Splicing fibres and speed questions...

I am just wondering how long on average does it take a BT Fibre Splicer Engineer to splice/join a strand of fibre?

Also I recall a little while back we was discussing actual speeds down a single strand of fibre, I don't recall getting a definite answer.

Also not really knowing how many fibres get spliced from a strand of fibre.
So say a fibre cable leaving an exchange consists of 48 strands, I assume that will get spliced as it runs down the road, but to what amount of fibres get spliced from one of the 48 fibre strands?

I worked out the following which I am positive I am completely wrong and I am happy to be corrected.

My understanding was a fibre strand that is to be used for FTTP has a bandwidth of 10Gbps and each strand gets spliced off into 30 smaller ones.

Where as a fibre strand for FTTC has a bandwidth of 1Gbps that gets split up into 15 smaller strands.

And where exactly does the fibres get spliced for FTTP, is it as it goes down the road from the exchange to the first daisy chained FibreDP hardware.

Or does it only get spliced in the actual FibreDP hardware where 1 ro 2 strands are spliced into 15 strands on each resulting into 30 lines for 30 addresses on the same phone pole.

I am aware they would need to install extra tubing's for more addresses.

The main reason that I am asking these questions are due to BT have had work outside our exchange on roadworks since January stating
Safe Access to Underground BT footway and carriageway boxes for fibre cabling and jointing works in existing duct. Required for new customer connection

Now that work never happened due to they required some lanes to be closed for safety reasons, which I can understand.

Then then rescheduled that work 1 month later i.e. 23 Feb - 24 Feb with lane closures.

I just noticed on roadworks today that they have two lots of work down as the following.

1. Safe Access to Underground BT footway and carriageway boxes for fibre cabling and jointing works in existing duct.
   Required for new customer connection we did not finish all the work last time we where there that is why we need to rebook it
2. Safe Access to Underground BT footway and carriageway boxes for fibre cabling and jointing works in existing duct.
   Required for new customer connection we did not finish all the work off last time we where there so that is why we need to go back there

Basically the same thing, but it seems that the tile allocated for 23 to 24 wasn't long enough, so I am assuming that there must be a lot of jointing work to be done if they could do it in that allocated time.

We have been told by BT that they are looking into our FTTP issue that has been delayed for 50 months now, and BTOR has told me the work will be completed end of Feb then up-to a further 2 weeks for the database to get updated and then activated.
We have around 18,175 FTTP lines partly done leaving 12,303 FTTP lines including the ~400 line in our area.

Our area is hoping its for us and the remaining FTTP connections.

My guesses are our fibre has already been blow due to they spliced our fibres in the FibreDP hardware end of July 2015, so I am thinking that they are just joining them up at our exchange end.

I was told by many different BT Fibre Engineers that there was a big chunk of our fibres got damaged back end of 2011 and that FTTP fibres come form a different place or cable or node that FTTC does which was why the FTTC got all done leaving the FTTP partly completed, now whether those engineers were correct or not I cannot say, but that would explain why every engineer that looks in the chamber by our phone pole all say its done.

Thanks

Paul

I am just wondering how long on average does it take a BT Fibre Splicer Engineer to splice/join a strand of fibre?

Lots of variables to take into account, but once all set up OK, strip/cleave/clean/splice, a couple of minutes.

https://www.youtube.com/watch?v=kfYNj3nIPV8

..but the old guy looks a little slow to me ....

.. nice to have it all laid out on a table ..

In reply to a post by Zarjaz:

I am just wondering how long on average does it take a BT Fibre Splicer Engineer to splice/join a strand of fibre?

Lots of variables to take into account, but once all set up OK, strip/cleave/clean/splice, a couple of minutes.

Ah, so my guess of 2 mins was about right ,I know there is a machine that thermally joins the fibres, which is a lot better than what we used 20 years ago LOL all we had was an eye lens a knife, very fine grit stone and what looked like washing up liquid which was used to polish the fibre ends where we then had a section that had glue in it and we pushed the two end into that LOL.

Do you know answers to any of the other questions ?

Paul

Jointing 48 fibres and closing them is pretty quick work. The delay will be down to traffic management, cars parked on boxes and cabling problems such as blocked ducts etc.

Jointing 4800 copper pairs and closing them, long time.

In reply to a post by Zarjaz:

https://www.youtube.com/watch?v=kfYNj3nIPV8

..but the old guy looks a little slow to me ....

.. nice to have it all laid out on a table ..

Yeah, that's what I am saying, we never had all that to do it for us 20 years ago LOL

So easy nowadays

Also that last part with the shrinking part, that didn't look like it was done due to it was the same size, heat shrinkable tubing I use all the time and they normally always shrink in diameter, like 3:1 or 2:1, I have also worked with a 5:1 tubing when I have had to cram loads of copper wires through them.

Paul

In reply to a post by partial:

Jointing 48 fibres and closing them is pretty quick work. The delay will be down to traffic management, cars parked on boxes and cabling problems such as blocked ducts etc.

Jointing 4800 copper pairs and closing them, long time.

Ah, well I did some maths LOL.

Still not fully sure on how many strands gets spliced off each of those 48 strands, like I said I am probably wrong when I say each strands gets spliced into 30 strands.

If that is correct and we only require another 12,303 FTTP to be completed, so that would be about 9 lots of fibre cables with 48 strands in them, and 7 cables would be all used up and would also use up 17 strands of the 9th cable, or maybe they will spread them across all of them.

That is assuming I am right and that this work is for us, but 2 days wasn't enough time so it must of been a lot of work to do to request for another 2 days to complete the rest.

