The next generation of passive optical network (PON) technology, known as 25G PON, has seen relatively few deployments, but that appears set to change. Dell’Oro Group recently raised its forecast for 25G PON, also known as 25GS PON, and expects 25G PON revenues to triple between year-end 2023 and year-end 2025. Here’s what service providers should know about the technology.
As Stefaan Vanhastel, head of marketing and innovation for fixed networks for Nokia, explained in an interview with Telecompetitor, most service providers are looking at 25G PON as an opportunity to generate additional revenue from business customers. Nokia is the only company that currently has 25G PON equipment commercially available, although that is expected to change soon.
Some businesses will prefer 25G PON because they are used to 10 Gbps symmetrical service and, with 13% overhead, XGS-PON doesn’t support full 10 Gbps speeds, Vanhastel explained.
Julie Kunstler, chief analyst at Omdia, agreed.
“Some enterprises want full 10G symmetrical services,” she wrote in an email in response to questions from Telecompetitor.
Traditionally, businesses used point-to-point active Ethernet to get 10 Gbps symmetrical service.
But as Kunstler noted, “PON is optics and fiber efficient compared to point-to-point active Ethernet. 25G PON enables operators to support enterprises and xHaul transport in a less costly and more sustainable way.”
According to Vanhastel, the cost of 25G PON equipment is less than two-and-a-half times the cost of XGS-PON. That makes it more cost-efficient on a per-gigabit basis.
Although some people in the industry are using the term 25GS PON to indicate that speeds are symmetrical, Vanhastel said 25G PON is symmetrical and is synonymous with 25GS PON.
It’s worth noting that some operators are offering 25G PON residentially. For example, EPB – the Chattanooga utility that pioneered gigabit PON—has deployed 25G PON citywide.
25G PON Co-existence
Deploying 25G PON is relatively easy for providers that already have PON infrastructure in place. The reason is that 25G PON can be deployed on top of, and co-exist with, previously deployed PON infrastructure because it can use a different wavelength.
“You can have three generations of PON at the same time,” said Vanhastel.
As Vanhastel explained, operators can deploy GPON, XGS-PON and 25G PON over the same infrastructure. He also noted that 25G PON can use any of three different wavelengths.
It’s also worth noting that, according to Kunstler, 25G PON is less costly than NG-PON2 – the PON technology that Verizon has chosen for its 10 Gbps deployments. NG-PON2 currently supports four 10 Gbps wavelengths that can be aggregated to boost speeds. Support for eight wavelengths is planned.
