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Standard User ft247
(newbie) Fri 08-Jan-21 12:32:23
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Handover exchanges


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The concept of handover exchanges, which as I understand it is where connections move from the Openreach FTTP/FTTC infrastructure to the ISP's network, is not well understood. I'm writing this post both to help others, and to invite any errors to be corrected.

As I understand it, not every telephone exchange contains headend equipment for FTTP/FTTC (OLT etc.). In some cases the fibre from these services terminates at a handover exchange further away, which will allow consolidation of exchanges and eventual sale of some sites once copper is retired.

In the LLU days we had lists of which exchanges had each ISP's DSLAMs in them, but there doesn't seem to be any equivalent resource now. I'm reading here about cases where FTTP ISPs offer differing product availability due to the presence (or not) of enough 10G cablelinks (an Openreach term for the link to the ISP's own network) in each handover exchange.

BT Wholesale is a case I don't understand well - I appreciate that BTW will move the traffic from the handover exchange further, but I'm not sure whether they directly provide routing to the Internet to customers, and it's simply a rebadged BT service, or whether the traffic is just backhauled by BTW to an ISP datacentre.

I spent a bit of time looking at information on central and South London exchanges to see what I could find out. There aren't as many being lined up for closure as I would have thought. Also, I can imagine there is significant cost in maintaining a backhaul network from so many handover points.

Exchanges appearing to have a different handover point:
Shepherd's Bush -> Hammersmith
Bayswater, Kensington Gardens, Chelsea, Sloane, Nine Elms, Battersea -> South Kensington (it must be busy in there)
Paddington, North Paddington -> Marylebone
Monument -> Faraday
Wapping -> Bishopsgate
Southwark, New Cross -> Bermondsey
Vauxhall -> Walworth
Tulse Hill -> Gipsy Hill
Putney -> Parsons Green
Westminster -> Whitehall

Exchanges appearing to contain their own handover point:
Fulham
Bloomsbury
Stepney Green
Poplar
Greenwich
Deptford
Lee Green
Rushey Green
Brixton
Wandsworth
Wimbledon
Balham (seems odd, maybe some ECI here? FTTP-only appears limited to 330/50, where copper is also present 1000/220 is OK)
Merton Park
Mitcham
Sutton Cheam
Wallington
Croydon
Thornton Heath
West Wickham
Beckenham
Sydenham
Beulah Hill

Unknown status - usually no FTTP-only sites at present:
Mayfair
Earls Court
Soho
Covent Garden
Holborn
Fleet
Wood Street
Moorgate
Canary Wharf
Belgravia
Southbank (presumed its own - what is Southbank RS?)
South Clapham
Norbury
Streatham
Dulwich
North Cheam
Addiscombe
Catford

Edited by ft247 (Fri 08-Jan-21 12:38:25)

Standard User _Icaras_
(newbie) Fri 08-Jan-21 13:15:45
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Re: Handover exchanges


[re: ft247] [link to this post]
 
There will be lots of closures, but only a small amount have been announced for now.

I imagine there will be some conflict between BT and Openreach also, if it were just up to BT a heck of a lot more buildings would close.

Icaras
Standard User dect
(fountain of knowledge) Fri 08-Jan-21 13:17:37
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Re: Handover exchanges


[re: ft247] [link to this post]
 
Wood Street exchange went a long time ago (80's if I remember correctly), all copper main cables were diverted to Faraday via a bunker under the old exchange building. Faraday exchange is/was a big exchange so if it does have a fibre headend I suspect Wood Street fibre will go back there as well.


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Standard User ft247
(newbie) Fri 08-Jan-21 13:21:58
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Re: Handover exchanges


[re: _Icaras_] [link to this post]
 
In reply to a post by _Icaras_:
if it were just up to BT a heck of a lot more buildings would close.


Sounds about right, someone has almost certainly tried to figure out if the network can be operated without any buildings other than a shiny management office.
Standard User heathrow
(newbie) Fri 08-Jan-21 13:36:41
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Re: Handover exchanges


[re: ft247] [link to this post]
 
IS there a way of working out if an exchange is a handover point or not?
Standard User dect
(fountain of knowledge) Fri 08-Jan-21 13:41:56
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Re: Handover exchanges


[re: heathrow] [link to this post]
 
The best way is to find some new build properties in your exchange area with ONLY Openreach fttp (no copper service), then use the DSL checker to see what exchange they are served from, that will show you what is the handover exchange for your exchange area.
Standard User ft247
(newbie) Fri 08-Jan-21 13:42:28
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Re: Handover exchanges


[re: dect] [link to this post]
 
In reply to a post by dect:
Wood Street exchange went a long time ago (80's if I remember correctly), all copper main cables were diverted to Faraday via a bunker under the old exchange building.


I just read about this. Apparently the new building was constructed around the bunker - sounds like a good engineering challenge.
Standard User ft247
(newbie) Fri 08-Jan-21 13:43:50
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Re: Handover exchanges


[re: dect] [link to this post]
 
In reply to a post by dect:
The best way is to find some new build properties in your exchange area with ONLY Openreach fttp (no copper service), then use the DSL checker to see what exchange they are served from, that will show you what is the handover exchange for your exchange area.


That's what I did. I was surprised the list isn't out in the public domain yet.
Standard User dect
(fountain of knowledge) Fri 08-Jan-21 13:48:48
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Re: Handover exchanges


[re: ft247] [link to this post]
 
In reply to a post by ft247:
That's what I did. I was surprised the list isn't out in the public domain yet.
Are there new build properties in the Monument exchange area with fttp only?
Standard User j0hn83
(fountain of knowledge) Fri 08-Jan-21 14:06:19
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Re: Handover exchanges


[re: ft247] [link to this post]
 
In reply to a post by ft247:
BT Wholesale is a case I don't understand well - I appreciate that BTW will move the traffic from the handover exchange further, but I'm not sure whether they directly provide routing to the Internet to customers, and it's simply a rebadged BT service, or whether the traffic is just backhauled by BTW to an ISP datacentre.


They backhaul traffic to the ISP.
It's very different from a rebadged BT service.
Just the same as using Talktalk Business backhaul is very different from a Talktalk residential connection.

My understanding (some bits may not be 100% accurate)...

The GEA cablelinks connect between the Layer 2 Switch (L2S) and the CP's equipment in the exchange.
Multiple DSLAM's and multiple FTTP PON's connect to each OLT and multiple OLT's can connect to an L2S.

There are many reasons why ISP's may only have 1Gb cablelinks.
The main reason being that a 10Gb cablelink used to cost around £10k.
They now cost around £1k.

To add to that there are now FTTP only L2S so if a provider had a GEA cablelink connected to a L2S for FTTC then this cannot be used for any properties connected to an FTTP only L2S.

My exchange (ESDAL) is a Handover exchange.
It has very little FTTP at present. It's almost exclusively new builds and retro new build work.
This means it isn't worth it for some backhaul providers to buy a 10Gb GEA cablelink yet.

As the FTTP coverage grows then so will the number of providers with 10Gb cablelinks in place.

In the LLU days we had lists of which exchanges had each ISP's DSLAMs in them, but there doesn't seem to be any equivalent resource now.


If you're referring to Samknows it has never, ever, been fully accurate for my exchange.
It is now just plain wrong for my exchange.
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