Well I am just assuming here, but I am thinking that where there was loads of talk about broken fibre cables back end of 2011, I was thinking that the actual break was in between those two chambers and that they would just need to cut the broken fibre cables in each chambers and then pull them out and replace those removed with new cables and then re-join those back up in both chambers and that's it.

I am aware its a main road that there is a lane closure, but doesn't stop a car from hitting you

I am also not sure if the work is for both sides of the road, so yeah, that becomes more of an issue and delays, but it looks like the chambers are on either side of the road.

The nearest postcode to it is IG1 2FB and select 2 weeks or longer and you will see the two jobs pop up.

Paul

I feel a long post coming on...

In reply to a post by PaulKirby:

I am just wondering how long on average does it take a BT Fibre Splicer Engineer to splice/join a strand of fibre?

Another video, courtesy B4RN.
https://www.youtube.com/watch?v=PpjVHpYHFQA

A mix of stills and video, but useful part is around 5 mins in.

In reply to a post by PaulKirby:

Also I recall a little while back we was discussing actual speeds down a single strand of fibre, I don't recall getting a definite answer.

How long is a piece of string?

Minimum speed probably around 100Mbps. Maximum speed achieved in a trial between Huawei and BT in 2014 was 3Tbps. But achieving that required a "grid" of wavelengths on the same fibre: 15 wavelengths of 200Gbps each. That is backed by serious transmission hardware.

For the access network, they need cheaper hardware at each end of the fibre.

The GPON system BT are trying desperately to put in your street is 2.5Gbps downstream, 1Gbps upstream, shared. With a distance limitation of around 20km.

The fibre network being deployed is quite capable of carry 10G-PON signals too, which is 10Gbps downstream, all to be shared.

Those speeds are more limited by the hardware they put at each end of the fibre than on the fibre itself.

Meanwhile, the fibres used for FTTC carry a point-to-point connection running at 1Gbps. They too could be upgraded to higher speed PtP connections in the future, depending on the hardware in the OLT and the DSLAM.

Standardised speeds, cheap-to-achieve, suitable for 1 wavelength on a fibre in the access network seem to be 100Mbps, 1Gbps, 10Gbps. With perhaps 25Gbps coming.

In reply to a post by PaulKirby:

Also not really knowing how many fibres get spliced from a strand of fibre.
So say a fibre cable leaving an exchange consists of 48 strands, I assume that will get spliced as it runs down the road, but to what amount of fibres get spliced from one of the 48 fibre strands?

One fibre will be spliced to one fibre. No question about that.

When you see B4RN's video, watch the screen showing the two fibres being spliced ... there is no room to branch the connection there.

In reply to a post by PaulKirby:

My understanding was a fibre strand that is to be used for FTTP has a bandwidth of 10Gbps and each strand gets spliced off into 30 smaller ones.

Where as a fibre strand for FTTC has a bandwidth of 1Gbps that gets split up into 15 smaller strands.

The fibre strand that exits the exchange, identical for FTTP and FTTC, will be one strand within a cable of up to 288 - but usually in groups of 12 strands known as an element.

Where one fibre (at the exchange end) is used to serve multiple homes in an FTTP GPON, the division isn't done by "splicing off 30 smaller ones". It is done by splicing that single fibre to one end of a "splitter device". That device will have 4, 8, 16 or 32 fibres at the other end - all ready to be spliced onto by the fibres strands that (eventually) make it to your house.

The splitter devices appear to be passive silicon wave-guide devices.
http://www.fiber-optic-tutorial.com/tag/optical-spli...

At first, BT seemed to be set on using a single level of splitter: one 32-way splitter device. This would be housed within a "splitter node" which had room for 4 devices, so could serve 128 properties, all from 4 fibres back to the exchange. Towards the homes, there would be a final splice at a fibre DP - where the fibre strands would change from being within a cable alongside other subscribers, to a fibre blown down a BFT that is exclusively for your house.

Nowadays, BT seem to be planning for two levels of split: The first level would be an 8-way primary splitter, and the second level would have 8 four-way secondary splitters. It still amounts to one fibre in, 32 homes served.

The 8-way splitter looks likely to be housed alongside 3 others in a smaller splitter node, while the 4-way splitter might be housed underground, in a pole-mounted housing or even at the top of the pole (in the new FoD2-style of connectorisation). In this 2-level setup, the secondary splitter is likely to act as a DP too.

The fibre for FTTC doesn't go through a splitter device at all. It is spliced 1:1 through the aggregation node to a port on the FTTC cabinet.

And where exactly does the fibres get spliced for FTTP, is it as it goes down the road from the exchange to the first daisy chained FibreDP hardware.

Or does it only get spliced in the actual FibreDP hardware where 1 ro 2 strands are spliced into 15 strands on each resulting into 30 lines for 30 addresses on the same phone pole.

There are lots of places that splices happen, for a multitude of purposes.

First, take a look at some example architectures for FTTP.
This PDF includes BT's thoughts for the whole access network circa 2010:
IWCS presentation 2010

This image is of a considerably more modern look
Two-level of split FTTP

Finally, you can also see some details of the architectural changes for FoD2:
TBB Blog on FoD2

Here's how the architecture boils down to a set of splices...

Stage 1 - Out of the building
1. The FTTP fibre starts as a connector plugged into a GPON port on the OLT.
2. The first splice is within the OCR (Optical consolidation rack), where it starts to joining up with all the other strands heading to the same area of town.
3. The yellow cables from the OCR are probably internal grade (low smoke). They will be spliced to external-grade cables down in the "cable chamber" in the basement - A "CCJ" (cable chamber joint?)
4. The cable leaving the exchange, via the chamber, will be up to 288 strands of fibre, and will form one of the fibre spines snaking out of the exchange to an area of the town.

