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[Weaver]

Is it correct that some of the non-BT FTTP service providers (leaving aside B4RN) offer symmetric throughput? If so, how does the last mile service providers’ costings work regarding symmetric vs asymmetric services?

[XGS_Is_On]

All the ones using XGSPON are symmetrical. CityFibre are symmetrical despite using GPON, they just accept the possibility of some congestion on the upstream which PON handles quite well.

No cost implication really. The ratio of usage across the customer base is 12-15:1 in favour of downstream even during lockdown times with lots more home working.

Whether GPON or XGSPON not a big deal. B4RN is point to point so nothing to see there, either, for cost.

[meritez]

£15 for 100/100 Symmetric FTTP: https://www.ispreview.co.uk/index.php/2022/11/rural-uk-isp-gigaclear-cuts-100mbps-broadband-to-just-15.html

[Weaver]

Apologies in advance for my being a bit slow. Is there a good reason why BT doesn’t deliver domestic symmetric FTTP then? I’m aware that for silly money you can order a dedicated link from BT via the ISP of your choice. I can’t remember the numbers but I do recall that AA’s resale prices for a BT dedicated fibre link were so scary that they didn’t even want to publish them. But leaving those truly business-oriented services aside, I’m wondering if BT wants to protect the pricey services by making sure that the PON service isn’t good enough for businesses because of an inadequate upstream for a business’s needs. Last thing BT wants is to be ‘competing with itself’ between its own service offerings. So there could be non-technical factors that drive the symmetric-vs-asymmetric provision decision.

@meritez - just, wow!

[dee.jay]

Yes, BTs system is GPON and not capable of symmetric. That’s all there is to it.

The dedicated link is presumably connecting your house to a single Ethernet port somewhere (hence AA branding that as such). It’s a dedicated port thus you are the only customer on it - that goes some way as to why it’s so expensive - an XGSPON port for example could potentially have up to 64 customers on it.

[Chrysalis]

Weaver I expect the reason BT restrict their upstream is to protect their leased line business alongside that in the consumer market the marketing benefit of gigabit upload is too low for the risk of the loss of revenue on LL.  If people can save money for something they perceive almost as good as something much more expensive then they might do so.

[Alex Atkin UK]

Yes, BTs system is GPON and not capable of symmetric. That’s all there is to it.

There's a big difference between not capable and not provisioned.  As already mentioned in another thread, its not that we can't do full upload speed, its that they are limiting how long we can do it for, so the average speed tops out at 115Mbit on residential.

[Weaver]

@Chrys - you and I are in agreement.

[XGS_Is_On]

Yes, BTs system is GPON and not capable of symmetric. That’s all there is to it.

Mmm CityFibre are GPON everywhere besides York and are symmetrical. Verizon and AT&T are symmetrical via GPON. Google Fiber, Singtel, Bell Canada, Rogers, etc.

Definitely fair to ask why Openreach are so asymmetrical and charge such a heavy premium for pretty poor upload speeds on the business services though. Given the network capacity 1000/500 isn't an unreasonable ask.

[dee.jay]

There's a big difference between not capable and not provisioned.  As already mentioned in another thread, its not that we can't do full upload speed, its that they are limiting how long we can do it for, so the average speed tops out at 115Mbit on residential.

So do you get more than 115 as a burst?

[j0hn]

So do you get more than 115 as a burst?

No. Openreach have taken a business decision not to sell more than 115Mb/s upstream on residential packages.

There is 220Mb/s upstream available to business customers but those packages come with £500+vat install fee and considerably higher monthly rental.

Yes, BTs system is GPON and not capable of symmetric. That’s all there is to it.

All the operators who sell symmetrical on GPON would disagree.

Openreach's low upstream are entirely a business decision to protect their (very) lucrative leased line business.

GPON is a 2:1 ratio on downstream v upstream but Openreach sell it as 10:1.
It's not a technical limitation of GPON.
CityFibre manage symmetrical gigabit on GPON no problem.

an XGSPON port for example could potentially have up to 64 customers on it.

Up to 64?
It can do 128 customers on a single port, same as GPON.

Much of Europe's GPON is a 128:1 split.

[dee.jay]

No. Openreach have taken a business decision not to sell more than 115Mb/s upstream on residential packages.

There is 220Mb/s upstream available to business customers but those packages come with £500+vat install fee and considerably higher monthly rental.

All the operators who sell symmetrical on GPON would disagree.

Openreach's low upstream are entirely a business decision to protect their (very) lucrative leased line business.

GPON is a 2:1 ratio on downstream v upstream but Openreach sell it as 10:1.
It's not a technical limitation of GPON.
CityFibre manage symmetrical gigabit on GPON no problem.

Up to 64?
It can do 128 customers on a single port, same as GPON.

Much of Europe's GPON is a 128:1 split.

OK yes I stand corrected on the upload speed.

With splits - different companies may have different policies on how far they split. Whilst 128 is *technically* possible - I can tell you some providers don't split to 128.

[XGS_Is_On]

OK yes I stand corrected on the upload speed.

With splits - different companies may have different policies on how far they split. Whilst 128 is *technically* possible - I can tell you some providers don't split to 128.

Indeed many don't. It's not a part of the original standards and reduces the power budget relative to a 32 split by 6dB + splitter insertion loss. What you may save on OLT ports is offset to an extent by having to pay for higher grade optics in both modules and ONTs to get the range you need.

[bogof]

Openreach's low upstream are entirely a business decision to protect their (very) lucrative leased line business.

GPON is a 2:1 ratio on downstream v upstream but Openreach sell it as 10:1.
It's not a technical limitation of GPON.

I wonder if one reason they have done this to facilitate being able to offer "FTTP ethernet leased line" product with guaranteed upstream to customers willing to pay, on the same GPON.  Plus if they offered symmetrical upstream there would be many more times when you wouldn't get "line rate" on the upstream, perhaps giving the product a worse image (as it is, you'll nearly always hit the upstream throughput).

I see for £250 / pm Spitfire for instance are offering 100/100 uncontended FTTP service.
https://www.spitfire.co.uk/connectivity/fttp-ethernet/
https://www.ispreview.co.uk/index.php/2020/09/bt-launch-uk-ethernet-fttp-service-for-wholesale-customers.html

[dee.jay]

I wonder if one reason they have done this to facilitate being able to offer "FTTP ethernet leased line" product with guaranteed upstream to customers willing to pay, on the same GPON.  Plus if they offered symmetrical upstream there would be many more times when you wouldn't get "line rate" on the upstream, perhaps giving the product a worse image (as it is, you'll nearly always hit the upstream throughput).

I see for £250 / pm Spitfire for instance are offering 100/100 uncontended FTTP service.
https://www.spitfire.co.uk/connectivity/fttp-ethernet/
https://www.ispreview.co.uk/index.php/2020/09/bt-launch-uk-ethernet-fttp-service-for-wholesale-customers.html

In case anyone is wondering, £250/pm basically gets you a dedicated port on a switch, as opposed to the shared model in GPON/XGSPON.