FTTC box overheating

[#1]

@ Alex Rolls,
FYI the ticket No. in question is #44208926, started 5th July.
@ Matt_2k34,
The latest modem (No. 3) has been stood as you mention since it was installed on Wednesday 10th August, with the desk fan turned off.
It only feels slightly warm, as expected.
Modem No.1 had the fan installed as soon as the disconnections started & the fan remained on 24/7 until the modem was replaced
Modem No. 2 was only installed last Thursday (4th August). Again the desk fan was on 24/7, which made the modem feel quite cool.
I had a number of disconnections & a crackly phone line Friday 5th that were reported to Plusnet as they now provide both the phone & FTTC services.
I have done loads of BT & speedtest.net speed tests at various times of day, even staying up until after 1:00am & getting up before 7:00am.
I have all the results, either as screenshots, or exported to spreadsheets.
Quite a few of these have been attached to the open ticket.
Edit: 12/08/2011 - I forgot to mention earlier, so here are today's results from the BT performance tester (07:35am):-
Download speed: 21552 Kbps
Max Achievable Speed: 23149 Kbps
Acceptable Range of Speeds: 16204-23149 Kbps
IP Profile for my line: 23149 Kbps
These results have been pretty constant since modem No. 3 was installed.
Prior to the issues, I was regularly downloading at 32-33 Mbps, so I guess my IP Profile would have been around 34000-35000 Kbps.
Upload speeds look OK so I won't quote them.
Paul.

[#2]

Quote from: Baldeagle1

@ Alex Rolls: I think you may even have had a dabble in the early days of my now very long open ticket.

I was infact the first person to look at this fault yes.
This issue is common.  If the BT VDSL modem begins to overheat it seems to cause lots and lots of disconnections in a short period of time.  This upsets the DLM enormously as the line will be detected as a "Chronic Flapping" line to quote the technical term.  I believe the threshold is 10 sync events with a 1 hour period.  This seems to have a far greater effect on FTTC connections than it does with normal ADSL connections.  In my experience most customers are reduced down to a 20Mbps speed for a period of time following the period of disconnections.  Sadly we don't have any documentation on how the DLM for FTTC actually works yet so I can't tell you how long it should take for the speed to return to normal.  I have been assured however that the DLM system for FTTC will increase the line speed back to normal eventually.  Sadly it seems that it is much slower to react that the ADSL DLM to the tune of 10 to 14 days of stable connectivity.  Additionally to this we have no ability to remotely reset the line configuration to default.  We can't action this via BT fault diagnostics either.  Only an engineer who is on site can reset the line and this I believe is done via an engineers helpdesk rather than the engineer having to actually perform any manual tasks on the line.  Hopefully this won't always be the case as the product develops.
It's worth stating that this is entirely in my experience of this type of problem and the FTTC DLM.  Until we receive some technical details regarding this then we can't make any firm statements about how a line is managed by the various systems involved.
My advice is to keep your new modem powered and connected to your line for as long as possible.  The DLM will (eventually) make the right decision in terms of line management and will ensure you have a consistent service at the highest possible speed.

[#3]

@ Alex Rolls
Thanks for responding.
My large concern is that Plusnet originally estimated my speeds at 14.6 Mb & that the feeiling is that as I am currently achieving downloads in excess of this estimate, nothing is wrong.
I felt this estimate was artificially very conservative (I knew which cabinet I would be connected to & I knew its exact location) & may have been calculated (by BT???) based on a line length of 5283 m (as also quoted by M***n yesterday), so I went ahead & had FTTC installed.
I had also seen this line length quoted elsewhere.
Indeed, I achieved 32-33 Mb downloads solidly until the issues started.
I live only around 600m or so from the cabinet (by road, not in a straight line & I can see the vast majority of the overhead cables), so I would expect much higher download speeds than I am currently experiencing.
M***n was unable to confirm how line lengths and speed estimates are calculated. However, my current FTTC downstream Line Attenuation of 30.2 dB appears to suggest quite a long line from the FTTC cabinet (maybe over 2 km if the same method of calculations as used for ADSL is applied?)
A possible explanation for high attenuation COULD be a high resistance issue in the cable between the cabinet & my home.
I was led to believe the latest "special faults" engineer was being sent to check this, especially when considering the other issues within my very long ticket.
I believe that both BT & Plusnet currently feel my expectations are too high, but if speeds have been estimated using invalid data in BT's database, maybe they are not too high.
It has after all been proved that 30+ Mbps downloads were indeed achievable prior to the issues, that I am not now actually convinced were an overheating modem issue at all.
I do leave the equipment switched on 24/7 & will try to be patient while I await the DLM's "right" decision.
I hope you realise I am not really complaining (yet), & am willing to accept that as the technology is reasonably new, not everyone has a full undertanding of it.
Finally, apologies for hijacking someone else's thread. I will start another thread, unless the details assist others in any way.