Stage 2 - Fibre Spine
5. When the cable gets to the first area to service, it will go into an aggregation node. Here , perhaps some 48-60 of the fibres will be extracted from the spine, and "laid up" in splice trays for future use. The remainder will pass straight through unspliced to the next aggregation node in the daisy-chain.
6. Each aggregation node is a "flexibility point" like today's PCP, in that this is one of the main locations for swapping connections in the case of failures or breakages. It will support up to 1500 premises, so is perhaps equivalent to 2-4 PCP's in scale.
7. A fibre spine that starts as 288 fibres might drop 48-60 of them at each aggregation node. That might make for 5 large aggregation nodes along one spine, or more smaller ones.
8. Each fibre cable is of a limited length, so might not be able to run the complete distance between exchange and aggregation node. If so, extra "TJ"s will be inserted, complete with splices, so a new section of cable can be run. Track Joints? or Transit Joints?
9. The fibre spine is the equivalent to today's E-side cables. The fibre from the aggregation nodes towards the premises is the distribution fibre, equivalent to the D-side.

FTTC areas will only have the architecture above. FTTP areas will continue with the next level.

Stage3 - Distribution Fibre
10. The first step of the distribution fibre is to be routed to a tray in the aggregation node, and spliced to one of the spine fibres. The cable will then be fed through ducts into a splitter node. I guess that these cables are likely to have 36, 48 or 96 fibres.
11. In the example 2-level architecture, the distribution fibre will then, for example, be sent to one of the 8-way splitter nodes - where it will be located in a splice tray, and spliced to the input to the splitter device.
12. The output from the splitter device will then be located in another tray, and spliced to the fibre strand that is heading further in your direction. This fibre will be in another cable, fed through ducts towards the house.
13. This fibre will enter the 2nd-level splitter, and again put into a tray where it will be spliced to the input to the splitter device.
14. The output from the splitter will be routed into a separate tray, where it will be spliced onto another strand of fibre heading in your direction. If this secondary splitter forms the job of a DP too, then this strand will be the final strand of fibre destined for your house.
15. The final strand is likely to be fibre for blowing in BFT over to your house. Once it arrives, it will be put into the splice tray located on the outside of your property. Here it will be spliced onto cable suitable for running inside your house.

That's a lot of splices, but they're always 1 fibre strand to one fibre strand.

There are some pictures and descriptions of the exchange-side of this here:
http://connectingshropshire.co.uk/2015/01/fibre-fact...

There are some details of the insides of aggregation nodes, splitter nodes etc in here:
http://forums.thinkbroadband.com/fibre/4375161-fibre...
These guides show how fibre cable needs to be handled to form all the connection work within the nodes, but without detailing the fusion splicing itself.

Also that last part with the shrinking part, that didn't look like it was done due to it was the same size, heat shrinkable tubing I use all the time and they normally always shrink in diameter,

I use a 30ml splice protector which is heat shrunk over the recently made splice to , err, protect it.

We have, besides maybe some BDUK stuff I'm not aware of, zero native FTTP lines in our entire county so you're not doing badly regardless.

There has been some real pain with regards to street works in London. The powers that be are getting pretty anal about it apparently which may well have held things up.

Hey WWWombat

When I was referring to speeds, I was referring to the actual speeds that BT use down each strand.

It seems I was about right for the speed for the strands used for FTTC of 1Gbps.

TBH isn't 2.5Gbps downstream a bit low for FTTP?
I thought it would at least be 5Gbps up to 10Gbps.

I know the fibre cables that we have linking all our FibreDP hardware are all using 96 strands of fibre, they were 48 strands, but throughout July last year they replaced those cables for what they had on that huge fibre drum which was 96 strands.
They told me it make no difference if its only connected to a 48 strand the other end, which makes sense.

I am a bit confused, so your saying to supply say 18,175 connections would need 18,175 strands leaving the exchange, that would require 64 cables with 288 strands in each.

And I read some place that each home gets 4 strands of fibre where 2 or 3 are spare., so that would mean 4 times that.

Your saying that an aggregation node extracts 48 to 60 strands and that an aggregation node will support up to 1500 premises, so for that to happen it will have to splice off each of those strands to 25 to 32 smaller strands.

Or am I missing something here?

Paul

splice off each of those strands to 25 to 32 smaller strands

Paul I think you should use the correct terminology.....split not splice....you can only splice 1 to 1 .....

Reading the page that www pointed to...a single fibre can be split to into 32 fibres http://www.fiber-optic-tutorial.com/tag/optical-spli...

Surely there is no such thing as a fibre cable, There is a fibre duct (black with yellow stripe) and then this contains several sub-ducts that contain the actual fibre.

Paul

WWWombat went through it all well. You missed the Splitters in his write up.. Each strand leaving the exchange goes to a primary splitter that splits it to 4, 8, 16 or 32 fibres out the other end of the splitter. A secondary splitter can also be used.

My recollection was a max of 128 premises passed per 2.5Gb ( giving min uncontended 19.5Mb). WWWombat thinks only 32 ( giving min uncontended 78Mb). As not all customers will take the service up or will only take the lower speeds it is more likely to be 128.

There were ( are?) plans to increase this to 256 premises but this will be 10Gb ( giving min 39Mb uncontended).

The linked diagrams are not very clear.

Ian

Look at WWWombats IWCS link there are pictures of the cables.

A large cable will have 288 fibres in it ( could be 360 fibres with some cables)

Each cable will be pulled or blown for smaller ones through the duct.

Nobody ever uses 1 fibre down a subduct. Blown fibe is normally a 4 fibre cable or 8 fibres.

The black and yellow cables are not duct these would be far larger and can have many cables in.

