Kitz Forum

Broadband Related => ADSL Issues => Topic started by: aesmith on December 23, 2016, 02:00:41 PM

Title: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on December 23, 2016, 02:00:41 PM
Hi,

At the end of a recent visit the OR engineer ran a 5 minute DSL test on our line, he took the end of my RJ11 cable out of the router for his tester so cable, filter and everything we same as my installation.   His test ran effectively clean, one downstream CRC in five minutes, compared to their previous visit where it ran up a couple of hundred, and he synched at I think 4.3meg  All looking good.

However with my own router I get zillions of errors and a lower rate.   As soon as I saw that I swapped to  my spare router, a 582N and that showed the same and a worse synch rate ..

Yesterday 19:19:13
BT Test xDSL Status Check:Pass OK.pass OK. Circuit In Sync
BRAS=2500kb/s FTR=3200kb/s MSR=4000kb/s ServOpt=1 I/L=A
UNABLE TO REACH THE CHOSEN SERVICE OPTION BUT WILL CONTINUE TO FUNCTION UNDER DLM CONTROL (ILQ=R)
Up Sync=448kb/s LoopLoss=31dB SNR=19dB HIGH ErrSec=0 HECErr=0 Cells=103738
Down Sync=3232kb/s LoopLoss=56.5dB SNR=6dB ErrSec=737 HECErr=0 Cells=2577316


After a couple of hours swapped back to the Billion.   It occurred to me that the BT tester was used on the floor clear of any of the powered up equipment (phone, printer television stuff) whereas my router is nearby.  So I powered off all mains powered gear including lights in the room and the adjacent hallway, only the router powered up.  No improvement ..

Today 09:52:31
T Test xDSL Status Check:Pass OK.pass OK. Circuit In Sync
BRAS=2500kb/s FTR=3200kb/s MSR=4000kb/s ServOpt=1 I/L=A
UNABLE TO REACH THE CHOSEN SERVICE OPTION BUT WILL CONTINUE TO FUNCTION UNDER DLM CONTROL (ILQ=R)
Up Sync=448kb/s LoopLoss=30.5dB SNR=20dB HIGH ErrSec=0 HECErr=0 Cells=235326
Down Sync=3904kb/s LoopLoss=55.5dB SNR=7dB ErrSec=696 HECErr=0 Cells=4991342


Either BT or A&A, not sure who have raised the target to 9dB, still no improvement at that lower speed ..

Today 12:24:45
BT Test xDSL Status Check:Pass OK.pass OK. Circuit In Sync
BRAS=2500kb/s FTR=3200kb/s MSR=4000kb/s ServOpt=1 I/L=A
UNABLE TO REACH THE CHOSEN SERVICE OPTION BUT WILL CONTINUE TO FUNCTION UNDER DLM CONTROL (ILQ=R)
Up Sync=448kb/s LoopLoss=31dB SNR=19dB HIGH ErrSec=0 HECErr=0 Cells=308230
Down Sync=3520kb/s LoopLoss=55.5dB SNR=9dB ErrSec=732 HECErr=0 Cells=3827221


Any ideas about the sort of fault that would cause these issues when using my gear, but show clean on BT's DSL test?   I guess it's looking very much like my equipment is at fault, but two different routers showing the same symptoms is a little off.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on December 23, 2016, 04:35:50 PM
I wonder if it is a question of what is the chipset & analogue front-end in your modem/router(s) and in the "BT tester" used by the Openreach technician. I presume it was either a JDSU HST-3000c (with the current Broadcom based HST3000-WB2 SIM) or an Exfo AXS-200/635?  :-\
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: GigabitEthernet on December 23, 2016, 04:37:55 PM
I am not convinced the errors on the Openreach equipment are accurate. I remember when I had a fault and the tester displayed one FEC in 15 minutes. I put three different routers on and straight away I had hundreds within minutes.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on December 23, 2016, 04:48:45 PM
I am not convinced the errors on the Openreach equipment are accurate.

It really depends upon the SIM of the JDSU (if a HST-3000c was used) being up to date and Broadcom based. I know, for example, that Black Sheep was provided with the latest (Broadcom based) WB2 SIM to replace the Infineon one he was then using.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: Black Sheep on December 23, 2016, 05:26:48 PM
I tend to find this same scenario with CISCO routers used in business premises. They have to be set to at least 9dB on the DS SNR, but prefer to be at 12dB DS SNR to be completely error-free.

