The tech and speeds behind the ONT

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Dynamic

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#304122 6-Apr-2023 07:56

I've always been a little curious but never asked about the fibre speeds behind the ONT we see at home. With a Gigabit fibre connection I expect to be able to burst to roughly Gigabit download speeds but I don't expect to have a dedicated Gigabit connection between my home and the server I'm downloading from. Can anyone answer the following questions, and perhaps others would like to chime in with a few more?

What 'speed' is the raw fibre connection into the average home? Is it faster than gigabit? If I have two gigabit connections from two different ISPs on the same ONT (port 1 and port 2) and do a speedtest on both connections at once under ideal circumstances, would I see roughly 950mbps on each connection as the optical link speed is actually much faster than Gigabit, or roughly 475mbps on each connection because the optical connection is approximately gigabit speed?
The GPON tech used means that the fibre from the cabinet is passively split between up to 15 (?) homes. If all 15 homes had a single gigabit connection and under ideal circumstances all did a speedtest at once, would they see roughly 1/15th of Gigabit speed, or something different?
How does Hyperfibre get delivered over the same optical cable? Does the passive splitter get swapped out? Are more light spectrum colours used in the Hyperfibre ONT that the regular ONT does not recognise?

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#3059658 6-Apr-2023 08:16

There is a talk somewhere from a chorus engineer at one of the networking community conferences (NZNOG maybe).

Also some of these questions are just how does fibre work, e.g. capacity of a single fibre strand etc.

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#3059666 6-Apr-2023 08:49

"How does Hyperfibre get delivered over the same optical cable? Does the passive splitter get swapped out? Are more light spectrum colours used in the Hyperfibre ONT that the regular ONT does not recognise?"

You can stuff multiple polarities and amplitudes of light down a single strandm

in 2011 NEC managed to get 101.7 terabits per second over 165 kilometres of a single fibre strand, so physically there is plenty of capacity... that's why going for a FTTH network was a wonderful move for NZ, compared to hybrid networks in some other countries

https://www.newscientist.com/article/mg21028095-500-ultrafast-fibre-optics-set-new-speed-record/

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#3059667 6-Apr-2023 08:55

Hi, once you start passing traffic over a WAN lots of stuff can happen, however with respect to the ONT itself, the GPON interface between the ONT and the OLT back at the exchange is infact 2.5Gb/s downstream and 1.25Gb/s upstream connection, however this is shared with upto around 16 other ONTs in your neighbourhood. Obviously your plan and the copper interface you connect to are only GigE, that said real world contention of local GPON would be such that you are unlikely to see anything other than your full plan GigE/0.5GigE betweent your ONT and the OLT, unless you have a street full of nurds siphoning the entire internet onto god knows what 24/7.

The OLT is connected via multiple 10Gig ethernet links upstream to Chorus's network, Chorus ensure those links and the local GPON never reach full load.

From there its upto your ISP and the route to your servers that will dictate what you get, it should be easily possible to achieve GigE or very close to your server if its hosted in NZ and connected via a suitable GigE path, if your Server is connected via a GPON UFB connection then you will only ever see 0.5GigE at best as thats the upload limit. I have several machines in various parts of the country on UFB GPON connections and regularly see 450-500Mb/s sftp transfers.

Cyril

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#3059713 6-Apr-2023 11:02

The regular GPON is 2.4Gbit Full Duplex split I think across potentially up to 16 terminals. In many cases less. AS mentioned in the previous post the upstream may be limited in some way... perhaps down to 1.2Gbps.

XGSPON (which has been branded as a hyperfibre product) I am not sure is approximately 10Gig -> 25Gbps.

As for copying data from a server outside the country or far away, most of the time it will be the latency that is killing your speed experience. We have managed to overcome this and have built a product that will easily be capable of flatlining 4Gbps speeds to USA Datacentres on a 4Gbit hyperfibre connection. In short (There's bandwidth in the pipes, your network setup/machines will not be able to tolerate it).

I have posted more info on the product we built in the Startups Forum.

