AT&T Disaggregation Drive Hits Traffic Milestone

Dec 09, 2023

Articles / Interview

AT&T's decade-long disaggregation journey to virtualize its network functions recently hit a new traffic-carrying milestone that will also prove key to the carrier's robust 5G and fiber expansion plans.

Mike Satterlee, VP of AT&T's Network Core Infrastructure Services, told SDxCentral in an interview that the operator's open disaggregated core routing platform was carrying 52% of AT&T's traffic at the end of 2022. Satterlee described this platform as the carrier's "common" or "core backbone," which supports about 594 petabytes of data traffic per day.

This core backbone is a multi-part architecture spanning from AT&T's nationwide network switch and cloud provider connections to its consumer- and enterprise-facing broadband and mobility services.

At its core – literally – is its next-generation core router and internet peering network. This platform uses Broadcom's Jericho2 hardware design and Ramon switching chips, the carrier's distributed disaggregated chassis (DCC) white box router architecture, and DriveNets Network Cloud (DNOS) software.

That system is fed by AT&T's edge router platform that sits in regional connection points. It uses the Broadcom architecture, Cisco software platform, and hardware from UfiSpace.

Satterlee said AT&T is running a nearly identical architecture in its core and edge environments, though the edge system runs Cisco's disaggregates software. Cisco and DriveNets have been active parts of AT&T's disaggregation process, though DriveNets’ earlier push provided it with more maturity compared to Cisco.

"DriveNets really came in as a disruptor in the space," Satterlee said. "They don't sell hardware platforms. They are a software-based company and they were really the first to do this right."

AT&T began running some of its network backbone on DriveNets core routing software beginning in September 2020. The vendor at that time said it expected to be supporting all of AT&T's traffic through its system by the end of 2022.

The carrier pulled Cisco into the platform shortly after.

Satterlee said the disaggregation execution provides AT&T with "a lot of flexibility in how it manages those resources."

"It's completely open in the sense that either vendor software could run in either places of the network," Satterlee explained, adding that this was very helpful during the COVID-19 pandemic. "By having a common platform it's just a matter of switching out the [network operating system] so we were able to very quickly redirect equipment for different use cases within AT&T and it was just a simple software change controlled by SDN."

The edge router platform is fed by AT&T's Ethernet Mux system that sits on the carrier's metro Ethernet and fiber footprint. It aggregates 1-gigabit and 10-gigabit access ports for 100-gigabit transport. This platform is based on Broadcom's Qumran-MX chips, EdgeCore hardware, and Ciena's SAOS network operating system (NOS).

That aggregation need comes from the trio of sources.

One is cell site gateway routers that sit at tens-of-thousands of cell sites. These use hardware from UfiSpace, Broadcom Qumran chips, and Ciena's Vyatta NOS software, and support up to 100 GB/s mobility transport for 5G services.

There are also customer gateways that provide consumer broadband services, and SD-WAN platforms that feed enterprise customers. The latter uses hardware and chips from Intel, Broadcom, Marvell, and Silicom, with Ciena's Vyatta NOS software.

AT&T's disaggregation efforts also support increasing transport management through reconfigurable optical add/drop multiplexers (ROADMs) that are OpenROADM compliant. ROADMs are like a network switch that manages data traveling across fiber optic lines.

Adding software control supports dynamic bandwidth management, while the open nature allows the platform to use components from Ciena, Cisco, Fujitsu, Infinera, and Nokia to provide high-speed and high-capacity optical transport support for fiber-based broadband and 5G backhaul. AT&T has installed more than 75 of these nodes that control 100-gigabit and 400-gigabit wavelengths.

John Gibbons, assistant VP for AT&T's Network Infrastructure Services, added that this also paves the way for the carrier to roll out 800-gigabit support for its backbone.

"We don't have to swap out the core router to get to 800-gig," Gibbons said. "We can actually add to the current chassis. … We can add the new box to start growing it out from there. That's the flexibility. It's like the building-block model."

Satterlee was very complementary toward vendors supporting the carrier's extensive disaggregation process. He did note that one of the early challenges was in getting equipment and software to support legacy systems, but that has since improved.

"It honestly would have been a different story if you talked to us two years ago," Satterlee said. "We would have told you that some of the vendors are dragging their feet, but I think everyone kind of understands that this is where it's going right now. And not just the carriers like AT&T, but the hyperscalers as well. We spend a lot of time partnering with them on architectures and where we want to take these platforms."

Where the carrier is taking its platform is targeting 65% of its traffic running on the disaggregated architecture by the end of this year. This will be important to support AT&T's fiber and 5G push, which was enhanced late last year through a deal the carrier struck with BlackRock to expand its fiber footprint.

"Pretty much everything we spoke about supports our two biggest initiatives, which is growing the AT&T fiber broadband as well as 5G, and it's all the underpinnings of those services," Gibbons said.