For fibre network operators who have built their infrastructure using Active Ethernet technology, it costs them no more to offer a 10Mbps line than it does 1Gbps.
Gigabit Passive Optical Network (GPON), an alternative technology, works on different principles. It offers cost savings but at a performance penalty.
Vumatel is a major user of Active Ethernet technology, whereas its competitors like Openserve generally use GPON.
“The technology deployed determines whether a fibre service is symmetrical or asymmetrical by design, and the underlying implementation determines the cost,” Cybersmart technology chief Laurie Fialkov explained to MyBroadband.
A symmetrical fibre service is one where the download and upload speeds are equal.
Fialkov said that Cybersmart uses wavelength division multiplexing (WDM), which is Active Ethernet for all intents and purposes.
“Instead of provisioning a fibre per customer, we provide a wavelength of light per customer — hence the name Lightspeed — and a wavelength of light exhibits the same properties as a fibre strand,” Fialkov stated.
“So WDM is merely Active Ethernet with a lower fibre count.”
Fialkov explained that in their implementation, 40 subscribers could plug into a single switch with an uncontended 1Gbps per client.
Uncontended means that the bandwidth on a line, whether strand or wavelength, is not shared between subscribers.
Cybersmart provisions 40Gbps of uplink capacity per switch, regardless of whether clients choose to buy an account that can make use of the full speed or not.
Therefore, from the perspective of an FNO that uses Active Ethernet, it costs the same to provide a 25Mbps or 1Gbps line.
It’s a different story from the Internet service provider’s perspective, whose costs increase the more data a subscriber consumes.
Since a client on an uncapped 1Gbps connection can consume much more bandwidth than one on a 25Mpbs line, ISPs charge more for uncapped accounts that offer faster speeds.
Fialkov said that, for support reasons, they chose to limit their service to 500Mbps split symmetrically — 250Mbps download and 250Mbps upload.
“Most entry-level laptops can’t achieve that speed, and 2.4Ghz Wi-Fi definitely can’t,” he said.
“To avoid appearing that we are underdelivering, we limit the service to what is realistically achievable on a speedtest even though it costs the same to provision the service at 1Gbps.”
GPON, on the other hand, is asymmetrical by design. It also lets the fibre operator split a single strand of fibre hundreds of times.
However, Fialkov said that before beginning a comparison of Active Ethernet and GPON technologies, it is essential to note that there are hundreds of different GPON suppliers — all with various features.
“These are broad statements to illustrate the issue,” he said.
“Some GPON equipment even has a few Active Ethernet ports.”
Fialkov explained that GPON generally offers a total of 2.5Gbps of download capacity and 1.25Gbps upload capacity per site.
“This is why you see a lot of asymmetrical services with upload speed half the download, as this mirrors GPON’s total capacity,” said Fialkov.
Since most home users download more than they upload, this arrangement suits FNOs and Internet service providers (ISPs).
In addition to the asymmetry, GPON also lets network operators split a single fibre strand 128 times — on some implementations up to 512 times.
However, Fialkov said that few FNOs split a fibre more than 64 times.
This is because the total bandwidth is split too. So if you split a strand 128 times, the maximum uncontended speed you get per port is around 20Mbps download with 10Mbps upload.
“If you want to offer higher speeds and keep your cost the same, you need to contend the fibre,” explained Fialkov.
Alternatively, you can decrease the number of ports if you don’t want contention, but your cost per port goes up, assuming your equipment and backhaul costs remain the same.
Similarly, if you want to offer symmetrical services on GPON, you have to halve your split ratio by halving the number of ports, in which case your cost per port doubles.
Alternatively, you have to double your contention ratio — in other words, share the same bandwidth between two subscribers, degrading their overall performance.
“Remember there are two places the service can be contended,” Fialkov said.
- If it’s GPON, it can be contended at the fibre network operator level. On Active Ethernet for services under 1Gbps, there cannot be contention.
- It can be further contended on the bandwidth side by the ISP.
“For this reason, companies who are taking ‘enterprise’ services provisioned over GPON must be out of their minds,” Fialkov stated.
“An enterprise service provisioned over GPON is like buying a second-hand car — all the specs are the same as a new car, but you have no idea what you are getting until you have got it.”
He also said that with GPON, if the service says 100/100Mbps you have no idea whether the FNO has done that by contending the fibre to minimise their cost per port or kept it uncontended and increased their cost.
“You can be pretty certain that for services less than 1Gbps on an Active Ethernet implementation that the service is uncontended on the FNO level.”
Source: MyBroadband
