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FTTC Trial - 3 Days In - Status Report

phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

FTTC Trial - 3 Days In - Status Report

BT converted my connection from 3 Meg (give or take a few) via ADSL to FTTC on Friday 5th. The engineering works took about 45 minutes from the initial phonecall from the Techie to the first log in via FTTC and the downstream speed peaked at approx 15 Mbit/sec.
I tidied up my cabling and provided power to the VDSL modem location in advance of BT's visit, so it was a simple case of fitting the new filter faceplate and mounting the modem and we were in business.
It was the first non-BTInternet installation carried out by this Techie and he had been told during his training that the FTTC service would not work without a BT HomeHub/router. A quick call to his Control Point cleared up that misunderstanding and the install continued to a satisfactory conclusion.
Since Friday, the VDSL modem has locked up twice at approximately 14:45 on both Sunday and today. The Huawei HG612 modem indicators show power and LAN1 OK, but the DSL status LED is alternately flashing quickly then extinguished on a 14 second cycle.
A power off/on of the modem clears the problem and it trains up in approximately 10 seconds.
Downstream speed has now dropped to approx 12 Mbit/sec and a ticket has been raised. Hope it's not terminal....

Phil
17 REPLIES
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Re: FTTC Trial - 3 Days In - Status Report

Hi Phil,
I've run a test and left you a voicemail and reply to your ticket. Looks like we need to book an engineer visit and the line has sync'd below 15Mbps and seems unstable at 16Mbps so best thing is for an engineer to take a look.
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

Thanks Dave,
I've replied on the ticket.
Let's see what BT can find...
Phil
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Re: FTTC Trial - 3 Days In - Status Report

The test has change its mind about the engineer as the upstream sync speed has decreased below 2Mbps. I've sent it on to BT to see what they say.
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

Hi Dave,
The downstream speed dipped to approx 6 Mbit/sec yesterday evening but has returned to approx 12 Mbit/sec this morning. Upstream is currently 0.67 Mbit/sec which is approximately double my typical ADSL upstream speed.
The best I have seen since FTTC installation was 17 meg down and 2.1 meg up (but these two figures were not achieved in the same speed checker run).
It would be good if BT could monitor the DSL between 14:30 and 15:00 today as all of the failures so far have occurred in this window.
Regards,
Phil
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Re: FTTC Trial - 3 Days In - Status Report

It dropped at 12:07pm and 5:17pm by the looks of it but reconnected immediately. BT want to book an engineer now so if you can post back on the ticket we'll get it booked for you.
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

Dave,
The BT Techie visited my premises yesterday at approx 11:50 and she confirmed that the link was synching at approx 15 Mbit/sec on her tester. She also advised that it was her second visit to a user where the modem was apparently locking up.
The sequence of actions taken was as follows:
- Swapped out the modem and power supply (just in case it might be a modem issue)
- Techie went to the cab
- Checked synch speed at the cab (Congleton Cab 2) - 15 Mbit/sec there too!
- Spoke to the BT Control Centre who advised that the synch rate had been managed down to 15 Mbit/sec max
- Control Centre applied temporary override to wind the max synch rate back to 40 Mbit/sec
- Full 40 Mbit/sec synch rate measured at the cab
- Copper circuit reconnected onwards to my premises (all underground cabling)
- Modem refused to synch and it displayed the same symptoms as the apparent "lock up" reported previously
- Control centre re-applied the 15 Mbit/sec max synch rate
- Modem synched at approx 13:20 and has remained in synch since then.
Conclusion:
BT suspect that there is a latent cabling problem between the cab and my premises (approx 875 metres) although the analogue evidence suggests that there isn't an earthy fault as there are no audible clicks bangs or whistles. It looks like 15 Mbit/sec synch (which translates to approx 13.5 Mbit/sec traffic speed) is the best we are likely to achieve without an extensive investigation by BT. I suspect (and I'm grasping at straws here) that the distribution cabling around our estate has a number of "stumped pairs" where the original jointers have hedged their bets and have tee'd together a few of the branch cables to improve the planners' flexibility to provide service around the estate. This means that the pair between the cab and my premises might have an open circuit stub somewhere along its length and this might be compromising the performance of the modem in some way.
I don't know how you want to play this. The BT Techie said that the service should not have been handed to us with a synch rate below 15 Mbit/sec, so the performance was at best marginal from the outset. Without a local comparison, it will be difficult to state exactly what speeds we should be getting over a tail circuit of this length - perhaps you could press BT for guidance?  The cable length of 875 metres is measured from the route taken by the footway junction boxes between the cab and my premises and represents the longest possible routing. The circuit may indeed be shorter, but a TDR test from my premises yesterday came up with a ridiculously short measurement of a couple of hundred metres to the first reflection - perhaps this might be the location of the branch stub?
Obviously, I'm ecstatic that my link speed has improved four-fold from the 3 Mbit/sec rate I enjoyed via ADSL, but I almost feel cheated that I may be missing out on a possible 20-25 Mbit/sec service.
Regards,
Phil
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Re: FTTC Trial - 3 Days In - Status Report

