Comcast tests symmetrical 1.25-Gig on HFC

Crossing milestones on the path to '10G,' Comcast says the trial is running on a live production, 'all digital' HFC network in Jacksonville using remote PHY digital nodes and a virtualized CMTS.

Jeff Baumgartner, Senior Editor

October 8, 2020

4 Min Read
Comcast tests symmetrical 1.25-Gig on HFC

Comcast is proclaiming a "10G technical milestone" with word of a trial that's delivering symmetrical speeds of 1.25 Gbit/s on a live production HFC network that takes advantage of new distributed access and network virtualization technologies.

The test, initially focused on an employee home in Jacksonville, Florida, is being powered by a distributed access architecture (DAA) that Comcast has deployed throughout the area that employs a mix of digital fiber optics, new remote PHY digital nodes and a cloud-based virtualized cable modem termination system (vCMTS).

Comcast, which has been working closely with Harmonic on its vCMTS rollouts, said its tech team has "consistently measured" speeds of 1.25 Gbit/s up and 1.25 Gbit/s down over the test connection.

For the trial, Comcast has enabled a "high-split" upgrade that increases the spectrum dedicated to the upstream to a range of 5MHz-204MHz, according to Elad Nafshi, SVP of next-generation access technologies at Comcast.

In Jacksonville, Comcast is also using a "node+0" architecture that eliminates the amplifiers between the home and the node, but the architecture that the cable operator is using for DAA can also be applied to areas that do not utilize node+0, Nafshi said.

Comcast is using remote PHY nodes from Harmonic in Jacksonville, but the operator is also deploying high-split nodes from other suppliers such as Cisco and CommScope. "We [support] interoperability and interchangeability on the DAA platform," Nafshi said.

The cable op said it expects to expand the trial to more homes as it kicks the tires on the performance of the symmetrical service under a range of different home and network environments.

Timing on when Comcast might commercialize a symmetrical offering on HFC is still to be determined. Comcast's current top-end residential broadband plan on HFC/DOCSIS 3.1 delivers up to 1 Gbit/s down and 35 Mbit/s upstream. Comcast's FTTP-based Gigabit Pro service, which is being offered on a targeted basis, supports symmetrical speeds of 2 Gbit/s.

"We're at the very early stages here," Nafshi said with respect to delivering symmetrical 1.25 Gbit/s on HFC. "There's a lot of work to operationalize this."

But Comcast is well down the path with its general deployment of vCMTS and DAA. Comcast hasn't pinpointed the size and scope of that deployment, but confirmed that the combo has been rolled out to multiple markets and multiple regions.

"We are way past trials," Nafshi said with respect to the deployment of Comcast's vCMTS and DAA platform.

Comcast likewise claims that the trial is a marker along the way to multi-gigabit symmetrical speeds envisioned by the industry's 10G initiative. 10G is aiming for speeds up to 10 Gbit/s along with enhanced security and low-latency capabilities over multiple types of access networks, including HFC, fiber-to-the-premises and even wireless.

Rapid scale

Comcast said its approach enables it to rapidly scale multi-gigabit capabilities to millions of homes without having to perform major surgery on its network.

"The great strength of our network technology is that we will have the ability to scale these next-generation speeds to tens of millions of homes in the future without digging up yards, or starting massive construction projects," Tony Werner, president of technology, product, Xperience at Comcast, said in a statement. "This technology provides a path to meeting the needs of the future and making multi-gigabit symmetrical speeds a reality for everyone, not just a select few."

Comcast's announcement is part of a build-up to next week's all-virtual SCTE/ISBE Cable-Tec Expo, which will include 10G developments among its focus areas.

Tied in, the NCTA – The Internet & Television Association and Telecom Advisory Services issued a report (PDF) this week – "Assessing the Economic Potential of 10G Networks in the United States – holding that network investment in 10G will generate at least $330 billion in total economic output and the creation of more than 676,000 new jobs over seven years.

The study, by Dr. Raul Katz of Telecom Advisory Services, further claims that 10G will usher in the "fourth industrial revolution" and accelerate the deployment of "smart" homes, cities and industries, including agriculture and manufacturing.

More tech tests

Comcast is the latest US cable op to show off its next-gen network chops and cross a mile marker on the way to 10G.

Last month, Mediacom Communications, in tandem with CableLabs and NCTA, hosted a "10G Smart Home" in Ames, Iowa, that demonstrated an enhanced DOCSIS 3.1 network that had been upgraded to 1.2GHz (from 860MHz), outfitted with remote PHY devices from CommScope and Casa Systems, and employed a high-split upstream upgrade.

Mediacom CTO JR Walden estimated that the setup enabled the network to deliver about 5 Gbit/s down and 1.2 Gbit/s upstream to the back of the DOCSIS 3.1 modem used for the demo, which showed off 8K video, a light field display and other bandwidth-intensive apps.

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— Jeff Baumgartner, Senior Editor, Light Reading

About the Author(s)

Jeff Baumgartner

Senior Editor, Light Reading

Jeff Baumgartner is a Senior Editor for Light Reading and is responsible for the day-to-day news coverage and analysis of the cable and video sectors. Follow him on X and LinkedIn.

Baumgartner also served as Site Editor for Light Reading Cable from 2007-2013. In between his two stints at Light Reading, he led tech coverage for Multichannel News and was a regular contributor to Broadcasting + Cable. Baumgartner was named to the 2018 class of the Cable TV Pioneers.

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