In reply to a post by ian007jen:

splice off each of those strands to 25 to 32 smaller strands

Paul I think you should use the correct terminology.....split not splice....you can only splice 1 to 1 .....

Yeah, sorry I was yapping to somebody here while posting.

In reply to a post by ian007jen:

Reading the page that www pointed to...a single fibre can be split to into 32 fibres http://www.fiber-optic-tutorial.com/tag/optical-spli...

Yeah, it was where WWWombat said

That's a lot of splices, but they're always 1 fibre strand to one fibre strand.

Thats where I got confused

But reading that PDF WWWobat linked to, I can see more.

Going by the images I see...
The Aggregation Node id fed a fibre cable of 200 odd strands and only splices off the 48 that it needs and passes through the rest to go onto the next Aggregation Node and so on.

And those 48 strands goes to a splitter that splices off 4 strands and passes through the rest that goes to the next splitter and so on.

Now each of these 4 strands gets split up into 32 strands giving about 128 strands that go to the FibreDP where it splices off < 20 strands and passes the rest to the next FibreDP and so on.

Is that right.

In reply to a post by ian007jen:

Surely there is no such thing as a fibre cable, There is a fibre duct (black with yellow stripe) and then this contains several sub-ducts that contain the actual fibre.

Ermm, I think there is, I recall throughout July 2015 then replacing the fibre cable that run between all our FibreDP harware, they replced the original 48 stands with a 96 srtand cable and that was all spliced and joint up after they replaced the cables.
So they didn't replace any ducts and blew the fibres.

Ah, I think I know what you mean now, the 96 strand fibre cable is labelled as Subduct - 14 x 10mm, but does that come with all the fibre strands in? due to I didn't see them blow any fibres in and the splicer/jointer guy was sitting on the edge of the chamber with the FibreDP hardware folded up on its arm and he was doing stuff with the wafers.

Paul

but does that come with all the fibre strands in?

No......I'm sure Mr S has said before all fibres are blown in after the subduct is pulled; they are much to fragile to be inside whilst the subduct is installed.

In reply to a post by kitcat:

Paul

WWWombat went through it all well. You missed the Splitters in his write up.. Each strand leaving the exchange goes to a primary splitter that splits it to 4, 8, 16 or 32 fibres out the other end of the splitter. A secondary splitter can also be used.

Yeah, the phone rang and I lost concentration, I knew it split up the fibres, I just wasn't too sure if it split any in the Aggregation Node.
So in theory each 288 strand fibre cable (COF 200 Cable) will get split into about 9,216 strands.

In reply to a post by kitcat:

My recollection was a max of 128 premises passed per 2.5Gb ( giving min uncontended 19.5Mb). WWWombat thinks only 32 ( giving min uncontended 78Mb). As not all customers will take the service up or will only take the lower speeds it is more likely to be 128.

That to me doesn't seem right to me, if everyone i.e. FTTC and FTTP users are all the same as that then the FTTP users are being shafted and ripped off.
Are you sure its 2.5Gbps for both FTTC and FTTP Customers?

Nope your right, it seems that its 2.5Gbps downstream and 1.2Gbps upstream, still doesn't see right to me.
That 2.5Gbps according to the docs that was linked say its gets split by 32, and where 4 strands go into the splitter resulting in 4 x 32 is 128 homes, so its 128 homes over 4 strands, that's my understanding (read it 4 times now LOL).

In reply to a post by kitcat:

There were ( are?) plans to increase this to 256 premises but this will be 10Gb ( giving min 39Mb uncontended).

I did read some place on the BT or openreach page that BT are working on 40Gbp over a single strand, Denmark has working 43Tbps over a single strand [shock]

In reply to a post by kitcat:

The linked diagrams are not very clear.

Yeah, doesn't really halp when they don't say what some of the names they use, like SASA, SPN, EU etc.

Paul

In reply to a post by ian007jen:

but does that come with all the fibre strands in?

No......I'm sure Mr S has said before all fibres are blown in after the subduct is pulled; they are much to fragile to be inside whilst the subduct is installed.

Well when I asked them will they be blowing in the fibre once the tubing has been installed and the exact words from the fibre engineers was "there is no need to blow any fibre in on these shot distances" and that the cables they was putting in already had the fibre strands in.

So I am only going by what I was told, and for the splicer/jointer guy did hid part not long after they put the cables in confirms this.

Paul

The cables that they replaced between all our FibreDP hardware was black with the yellow strip, but was a lot thinner that the tubing that goes up the phone pole, looking at that BT Doc it looks like the 96 core subduct cable (14 x 10mm), I say 96 due to that's what the guys said that installed.


When you say "Blown fibre is normally a 4 fibre cable or 8 fibres" is that why FTTP gets 4 fibre blown to their external termination box, like 3 spare ones for future use or redundancy?

Paul

This type does exist - and is part of the changes to try and reduce work load but mainly in the FoD2 and G.fast trials for now

Redundancy usually

And I read some place that each home gets 4 strands of fibre where 2 or 3 are spare., so that would mean 4 times that.

That is just in the blow from the DP node to the CSP at the premises. Ask Robertos I know he has a couple of photo's that show this, I don't know how to post them on here.

I think by making it a little thicker, as in adding 3 spares and its waxy coating makes it a little more robust for the blowing, as well as adding some redundancy.

Now I have to work out which one, and had a nicely liquid afternoon so not today.

The ones of the CSP on the wall Bob ..... now go sleep it off

In reply to a post by Zarjaz:

And I read some place that each home gets 4 strands of fibre where 2 or 3 are spare., so that would mean 4 times that.