Paul.

[#4]

For speed estimation we use a line checker which is provided by BT and the information is kept up to date.  For ADSL the checker tends to be fairly accurate but for FTTC it is normally within 1Mbps.  Your line estimate for downstream is 14600kbps which is pretty far off the mark but it's exactly that.  An estimate!
In terms of how BT actually calculate the estimates is not something I could answer with 100% accuracy.  I would assume that it's based on line length figures and current average sync rates in the area.

[#5]

Oh No!!!!!!!
Just noticed another disconnection had occured whilst I was typing my previous response:-
[Internet connected] IP address: 87.113.197.174, Friday, Aug 12,2011 11:58:41
[Internet disconnected] Friday, Aug 12,2011 11:50:34
IP profile has now dropped down to 17657 Kbps (please see the attachment).
Surely this cannot be another overheating modem issue? It feels only slightly warm to the touch.
The 'phone line is currently quiet though.
Paul.

[#6]

Doesn't look like a modem issue from our logs.  I'd say it's nothing to worry about unless it becomes more frequent and service affecting.

[#7]

Thanks Alex,
I have to go to work now, but I'll check my router stats later on.
That bloomin' interleaving hasn't automatically been turned on again has it?
My download speeds have certainly been affected downward again
Paul.

[#8]

To find out i'd need to run a test that would cause a further disconnection to occur as your port is taken out of service for about 30 seconds during the test proceedure.
Are you sure you want me to check?

[#9]

No thanks Alex,
Let's at least hang on until I get back from work later on.
It seems like I can't afford any "unnecessary" disconnections
Paul.

[#10]

@ Alex Rolls or A.N. Other Plusnet Representative,
If the modem isn't the issue (I think we all now believe it isn't), the only alternative is that the line length and/or its quality is the issue.
The installation engineer connected the new master socket at the end of my own existing extension cable, saying something on the lines of "that's bloody good stuff" (shielded "high speed data cable" bought from Maplins over a year ago).
The latest engineer saw it but wouldn't test FTTC line speed/quality at the entry point (original master socket position), saying that if a BT engineer had checked & hard-wired the extension cable it must be O.K.
Potential area for concern? Possibly not, as the extension cable is loose laid i.e. no staples to damage it.
We are having some difficulty in establishing the actual effective FTTC line length as M***n quoted a length of 5283m. I have also obtained this exact "reported" value from elsewhere.
The FTTC cabinet is only around 600m or so from my house, so it would appear incredibly unlikely that, even with inevitable detours, the real line length will be anywhere near 5283m.
As you are aware from my ticket, I have recently experienced a number of recent line issues (recent complete loss of service, crackly phone line since service was resumed - currently quiet, a number of uninitiated disconnections etc.)
I did discuss these intermittent issues with Plusnet's H**** O & he arranged for a BT Special Faults engineer's visit to carry out line tests.
It appears that lines of communication between Plusnet & BT are not quite perfect.
The engineer did not show up or contact me on the day the visit had been arranged, so I lost a day from work.
The engineer that did visit the next day just replaced the modem again & confirmed I was connecting at more than 15 Mb.
I achieved 32-33 Mb downloads for a couple of weeks, which I believe is proof that my line must be a lot shorter than 5283m. 33Mb download speeds on a 40 Mb service probably point to an actual line length more like 800m or so, as suggested by Ofcom's chart (attached for reference).
With this information, do you believe we now have a chance of BT carrying out whatever tests are now required with a view to a permanent elimination of the "intermittent" faults, at no cost to myself? e.g. yesterday's disconnection. What caused it & why did it immediqately lower my IP Profile & therefore download speeds to around 17 Mb?
I apologise for being a P.I.T.A. with this matter. I just feel that as my line has achieved decent speeds at one time, I can reasonably expect any faults outside my own control to be suitably addressed.
I am not too comfortable trying to resolve this issue in a public forum, but it does appear to generate a response somewhat quicker than your ticket system.
Regards,
Paul.