I have no idea as to the technical reason behind this, it just is. Proven hundreds of times over many years of faulting.

Now for the really strange thing, and maybe what's happening with the OP ........... I've had this a couple of dozen times over the years.
I run a '5 minute DSL Close-out test' as required in the job standards, and the circuit is completely error-free, bearing in mind we only see CRC/FEC on our screens .... not HEC. This test logs on to the ISP's server.
Now, when I run a bog-standard xDSL test, which only 'talks' to the DSLAM in the Cab/Exchange ..... I see incrementing errors ???

Alas, I can't remember what the fixes were on all occasions, but there were definitely miniscule HR's on a few of them. I don't want to get the OP's hopes up, as this is just me recounting a few anomalies.  :) It could very easily be down to the EU's equipment ??.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on December 24, 2016, 08:00:11 AM
BT tester showed zero FECs, which did strike me as a bit odd.  Regarding the kit, both the Billion and Thomson routers have worked for me in the past with normal 6dB target so I don't think the type of kit is the issue, although of course it's possible they're both faulty.

I'm running a brief test at 12dB and so far it look like error rate is unchanged.   Will give that 30 mins at least.

Sent from my Nexus 7 using Tapatalk

Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on December 24, 2016, 08:59:00 AM
As initially thought, even 12dB doesn't clean it up.  At that point we're down to 2.8meg from normal 4meg, and below FTR.  Long shot maybe, but I'm going to see if I could test my router on a neighbour's line.  Can't really think what else I can do to rule out our equipment because I agree, on the face of it with BT test passing and my kit failing it looks like my kit.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: ejs on December 24, 2016, 09:23:28 AM
I suppose that unlike the BT handheld tester, both the Billion and the Technicolor were powered by their mains switched-mode power adapters?
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on December 24, 2016, 03:42:30 PM
Yes they are (were) although only one was plugged in at a time, ie Billion PSU not plugged in when using Thomson router.  Anyway things have moved on.  It certainly appears that A&A push things along quicker than I'm used to .. OR engineer turned up this morning with a different model tester, his DSL test showed loads of errors, CRCs and FECs.   Mirroring ejs's thoughts he tested with and without the Billion PSU plugged in, and saw no difference.  Everything else in the room and adjacent room was powered off anyway.

They're now thinking REIN but nothing's going to happen for a while.  Today's engineer said he's keeping the call and will try to get hold of a REIN tester to do some checks himself.   Is there a different term for continuous interference?   I don't see the sharp drops and rises in SNR that others have shown when suffering from REIN.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: ejs on December 24, 2016, 04:47:06 PM
I don't think you need a different term, REIN can be 100 impulses per second, which would appear as continuous in terms of clocking up CRC/FEC errors, even if you polled the stats every second. I get the occasional odd period with a greatly elevated FEC rate but little change in the SNRM.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on December 29, 2016, 03:28:50 PM
Seems to be a stalemate after that original REIN speculation.   REIN helpdesk have said it's not REIN. All they've managed to find out is that testing at our pole they get errors, and this persists even after swapping pairs between pole and exchange, and swapping port at the exchange.  To me that sounds like an issue between pole and exchange, but engineer's notes are saying either customer equipment or CP server as the underlying issue.  Surely if they're testing at the pole (1/2 mile from the house) it can't be customer equipment causing the errors, and surely A&A's servers can't be causing CRC errors both up and down on the DSL.  Or am I missing something?
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 03, 2017, 03:54:43 PM
A&A now pushing for a "lift and shift",  as opposed to a "TPM" which apparently causes 24 hours or more of downtime.   Not sure why, given "lift and shift" is exactly what the engineer notes said was done on 29th.   I guess it may be just one of the hoops they have to jump through, in the email A&A said they wanted to get us moved onto a different card but he was concerned about downtime.   
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: Black Sheep on January 03, 2017, 07:22:27 PM
A&A now pushing for a "lift and shift",  as opposed to a "TPM" which apparently causes 24 hours or more of downtime.   Not sure why, given "lift and shift" is exactly what the engineer notes said was done on 29th.   I guess it may be just one of the hoops they have to jump through, in the email A&A said they wanted to get us moved onto a different card but he was concerned about downtime.

