Could you link to the pictures you have of what you believe is the aggregation node.

It's a small central part of a scattered village, 12 miles west of Perth where the head exchange is located. Currently we get ADSL from Madderty exchange. The nearest FTTC cabinets are in Crieff, 5 miles to our west or Auchterarder, 5 miles south. We are told the fibre runs along the A85 between Perth and Crieff.

I will attempt to post a picture here of what I was told is an aggregation node. I took this back in 2016.

Better quality image - I hope

Edited by chriswillsher (Tue 12-Jan-21 12:37:38)

In reply to a post by chriswillsher:

There are a couple of isolated properties that this spine will pass that I tried to get included in the project but this was declined although they could have been included if we enlarged the CFP to cover a much bigger area. This I declined as being unmanageable. Whilst I appreciate one cannot just break into a fibre and pick up a twisted pair as would happen with copper, how will Openreach connect individual isolated properties?

Think of the FTTP design as a tree:

aggregation node --< splitter nodes --< CBTs

(root --< branches --< leaves)

The splitters are placed at locations in the FTTP design for that area, and each one covers a certain set of properties in its design footprint.

For the isolated properties: every one will be in the footprint of some splitter - which either already exists, or exists only on paper in a plan. The CBT(s) serving those properties will be connected back to that splitter, in a star arrangement.

If that splitter doesn't already exist, then that splitter will need to be installed, and a cable pulled to connect it back to its parent fibre aggregation node.

It's possible that part of the path back to the aggregation node is also taken by the cables to one or more other splitters. In that case, normally the cables will sit side by side in the same duct.

In reply to a post by chriswillsher:

I believe that fibre now comes in various formats including armoured surround that does not need a duct or will every property need a mini duct of some sort that could have to run for miles?

Fibre cables can also be run between poles. If the existing telephony service uses directly buried cables (Direct-In-Ground / DIG) then it is common for Openreach to install poles for fibre, rather than dig new ducts.

However if the existing service to the property is via underground ducts, usually they would re-use those. Such underground service can usually be identified by footway boxes in the pavement every few properties.

I'm pretty sure that's an aggregation node

In reply to a post by candlerb:

Working backwards: at the endpoint, there are CBTs with say 4 or 8 or 12 ports. They are sized to cover the number of properties served.

So are you saying I'm backwards in my thinking?

Instead of wondering how a big fat cable is split up as it travels down a road, I should ask how all the small cables are joined as it goes up the road?

Er, is that why they're called aggregation nodes?

Many thanks. That is helpful. Whether it is a primary splitter or an aggregation node in the manhole I am not certain but in any event, Openreach contractors have distributed the fibre around the village on the existing telephone line poles. Several of these also have what I assume are (Prysmian) secondary splitters on them leading up to CBTs on the tops.

We just now need to wait until they complete the link back to the main fibre spine some miles away. The initial work was all done in 2016, they came back and changed all the connections to the new type and installed secondary splitters and CBTs in May 2020 and then cancelled the whole project when they found a duct needed replacing! We were told that the DSSB (BDUK) project had finished leaving us in the lurch yet again. Hopefully having got a CFP confirmed they will finish the job this time?

"secondary splitters": Does the agg node actually perform a splitting function? My working assumption was that each subscriber was at the end of 1 32-way split subsequent to the agg node and that the agg node served mainly to physically bundle fibres into larger trunk cables.

Written from a position of ignorance though, so genuinely happy to be corrected!

Can I ask how much in monetary terms you have been quoted to do the CFP to those 40 properties.

In reply to a post by dect:

Can I ask how much in monetary terms you have been quoted to do the CFP to those 40 properties.

£108,000 or thereabouts. This is for 41 properties. I had another quote for 74 properties when I was considering a larger area to include some outlying clusters and that was nearly 4x as much. I may be talking rubbish but as the original work was aborted before completion, perhaps this includes the cost of the work already done as they might not have been paid for work that did not result in completed connections? Given that all that should now be required is 1.5Km of fibre in a duct that seems a lot of money. That's not my problem as the vouchers will cover the full cost and DCMS has authorised the project to proceed. I just want the work completed.

Thanks for sharing that, I was surprised to hear that it would be 4x as much to add 33 additional properties but not knowing the geography of your area its hard to understand the extra work involved. A few years ago I helped with a CFP and the cost actually went down when adding extra properties as the cost to add those properties was less that the extra contribution from Openreach, I appreciate every CFP is different and if you can cover the cost with vouchers its happy days for all those benefiting from it

Edited by dect (Tue 12-Jan-21 16:01:46)