Thanks for the detailed feedback Phil. From the lines we've done so far I think the maximum speeds seem to tail off from around 400-500m and then tail off quite quick. 1-1.5km seems to be about the upper limit to stay above 15Mbps so if it's 875m it's quite close to that boundary so yeah with good quality copper it may well get to 20Mbps. As for the next step, not sure we'll wait and see what the engineer notes say too and then see.
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

Hi Dave,
I'll try to get some confirmation of the tail circuit length from the engineer tomorrow morning. The 875m was derived by walking the logical cable route, following the footway joint boxes from my premises to the cab, then measuring the track on a 1:25000 OS map. Maybe the actual cable route cuts a few corners here and there...
Phil
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

Dave,
This update is also on the ticket.
BT have just handed the service back after an extensive investigation into the cabling between the cabinet and our premises.
The actual route length is approximately 950 metres as it loops round the estate to reach my road.
The engineer retraced the steps taken by his colleague earlier this week, but this time he tested the synch speed at every
accessible joint along the route. Speeds of 30 Mbit/sec or better were measured up to a point approximately 200 metres
from my premises where the cable changed from copper to aluminium. From that point, the synch speed decayed rapidly
to 15 Mbit/sec at my location. The copper to aluminium transition may well account for the TDR reflection observed on Tuesday.
The engineer swapped my connection to a different pair within the aluminium segment of the route and also remade
some crimped joints in an effort to tease out a few more megs of bandwidth, to no avail.
Unfortunately, it looks like the aluminium cable is directly buried and not in a duct, so its replacement  with copper will entail
digging up all the front gardens between the transition point and my premises.
I understand from a neighbour a few houses further down the cable route that BT have declined an order for FTTC
broadband because the survey indicated that the link would not achieve the minimum 15 Mbit/sec synch rate.
The BT engineer has fed back the aluminium cable issue to his designers as the bad section of cable is common to a
considerable number of premises in my flank of the estate. I guess that for now we must leave the issue with BT.
Thanks for all your help.
Regards,
Phil
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

The fault ticket was updated earlier today by Thomas at PlusNet who advised that BT are investigating the possible replacement of the aluminium cable with copper in an effort to improve the FTTC performance to my corner of the estate.
I'm getting 12-13 Megs downstream and 1.8-2.0 Megs upstream, but the pings are quite long (I have seen round trip times up to approx 90-100ms) so I suspect that the traffic is heavily interleaved to overcome a high BER. Long pings don't cause me too much trouble as I'm not an online gamer.
My next-door-but-one neighbour (also with PlusNet) was migrated to FTTC earlier today and he is getting very similar performance; others (not currently with PlusNet) are waiting in the wings to see how we get on so hopefully BT will invest a little to keep us all happy.
Regards,
Phil
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Re: FTTC Trial - 3 Days In - Status Report

I'm keeping my fingers crossed, just replied to your neighbour's post too. The lower speed profiles do have quite high interleave on them I think to try and keep the line stable and correct errors, I think it works slightly differently to ADSL. Hopefully they can replace the aluminium, once done it should be a case of asking the engineer to call back to base to reset the line profile.
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

Hi Dave,
Your man Sean has updated the ticket and also called me (thanks for that Sean) to advise
that BT have stated that they are not willing to replace the aluminium cable with copper
due to the costs associated with digging up the directly buried inferior cable. If only they had
run the cable in a duct...
BT have apparently quoted long lead times and a cost of several thousand pounds because
they would need to negotiate permission to dig up other residents' front gardens. This may
not be too difficult as everyone on the estate is aware of the service strip under which all
utility cables are buried - see the attached local authority search response which was issued
to all purchasers of houses on the estate.
If BT are truly treating the FTTC trial as a method of developing their 21CN customer service
methodology, then problems like this are good learning opportunities and should not be filed
away as "too difficult".
Sean has asked BT to provide a more detailed breakdown of their estimate and Sean will
forward that to me in due course.
Regards,
Phil
G3YBO
Grafter
Posts: 103
Registered: 27-11-2010

Re: FTTC Trial - 3 Days In - Status Report

How far is your VDSL router from the master socket............Good luck with the new system......BT fitted a new big green box
outside my house friday so hope it wont be long for FTTC here..........
phil_o99
Dabbler
Posts: 18
Registered: 04-08-2007

Re: FTTC Trial - 3 Days In - Status Report

G3YBO,
The two-pair BT external armoured cable terminates in a weatherproof box on the outside wall of the house, just above DPC level. Approximately 1 metre of CAT5 extends the working pair through the cavity wall to the master jack/filter unit which is fitted at the bottom left corner of the backboard shown in the earlier photo. A custom made RJ12 cable approx 25 cm long connects the filter to the BT supplied VDSL2 modem.
The connection between the modem and my router uses pre-existing CAT5 cable via a standard RJ45 patch field in the study upstairs.
BT aren't bothered about anything beyond their modem if the service is operated by a non-BT ISP (e.g. PlusNet in this instance).

Regards,
Phil