That is just in the blow from the DP node to the CSP at the premises. Ask Robertos I know he has a couple of photo's that show this, I don't know how to post them on here.

If you are referring to the Termination box on the wall I have pictures of those, also our area has loads of them on their wall, ranging from brown, grey, white etc in colour.

Thinking about it, the redundant 3 strands don't get connected anywhere, so no extra line strands.

Paul

Ok, did some more reading, so I hope I now have it right now LOL.
This was from the link posted back a few posts, basically pages FTTP - Brown Field Capture and FTTP GEA Network Architecture

The downstream bandwidth per strand is 2.5Gbps, so the 288 strand cable has a total bandwidth of 720Gbps downstream, and the upstream per strand is 1.25Gbps with a total per 288 strand cable of 360Gbps.

• There are multi 288 strand fibre cable (COF 200 Cable) that leaves the exchange.
• The 288 strands go into a Aggregation Node that takes 48 strands and passes the rest through to go onto the next Aggregation Node.
• These 48 strands gets put into 12 cables with 4 strands that goes into a 32 way splitter resulting in 128 strands.
• These 128 strands then goes into the FibreDP Hardware that takes < 20 strands and passes the rest through to the next FibreDP Hardware daisy chained to it.
• Now a 4 strand fibre is used where only 1 strand of it is connected to one of the <20 strands and goes up the pole to the address etc.

Hopefully that is more right.

So each strand is shared with 32 connections (Downstream: 2.5Gbps / 32 = 78.125Mbps, Upstream: 1.25Gbps / 32 = 39.0625Mbps when hammered)
Granted we lose a fair amount of downstream when everyone hammers the downstream at the same time, this is unlikely but could happen, where as the upstream no matter how much you hammer it you will always be able to get 30Mbps which makes sense.

So in theory a 288 strand cable (COF 200 Cable) can handle around 9,216 connections, so only 2 of these cables would be required to handle all our FTTP connections which is about 18,176 give or take and 1 cable for all the FTTC connections which is about 5,377 give or take.

So if all above is correct our exchange would only require 3 lots of the 288 strand cables to support it and also leaving loads free for future use.

Paul

Houston, ....

Yeah but the pictures I am referring to show the insides.

In reply to a post by Zarjaz:

Yeah but the pictures I am referring to show the insides.

Ah ok, are you referring to the wafer inside where the fibre gets wrapped round?

I have an image with it closed and opened

Maybe Robs images will show more.

Paul

That is indeed a CSP, but has not yet had the fibre blown in to it and the other bits added, so shows nothing pertinent to what I was trying to show.

I shall try to retrieve the pics tomorrow Paul. They are intended to go on a revamp of my website but at the moment have got tired of waiting and gone for a walk.

I'll upload them ASAP.

In reply to a post by Zarjaz:

That is indeed a CSP, but has not yet had the fibre blown in to it and the other bits added, so shows nothing pertinent to what I was trying to show.

Ah ok, well that was all that I could find on Google LOL, I hardly think anyone at the top of my road and side roads will let me look in theirs LOL

Paul

In reply to a post by RobertoS:

I shall try to retrieve the pics tomorrow Paul. They are intended to go on a revamp of my website but at the moment have got tired of waiting and gone for a walk.

I'll upload them ASAP.

Cool

Paul

In reply to a post by kitcat:

My recollection was a max of 128 premises passed per 2.5Gb ( giving min uncontended 19.5Mb). WWWombat thinks only 32 ( giving min uncontended 78Mb). As not all customers will take the service up or will only take the lower speeds it is more likely to be 128.

I've certainly seen that GPON can support a 64-way split, and more might be technically feasible.

However, increasing from 32 to 64 decreases the signal strength by 3dB, halving the distance the fibre can run. An increase to 128 will halve it again.

I suspect that the maximum split has already been planned into the network by the location of the FTTP head-ends, and the new maximum distances to EUs. If BT are hoping to close many small rural exchanges in the future, a large split ratio would be a false economy.

In reply to a post by PaulKirby:

That to me doesn't seem right to me, if everyone i.e. FTTC and FTTP users are all the same as that then the FTTP users are being shafted and ripped off.
Are you sure its 2.5Gbps for both FTTC and FTTP Customers?

Nope your right, it seems that its 2.5Gbps downstream and 1.2Gbps upstream, still doesn't see right to me.

Yes, it is shared, contended bandwidth.

2.5Gbps shared over 32 homes sounds bad if you think everyone loads their line fully at the same time.

But compare with VM on their current DOCSIS 3.0 setup. There, they could be running 200+ homes on a shared 450Mbps segment, though they're probably increasing that to more like 700Mbps.

FTTC will use PtP 1Gbps circuits, but there can be multiple fibres for each cabinet.

In reply to a post by WWWombat:

In reply to a post by kitcat:

My recollection was a max of 128 premises passed per 2.5Gb ( giving min uncontended 19.5Mb). WWWombat thinks only 32 ( giving min uncontended 78Mb). As not all customers will take the service up or will only take the lower speeds it is more likely to be 128.

I've certainly seen that GPON can support a 64-way split, and more might be technically feasible.

However, increasing from 32 to 64 decreases the signal strength by 3dB, halving the distance the fibre can run. An increase to 128 will halve it again.

Well I know in one of those drawings in that BT Doc it showed a 2x32 splitter so maybe its that.

Maybe the 64way split will be for when they increase the bandwidth down each fibre strand.

Paul

In reply to a post by WWWombat:

In reply to a post by PaulKirby:

That to me doesn't seem right to me, if everyone i.e. FTTC and FTTP users are all the same as that then the FTTP users are being shafted and ripped off.
Are you sure its 2.5Gbps for both FTTC and FTTP Customers?

