No it won’t make a difference.

Ultimately it’s the OLT in the headend exchange that sets the line rate and 1000 Mbps is the highest downstream profile on Openreach based GPON kit. In any event the 1000BaseT port on the box becomes the hard limit anyway. You physically cannot push more than ~940 Mbps (net) through such a port due to Ethernet framing and overheads.

Where other AltNet providers (not CityFibre or Openreach) are deploying XGS-PON based gear, then for customers wanting a greater then gigabit connection they will provision ONTs with port speeds with either 2.5Gbps or 10 Gbps capable copper LAN port(s) (indeed sometimes SFP+ cages) so that the Ethernet LAN port not a bottleneck.

Edited by Pheasant (Tue 31-May-22 22:10:15)

Thanks, although I don’t think you quite got my (CityFibre) question which whether they are using the limits of the 1Gbe port as a very crude bandwidth limiter. After all GPON is capable of just under 2.5Gbps down. Hence the question about the 2.5 Huawei equipment. It just strikes me as strange that the fastest speed available is exactly the same as 1Gbe. Anyway you sort of answered my question - the line speed is set at the exchange. Thanks!

No they are not using the port as any sort of bandwidth limitation device. GPON profiles are decided by the operator and set/configured the OLT.

Although GPON has a standards set 2.488 Gbps downstream and 1.2 Gbps upstream bandwidth limit. That is the total aggregate bandwidth available on the PON. There are no operators in this country which offer > 1 Gbps at the customer connection on GPON. There are several operators overseas that I'm aware of that do offer > 1 Gbps on GPON, but its not typical. This is generally because doing so compromises the available downstream bandwidth with other subscribers on the same PON.

Upload bandwidth on GPON is a slightly different matter. Recall than residential broadband users typically consume data on their connections in roughly 10:1 down/up ratio - therefore the upstream bandwidth can more 'safely' be over-subscribed - and that is exactly what CityFibre do on their network they oversubscribe their upload, such that they can offer a 1 Gbps nominal symmetric service.

On the other hand Openreach take a far more conservative view on upload and they will only ever allow up to a 220 Mbps customer connection upstream on their GPON net.

Back to the question related to Carl's "experiment", not that I want to step on his toes here, but the original 4-port Huawei ONT (no longer been installed since around 2019) as supplied by Opnreach had to my knowledge a shared 1 Gbps backplane connecting the optical GPON side of the device to the 4 Gigabit Ethernet ports, thus somewhat limiting the full throughput where there were more than 2 subscribers connected to the ONT. Swapping to a later model with a 2.5 Gbps connection on the backplane removes that impediment so that if your had 2 x Gigabit subscriptions they could 'pull' their full downstream bandwidth without this artificial limit die to the chipset design.

Thanks, that’s very insightful!

In reply to a post by kevinherring:

CarlTSpeak, you mentioned your Huawei 4-port ONT has 2.5Gbe - does it does it enable you to get higher speeds, or are they limiting it further upstream?

As Pheasant pointed out in his detailed reply, Carl only gets benefit from using a different ONT as the original supplied Openreach ONT is limited to 1Gb between the optical and Ethernet switch.
Carl has (or had) 3 separate connections running on that single 4 port ONT. 2 X 1 Gb and 1 x 330Mb.
With the Openreach 4 port ONT this would severely limit his throughput he can almost consume the entire PON with his own Huawei ONT.
Openreach allows all 4 ports to be used for 4 separate services.

As CityFibre don't allow multiple connections over a single ONT there would be no benefit to swapping it.

They will rate limit the line to your package speed at the OLT.

Edited by j0hn83 (Wed 01-Jun-22 17:40:02)

This ONT on a stick SFP from fs.com can allegedly be SSH'ed into and customised to your hearts content.

https://www.fs.com/products/133619.html

I have a feeling the Ubiquity ONT on a stick can also be customised too, but I have not looked into that. As time goes by unless the network vendors offer it as a solution it is inevitable that third parties will set into the void that they are leaving. A lot of it could IMHO be circumvented by offering PoE on the ONT. If Mikrotik can do it on a £25 wireless access point then it should be no problem to add to an ONT. I note that the Ubiquiti ONT can be powered via PoE. One suspects the option would solve a whole bunch of powering issues where there is currently no mains power at the most suitable location for the ONT. If it where a thing you would also start getting routers providing PoE on the WAN port too.

In reply to a post by Pheasant:

Although GPON has a standards set 2.488 Gbps downstream and 1.2 Gbps upstream bandwidth limit. That is the total aggregate bandwidth available on the PON. There are no operators in this country which offer > 1 Gbps at the customer connection on GPON. There are several operators overseas that I'm aware of that do offer > 1 Gbps on GPON, but its not typical. This is generally because doing so compromises the available downstream bandwidth with other subscribers on the same PON.

GPON (G.984.1) can also 2.4 Gbit/s up, 2.4 Gbit/s down, but most using profile 1.2 Gbit/s up, 2.4 Gbit/s down. Both Openreach and Cityfibre are using 1.2 Gbit/s up, 2.4 Gbit/s down.

BT was one main inventors of PON in 1980's. That fact everyone would had fibre in 1990's if BT had there way, there is a lot blame upon Margaret Thatcher who blocked that from happing.

I believe it’s EPON rather than GPON that you are referring to there. The former is an IEEE 802.3 derived standard. Not used at all in the UK in commercial rollouts but used extensively in places like Asia.

BT were indeed pioneers of PON and some of their early research papers are findable with a casual search. They also pioneered blown fibre, which for a long while they kept back from the competition. Some of the more (commercially) successful projects to have come out of Adastral Park.

GPON as 2.4 Gbit/s up, 2.4 Gbit/s down exists. I have no idea why no one using it. There is so little documented infomation about it. Even can not find anywhere there it is being used, which make it an even greater fascinating to me. What going on? Why?

You find it under heading 7 Bit Rate
https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-...