The path forward on the access network is expected to vary by cable operator, but it's becoming clear that a move to a distributed access architecture (DAA) that can support both DOCSIS 4.0 and a full (or targeted) leap to fiber-to-the-premises (FTTP) will be a common play for many.

At least that was a general consensus discussed this week at Light Reading's Cable Next-Gen Europe digital symposium.

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Whether cable operators opt to deploy FTTP now in targeted situations such as greenfields or via network extensions to areas adjacent to existing plants or make a move to all-fiber access networks in ten or more years, it will take an evolutionary process to pull it off, Chris Stengrim, VP of technology and strategy and program general manager at CableLabs, said during a keynote presentation.

Most operators will still need to maintain or enhance their hybrid fiber/coax (HFC) networks for some time, but a baseline move to DAA will put cable operators in a position to upgrade to DOCSIS 4.0 as well as FTTP, Stengrim explained.

The general idea is to extend fiber deeper into the access network to more capable and flexible DAA nodes that can support DOCSIS 4.0 on a next-gen HFC network and/or tack on FTTP capabilities with a remote OLT (optical line terminal) that can be dropped into the node.

That, Stengrim said, will enable cable operators to develop a common, virtualized/cloud-focused, multi-access platform supporting both PON and DOCSIS technologies and, potentially, fixed wireless access (FWA).

"The main point is that this platform sets you up for fiber-to-the-home" gradually and selectively, Stengrim said. "It's a platform. You're evolving your HFC network and making these investments."

Once fiber is deployed deeper in the network, operators have more options to migrate their networks to new DOCSIS technologies for PON, Richard Rommes, Harmonic's VP of access network solutions and strategy, explained in a follow-up panel.

That activity is leading to more work focused on network and service convergence. CableLabs heads up the specs for DOCSIS 4.0 and DAA, but is exploring the network convergence angle in other ways. Among them is "Connexus," a project that aims to facilitate industry alignment around mobile/fixed convergence and a common toolkit that can lead to the convergence of elements that include the network, applications and security.

That project is starting out with wired infrastructure but will broaden out to extending into headends and the provisioning of wireless from the same systems, Curtis Knittle, VP of wired technologies at CableLabs, said.

Network strategies vary

Those ideas are also taking shape as cable operators around the globe start to make decisions on how to proceed with the access network. While some operators, such as Altice USA and Virgin Media 02, are being aggressive by overlaying their HFC networks with FTTP and sidestepping DOCSIS 4.0 completely, others will lean on D4.0 and go with FTTP on a targeted, opportunistic basis. Meanwhile, some operators have plans to demission portions of their DOCSIS networks in the coming years.

Count Norlys, a provider in Denmark, in the camp that will eventually say good-bye to some of its HFC network because of regulatory requirements. Norlys has deployed a mix of DOCSIS 3.1/DAA and FTTP in its footprint, but is facing significant pressure from fiber-fueled competition.

Norlys offers 1-Gig on both fiber and HFC, "but in a very short time we have to decide if we're going any further on the DOCSIS platform," Kjeld Balmer, head of network technology at Norlys, explained. He put forth the idea that HFC could handle the "mainstream users" and fiber will be used to deliver services to power users who gobble up much more data.

On the HFC side, Norlys does plan to rip and replace HFC networks that are serving about 68,000 customers with XGS-PON in order to provide 10-Gig services. Elsewhere, Balmer said it's unlikely that Norlys will upgrade to DOCSIS 4.0, with an expectation that the company will be out of the HFC business by around 2035.

Belgium's Telenet has been deploying FTTP in greenfields using RF over Glass (an approach that uses fiber but relies on existing DOCSIS backoffice systems and legacy customer premises equipment such as DOCSIS modems and set-top boxes to pass along services to the home), but is starting to implement XGS-PON.

"It [XGS-PON] just made sense for us," Bart Acke, Telenet's VP of network build and field services, said.

10G's role: instant gratification?

The discussion also led to when there will be a true need for 10G services. There's still little to no need for that kind of capacity for the vast majority of consumers. However, Knittle suggested that it could help fuel the need to fulfill "instant gratification" – like being able to download a movie to a laptop in a snap when one is running late to the airport.

He likened it to turning on a light switch or turning on the water faucet. "It's there," he said.

Kevin Noll, principal access architect, office of the CTO, at Vecima, agreed, holding that a growing dependence on the cloud for access to apps and content means the access network has effectively become an extension of the backplane of a PC or laptop. He suggested that a 2-Gig transfer rate is what could be sufficient to deliver on this notion of instant gratification.

No supply chain relief in sight

The panel also dug into ongoing supply chain constraints that are hamstringing the entire telecom industry.

Julie Kunstler, chief analyst at Omdia, doesn't expect the situation to be resolved anytime soon. To help mitigate some of the supply chain issues, some network tech vendors are making extra efforts to negotiate for parts and components or to conduct tests on parts that they can procure from new sources and suppliers. Those delays, she noted, create problems not just for those building the networks but for marketing departments that want to get out into the market with speeds that match up with competitors.

"It's definitely an area where suppliers are investing in resources in terms of people working on that," Kunstler said.

This contention on labor and materials is also filtering down to how operators are executing their planning cycles. Rather than thinking about what they can do in the next year, certain parts of the planning cycle are now extending out to about five years, Vecima's Noll said.

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— Jeff Baumgartner, Senior Editor, Light Reading