Comcast head talks progress from DAA to DOCSIS

DENVER — Comcast touted its progress migrating to a distributed access architecture (DAA) with updated virtualized network functions as it plans to roll out DOCSIS 4.0 more broadly.

At the 40th annual SCTE Cable-Tec Expo this week, Comcast Chief Network Officer Elad Nafshi told a crowded room the company continues to look for ways to address the changing requirements of today’s networks.

Those changes can be attributed to several factors, including migrations to the cloud and edge. Network traffic is also changing. For example, new consumer realities like work from home have seen peak streaming times shift from Sunday nights to high traffic even during work hours.

Nafshi said a new generation of edge compute services will benefit from digital optics on software-defined networks to “fundamentally change how to deliver high speed data."

On that front, the Comcast milestones Nafshi mentioned include reaching the deployment of over 120,000 Remote-PHY digital nodes across its network this year. Remote-PHY nodes are supporting the company’s transition to DAA, a model that pushes functions that usually reside in the network hub closer to the user.

Comcast has also been working to retire its legacy cable modem termination systems (CMTS) in favor of virtualized platforms. Nafshi said the company’s analog CMTS requires 20 racks of equipment to get to 60,000 households passed, whereas its vCMTS uses one rack to reach 100,000 households.

He noted Comcast already has vCMTS-powered fiber-to-the-home (FTTH) powering multi-gig services nationwide, as the company is "quickly retiring [its] legacy CMTS architecture."

Traditionally, fiber and coaxial networks have relied on different platforms, but this year Comcast completed its first virtual broadband network gateway (vBNG) trial, in which it connected a fiber customer to its new vBNG/rOLT (remote optical line terminal) platform powered by the same vCMTS platform delivering gig service to its coaxial customers.

At the time the company claimed the trial "represents the first time anywhere across the industry where the vision of the converged DAA has become a reality and is being delivered to live customers."

The upgraded technology and shift to DAA has been key to Comcast’s implementation of Full-Duplex DOCSIS 4.0. Last week the company was the first to announce a DOCSIS 4.0 deployment, with symmetrical 2-gig speeds now available to customers in its Colorado Springs market.  

Comcast is deploying these new multi-gig speeds on an end-to-end DOCSIS 4.0 system, instead of using a DOCSIS 3.1 CMTS in a high split configuration with a DOCSIS 4.0 modem.

Comcast plans to deploy DOCSIS 4.0 to the Atlanta and Philadelphia metro areas before year-end, “and then we are going to go anywhere,” said Nafshi at this week's event. “We are full steam ahead on DOCSIS 4.0.”

Also, Comcast this week announced it will work with Broadcom to develop a DOCSIS 4.0-compatible chipset with artificial intelligence (AI) capabilities that will enable the company to auto detect patterns in traffic and self-heal network impairments.

The chips will “enable the industry to move to DOCSIS 4.0 faster than we were hoping,” said Nafshi.  

He lauded the chips “as truly transformational,” as they can provide optionality for operators charting out their paths to DOCSIS 4.0 to either use full duplex (FDX) or extended spectrum DOCSIS (ESD).

Comcast is a proponent of FDX, which involves the simultaneous transmission of data upstream using the same spectrum. ESD – favored by Charter and Cox – increases spectrum to 1.8 GHz while using dedicated chunks of spectrum for upstream and downstream traffic flows.

Comcast and Broadcom expect to begin trials for the chipset in early 2024, with plans to start deploying them in live networks before the end of next year.