GPons and any other sort of pons :)

I always thought that a Pon was one thing, like a box on a unit, but looking into it today for a post on another forum, i think I was wrong. Looking at it, it seems Pon is just a name given for a bunch of stuff that works as a network, so it is a combination of the OLT, the splitters and the rest of the network all the way to the end user's ONT.
Am I right?

If so, then the splitters would be in the street? Which means that there would to two slitters serving my street which has around 55 houses here, I presume the second splitter would also serve another street.
as well. So
The post was about FTTP being a shared network and while I knew that, I did not realise that so many people shared the same bandwidth, or maybe I missed that. So since take up is pretty slow at the moment, the ones who have taken it up early will have no problem with speed.


I am interested in the technology and how it works.

The clue is in the name, passive optical network.

So yes, it is the whole network and not just one box.

As I understand it, with OpenReach FTTP it is up to 32 subscribers sharing 2.4Gbps

I suspect the vast majority of people don't sign up for a gigabit connection, I'm guessing 160/30 is far more popular.

So it isn't like the old ADSL contention with a 1:50 contention ratio.

AAISP list the "MINIMUM DOWNSTREAM THROUGHPUT" that BT expect (which tops out at 195 mb/s for the gigabit services):

https://www.aa.net.uk/broadband/fttp-speeds/

Edited by andynormancx (Tue 25-Apr-23 15:09:52)

Ive a 700mb stay fast guarantee with BT

Which they definitely can't actually be absolutely sure to guarantee to provide in practice, given the shared nature of the service (and that you are sharing with other FTTP users not under BT's control).

And if you look at the wording of the guarantee it is really more of a promise that you can cancel your contract early, rather than a guarantee that you'll always get 700mb.

"If your speeds aren't back to normal after 30 days, we'll give you £20 back. You can also choose to exit your contract without paying a charge for cancelling it early."

https://www.bt.com/help/broadband/what-is-bt-s-stay-...

The PON is indeed all of the passive optical goodness in between OLT in the exchange or cabinet and the ONT in the home or office.

The sharing isn't an issue 99.99% of the time. It's not uncommon for a single PON to cover 64 or 128 premises. People aren't using anywhere near their full capacity for any length of time.

Openreach use a 1:30 ratio with 2 spares, CityFibre 1:32 on GPON, 1:64 on XGSPON, altnets are usually either 1:64 or 1:128.

I see over 8 Gbit/s via XGSPON all the time and saw 2.1 Gbit/s basically all the time on GPON. Very occasionally there are segments that are problematic but it's usually not an issue. FTTC you're sharing backhaul with everyone on the cabinet.

In reply to a post by andynormancx:

The clue is in the name, passive optical network.

So yes, it is the whole network and not just one box.

I know what passive is and optical and I know what a network is, so yes I should have put it together. Thanks for the info peeps. I now know a bit more than I did