AT&T’s five-year journey to virtualize its network reached another turning point this week. The operator says 75% of the data running through MPLS tunnels is now under SDN control.

This achievement, while related, is separate from the company’s often-stated goal of virtualizing 75% of its network functions by 2020. AT&T CTO Andre Fuetsch reiterated that goal during a keynote at ONF Connect today.

“We have taken a long journey here and made it happen. There was no way we could have done this alone. We really needed the help of a community and that community was really this ecosystem we need around SDN,” Fuetsch said.

“Eight years ago we were all trying to figure out what SDN was exactly and how it was going to solve all these network challenges we have, but really SDN is now becoming the network,” he said. “White box hardware coupled with open source software creates this disaggregated, virtualized, and software-defined environment that finally gives us a chance to survive all this growth and change.”

In a blog post, Mike Paradise, AT&T”s global VP of IP operations, compared the carrier’s virtualization goals to that of building a highway with modern traffic management tools, lighting systems, and maintenance capabilities, adding that “it doesn’t mean much until you open it up to cars and trucks and semis."

In the realm of NFV and SDN, AT&T is among the leaders in transitioning its network to this new architecture, said Chris Antlitz, telecom principal analyst at Technology Business Research.

“The 75% is a significant number. They’ve built an underlay I believe for their SD-WAN ... versus a lot of other operators that are doing an [over-the-top] type play,” Antlitz said. “AT&T is doing it more from the ground up and from that viewpoint this makes it a little bit more significant.”

Verizon has also been working aggressively on SDN, but it hasn’t been as vocal as AT&T, he added. “AT&T was a big bang adopter with NFV [and] SDN. They were going to go big early-on and I would say relative to everybody they’re probably still leading in this regard.”

Joe Madden, founder and president at Mobile Experts, agrees with that assessment. “Having 75% of traffic running under SDN control is significant, and above average in terms of maturity for SDN in a mobile network,” he said.

AT&T has been paving the foundation for SDN since 2014, but not until more recently has the operator been pushing network traffic through SDN. Referencing a “major inflection point” with 75% of data traffic running through MPLS tunnels, AT&T's Paradise framed those tunnels as “the interstates of our network that connect major cities and regions of the country. While the tunnels aren’t the only part of our network, they are the element that will benefit the most from [SDN].”

Paradise also explained that the new architecture enables AT&T to move traffic around to parts of the network that might be overly burned or underused as demand fluctuates. These developments put AT&T one step closer to delivering on the promise of 5G, specifically more visionary capabilities like network slicing and the fostering of new use cases, according to Antlitz.

“When we talk about the promise of 5G, SDN is a foundational component of the 5G architecture,” he said.

“If we look at that more visionary thought of 5G then yes, absolutely, SDN is a must-have for that architecture and so is NFV. And both of those are foundational for building a dynamic, agile, composable infrastructure where you can dynamically orchestrate network resources ... make network slices in near real time, [and] automate the network.”

SDxCentral Managing Editor Jessica Lyons Hardcastle contributed to this report.