’ colleague Catherine Lefèvre, associate vice president for Network Cloud and infrastructure at AT&T Labs, who said the carrier’s work with that ecosystem is very collaborative.

“It’s not just thinking about yourself, but what needs to be developed beyond just your own needs,” Lefèvre said of working in the open source community.

AT&T is also using open source to power its ambitious white box router program. The carrier earlier this year said it planned to deploy 60,000 open source, software-powered white boxes across its network over the next several years in support of its 5G plans.

Around the same time, the operator contributed its disaggregated network operating system to the Linux Foundation as part of the DANOS open source project. DANOS is the operating system that runs on these white box routers. Some of the DANOS code originally came from AT&T’s purchase of the Vyatta assets from Brocade.

AT&T’s depth in SDN also shows in its different SD-WAN platforms. These include an an over-the-top (OTT) offering, a network-based service, and plans for one to be offered as a VNF.

The OTT platform was initially announced in late 2016, and launched early last year. It’s based on VeloCloud’s technology.

AT&T’s network-based offering is a “dynamic” version of that OTT service. This includes dynamic application aware routing as well as built-in resiliency when architected through the AT&T Network Cloud platform.

The carrier is also integrating a Viptela-powered SD-WAN service that will be offered as a VNF on Cisco’s 5000 Series Enterprise Network Compute System (ENCS) hardware and Cisco software.

Financially, AT&T CFO John Stephens recently told an investor conference that part of the carrier’s $25 billion in planned capex spend for 2018 was targeted at SDN. Those efforts remain on track and are expected to eventually reduce total capex.

“But once you get there those investments you are making to achieve that goal ebb out. They either come down or effectively stabilize,” Stephens said. “So then you have the full benefit of that.”