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Repetitive daily loss of sync (Possibly Now Resolved)

MrT
Grafter
Posts: 379
Registered: 30-06-2010

Repetitive daily loss of sync (Possibly Now Resolved)

Until recently, my router had consistently synced above 4500kbps with a resultant line speed of about 3900kbps. The line stayed in sync for between 10 and 90 days. Target SNM was/is 3dB.
Since about the middle of June things have been getting progressively worse. I have now reached the point where the sync duration does not exceed 1 day and the sync rate is around 2900kbps resulting in a line speed of about 2500kbps. Target SNM remains at 3dB.
Over the past 4 evenings, I have been monitoring the connection with RouterStats and have witnessed a disturbing repetitive pattern of events.
The line is stable with a SN margin around 12dB until about 21:20. The router then resyncs twice and the SN margin is around 3.5dB. The SN margin increases to around 9 or 10dB by about 21:40. There is a further step up to 12dB around 22:25. This behaviour is shown on the attached image. The graph is virtually identical for all 4 evenings.
There is nothing in my house that switches on or off within this timeframe so I am led to think that the cause is external to my house.
Any thoughts/ideas would be much appreciated.
21 REPLIES
Plusnet Help Team
Plusnet Help Team
Posts: 13,479
Thanks: 246
Fixes: 68
Registered: 27-04-2007

Re: Repetitive daily loss of sync

Hi MrT,
I'd keep monitoring that if you can but I'd agree that it sounds like something external might be affecting your connection, it could possibly be a REIN/SHINE fault as you might have seen mentioned on other posts such as this one http://community.plus.net/forum/index.php/topic,111551.80.html
It certainly looks like it's been an issue for at least the past week according to the connection graph I've posted below so it would be well worth raising a fault: http://faults.plus.net
<img src="http://community.plus.net/visualradius/generated/image13770981954253.png"/>
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: Repetitive daily loss of sync

What time do the lights come on in your street?
Highlighted
MrT
Grafter
Posts: 379
Registered: 30-06-2010

Re: Repetitive daily loss of sync

Well, much as expected, I had the same problem occur at the same time last evening and the graph from RouterStats was little different!
@Adam - I'll keep monitoring with RouterStats at least until Tuesday next. I'm going away for a few days then and had intended switching off the router. But now I'll leave it on so that I'll have the router log if nothing else to show what has been happening.
I've read through the posts re REIN/SHINE that you gave me. These posts seemed to end abruptly in February without a conclusion. I wonder whether the OP ever got his problem sorted.
On the connection graph that you included in your post, the PPP disconnects on 16/08 at 20:15 and 21/08 at 04:15 were not accompanied by a loss of sync.
@James - my street lights all came on at 20:30 last evening (some 50 minutes before resync time). All the lamps are the new modern energy-efficient variety and have only been installed this year.
There are ongoing road works between my house and the exchange (I think Severn Trent are doing some sewer works - but I don't think they work late into the evening). I don't know the route that the BT cable follows from the exchange to my house so this could be a total red herring!
My connection is quite stable during the day. I have attached the router stats from some 30 minutes prior to resync last evening. The 197 error seconds is a cumulative count from last warm restart on 12th August.
I also did a quiet line test, using a corded phone plugged into the master socket,  last evening which covered the resync time. I did not hear any increase in line noise during the resync period.
MrT
Grafter
Posts: 379
Registered: 30-06-2010

Re: Repetitive daily loss of sync

On the 3rd September, I went through the fault logging process resulting in Question 74022503.
On 7th September, target SNR margin was set to 6dB and retraining of my line began (in the hope that this would fix the problem). Stability was not an issue and the fault persisted. The result of resetting the target SNR margin only served to reduce my line speed by about 300Kbps. So, post-resync I was getting a rate of about 2600Kbps.
In the early hours of this morning there was another resync (presumably under DLM control). It seems this was caused by changing target SNR margin back to 3dB. My line is now synced at 4738Kbps - at least until the next occurrence of the fault when it will no doubt return to around 2900Kbps.
I was just wondering whether a new 10 day retraining period would have been triggered this morning.  Undecided
PeeGee
Aspiring Pro
Posts: 1,098
Thanks: 51
Fixes: 3
Registered: 05-04-2009

Re: Repetitive daily loss of sync

I suspect it is a case of the DLM algorithms indicating your line is sufficiently stable to try the new settings for the last few days of training.
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
MrT
Grafter
Posts: 379
Registered: 30-06-2010

