With an eye fixed on how it might stay ahead of future network data demands, Verizon said it successfully tested an 800Gbit/s connection across 400 miles of its ultra-long-haul fiber route between Dallas and Atlanta using ICE6 equipment from Infinera.

The effort reflects Verizon's intention to prepare its fiber backbone for the traffic increases it expects over the next few years from enterprise customers, 5G users and other Internet surfers.

Fiber remains "key to everything we're doing," Kevin Smith, Verizon's VP of technology development and planning, told Light Reading.

But some analysts argue that the noise around 800G may not ultimately result in a widespread push toward the technology when other options like 400G are on the table.

Smith explained that Verizon plans to install increasingly advanced fiber technologies, ranging from 400G to 800G, into its metro, long-haul and ultra-long-haul fiber networks. The goal, he said, is to stay ahead of the overall growth in Internet traffic, driven in large part by Verizon's big enterprise customers but also due to the growing number of consumers with Verizon's 5G smartphones.

However, Smith explained that Verizon has no intention of deploying 800G fiber technology across its entire backbone. Instead, he said that over the next two to five years he expects the company to strategically deploy 800G equipment in locations where it is needed, based on the growth in traffic over Verizon's network. He declined to provide any financial details about Verizon's fiber network upgrade efforts.

Verizon has indicated it will begin commercially deploying 800G in parts of its fiber network as soon as the second half of 2020.

Verizon's 800G forays
This isn't the first time Verizon has expressed an interest in putting 800G technology into its fiber network. The company announced in February an 800G test with Ciena and Juniper Networks, though Smith points out that effort centered on Verizon's metro fiber network, not in its long-haul routes.

Verizon is in the process of building fiber connections across an additional 60 major US metro areas, but it also operates long-haul fiber networks (which can stretch dozens of miles) and ultra-long-haul (ULH) fiber networks (which can stretch hundreds or thousands of miles) around the country. Metro fiber networks stretch like spider webs across one city, but then connect to long-haul and ULH networks to reach other cities or countries. Smith said most of Verizon's long-haul and ULH fiber networks – networks that comprise the backbone of the world's Internet connections – operate on 100G or, in some cases, 200G technologies.

Smith added that long-haul and ULH routes typically contain around 50 strands of fiber, far fewer than the minimum 864 strands of fiber Verizon is installing in metro areas. Partly as a result, the company is looking to increase the capacity of its long-haul and ULH fiber networks by upgrading them to 400G, 600G or 800G. Smith said that upgrading a 100G network to 800G can increase the capacity across that route by a factor of four.

Importantly, Smith said that upgrading a long-haul or ULH fiber route involves the installation of new line cards and, in some cases, new amplification nodes along the route. But he said it does not involve laying new fiber, which would be an expensive proposition.

The result, Smith said, is that a 30-year-old 100G fiber route can be upgraded to 800G technology – thus quadrupling the capacity of the line – without physically replacing the line. "It allows us to take advantage of the legacy fiber investments that we've got out there," he said of such technologies.

But the complexities involved in upgrading a fiber network can be seen in Verizon's new 800G test with Infinera. Verizon said that it only tested an 800G connection across 400 miles of the roughly 800-mile distance between Dallas to Atlanta. The remainder of the route, which Verizon obtained via its acquisition of XO Communications, involved 600G and 400G connections.

800G vs. 400G
Verizon isn't the only operator banging on the 800G drum in long-haul scenarios. For example, Windstream and Infinera tested an 800G transmission across roughly 450 miles of the operator's long-haul network between San Diego and Phoenix.

But Heavy Reading analyst Sterling Perrin explained that the Verizon and Windstream moves toward 800G may not ultimately result in a widespread deployment of the technology.

"As 800G goes longer distances, the appeal [of the technology to operators] increases," he said, adding that "operators can always dial down data rates to 700G or 600G to boost reach further. So there will be a mix of line-side data rates in networks for a long time. Operators will pick the greatest capacity and spectral efficiency that matches their reach requirements."

Perrin said that there is a widespread industry push to upgrade 100G lines to 400G, and that the OIF 400ZR specification is helping to standardize 400G technology. And that, he explained, raises the question of whether 800G will obtain widespread support.

"If 400G becomes the networking currency, do operators need 800G?" Perrin said. "Ciena and Infinera are the first vendors to 800G, so they say 'yes.' Nokia is not investing in 800G, so they make an argument that 800G is a solution looking for a problem to solve."

Concluded Perrin: "Operators like boasting, too – so we are starting to see operators promote their own 800G trials. That doesn't necessarily mean these will turn into massive commercial deployments soon. In the end, it's all about economics."

— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano