Comcast unleashes DOCSIS 4.0 service under 'X-Class Internet' brand

Promising symmetrical speeds up to 2 Gbit/s, Comcast is officially kicking off the DOCSIS 4.0 era with its first-ever commercial launch of an upgraded hybrid fiber/coax (HFC) network in Colorado Springs. Comcast said it will launch similar speeds on DOCSIS 4.0 in parts of Philadelphia and Atlanta before the end of the year.

Comcast plans to deploy DOCSIS 4.0 across its entire HFC footprint, but the operator has not announced when it expects to complete the rollout. Comcast ended Q2 with a footprint of 61.83 million homes and businesses passed, with most of them served on HFC.

"We're working as hard as we can to roll out this technology as quickly as we can," Elad Nafshi, Comcast's chief network officer, told Light Reading.

Comcast's initial wave of DOCSIS 4.0 network launches are getting underway as it and other cable operators look to use the new platform to shore up competition against fiber-to-the-premises (FTTP) service providers that have hit the market with symmetrical, multi-gigabit speeds.

'X-Class Internet' branding

Comcast has designated "X-Class Internet" as the brand for its new portfolio of symmetrical broadband services for residential customers delivered on DOCSIS 4.0 (Comcast previously used that branding for its initial family of smart TVs before the "Xumo" brand was established by the Comcast-Charter Communications national streaming joint venture).

Related:Comcast completes multi-gig DOCSIS 4.0 trial in Philly

Comcast is starting with four X-Class Internet tiers: 300 Mbit/s, 500 Mbit/s, 1 Gbit/s and 2 Gbit/s. Everyday/non-promotional pricing for the standalone X-Class offering will start at $55 per month for the 300-Meg tier up to $115 per month for the new 2-Gig offering.

Comcast will bake in its unlimited data plan (typically an extra $30 per month) for the DOCSIS 4.0/X-Class services being introduced in Colorado Springs. Pricing and packaging for future DOCSIS 4.0 markets are still being determined, an official said.

Comcast's DOCSIS 4.0 network utilizes the remote PHY option of a distributed access architecture (DAA) paired with a virtual cable modem termination system (vCMTS). Comcast's vCMTS is based on Harmonic's "CableOS" platform and Comcast is initially using Harmonic-made remote PHY nodes.

'Fully and completely committed to FDX'

Comcast is going with the Full Duplex (FDX) flavor of DOCSIS 4.0, a version that envisions HFC built out to 1.2GHz and equipped with a new FDX band that allows upstream and downstream traffic to operate on the same block of spectrum. The other option, called Extended Spectrum DOCSIS (ESD), envisions HFC built to 1.8GHz while running upstream and downstream traffic in separate, dedicated spectrum.

Related:Comcast gets its mitts on 'missing piece' of its DOCSIS 4.0 network

Nafshi said Comcast recognizes that DOCSIS 4.0 provides operators with "optionality," but he stressed that Comcast will focus its DOCSIS 4.0 deployment on FDX.

"We are fully and completely committed to FDX. We believe that is the right technology choice for DOCSIS 4.0," Nafshi added.

Comcast's initial DOCSIS 4.0 deployments use an "N+0" architecture that involves pulling fiber deep enough to eliminate all the amplifiers between the home and the node. The company plans to expand the reach of DOCSIS 4.0 to the bulk of its markets with the help of a new FDX Amplifier being built by CommScope. Recent tests of the FDX Amplifier were run on plant with as many as six amps between the home and the node.

Nafshi said that "great progress is being made" on the FDX Amplifier and hinted that more detail will be shared at next week's SCTE Cable-Tec Expo in Denver.

Though the majority of Comcast's HFC network is built out to 1GHz, the operator's network in Colorado Springs is built out to 1.2GHz. "We don't have a concentrated effort to extend the plant beyond 1GHz," Nafshi said.

Residential modem-router combo

In the home, Comcast will use a new, production-ready DOCSIS 4.0 modem based on Broadcom silicon, but the company didn't announce its initial device partner. Early on, Comcast will use a two-box combo for DOCSIS 4.0 – the stand-alone D4.0 modem and a router outfitted with Wi-Fi 6E. Future DOCSIS 4.0 gateways will combine those functions.

Related:Ten suppliers hook into CableLabs' first DOCSIS 4.0 interop

CableLabs announced in June that the organization is ready to begin official certification qualification testing on DOCSIS 4.0 modems but has yet to award any certifications. However, CableLabs has conducted some DOCSIS 4.0 interops with an initial group of ten suppliers.

"We feel very good about what we have," Nafshi said of the modems Comcast will use for its initial D4.0 deployments.

Comcast is also working on a plan to pair higher speeds with lower latency on its DOCSIS network. The operator is conducting field trials of new Low Latency DOCSIS (LLD) technology.

Nafshi said he's pleased with the early results of those trials and is looking forward to deploying LLD sometime in 2024.