Re: Repetitive daily loss of sync

Oh No! It happened again last evening. See attached image.
I've asked PN via my ticket to "pass this on to their suppliers".
Will this move my ticket back to the bottom of the pile? Will I have to wait 48 hours for a progress update?
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Repetitive daily loss of sync

Hi, looks like it's been picked up and an appointment booked for you, hope that gets things sorted Smiley
MrT
Grafter
Posts: 379
Registered: 30-06-2010

Re: Repetitive daily loss of sync (Possibly Now Resolved)

An update of progress towards resolution:
A BT Engineer came on Thursday afternoon 19th September, as planned.
He discovered that the wiring from the cable entry point to the master socket was incorrect. I forget the term he used for this situation (I wish I could remember!) but I think he said that the master socket was connected to one wire from each of the two incoming pairs. This wiring has been untouched since we bought our house 29 years ago. It is rather strange that I have had a fully functioning telephone during all these years and for the past 6 years, apart from my recent problem, have had a decent Broadband connection.
After the Engineer had modified the incoming wiring, the line achieved sync at 4950Kbps. This is at the high end of my previously 'normal' range. The line has been stable at this rate for 2 days.
I am now waiting for my Line Speed to catch up with my IP Profile of 4.37Mbps.
Community Veteran
Posts: 1,616
Thanks: 22
Registered: 29-06-2010

Re: Repetitive daily loss of sync (Possibly Now Resolved)

It's called a "split pair" and will usually not cause problems with voice usage, but seriously affects ADSL.
nanotm
Pro
Posts: 5,712
Thanks: 120
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Registered: 11-02-2013

Re: Repetitive daily loss of sync (Possibly Now Resolved)

when they swapped you onto PlusNet they probably correct the split pair wiring at the exchange end and thus caused the fault on your end to become apparent, it could well of been something they did to rectify a fault before you moved in back in the days of the old mechanical exchanges.....
just because your paranoid doesn't mean they aren't out to get you
MrT
Grafter
Posts: 379
Registered: 30-06-2010

Re: Repetitive daily loss of sync (Possibly Now Resolved)

Just to clarify
I have been with Plusnet for the last 3 years. This problem has only arisen in the last 6 weeks.
nanotm
Pro
Posts: 5,712
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Registered: 11-02-2013

Re: Repetitive daily loss of sync (Possibly Now Resolved)

ahh then it could be part of some other BT works, like moving things around for the FTTC upgrades (final cable runs etc)
if it was all working fine with a split pair (which it couldn't do unless both ends were the same split pair) that's the only logical explanation, chances are there was something that made a bt engineer do it years ago (crosstalk elimination probably) and its only just been undone as part of background maint or upgrade work that "shouldn't interfere with normal connectivity" but in your case has thrown up problem ....
just because your paranoid doesn't mean they aren't out to get you
MrT
Grafter
Posts: 379
Registered: 30-06-2010

Re: Repetitive daily loss of sync (Possibly Now Resolved)

Quote from: nanotm
if it was all working fine with a split pair

It sure was. I had continuous ADSL connections for periods up to 88 days.
FTTC has been in my area for about a year now. So no logical explanation as to what happened.
It's possible that 2 wires were connected together at the cab and have now been split but this is pure speculation on my part. Also it should have meant a loss of voice - which just didn't happen.
nanotm
Pro
Posts: 5,712
Thanks: 120
Fixes: 2
Registered: 11-02-2013

Re: Repetitive daily loss of sync (Possibly Now Resolved)

old voice wires (we are talking pre 1990) were bundled as 4 twisted pairs or 8 twisted pairs for a twin line, couldn't be used for second lines because of crosstalk, the active phone line carries 50vdc and cases the analogue voice signal to be transmitted through all 4 (unconnected) pairs, if the split pair are touching and the conditions are good with zero interference it can even carry a good adsl signal through Electromagnetic propagation in matched antenna (exact same length and impedance line as the transmitter within close proximity) but tiny changes in local conditions can disrupt the unpowered signal (hence the frequent drops)
however bt (being a national company) didn't change the lines they ordered to having fewer pairs despite the fact they couldn't utilise the extra line ability unless a pabx unit was whacked on the end of the line (because the signalling was wave multiplexed at the point it entered the line so crosstalk wasn't a problem) on the grounds it was cheaper to only use 1 sort of cable......
consequently a tight line pack(as it entered the exchange) could cause crosstalk over many lines, and a common fault rectification was to change to using crosstalk free split pairs,
as for the fttc upgrade it sounds like they just got through the final works of tidying up the exchange end (removing some DSL cards and moving remaining customers into empty slots on others....) which would make sense
just because your paranoid doesn't mean they aren't out to get you