I don't know why ?? If the 'Lift & Shift' is to a different card in the same FTTC Cab, then the downtime is exactly the same as it would be for a 'Lift & Shift' auto-allocated to the next available port, on the same card.  ::)

The time element only applies to our DCoE advisors, who have to manually go through the available ports and temporarily mark them as 'faulty', up to the point the auto-allocator would only see the next available port as being on a different card.

Even if there were quite a few to be marked as 'faulty' ...... this is a 10 minute job for the guys, and as I say has no bearing on your downtime. The downtime begins when the new port is actually allocated (on whatever card is chosen), as the robotic tools at play start 'Lifting and shifting' your details from the old port to the new one ...... a task that is averaged out at about 20mins.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 04, 2017, 08:53:11 AM
Cheers Black Sheep (and Happy New Year).   The trouble from my point of view is that I'm interpreting 3rd of 4th hand information, what A&A tell me that BTW told them that Openreach said or did, so plenty of scope for me to misunderstand (for example A&A's emails refer to changing card vs changing to different port on the same card, while the case notes refer to TPM vs Lift and Shift).  I do wonder whether our 20CN exchange made be more manual that you're thinking of as well.
Quote from: A&A to me
BT want to put your circuit onto another line card and port but I am just checking with them to make sure they do not disconnect the existing port first, as otherwise you could be completely off line for 24 hours or more.

Quote from: BT (shown in case notes)
Please confirm can I go ahead and place TPM order. But once I will place TPM order, circuit will go down. Please confirm so that i can take action accordingly.  We are not re-arranging the Port to move the customer to different VP. It's with the same VP but customer will move to different port and customer circuit will go down.  Please confirm can I go ahead for TPM or I will raise LL13 for Lift and shift.

Quote from: A&A to me
They are going to just move it to a new new port by way of a lift & shift, minimal down time.

Case notes suggest two working days time scale for this, and it needs engineer at the exchange.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: Black Sheep on January 04, 2017, 10:01:42 AM
Oops, my bad ............ I've been assuming you're talking about FTTC, not ADSL. That'll teach me (again) for not being ar5ed to read the thread fully.

Either way though, whatever the product ............ the timescales are the same for any port change ............ same card or different.

HNY.  :)
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 04, 2017, 11:37:45 AM
Cheers.  So can I ask .. what's the actual difference between a "lift and shift" and a "TPM"?   It sounds like TPM was BT's preferred action, only knocked back because of downtime concerns (whether rightly or wrongly on that count).
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 04, 2017, 11:44:52 AM
Found something on TPM from the Rev's blog, it's from 2010 but I don't think anything's changed on 20CN since well before that time .. The dreaded tie pair modification (http://www.revk.uk/2010/01/dreaded-tie-pair-modification.html)

Quote from: Rev K
"Apparently the process is to disable the existing (and typically mostly working) port immediately and then request an engineer move the service to a new port on the DSLAM (1-3 days) which is configured ready to work. So the line goes off for UP TO THREE DAYS."
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: Black Sheep on January 04, 2017, 12:29:00 PM
All I can speak from is experience. If I am working on a live fault and it requires a TPM/'Lift & Shift' .......... then it is done in the here and now.
I will ring the owning ISP and they will either agree or disagree with my request.

If they agree (which they do 99% of the time), then they will seek a new DSL port on their equipment in the particular Exchange I am working in, and then perform the 'Lift & Shift' ............... it is at this point the downtime begins, and is only exacerbated by the physical time is takes to re-run the connecting wire to the new port on the Main Distribution Frame (MDF) in the Exchange.

Even on a large split-building scenario like Wigan have, this is 90mins at the most. Average probably about 30mins ??.

I can only assume Rev is talking about a pre-ordered TPM ?? By that I mean the service provider booking a slot for a 'Frames (MDF) Engineer' to re-run the wires to the new port that they themselves have allocated. Unfortunately, they are unlikely to get a next-day service as all our work is pre-planned. If I were him, I'd be tempted to ask what date the physical TPM would be carried out by the Frames Engineer, and then have his guys remotely switch the ports on that day, thus keeping downtime to a minimum.

