Interesting, and after so many used to like the no DLM system seems it has maybe arrived at TalkTalk, the trick will be now seeing how it works in practice.

I've (and I suspect others) to be sceptical of descriptions as Chinese whispers play a big part, but the explanation you've had sounds perfectly reasonable.

Sorry for the delay, busy day today.

Here is the link to the TT Community - unlimited broadband (ADSL) page that details the text I copied to my original answer ref DLM;

and my question on there that I asked the community ref DLM is here

Thanks for those two links .

Yes MrSaffron, the explanation I've had does sound perfectly reasonable and is what I've been told here too, so I'm no longer concerned about the SN margin. Now I understand DLM and know that it will take care of any problems that may arise. I was pleased to hear that my line is good, after the problems I've had with it in the past.

RobertoS, very good article. I noticed the SN margin dropped at night and wondered why......you've explained. >>

"On virtually all lines the background noise rises as the sun falls and falls again as the sun rises. This mainly due to the effect the sun has on the radio-reflecting layer of the atmosphere, particularly medium-wave signals. So the noise margin (SNRM) will fall near dusk and not fully recover till well after dawn. Other causes are covered in Miscellaneous Nasties on the Troubleshooting pages"

I asked the TalkTalk CEO >>

Is this TalkTalk's own Dynamic Line Management system, BT Wholesale's or purchased from elsewhere? Answer today >>

"As far as I am aware it is TalkTalks own system and not BTs."

Need to understand total errors seconds. Would someone kindly tell me...

What is the threshold......what is an acceptable level and what is not?

Why are the total errors seconds almost double what they were when I first posted......do they normally fluctuate like this? >>

I copied this this morning:

ADSL (Sync) Summary
System uptime: 85:34:36
Modem ADSL (Sync) uptime: 85:32:51
Interleaving: On
ADSL mode: ADSL2+
ADSL settings: PVC:0/38
ADSL line speed (kbps): up 1136 down 9206
Line attentuation (dB): up 23.8 down 43.0
SN margin (dB): up 6.2 down 2.8
Total errors seconds: 793

Edited by deleted (Wed 30-Nov-16 14:32:05)

In reply to a post by EloiseJane:

I asked the TalkTalk CEO >>

Is this TalkTalk's own Dynamic Line Management system, BT Wholesale's or purchased from elsewhere? Answer today >>

"As far as I am aware it is TalkTalks own system and not BTs."

It could be that your exchange is not TalkTalk LLU'd and/or you are not on MPF, i.e. not fully unbundled.

The proper name is an "errored second". Each errored second is one second-long period where an error has been seen in the bitstream.

That means you can accumulate a maximum of 60 errored seconds per minute.

ES's only ever accumulate, though they'll start at zero after a power cycle.

In BT's DLM, they are the primary statistic that is used to determine, alongside the count of resyncs, whether your line is "low quality". BT allows for different thresholds for DLM intervention, but their least-stringent setting allows for an ES count of 2880 over 24 hours - though that is on FTTC rather than ADSL. ISPs can choose more severe thresholds are 1440 and (I guess) 720 for more stability.

On an old line, I'd get 600-800 per day. On the current line, with G.INP, I get zero.

No idea what TT will have for thresholds.

Honestly you are really really over analysing it.

DLM is there to run 24/7, it never stops running. If the line is unstable and the errors are too high believe me DLM will raise the noise margin automatically and/or increase interleaving as required. It is designed to run permanently and kick in and make adjustments as and when is necessary.

The best thing you can do is just relax and stop monitoring it.

DLM only applies 3db noise margin on very stable lines, hence your line is one of the better ones and you have nothing to worry about. There are plenty of people with 15db noise margins as their line is that bad! To get a 3db noise margin you must have sustained uptime without drop outs and a low error build up over a long period of time.

This is why when you posted here everyone was asking whether you actually had stability issues, as it's hard to believe a line would ever get to a 3db noise margin if it was unstable.

Overall stop worrying it's perfect and have a beer

Thank you very much to all of you for explaining and helping to put my mind at rest.

4M2 - I had been wondering if this was TalkTalk's own DLM or if it had been acquired from elsewhere. Was told yesterday it is their own.

WWWombat - Sorry should have made clearer. I run 2 separate 80 hour (approx) ADSL syncs, which resulted in 2 very different errored seconds rates (see my first post for original stats). I was wondering why the second one had almost doubled and if this normally fluctuated. Errored seconds have now gone back to original rate.

Not heard of G.INP, just been reading about it - you get zero errors with it - I want it, will it be coming to everyone?

ukhardy07 - When you have had the long term loss of broadband connection problem I have had with numerous BT and TalkTalk engineer visits to your home, new parts and equipment over several years and you're not in the know, believe me you are going to analyse a new system and be concerned with errors and when you see the SN margin you were previously told should be at least above 6dB drop below it.

If I don't ask I won't understand and know in future...

The down SN margin has been dropping as low as 0.7 in the last few days, but now I know that this shouldn't concern me with DLM.

As I mentioned earlier I have a curious mind and I need to make an informed decision before I answer this question I was asked by the TalkTalk CEO handling my case yesterday:

"Are you happy for me to close your complaint now with full and final resolution? (concerns are labelled complaints)

Edited by deleted (Thu 01-Dec-16 13:17:11)

I do not know if I agree with DLM, as if often masks a fault.

E.g. when a line drops continuously at 6db noise margin, DLM increases the noise margin to 9db and the speed drops, this consequently reduces the likelihood of the line dropping.

If it carries on dropping, we commonly see the noise margin go to 12db and then even 15db.

With a 15db noise margin you often lose a lot of Mbps, say 5Mbps speed on a short line!

Here, the underlying fault is masked and the user just has far slower broadband, but no engineer callout is required and the customer can use their broadband. Unfortunately customers often just switch ISP when they have a fault, and commonly the new ISP has stricter DLM so the fault appears to be "fixed" when they move, but their speeds are actually slower and the fault is masked. Due to consumers switching rather than reporting faults DLM has become almost necessary.

Also commonly people have very poor internal setups IE a 25m poundland extension cable, and here DLM has to intervene to keep the line stable, whereas really the consumer should be told this cable needs to be binned. The issue is if the consumer used this cable on BT, where DLM was used, and moves to a provider where DLM is not used (as talktalk used to be), they will blame the ISP not their wiring, so every provider ends up using DLM.

Edited by ukhardy07 (Thu 01-Dec-16 13:41:29)