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converse420
Contributor
1,787 Views
Message 1 of 15

Contention within BT FTTP Network?

Contention within the Virgin Cable/DOCSIS network is well known and demonstrated  a clear benefit to using BT as a preference.

From memory, I seem to recall that the downstream speed for FTTP is about 2.5Gb. With service offerings rising to approx 500 Mbps, does anyone know how contention is managed ?

 

Regards

 

Dale

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14 REPLIES 14
NigelB72
Recognised Expert
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Message 2 of 15

Re: Contention within BT FTTP Network?

I don't know about full fibre but I'm on G-Fast with a quoted speed of 130mbps... I regularly get 140+.  My brother is on VM and about half a mile from me. He's on their 100mbps (last time I checked) and he gets around half that on a good day...at peak times it can be less... I clock at the lowest 120mbps during peak times.. we are within a mile of Leicester city centre...  Hope this gives you an insight into the difference.. 

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pippincp
Sage
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Message 3 of 15

Re: Contention within BT FTTP Network?

Simple, increase bandwidth. BT's service offering is now 900Mb.

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converse420
Contributor
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Message 4 of 15

Re: Contention within BT FTTP Network?

Thanks pippincp,

I'm not sure how to ask the same question differently....

BT FTTP Is GPON right?

I seem to remember from my BT days that for each 'trunk' there was capacity of 2.488 Gb/s which depending on configuration was 'split' passively amongst a number of clients (up to 32:1 as I recall). So my question is has Openreach updated to a higher spec, as if not I cannot see how BT could provide 900Mb to more than 2 or three clients served by a particular 'trunk' without significant contention?

Thanks

D

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licquorice
Distinguished Sage
Distinguished Sage
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Message 5 of 15

Re: Contention within BT FTTP Network?

As far as I'm aware, that capacity is now 10 Gb/s rather than 2.5Gb/s.  Obviously relying on the fact that not all clients will (a) be 900Mb (b) all operating at full capacity simultaneously. I don't know if the number of clients are reduced from 32, but that is a possibility. Perhaps providing 2x 10Gb/s links for 2x 16 clients.

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iniltous
Guru
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Message 6 of 15

Re: Contention within BT FTTP Network?

As with all things , there is a trade off to keep a service affordable , it doesn’t necessarily follow that all 32 splits are used, but even if they are, the chance of every customer demanding their maximum bandwidth simultaneously is remote, theoretically everyone won’t get the throughput they are ‘paying for’ if everyone did hammer their connection at the same time, but what in the real world would they be doing to run out of bandwidth, 100 HDR streams over the 32 would just about be possible, how likely is it that each one of the 32 is watching 3 HDR streams ?
The VM over utilisation problem ( supposedly resolved ) may well have had more customers sharing a link or the original links didn’t have a similar  bandwidth, so it’s not a direct comparison, I dare say many domestic consumers with 900Mb+ connections rarely come close to needing a 20th of that , and if some killer application becomes commonplace and FTTP does hit over utilisation problems , it can be upgraded.

If the point is, 32 x 900Mb is more that 2.5Gb, that is true, but what would be the point of providing enough bandwidth to satisfy a maximum of 32x 900Mb, when all that bandwidth needs to be paid for ( ultimately by the end users much more  ) for it to sit idle

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converse420
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Message 7 of 15

Re: Contention within BT FTTP Network?

I think it may still be 2.5 Gb/s, but I did see that there was an Openreach announcement about using Nokia kit to achieve 10Gb/s at the end of May:

https://www.ispreview.co.uk/index.php/2020/05/openreach-adopts-nokias-10gbps-fttp-broadband-kit-for-...

 

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pippincp
Sage
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Message 8 of 15

Re: Contention within BT FTTP Network?


@converse420wrote:

I think it may still be 2.5 Gb/s, but I did see that there was an Openreach announcement about using Nokia kit to achieve 10Gb/s at the end of May:

https://www.ispreview.co.uk/index.php/2020/05/openreach-adopts-nokias-10gbps-fttp-broadband-kit-for-...

 


How would a 10Gb ONT mean the infrastrucre is still 2.5Gb. Openreach would not be able to offer 1Gb connections on a 2.5Gb infrastructure. You have totally misread the article.

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converse420
Contributor
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Message 9 of 15

Re: Contention within BT FTTP Network?

Thank you,

I am not aware of any evidence that the Openreach GPON deployment is not 2.5/1.2Gb/s. I'm happy to be corrected with evidence.

I understand the situation based on my own technical understanding and other news and documents that  become available.

 Your have played back my original question by stating that :Openreach would not be able to offer 1Gb connections on a 2.5Gb infrastructure. 

having looked at the tech, I now have a better understanding of how BT can sell 900Mb in this environment and can se how they might be managing this.

 I 'suspect' that we are still on the original 2.5 Gb/s spec and the new Nokia solution will allow 10Gb, requiring new OLT and ONT devices. 

Another reference for information

It would be nice if anyone on this forum could provide fact rather than speculation (and I include myself in this)!

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pippincp
Sage
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Message 10 of 15

Re: Contention within BT FTTP Network?

You can suspect whatever you like, TBH I don't care. The Nokia solution you are reading about is to be able to offer up to 10Gb synchronous connections instead of the present asynchronous offering.

As this is all hardware related you now have to figure out how a hardware change will allow a 2.5Gb network to be able to provide a 10Gb synchronous connection with no additional fibre.

I look forward to your reply.

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