Nope your right, it seems that its 2.5Gbps downstream and 1.2Gbps upstream, still doesn't see right to me.

Yes, it is shared, contended bandwidth.

Oh I know its right and shared, I was just shocked that's all.

In reply to a post by WWWombat:

2.5Gbps shared over 32 homes sounds bad if you think everyone loads their line fully at the same time.

Oh, its just me looking at the worst cases, due to it "could" happen, but 78.125Mbps is still very good compared to our ADSL2+ connection

In reply to a post by WWWombat:

But compare with VM on their current DOCSIS 3.0 setup. There, they could be running 200+ homes on a shared 450Mbps segment, though they're probably increasing that to more like 700Mbps.

Well one of my friends up north is on VM and has no issues at all, so either he doesn't do much traffic wise online or he has just been lucky, I know he has had some latency issues a little while back.

But still 700Mbps shared with 200 homes, if all hammered their connection they would each get 3.5 Mbps OUCH, maybe that's why they cap the connection if people start to abuse the downstream.

In reply to a post by WWWombat:

FTTC will use PtP 1Gbps circuits, but there can be multiple fibres for each cabinet.

Yeah, I saw that they had multi 1Gbps fibres going to it.

Paul

In reply to a post by PaulKirby:

Ok, did some more reading, so I hope I now have it right now LOL.

Yup, getting there.

Remember that the number of fibres you've calculated are the working set. There would probably be a lot of spares, and they'd probably round up to multiples of 12.

Aggregation nodes look like they'd handle many more fibres than 48, so perhaps they're dimensioned for a lot of spares.

The 2x32 notation means that there can be two fibres coming in at the top end, rather than one.

It is used to allow the splitter to be connected to two separate head-ends, allowing one to be a standby. That adds a form of redundancy, but it might only be used for high-value locations such as business parks.

In reply to a post by PaulKirby:

Oh I know its right and shared, I was just shocked that's all.

Yup. I've pointed out for a while that GPON fibre doesn't actually distribute more aggregate speed over, say, 2-3 streets than FTTC. It just allows one property to achieve a higher burst within the aggregate.

Could it be possible that G.Fast DPUs could achieve a higher density?

So after some mishaps here is a selection of FTTP bits and pieces ...


The first three photo's are of an FVA interstitial plate showing how the copper link from the ONTE terminates on the rear of it. Also the switch on top for switching between copper/fibre voice service.

Photo four is of an NTE and battery back up unit (they really need to work on those aesthetics don't they)

Photo's 5 to 9 show an MDU (multi dwelling unit) fibre DP. You can see the 2 fibre ruggedised leads which the builders have fitted between individual flats and the DP coiled up next to it.

In photo 7 you can see the completed splice at the top of the tray (it's glowing due to my light source being connected in the customers property) The somewhat OTT looking looping of the fibres going the tray is how the bend radius is kept to stop light leaking out .

Photo 10 is of my trusty splicer waiting to do its thang at a splitter node.

11 to 16 are various photo's of another splitter node. The red trays hold the spare incoming fibres (E-sides in a copper cab would sort of be a good analogy) The tray trays beneath holding the individual fibres going to the DP nodes.


Sadly Bob's mail people have lost the couple of pictures clearly showing the inside of a CSP with all the gubbins and the four fibre bundle I was originally alluding too. Me, being the OCD kid, had deleted them all from my phone once sent to Bob. Marvellous.

I shall try and get a replacement.

Thanks Zarjaz for the pictures.

So with the first 3 pictures of the new faceplate, I assume that the xDSL filter face plate gets removed and that this place is the only one that is connected to the NTE5A Master Socket back plate.

So if I wanted to speed up their job, I could install both the BT80 and the NTE5A back plate and wire those two and just leaving the engineer to move the copper line and install the fibre, and that would just leave me to connect the ONT to my HH (whatever I get given) then onto our LAN, and then also connecting the NTE5A new face plate to our existing phone extension.

Leaving the engineers time for a couple cups of Tea and Jammie Dodgers

In picture 4, when you say NTE don't you mean ONT that is next to the BBU?

I guess that pictures 5 to 9 are of a much larger version of the external one that I would get.

10 to 16, of the splitter node, I always wondered what the red wafers was for, also what are the 6 wafers above the red 4, are they for spare or just to protect the red wafer, and I guess the spare bottom 2 are also to protect the bottom of the 32 wafers.

When I first saw pictures 14 to 16, I first thought is that the new FibreDP, due to we have the old version of the FibreDP's installed in our areas.

I have a question, where about would the Splitter Node be placed, I would of thought very close to an area that it is covering, I know the route that our cable runs due to when they replaced all the cables back in July 2015, and I think there is more homes than the 120 to 128 that a splitter splits from the 4 that enters it, so does that mean we would be using either another splitter or would it be using the extra wafers the other side and have an extra cables feeding it?

Paul

Firstly, yes that should say ONTE ... and now I cannot edit it. [censored].

So if I wanted to speed up their job, I could install both the BT80 and the NTE5A back plate and wire those two and just leaving the engineer to move the copper line and install the fibre, and that would just leave me to connect the ONT to my HH (whatever I get given) then onto our LAN, and then also connecting the NTE5A new face plate to our existing phone extension.

What BT80 ?? I would suggest you wait for the installer and then ask them if you can help in any way when they are on site.

I guess that pictures 5 to 9 are of a much larger version of the external one that I would get.

They are of one form of fibre DP, 'you' won't be getting one, your service will go through one, but there won't be one in/on your property.

The splitter is where the splitter will be where sited by the planners. I suspect you are fretting unduly, capacity will be built into the scheme.