Alas, I don't know what goes on behind the scenes, I just know how long it takes to do the physical side of the work, on average.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 06, 2017, 11:29:55 AM
Well the lift and shift didn't go ahead, the engineer went to the exchange decided or not (or wasn't permitted) to make the port reassignment.  A&A seem to be able to keep things moving, but it still takes an incredible amount of time.  BTW want an onsite appointment, and I can't manage that now until next Thursday.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: Black Sheep on January 06, 2017, 06:24:26 PM
Well the lift and shift didn't go ahead, the engineer went to the exchange decided or not (or wasn't permitted) to make the port reassignment.  A&A seem to be able to keep things moving, but it still takes an incredible amount of time.  BTW want an onsite appointment, and I can't manage that now until next Thursday.

The engineer doesn't make the decision, the ISP hold all the aces.
All we do is ring them, once our tester is connected to their DSL port at the HDU in the Exchange. They will look at current performance and historic performance, and then make a decision whether to carry out a 'L&S' based on that info.

The engineer is nothing but a lap-dog during this procedure.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 06, 2017, 07:30:45 PM
Well I must admit none of this makes sense based on what's visible to me. The notes seem to clearly show BTW suggesting lift and shift, even though it was supposed to have already been done (although they seem to prefer this TPM with it's extended downtime) ..

Quote from: BTW to A&A
"I have checked and can see error seconds present on the circuit.  Please confirm can I go ahead and place TPM order. But once I will place TPM order, circuit will go down. Please confirm so that i can take action accordingly.  We are not re-arranging the Port to move the customer to different VP. It's with the same VP but customer will move to different port and customer circuit will go down.

Please confirm can I go ahead for TPM or I will raise LL13 for Lift and shift."

Quote from: A&A response
"Note please arrange a lift & shift then as extended downtime on a TPM is not acceptable "

Quote from: BTW report
"Engineer completed the job. Notes states that All working ok at the MDF. This circuit has already had a lift and shift completed on the 28/12/16 so by wholesale will not change again. No errors whatsoever. Sync showing 8128 Kbps. Snrm is set to 9db. DCOE are happy that this circuit is working ok at the mdf. Ft2 test passing."

Then they're back to suggesting TPM again ..
Quote from: BTW
"Yes the engineer didn't perform Lift and Shift because the Port was not faulty but i can see the errors are still on the line.  Customer has an active working session for last 18hhs without drops. Please monitor the connection.   If you still want further investigation, we need to book an appointment for the customer or we need to go for TPM order(1 day Lead time)."

It's almost as if in this instance BT Wholesale are making the decisions that you'd expect to come from the ISP.  Maybe a question of ISP scale as to how much direct control they have?
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: Black Sheep on January 06, 2017, 08:26:56 PM
Hmmm ?? I can see how that comes over as confusing ...... I'm not sure myself what's going on now ??
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 07, 2017, 09:31:58 AM
Will just have to see what happens at the next visit.  If that doesn't resolve I might see whether A&A can arrange this "TPM" for Mon/Tue/We the following week, that's when we could best accommodate up to three days downtime.

Meanwhile just to show the irrational nature of the fault, errors dropped to effectively zero at 02:34 this morning.   Only 1 or 2 errors in each hour since.  There have been previous error free episodes in the past, at random times of day and varying between a few minutes and a couple of hours.  I can only assume the original BT test struck one of those periods.  The sudden change doesn't correspond with any apparent change in the noise margin behaviour ..

Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 13, 2017, 09:59:45 AM
REIN case now raised.   The last engineer found the line failing again on insulation and fixed a completely unrelated fault.  However he didn't expect that to fix the errors, nor did it do so.  He thinks it's an electric fence, but we'll see what the REIN guys come up with.   The engineer said he could see the same symptoms on our two neighbours, one he tested directly and the other one by looking up the line on BTW systems.

One think I noted on the DSL Status Check ..