[#11]

I notice you added the extension cable and subsequently a new master socket was fitted to it.
This might not be relevant to your problem but:
I had an extension cable with a new master socket fitted by BT when I got ADSL originally. When I had fibre
fitted I was told it couldn't be done at this master socket as I had telephone points running from before
the extension cable and hence before the master socket. Perhaps you also have and this is causing your problem.

[#12]

@ Baldeagle1
Our line tests shows you currently connected at 23Mbps.  As your line estimate is 14.6Mbps and your line is currently operating over the Fault Threshold Rate of 15Mbps there is little else that we could arrange with BT to improve your speed.  Although your cabinet is approximately 600 metres away it should now be left to the broadband systems in the cabinet to establish the best connection rate for your line which may vary as the line speed is totally dynamic.
Re: Line length.  The line length of 5283m is the length of the cabling all the way back to the exchange, not to the cabinet.

[#13]

@ Alex Rolls
Thanks for the update.
FYI, the single disconnection yesterday was caused by me this time. I am refurbishing my house & had to turn all the power off for a short while.
I did notice the slight improvement to my IP profile & download speed on reconnecting. It still seems to be around 10-12 Mb shy of what I first received.
I will try to keep the modem connected 24/7 to demonstrate (hopefully) a stable connection in the hope that DLM will at some stage reinstate the previously achieved speeds.
I realise the 5283m is the distance from the exchange & not the cabinet, which is why I find it strange that it is still being reported by BT & Plusnet.
However, via FTTC, this is a meaningless distance to quote.
As my Line Attenuation for downstream (30.2 dB), as reported by the last engineer's JDSU, appears quite high for the relevant FTTC distance, it would be really more helpful if FTTC distances were quoted in order for users to "have a feel" for their line conditions & expectations, possibly highlighting potential problem areas.
My line Attenuation for upstream also appears really high at 52.9dB, & in fact appears to be the complete opposite to ADSL attenuations.
Could this signify a problem area?
Is this normal for FTTC?
There is very little FTTC data available for us all at this early stage in its implementation. Hence all my queries & concerns.
Thanks again for responding.
We are probably all in the same boat regarding FTTC provision, which I am sure will become clearer as time progresses.

Paul.
jim:quote

[#14]

Quote from: Baldeagle1

I realise the 5283m is the distance from the exchange & not the cabinet, which is why I find it strange that it is still being reported by BT & Plusnet. However, via FTTC, this is a meaningless distance to quote.

At the moment we don't have a system to check this.

Quote from: Baldeagle1

As my Line Attenuation for downstream (30.2 dB), as reported by the last engineer's JDSU, appears quite high for the relevant FTTC distance, it would be really more helpful if FTTC distances were quoted in order for users to "have a feel" for their line conditions & expectations, possibly highlighting potential problem areas. My line Attenuation for upstream also appears really high at 52.9dB, & in fact appears to be the complete opposite to ADSL attenuations. Could this signify a problem area? Is this normal for FTTC?

Our line testers don't show any figures for Attenuation on FTTC or FTTP so it's hard to say what normal figures are.

[#15]

Quote from: Alex

Our line testers don't show any figures for Attenuation on FTTC or FTTP so it's hard to say what normal figures are.

Thanks Alex.
One last question for now (honest)
Will end users soon be given a means to monitor their own line conditions via the BT modem?
I'm sure it would save a helluvalot of questions for already overstretched staff such as yourself.
Paul.