Editor’s Corner—Verizon breaks ranks with AT&T, CenturyLink on next-gen FTTP, Gfast

Fiber optics, market research
Sean Buckley, FierceTelecom

Verizon always likes to carve its own path, and the service provider’s stance on next-gen fiber-to-the-premises (FTTP) architectures and Gfast set off ongoing debate with its counterparts AT&T and CenturyLink during the recent Adtran Connections event.

Being one of the first telcos to deploy a large BPON-based network in 2004one that still exists in congruence with GPONVerizon’s stance on these issues should be of little surprise. Out of the big three providers, it also launched an aggressive fiber build-out focusing on its wireless backhaul and business needs. The telco will likely leverage the NG-PON2 infrastructure for those efforts.

Service providers have three next-gen FTTP paths: 10G-PON, XGS-PON and NG-PON2. Similar to its move to go completely fiber with BPON in 2004 for Fios, Verizon plans to move directly to NG-PON2.

Vincent O’Byrne, director of access for Verizon, told Adtran attendees that XGS-PON and 10G-PON lack the future-proof capabilities of NG-PON2.

“From a long-term perspective, a single wavelength is something that is a short-term solution for business services," O'Byrne said.

AT&T, CenturyLink seek migration

Verizon may see NG-PON2 as the next logical step beyond GPON, but AT&T and CenturyLink are looking for more of a migration path.

Having already deployed GPON to 1.5 million customer locations, CenturyLink is confident it had better take advantage of XGS-PON immediately. The telco recently began a 10G-PON trial with Adtran with an eye toward future iterations of NG-PON2.

CenturyLink CTO Aamir Hussain told FierceTelecom that the migration approach allows it to take advantage of available software-defined access approaches today. 

“Because we need to control it through software, we are taking more of a migration path than just jumping to NG-PON2,” Hussain said. “NG-PON2 with full software orchestration is not available.”

CenturyLink can use this experience with service profiles in a virtualized network environment. It will also continue to leverage hardware-based optical network terminals.

AT&T, which announced its intent to conduct XGS-PON trials this year that will focus on how to provide multigigabit internet speeds to consumers and businesses, is taking a similar stance. Set to take place in late 2017, Eddy Barker, AVP and member of Technical Staff for AT&T, told FierceTelecom that XGS-PON is more about the most cost-effective approach today.

“NG-PON2 and XGS-PON is very similar from a standards point of view,” Barker said. “XGS uses fixed optics and it’s really kind of an economical thing.”

Barker added that “we agree with Verizon that NG-PON2 is a good way to evolve and will be business-oriented, but XGS uses the same optics as 10G-EPON, so we have a greater volume in the industry and the prices for optics is as economical as what we’re deploying today with GPON.”

Bypassing Gfast

Besides NG-PON2, Verizon isn’t a fan of using Gfast for multi-dwelling units (MDUs). The potential with Gfast is that a telco can drive fiber deep into a basement or nearby distribution point and use the existing copper to deliver higher speeds to each living unit.

Based on a bad experience it had with VDSL2 interoperability when using copper for MDU deployments, Verizon is focusing on wiring units with fiber. Potential benefits to replacing copper with fiber are speed and lower maintenance.

O’Byrne said that "with Gfast we see ourselves potentially being in the same situation five years from now where we would have to replace the same thing” to accommodate higher speeds. 

Even so, Verizon still faces the hefty challenge of getting landlord access to more MDUs, particularly in large cities such as Boston and New York City. The service provider claims it has seen well-documented issues with MDUs in New York City where landlords and other building owners have blocked access to install fiber and related equipment.

In contrast, AT&T and CenturyLink, which have sizable copper and coax in MDUs, see immediate value in Gfast to deliver higher broadband speeds.

Besides having a large amount of existing copper in its 22-state footprint, the service provider could leverage Gfast over the existing coax that resides in single-family homes and MDUs via its DirecTV acquisition. 

After conducting a Gfast trial in Minneapolis, AT&T just announced that it launched service in eight initial cities. Additionally, AT&T is selling Gfast to MDUs in parts of 14 other metros with deployments planned in the near future.

Leveraging existing copper and internal coaxial cable infrastructure, CenturyLink installed Gfast technology in 44 MDUs to provide up 500 Mbps to nearly 800 apartments in Platteville, Wisconsin. It is also conducting similar deployments in Minnesota.

Virtualized access

While these operators will initially use different last-mile transport mechanisms, all agree that a software-defined access platform will enable them to automate network provisioning and activation for future fiber-based broadband services.

Verizon completed a NG-PON2 interoperability trial at its Verizon Labs location in Waltham, Massachusetts. The service provider has been an advocate of channel bonding, which allows it to multiply the amount of bandwidth it delivers to businesses and residential customers without forklift technology upgrades.

Meanwhile, AT&T began a field trial in 2016 that uses an open vOLT application that runs as part of the ON.Lab Central Office Re-architected as Data Center (CORD) platform. This effort includes a virtual OLT (vOLT), which is part of the disaggregation phase of AT&T's implementation of NFV.

“Part of this effort for software-defined access has pieces that also contribute into CORD,” Barker said. “A lot of the things we’re developing with ON.Lab will also be part of CORD.”

What the differences in approaches represent are the nature of how each of these service providers operate. Despite these differences, these providers are looking to solve a few common issues: speed, agility and network response times. — Sean