BT Test xDSL Status Check:Pass OK.pass OK. Circuit In Sync
BRAS=3000kb/s FTR=288kb/s MSR=288kb/s ServOpt=1 I/L=A
A DSLAM Override is in place. Service Options will not operate whilst an override is present
Up Sync=448kb/s LoopLoss=30dB SNR=19dB HIGH ErrSec=0 HECErr=0 Cells=21275
Down Sync=4256kb/s LoopLoss=55dB SNR=6dB ErrSec=68 HECErr=0 Cells=46338


Does that mean that DLM won't intervene?   Hope so as in reality even this high error rate doesn't affect use or throughput of the Internet connection, it's only harmful if DLM starts to slow us to a crawl to try and clear it.   Annoyingly they seem to have lost the previous MSR/FTR.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on January 13, 2017, 06:23:28 PM
. . .
A DSLAM Override is in place. Service Options will not operate whilst an override is present
 . . .
Does that mean that DLM won't intervene?

Yes, that is how I interpret the statement.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 14, 2017, 08:14:09 PM
Apparently not, it drops us down to 9dB in the small hours this morning.  I'll be pretty hacked off if it keeps dropping the speed, considering that a main part of OR/BTW's argument is that the error rate doesn't affect usability so they don't have to fix it.  They're right to some extent - the errors don't have too great an effect, but slowing the speed down to a crawl certainly would.   Error rate is completely unchanged dropping to 9dB, pretty much constant 70-75 CRCs per minute.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: tickmike on January 16, 2017, 12:39:21 AM
Yes, that is how I interpret the statement.

Can an ISP get a ' DSLAM Override is in place.' put on ?.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on January 16, 2017, 01:36:24 AM
Can an ISP get a ' DSLAM Override is in place.' put on ?.

I am uncertain. The circuit under discussion is one from the G.992.{1|3|5} series, so the ISP/CP can make a request to BT Wholesale for configuration adjustments.  Whether a "DSLAM Override" is permissible . . .  :shrug2:
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 16, 2017, 09:11:49 AM
Down to 12dB now, error rate completely unchanged at around 70 per minute, 2800 ES per hour.  I'm swithering over whether to over ride at the router, but before I do that I've asked A&A what can be done.   Current speed is below FTR, at least below the FTR that was shown just before the last visit.   BT seem to have reset FTR to 288.

BT Test xDSL Status Check:Pass OK.pass OK. Circuit In Sync
BRAS=2500kb/s FTR=288kb/s MSR=288kb/s ServOpt=1 I/L=A
A DSLAM Override is in place. Service Options will not operate whilst an override is present
Up Sync=448kb/s LoopLoss=30dB SNR=19dB HIGH ErrSec=0 HECErr=0 Cells=22588
Down Sync=3040kb/s LoopLoss=55dB SNR=13dB ErrSec=734 HECErr=0 Cells=49508
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 16, 2017, 10:18:51 AM
I think I need more faith in A&A,  five minutes after I pointed this out to them this morning they've reset things including the IP profile ..

BT Test xDSL Status Check:Pass OK.pass OK. Circuit In Sync
BRAS=3500kb/s FTR=288kb/s MSR=288kb/s ServOpt=1 I/L=A
A DSLAM Override is in place. Service Options will not operate whilst an override is present
Up Sync=448kb/s LoopLoss=30dB SNR=19dB HIGH ErrSec=0 HECErr=0 Cells=20120
Down Sync=4192kb/s LoopLoss=55dB SNR=6dB ErrSec=732 HECErr=0 Cells=31601
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on January 16, 2017, 09:53:27 PM
I think I need more faith in A&A,  five minutes after I pointed this out to them this morning they've reset things including the IP profile ..

  :thumbs:
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 19, 2017, 01:49:55 PM
Openreach REIN guy turned up today.  He had a nifty little hand held tester that made all sorts of noises when he checked around, but what he focussed in on was a click at intervals of round about one second.  That noise, and the CRC errors continued with whole house switched off.  He headed off to look for electric fences, and at the second attempt found one that when switched off removed the noise and the errors.   No CRCs at all shown on my router since the line came up nearly 3 hours ago.   So that's a result.   The only concern is that he's not allowed to tell me the property where the fence was, so I can't check myself if the problem comes back.  Shame because I know my way round an electric fence and I'd be quite happy checking it for the farmer, fixing the earth or insulators etc.