Look the kingfisher drive estate There are 3 splitter nodes here already, and an aggregation node nearby too ......

In reply to a post by Zarjaz:

Firstly, yes that should say ONTE ... and now I cannot edit it. [censored].

So if I wanted to speed up their job, I could install both the BT80 and the NTE5A back plate and wire those two and just leaving the engineer to move the copper line and install the fibre, and that would just leave me to connect the ONT to my HH (whatever I get given) then onto our LAN, and then also connecting the NTE5A new face plate to our existing phone extension.

What BT80 ?? I would suggest you wait for the installer and then ask them if you can help in any way when they are on site.

I was referring when it all goes live, when I phone up BT, I will be asking to have it placed upstairs at the front of the house right by where the line goes down the wall.

This is due to there is no power sockets anywhere near where the NTE5A Master Socket is located at the moment, also the fibre cable would have to travel through our living room around a door frame, through that wall into our hall.

Where as if it was upstairs at the front of the house in an empty room (to be where all the LAN stuff will go, eventually) where no extra fibre cable needed and there is plenty of power sockets available in that room, and from that room I have easy access to our LAN and also the existing Phone Extension.

So if BT says yeah that's fine, and when the engineers arrive I will let them know (i.e. remind then in case BT never told them) where I would like it located.

But yeah, there is no harm in just waiting and asking the engineers if I can help, I will probably do that.

In reply to a post by Zarjaz:

I guess that pictures 5 to 9 are of a much larger version of the external one that I would get.

They are of one form of fibre DP, 'you' won't be getting one, your service will go through one, but there won't be one in/on your property.

Ah, ok, they just looked like the wafer that you get in that external White/Brown/Grey Box that we will get installed on our outside wall which the fibre(s) get wrapped around before its spliced and enters our home.

In reply to a post by Zarjaz:

The splitter is where the splitter will be where sited by the planners. I suspect you are fretting unduly, capacity will be built into the scheme.

Look the kingfisher drive estate There are 3 splitter nodes here already, and an aggregation node nearby too ......

Ah, ok, that's good to know, well it needs to handle 400+ lines, so that would be about 4 splitters at least.

Paul

You can tell BT what you like, but be assured, the amount of times those notes ever get as far down the food chain as to be visible to the engineers is enormously rare.

9/10 most engineers are going to prefer a short external cable run to anything internal.

The white/grey/brown box is the CSP (customer splice point ) These are the photo's which have been misplaced/deleted/grown legs and walked
I'll get some when next I get an opportunity.

In reply to a post by Zarjaz:

You can tell BT what you like, but be assured, the amount of times those notes ever get as far down the food chain as to be visible to the engineers is enormously rare.

So it might be best to have BTOR to move both boxes to where we would like it before we even are able to order FTTP.

In reply to a post by Zarjaz:

9/10 most engineers are going to prefer a short external cable run to anything internal.

Well that sucks, so if that is the case, they better have time to keep repairing the fibre that they will have to install inside our home so that it can reach a power socket.
Which will be in the kitchen at the back of the house.

Whereas having it all upstairs at the front of the house would be the best location for everyone.

In reply to a post by Zarjaz:

The white/grey/brown box is the CSP (customer splice point ) These are the photo's which have been misplaced/deleted/grown legs and walked
I'll get some when next I get an opportunity.

Ok, thanks

Paul

In reply to a post by PaulKirby:

Thanks Zarjaz for the pictures.

Yup. Thanks.

In reply to a post by PaulKirby:

10 to 16, of the splitter node, I always wondered what the red wafers was for, also what are the 6 wafers above the red 4, are they for spare or just to protect the red wafer, and I guess the spare bottom 2 are also to protect the bottom of the 32 wafers.

Manual for the splitter node can be found here, with the tray layouts.
http://forums.thinkbroadband.com/fibre/4375161-fibre...

It looks like the top-left, thick tray holds the first splitter device, with space above and opposite for three more, when demand increases.

Below that, according to that version of the manual, is one tray for the splices onto the input fibres into the splitters. The next 5 trays store unused "d side fibre", which I think means the spare fibres out to the DPs.

Next would be the 4 red trays, which say they hold the output from the splitter devices (ie 32 fibres from each of the 4 devices). I guess these are the ones Zarjaz takes down into the next 32 when they're needed for splicing into live service, to be attached to one of the Dside fibres to the DP.

The bottom 2 trays are used for splicing fibres that are passing through. It isn't clear whether these are intended for passing on fibres to the next splitter node in a chain, or for passing on point-to-point fibres. Because each splitter node only requires a few fibres on the E-side, I imagine the former is more likely.

In reply to a post by PaulKirby:

I have a question, where about would the Splitter Node be placed, I would of thought very close to an area that it is covering, I know the route that our cable runs due to when they replaced all the cables back in July 2015, and I think there is more homes than the 120 to 128 that a splitter splits from the 4 that enters it, so does that mean we would be using either another splitter or would it be using the extra wafers the other side and have an extra cables feeding it?

I would imagine the same - that the splitters get located correctly for when demand is high, but deployed with only one quarter of the complete capacity, to reduce spending while demand is low.

Paul

I still think that it is 19.5Mb per customer as there are usually 2 sets of splitters and the total split over both is 128.

19.5Mb is plenty as the last figures I saw were quoting around 200Kb per customer on average at peak. We have to remember that browsing/ Mail/social media use very little, gaming a little over a consistent period, downloading tends to burst high but infrequently, only Streaming uses a lot consistently.

Now you and I know that there are a lot of low users in the average and FTTC users will be the top 10%. However 19.5Mb each is still high even when you take streaming into account. I guess that FTTx connections are more like 1Mb on average at peak but may be out by a factor of 2 ( I would be surprised if the average is above 2Mb).