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#3059715 6-Apr-2023 11:14

Chris from Amuri gave a really good talk about GPON, XGSPON and how all this FTTH works at the NZNOG Conference this year, which showcases answers to this in a really good way, with everything from how the technologies work, to how the fibre goes into the ground and light spectrum/frequencies down the strand.

https://www.youtube.com/live/Ft24TOxtt7I?feature=share&t=8374

Worth a watch if you're curious! 😊

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#3059716 6-Apr-2023 11:18

darylblake:

The regular GPON is 2.4Gbit Full Duplex split I think across potentially up to 16 terminals. In many cases less. AS mentioned in the previous post the upstream may be limited in some way... perhaps down to 1.2Gbps.

There's a nice little graph here that outlies things, and a little more detail. Also mentions the wavelengths, etc. which OP might find interesting. And as Quic mentioned, Chris' talk was pretty good, and covers a pretty good overview from customer distribution to the network technology itself.

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#3059725 6-Apr-2023 11:40

darylblake:

XGSPON (which has been branded as a hyperfibre product) I am not sure is approximately 10Gig -> 25Gbps.

The X means 10 :) (10 Gigabit Symmetrical Passive Optical Network)

Dynamic

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#3059726 6-Apr-2023 11:41

Thank you all for the really informative answers. Curiosity well satisfied and I have definitely learned something today.

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BMarquis

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#3059743 6-Apr-2023 12:48

Others have answered some things for you. But I'll cover off each point @Dynamic

What 'speed' is the raw fibre connection into the average home? Is it faster than gigabit? If I have two gigabit connections from two different ISPs on the same ONT (port 1 and port 2) and do a speedtest on both connections at once under ideal circumstances, would I see roughly 950mbps on each connection as the optical link speed is actually much faster than Gigabit, or roughly 475mbps on each connection because the optical connection is approximately gigabit speed?

The fibre itself doesn't have a 'speed'. The fibre is more than capable of supporting the future evolution of fibre access technologies like 25gbps and 50gbps PON and beyond!

Our current technologies are:
GPON, which is 2.5gbps downstream and 1.25gbps upstream.
XGSPON (Hyperfibre) which is 10gbps downstream and 10gbps upstream
Note that these are the GPON layer rates, so the bandwidth available at the [OSI model] Layer2/Layer3 and above are less than the GPON rates due to protocol overheads, etc.
We then have different service offerings over these technologies (300/100, FibreMAX, etc)

2 Fibre MAX services on a single ONT with concurrent speedtest should get quite close to their 1gbps peak rate depending on other activity on that PON segment. It also depends on ONT model.

The GPON tech used means that the fibre from the cabinet is passively split between up to 15 (?) homes. If all 15 homes had a single gigabit connection and under ideal circumstances all did a speedtest at once, would they see roughly 1/15th of Gigabit speed, or something different?

The majority of our (Chorus) splitters are 1:16 and there are some 1:32 splits.
Yes, bandwidth is shared fairly under a contention situation. but it is incredibly unlikely that the scenario you are describing actually occurs.

I appreciate you are kind of focused on downstream, which is a "broadcast" on the PON. The OLT ensures fairness.
Upstream is a bit more fun :) GPON (and XGSPON) use TDMA transport with Dynamic Bandwidth Allocation where ONTs are allocated timeslots to transmit on. These timeslots are allocated, as the name suggests, dynamically based on current provisioned services and ONT usage. i.e an ONT not using much bandwidth will have it's timeslots allocated to other ONTs. This is how we ensure the 500mbps upstream peak rate can be realised to a reasonable degree when there is 1.25gbps of bandwidth for 16 customers. The joys of statistical multiplexing.

How does Hyperfibre get delivered over the same optical cable? Does the passive splitter get swapped out? Are more light spectrum colours used in the Hyperfibre ONT that the regular ONT does not recognise?

