August 05, 2021
Written by: Mary Cullen
GPON has been widely deployed for years, but Broadband Forum research shows likelihood of heavy growth in usage over the next several years. Managing Director Ken Ko joined the Fiber Broadband Association on a recent Fiber for Breakfast episode to discuss how these technologies are going to impact the networks of tomorrow.
Ko shared research from the Broadband Forum that shows GPON and XGS-PON capacity is running out sooner than we’d think. GPON capacity could start running into its reserves as early as 2023 and 10 Gigabit XGS-PON as early as 2028, affecting performance for users.
“Heavy growth is consistent in what I’ve actually seen and what I’ve seen documented from multiple sources in years past—not even to mention last year’s pandemic and the huge bump in growth of usage that we saw last year,” Ko noted.
While neither the projected heavy nor moderate growth rates hit the basic capacity of GPON, Ko said each growth projection exceeds GPON’s capacity minus the headroom needed in reserve.
“There needs to be enough headroom left in reserve on the PON over and above the usage that users are applying in order to actually meet the performance needs that you’re advertising for a Gigabit service,” he said.
Ko said the most common application wherein users are taking up that full Gigabit of capacity is a speed test.
“When users use that speed test, they get a direct indication of what their performance is,” he explained. “And if you haven’t left that full Gigabit in reserve, you will probably hear about it from them.”
Considering that fact and the Gigs that must be left on the reserve, Ko said we may start seeing GPON exhaustion on a 32-subscriber split as early as 2023.
“GPON, depending on your network design and the services that you’re offering, may or may not have several years of life left to it going forward in the decade,” he continued. “However, we are starting to see widespread deployment of XGS-PON, which allows for four times the capacity and close to 10 Gigabits, once you take the overhead off, as opposed to 2.5 Gigs on GPON.”
Ko said that is a vast improvement, but we must also consider that service rates are going to be steadily increasing over the years. Additionally, XGS-PON comes with its own capacity issues.
“Once you get to those higher levels of service and the amount of headroom you have to leave for them, you may or may not get to the end of the decade before you reach exhaustion with XGS-PON,” he said.
Ko noted that operators only supplying consumer services will likely reach the end of the decade without exhausting the network but acknowledged that most operators are looking at converging those consumer services with business services, which then throws another level of requirement as well as convergence opportunities.
“We really have to start considering new PON technologies in the not very distant future,” he said.
Ko noted we already know the requirements for our networks, and performance isn’t just speed. He noted considerations for latency, packet loss, security, timing and synchronization and reliability and availability. The good news is there are technologies helping to meet those requirements.
“The ITU-T is in the final stages of approving a 50 Gig PON which runs over a single lambda in each direction, and the initial recommendation—which may be approved later this year—supports 25 Gigs upstream, with a symmetric version for future study,” Ko explained. “IEEE has recently approved a 50 Gig PON as well, which runs over two wavelengths at 25 Gigs each.”
A third version that supports 25 Gigs symmetric has not been specified by ITU-T or IEEE, but by a multi-source agreement between a large group of vendors and service providers.
“These are the offerings that we are going to see in the near future for increasing PON performance,” Ko reiterated before noting that both IEEE and ITU-T are developing what is being called “SuperPON technologies” that will support up to 160 Gigabits aggregate over as many as 16 wavelengths.
“There is no shortage of innovation, or bandwidth when looking forward with modern technologies,” he concluded.