Verizon says channel bonding will future-proof its NG-PON2 deployments

As Verizon looks to migrate its fiber-to-the-x (FTTX) network to NG-PON2, it said the advent of channel bonding will enable it to multiply the amount of bandwidth it delivers to businesses and residential customers without forklift technology upgrades.

Similar to the way telcos and cable operators have used bonding technology to multiply bandwidth over traditional copper or hybrid fiber coax (HFC), channel bonding can deliver multiple channels or wavelengths of NG-PON2 technology over fiber.

Vincent O'Byrne
Vincent O’Byrne, director of access technology at Verizon, told FierceTelecom that channel bonding could enable the telco to achieve two main goals: Expanding double bandwidth to each subscriber or network location and providing a path to move from 10 Gbps to 20 Gbps and higher speeds without the need to deploy new technologies.

“As we were looking at NG-PON2, we have a technology that gets us up to 10/10 Gbps all the way to a system capacity on the fiber or 40/40 Gbps or potentially higher as you go to 8 channels,” O’Byrne said. “What concerned us as we went from BPON to GPON is it was a forklift upgrade where we had to deploy new optical line terminals (OLTs) in every CO and different wavelengths.”

Verizon has been an active voice in the NG-PON2 movement. In January, the telco completed an NG-PON2 interoperability trial at its Verizon Labs location in Waltham, Massachusetts. Adtran, Broadcom, Cortina Access and Ericsson participated in the interoperability trial, in partnership with Calix.

RELATED: Verizon completes NG-PON2 technology trial, signals next FTTP move

Calix has built a software defined access (SDA) platform that can bond multiple channels or wavelengths of NG-PON2 technology over fiber. In tandem with emerging ITU standards, Calix demonstrated the ability of the AXOS E9-2 Intelligent Edge System to leverage NG-PON2 channel bonding to deliver up to 40 Gbps downstream, or 80 Gbps of aggregate bandwidth over a single strand of fiber.

“This is the next way to evolve and is part of the work we have done with Adtran and Calix,” O’Byrne said. "For the past year, folks in the standards bodies are looking at how to do bonding efficiently."

A graceful migration

While the drive for 10G FTTX services may seem like overkill today, Verizon wants to have the infrastructure in place to satisfy such speeds as demand dictates without having to make wholesale upgrades to its network.

Previously, Verizon’s FTTH technology migration from BPON to GPON was done over the course of 5-6 years. Initially, Verizon offered speeds from 5-30 Mbps.  

Thanks to Google Fiber and AT&T making consumers and businesses aware of 1 Gbps speed services, Verizon would like to have a FTTX technology that could scale over time.

“We’re looking for a network that’s going to be out there for 5 or 10 years or more, we want something that’s going to grow more gracefully up to 2025 or beyond,” O’Byrne said. “It seems like a long time, but if we need more bandwidth the question is how are we going to do that more gracefully?”

In the standards efforts, Verizon had advocated for deploying 10 Gbps on a single wavelength for NG-PON2, a plan under which service providers would deploy multiple wavelengths. Similar to new DSL technologies like vectoring and bonding, which groups multiple copper pairs to get higher speeds, Verizon has advocated that service providers could bond multiple wavelengths.  

“We could start doing what we did in DSL technology, copper technology for many years and what cable companies do today, where they bond multiple 6 MHz channels and aggregate the throughput they get,” O’Byrne said. “We could do this optically and start taking advantage of the wavelengths we deploy and when we actually need them.”

Preparing for future bandwidth needs

While most consumers won’t need multiple gigabits of bandwidth, Verizon sees the initial application for channel bonding technology in the business market.

The telco also wants to have a network that can handle whatever future bandwidth needs any customer wants.   

“We’re still not sure if residential needs a gigabit,” O’Byrne said. “Over time the expectation is the needs will continue to grow, and we want to make sure that the network has the capability to offer more bandwidth the customer wants in the foreseeable future and we have means to handle that need if it comes faster than we initially think.”

What is also compelling about channel bonding is that there will be no major change of the technology. When Verizon sees a demand to go to 25 Gbps, for example, it won’t need to deploy a new Optical Line Terminal in the Central Office (CO).

Instead, the service provider would only have to deploy a special optical network terminal (ONT) at the customer premises. High-end customers that require higher bandwidth needs would be able to dial up 40 Gbps speeds as needed.

“If we have the ability to bond channels, it means we don’t have to put any new equipment out in the Central Offices,” O’Byrne said. “We just need a special ONT that can see 2 or 3 wavelengths and bond them together, so it moves costs from an installed-based cost to a success-based cost.”

As a result, O’Byrne said Verizon and other providers would be able to more rapidly increase speeds because “we only have to install an ONT rather than a OLT.”

However compelling channel bonding on NG-PON2 is, O’Byrne cautioned that the bonding approach is just an option that Verizon and other telcos can use if they find it fits a need.

“The way we’re looking at channel bonding is that it’s an option,” O’Byrne said. “It has shown to be viable in the copper industry and in the MSO industry, so it’s not a new thing, but it has a robust foundation and gives us the ability to evolve beyond 10 Gbps and potentially up to 40 Gbps by bonding all of the wavelengths.”

Quicker competitive response

But the advent of channel bonding is not just about sheer speed. When Verizon migrated from BPON to GPON, it took the telco nearly 5 years, but it wants a more rapid plan.

For Verizon, channel bonding will help it more quickly respond to competitive threats from cable and CLECs.

This is because the channel bonding capability of NG-PON2 allows Verizon to serve business and consumers on one platform.

“Channel bonding allows us to act much more quickly to the needs of the customers,” O’Byrne said. “This allows us to do something a lot quicker and give the ONTs specifically to customers that have a need for the higher footprint rather than spending it per customer.”

In the short term, Verizon could use the NG-PON2 bonding capabilities to provide 10G service for business over the PON network, for example.

“We have a 10G UNE we may be offering to businesses, and if we wanted to put that service on the PON network, we would turn off forward error correction (FEC) which would limit the distance for this service," O'Byrne said. "Bonding allows us to get above 10 Gbps and the original distance the PON technology was designed for."