Although numerous carriers have opted to deploy XGS-PON to deliver multi-gigabit service, Verizon has chosen a different path. The company’s 2 Gbps service launch in New York City last week using NG-PON2 is believed to be the first commercial launch of the technology in the U.S. and possibly the world, according to Kevin Smith, Verizon Vice President – Technology Development and Planning.
Telecompetitor talked to Smith about the company’s contrarian decision.
Verizon NG-PON2 Decision
According to Smith, the Verizon NG-PON2 decision was driven, in large part, by the company’s experience with having to upgrade to GPON beginning in 2008, just four years after beginning to deploy BPON.
“That experience of having to continually overlay your network with the next version of technology is what ultimately lead us to NG-PON2,” he said.
NG-PON2 is more costly than XGS-PON, a consideration that has driven AT&T, Frontier and other providers to deploy less costly XGS-PON, even though that technology is also less future-proof.
And according to Smith, it’s not just that NG-PON2 has 40 Gbps capacity in comparison with XGS-PON’s 10 Gbps capacity. NG-PON2 has four wavelengths, each operating at 10 Gbps, and Verizon already has tested bonding multiple wavelengths to support speeds above 10 Gbps.
“There are a lot of benefits when you have four wavelengths,” said Smith. “You can very gracefully co-mingle business and consumer services and you can offer higher-throughput 20, 30 or 40 gigabit services.”
Verizon’s Vice President – Technology Development & Planning
Customers also can be shifted from one wavelength to another, if for example, “you have a super-user who is crushing your PON – you can move that customer so they’re not disrupting other customers,” Smith said.
Verizon is deploying NG-PON2 as an overlay to existing GPON networks and can use existing fiber because GPON uses a different wavelength. Eventually, the company expects to upgrade its entire Fios footprint to NG-PON2, Smith noted.
The company also will be using NG-PON2 to provide connectivity for its 5G millimeter wave service and already has connected some of those sites.
“As you think about the density of millimeter wave, it’s another great tool in the toolbox to also provide millimeter wave services,” commented Smith.
The Future
GPON also can be easily upgraded to XGS-PON by adding just a single wavelength to existing GPON fiber. Smith noted, however, that the next upgrade after XGS-PON would be more difficult.
The next logical upgrade would be to 25G PON, and as Smith described the problem, “25G PON would use the same wavelength as XGS-PON.”
As he explained, “you might be able to co-mingle them in the OLT [optical line terminal] but you would need dedicated fiber and splitters.”
Verizon isn’t looking at 25G PON, Smith said.
As an alternative, he noted that there is discussion in the standards body responsible for NG-PON2 about moving to four 25G or 50G wavelengths that would still co-exist within existing fiber.
Moving forward, Smith also anticipates the cost of NG-PON2 coming down.
“We believe it’s expensive now because all the scale is driven by XGS-PON – once we start to scale and consume millions of units, it will bring the price down and maybe others will follow,” Smith said.
