In reply to a post by RobertoS:

If I understand "One thing I'm not sure on is if the fibre is routed *directly* from the consolidated exchange or whether there is any aggregation via the 'child' exchange?" correctly, I believe the FTTC cabinet is connected directly to the head-end exchange.

That's an interesting point. I can see that being the case for my cab because it's the first cab you'd come to when driving from the remote exchange toward my local exchange. However after that I'd have thought the fibre worked its way back to my local exchange before fanning out again. I assume that in most cases that's how the ducts are running.

Or are you just saying that there'd be no additional electronics in the local exchange?

Edited by Andrue (Thu 06-Oct-11 08:05:40)

If the plan is to close local exchanges then it does not make sense to route FTTC cables through them.

In reply to a post by Andrue:

Or are you just saying that there'd be no additional electronics in the local exchange?

A bit hazy as to where fibre routing and junctions may be sited, but there would certainly be no link into the national backhaul at the local one, therefore no need for any related electronics.

There are bound to be some posters around who know for a fact. This poster makes a good point.

Edited by RobertoS (Thu 06-Oct-11 09:24:34)

In reply to a post by Anonymous:

If the plan is to close local exchanges then it does not make sense to route FTTC cables through them.

Depends where the ducting is I suppose. Assuming that BT ducting is a star topography with the local exchange being the hub what other option is there? If you don't use the existing 'hub' then you've got a lot of digging to do. If the ducting is mostly below ground then it just sits there regardless of what's in the building above.

Granted it's not ideal to have cables underneath buildings but presumably all we're talking about is a relatively small box that splits/aggregates the signals. That could be sited in a cabinet just to one side. So perhaps what they would do is relocate the 'hub' so that it's on the edge of the exchange property then they close the exchange.

Edited by Andrue (Thu 06-Oct-11 10:12:24)

This diagram seems to suggest the local exchange is being bypassed (BTW anyone know what the "MDU" abbreviation stands for?), and there is an aggregation node outside the exchange?

Multiple Dwelling Unit - Flats

The exchange may or may not be bypassed. The eventual future will be less exchange buildings, replaced by smaller shed like buildings. Switching of line/services between providers handled electronically, rather than physically moving fibres around.

I only noticed recently that the deployment of the voice element of 21CN has stalled, and I did wonder if BT see FTTx as a way of dramatically reducing their physical plant & buildings once a credible voice over FTTx service is approved.

They might just as well sweat the System X/Y kit for a while longer because by the end of the decade I suspect things will look rather different.

Andre

Outside / alongside exchanges is a Cable chamber, on small sites this will just be a manhole. This is where the exterior Ducts will finish, cables can therefore bypass the building completely as not all cables will be required to enter every building.

All that will happen is the new fibres out to the cabinets will be spliced to the existing fibres back into the network if is there is capacity (or new cable if needed). As most exchanges already have fibre backhaul, (except extremely rural ones usually in Scottish highlands and Islands) many will not need additional backhaul fibres to the parent site.

If some cabinets are on existing fibre routes these can be spliced in at the nearest
Joint box big enough to fit a fibre joint in without going via the exchange cable chamber / manhole.

If/when you are able to empty the building you can sell / demolish without interfering with the cables.

In reply to a post by kitcat:

All that will happen is the new fibres out to the cabinets will be spliced to the existing fibres back into the network if is there is capacity (or new cable if needed). As most exchanges already have fibre backhaul, (except extremely rural ones usually in Scottish highlands and Islands) many will not need additional backhaul fibres to the parent site.

I understand that at a 'traditional' exchange where the exchange itself is being upgraded. What we're wondering about is what happens if the exchange itself is not being upgraded. My own exchange is one such example. Brackley is due to have FTTC in March 2012 but it's being provisioned from the Banbury exchange.

My question is what happens to the fibre when it arrives at Brackley. I can imagine it going straight to my cabinet because that's the sensible way to the town centre coming from Brackley. What I'm wondering about is what happens then? My assumption is that it will be blown the rest of the way to the cable chamber then split into multiple cables that are blown back to the remaining cabinets.

As most exchanges already have fibre backhaul

Of course but in this case my data will no longer be using Brackley's backhaul. I will be using Banbury's.

Edited by Andrue (Fri 07-Oct-11 15:35:45)

21CN voice, stalled I think due to reliability issues and time to roll-out at each exchange.