Over 128 connections traffic theory starts to be effective and contention is unlikely for a few years especially as fewer than 128 are likely to be working for a significant amount of time.

40% penetrations are still unusual so that would only give 50 workers @ 50Mb each. As you get above 40% lower users start to appear and therefore a lower average bandwidth demand per live user.

When you get to the headend a higher risk of contention appears but spread over more customers as the backhaul will be spread across many FTTC Cabs and FTTP PONS and will be in multiple 1Gbs or a 10Gb.

It will be interesting over the olympics to see if anyone starts to report slow downs on FTTC and FTTP infrastructure ( Rather than backhaul.)

Well I am only going by what the Openreach doc says which is that it is split by 32, and that a user is only split once.

And going by what their docs shows, it shows that 4 strands gets spliced off passing through the rest, each of those 4 strands gets split 32 times creating 128 strands which then gets passed onto the FibreDP's etc, there is nothing about splitting it any more.

Saying that the splitter can split off 2 lots of 32, that meaning that instead of 4 strands entering the splitter there would be 8 strands.
This will probably be used in areas that have loads of lines.

Paul

In reply to a post by PaulKirby:

Saying that the splitter can split off 2 lots of 32, that meaning that instead of 4 strands entering the splitter there would be 8 strands.

The second "input" fibre is to give the splitter a second parent - a separate route, to a separate head-end - for resilience purposes. If one exchange goes off the air, the other one can take over responsibility. If someone digs up one E-side fibre, the other remains available.

That kind of "high availability" is usually more of a requirement for businesses, who would be looking for backup connectivity. It tends to cost a lot, so I'd expect to see it appear in high-end business locations.

In reply to a post by WWWombat:

In reply to a post by PaulKirby:

Saying that the splitter can split off 2 lots of 32, that meaning that instead of 4 strands entering the splitter there would be 8 strands.

The second "input" fibre is to give the splitter a second parent - a separate route, to a separate head-end - for resilience purposes. If one exchange goes off the air, the other one can take over responsibility. If someone digs up one E-side fibre, the other remains available.

That kind of "high availability" is usually more of a requirement for businesses, who would be looking for backup connectivity. It tends to cost a lot, so I'd expect to see it appear in high-end business locations.

Maybe, not really got another exchange close to me, but being FTTP that wouldn't be an issue.
But TBH I haven't really looked too much into the second lot of inputs of the splitter.

As for a requirement fro businesses, my area that is down as FTTP also supplies loads of shops i.e. businesses, so this "might" also be the case for my area.

Paul

I read a presentation from the researchers at BT, that dates back to 2010. Unfortunately, the one website with a copy seems to have gone offline.

It made a proposal for a fibre grid, where the fibre spines didn't just radiate out from each exchange. Additionally, they built across the "no-mans land" between exchanges, allowing for fibre runs between the two.

Continue this chain across a few exchanges, and you end up with a link from one fibre head end to another. Continue it everywhere, and you can create a fully-flexible grid of access network connection. Greatly improved resilience, by building a small percentage of new ductingand fibre in those "no mans land" sections.

Whether BT actually did this is anyone's guess. Even though the splitters have the ability to be dual-parented, it doesn't mean that any of them are,

In reply to a post by WWWombat:

I read a presentation from the researchers at BT, that dates back to 2010. Unfortunately, the one website with a copy seems to have gone offline.

It made a proposal for a fibre grid, where the fibre spines didn't just radiate out from each exchange. Additionally, they built across the "no-mans land" between exchanges, allowing for fibre runs between the two.

Continue this chain across a few exchanges, and you end up with a link from one fibre head end to another. Continue it everywhere, and you can create a fully-flexible grid of access network connection. Greatly improved resilience, by building a small percentage of new ductingand fibre in those "no mans land" sections.

Whether BT actually did this is anyone's guess. Even though the splitters have the ability to be dual-parented, it doesn't mean that any of them are,

That would require huge amounts of fibre, but you would get a more redundant connection and it would allow for passing off some bandwidth from areas that are not using it to areas that are requiring more.
Also it would still work if a cable it sliced in have by road works.

Paul

I think you will find that the resilience is not automatically available but can be connected to if there is a failure. The splitter can use 2 inputs so give two seperate paths to a customer ( 2 FTTP connections) but each connection is permanantly connected to that input.

The splitter is not an active switch but a permanant connected path from input to output.

The splitter works on wavelengths and each output is 1 wavelength on the input side.

In reply to a post by PaulKirby:

That would require huge amounts of fibre, but you would get a more redundant connection and it would allow for passing off some bandwidth from areas that are not using it to areas that are requiring more.

It wouldn't need "huge" amounts of cable, but certainly extra fibre, and it would need to be deployed differently, in 2 separate ways...

First, where (say) a 288 fibre cable runs out along one spine, it would need to remain as a count of 288 fibres all the way out to the far end. That means, when (say) 60 fibres are pulled off for one aggregation node - as the primary feed from the exchange - the spine would continue to carry 60 fibres out towards the exchange boundary - as the secondary feed that will come back in from the distant exchange.

Second, the gap between exchange areas (ie between the ends of the fibre spines) would need to be dug, ducted, and filled with the same fibre count cable.

The presentation did some analysis in 3 urban exchange areas, and reckoned that it would need 5-10% extra cable length, and cover 3-4 gaps in each exchange, giving added resilience to 70%+ of businesses. No word on how many fibres, though.

They might not need to make every splitter resilient, and instead deploy a few splitters that are deployed specifically for business use. In that case, the fibre count out the extreme end of the fibre spine could drop, with only a few fibres allocated for secondary routes.