The fibre optic cable and splitter are not changed at all for Hyperfibre. We swap the OLT optical module (an SFP+-based transceiver) at the exchange side with what is called a MultiPon Module (MPM).
The MPM contains the optics to transmit GPON and XGSPON at different wavelengths and combine them onto the single fibre towards the splitter.
The ONT side optics are only tuned to either GPON or XGSPON, so to move between the technologies an ONT swapout is required.

While I don't fancy myself as a public speaker (please bear that in mind!). This is public, so someone was bound to find/post it.
The talk I ('the Chorus Engineer') did a few years back was referenced earlier. Here's the technical part of it:
https://www.youtube.com/live/4xGxotBk8AM?feature=share&t=17615

And there's where the talk starts if you want to watch the whole thing.
https://www.youtube.com/live/4xGxotBk8AM?feature=share&t=17176

Dynamic

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#3059747 6-Apr-2023 13:10

Thank you very much @BMarquis for the in-depth response. Of particular note for me was the difference in upstream and downstream (broadcast vs TDMA). Easter weekend might give me some time to watch the YouTube clip. :)

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coffeebaron

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#3059963 6-Apr-2023 21:52

Maybe get together with a bunch of neighbour's and see if you can overload the PON with a neighbourhood full of simultaneous speed tests :)

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#3063343 13-Apr-2023 20:34

coffeebaron: Maybe get together with a bunch of neighbour's and see if you can overload the PON with a neighbourhood full of simultaneous speed tests :)

you would all have to run the speed test exactly simultaneously. better luck getting the street to download Fortnite simultaneously :)

I also doubt the 1/16 split will be your direct Neighbours. so you would need to know what addresses are on your 1/16 split.

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#3063606 14-Apr-2023 12:05

Thanks for the question and the answers - This has been a really informative thread and I plan to watch the videos (or listen in the car)

My take aways from this are
A) get a business fibre plan at home - I have and it got the free bump from 100/100 to 300/300 and its a dream. Paying more for the Gigabit won't really see much benefit for the price - Does a business plan give a more guarantee'd speed??
B) Try and buy a house in an area filled with Technophobes so your neighbours are probably checking email, using facebook and watching netflix at the most.

My one question - Who sets up the speeds - Are these done on the ONT at the tenant or at the OLT or on the reseller network - I ask as I've had a few installs on Enable Fibre lately in Christchurch seeing 100 down and 300 up where its been provisioned wrong - I'm picking this is an Enable mistake not the reseller??

Matt Beechey Mobius Network Solutions

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#3063647 14-Apr-2023 13:36

mobiusnz:

Thanks for the question and the answers - This has been a really informative thread and I plan to watch the videos (or listen in the car)

My take aways from this are
A) get a business fibre plan at home - I have and it got the free bump from 100/100 to 300/300 and its a dream. Paying more for the Gigabit won't really see much benefit for the price - Does a business plan give a more guarantee'd speed??
B) Try and buy a house in an area filled with Technophobes so your neighbours are probably checking email, using facebook and watching netflix at the most.

My one question - Who sets up the speeds - Are these done on the ONT at the tenant or at the OLT or on the reseller network - I ask as I've had a few installs on Enable Fibre lately in Christchurch seeing 100 down and 300 up where its been provisioned wrong - I'm picking this is an Enable mistake not the reseller??

If you want dedicated bandwidth with absolutely no sharing, get DFAS, this is a point-to-point fiber between you and the exchange with absolutely no sharing with anyone.

Any views expressed on these forums are my own and don't necessarily reflect those of my employer.

Dynamic

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#3063653 14-Apr-2023 13:59

mobiusnz: My one question - Who sets up the speeds - Are these done on the ONT at the tenant or at the OLT or on the reseller network - I ask as I've had a few installs on Enable Fibre lately in Christchurch seeing 100 down and 300 up where its been provisioned wrong - I'm picking this is an Enable mistake not the reseller??

While I've never been an Enable customer, I believe their standard 300mbps offering is the same as Chorus, which is 300/100. 300/300 is available but it is a less common and more expensive business option.

Evidence: Speedupgrade | Enable

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