Still, looking good so far.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on January 19, 2017, 03:30:08 PM
Openreach REIN guy turned up today.  He had a nifty little hand held tester . . .

Was that an RF Tester 444B (http://www.kitz.co.uk/adsl/images/BT_444B.jpg), by any chance?

Quote
He headed off to look for electric fences, and at the second attempt found one that when switched off removed the noise and the errors.   No CRCs at all shown on my router since the line came up nearly 3 hours ago.   So that's a result.

Yes, a very good result.

Quote
The only concern is that he's not allowed to tell me the property where the fence was, so I can't check myself if the problem comes back.

If the problem should return, at least you will know for what to go and seek out.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 19, 2017, 04:47:03 PM
That's the tester.   Errors are back though ...
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on January 19, 2017, 05:02:28 PM
Errors are back though ...

  :(  <cat_curses>

Time to formulate a plan which involves all electric fences in the vicinity of your circuit . . .  :-X
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 19, 2017, 06:02:58 PM
I'll see what A&A say, if OR feel they've completed their remit then surely they should be telling me of A&A where they found the issue.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on January 26, 2017, 09:14:06 AM
Still waiting for OR's report.  However I had a quick look around, and there's one fence about a mile from us towards the exchange which runs for several hundred yards alongside the road and therefore right over the 50 pair cable to our pole.   However the fence looks really clean, only one conductor on insulators that all look OK, and I got almost a full reading on the fence tester.  If that fence was shorting I'd expect a low reading, same if the energiser had a poor earth.   The other thing is that this is a mile from our house, and on the main 50 pair.  If that was causing the problem then surely everyone on that cable would be affected.  Our next door neighbour was showing basically no errors at all, although OR said that his circuit was showing a high noise margin target.   I guess I'm finding it hard to believe that there's not something on our line making it vulnerable to interference, after all our error rate was completely unchanged going from 6dB to 12dB, I find it hard to believe the errors would disappear altogether at 15dB.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on January 26, 2017, 06:13:04 PM
I must admit that all the evidence you have discovered does not fit into a "nice" electric-fence pigeon-hole and your comment with respect to other users circuits in the 50 pair cable adds to the mystery.  :-\
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on February 04, 2017, 05:57:14 PM
I've just about persuaded myself that the errors clean up or at least reduce in wet weather.  For example went to zero in an instant around 0400 this morning when it's unlikely that an electric fence would be suddenly switched off.  If this is the case, then assuming I find the offending fence then I guess it's going to be either a poor earth rod (better when it's wet), or possibly a short that gets much worse when wet to the extent it saps all the power to earth somewhere away from the phone line.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: burakkucat on February 04, 2017, 06:22:58 PM
The mystery continues.  :(
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: jack21 on February 05, 2017, 09:38:48 AM
My (then) ADSL line suffered in the same way as your's for many years, with DLM taking corrective action and increasing default SNRM etc. Eventually, purely by chance, I found that a very long electric fence 800m (and in the opposite direction to the exchange and cabinet) was the culprit. The large CRC errors didn't have any noticeable impact on response or throughput, but the DLM actions very much did so!
I did not know the fence owner, and did not feel happy about approaching him about the matter.
In due course, a Plusnet support chap helped enormously, and after several tries of different actions decided to have DLM turned off on my line; that proved very successful, and my line was then able to operate happily for 18 months, even with the CRCs present, until fibre arrived in the village.
The CRC errors were also initially seen on FTTC too, but within 48 hours were neutralised by interleaving and INP, and the problem and symptoms then totally vanished.
Title: Re: BT DSL tester shows no errors, huge error rates from my router
Post by: aesmith on February 08, 2017, 04:15:28 PM
Luckily my router can over-ride the target noise margin, so I'm connecting at the normal speed (a bit over 4meg) even though DLM has done it's worst.  It's a bodge because with this interference I'm sure it's making SNR more variable than it should be.  Also if I have an unrelated fault BT tester is going to be connecting at 15dB target so around 1/2 my speed which may cause some misunderstanding.  I suppose in that case I could do an SNR reset prior to their visit.   The other thing that bugs me is that BT have changed my MSR/FTR from the previous 4000/3200 down to 2848/2278, I assume that's their way of saying the degradation is now official and permanent.