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[razpag]

Walter ...... it wouldn't be you sir if you'd said anything different. I just know you and Eric are gonna join forces and become one. Good luck, but flogging a dead horse springs to mind. 

[roseway]

I'm sorry RP, but you're crossing the line there and making this a personal issue. It isn't as far as I'm concerned, nor do I believe that it's personal for Walter. And we're not involved in any joining of forces, but each expressing our views, based on our individual experiences and knowledge.

If anyone has anything further to contribute I would like to hear it, but this sniping has got to stop.

[HPsauce]

Unless and until we have the complete design of ALL DLMs published (Under suitable patent protection for the investors), we are all blundering around in the dark.

Not necessarily.
We "could" treat the DLM as a "black box" and do some testing, though as noted above just 2 users would prove nothing. It would need a lot of people prepared to "sacrifice" their line speed, probably allied with a fair bit of detective on what sort of exchange equipment and services they are connected to.
Probably impractical. 

[strontium90]

Just to join in the fun , In my case DLM is not working...I had an interruption to my power on Friday due to NIE replacing poles and cutting branches...ip profile now as follows

Download speedachieved during the test was - 1801 Kbps
 For your connection, the acceptable range of speeds is 400-2000 Kbps.
 Additional Information:
 Your DSL Connection Rate :4352 Kbps(DOWN-STREAM), 448 Kbps(UP-STREAM)
 IP Profile for your line is - 2000 Kbps

The intersting thing to note is "acceptable range 400-2000kps" which means I'm on an "up to 2 meg service" rather than 8...each time this happens (ANY disconnection) I have to get BT to reset the profile manually...it really sucks!!!

BTW, does anyone know of the new profile system being implemented nationwide, were after a re-sync your profile immediately goes to 88.2% of your sync speed?

[Oranged]

I don't agree that just 2 users cannot prove this point one way or the other.

A BT IPStream interleaved connection with DLM will operate the same for every user but to be certain the 2 users must have BT as their ISP.

The DLM doesn't differentiate users, so using just 2 examples will, if razpag is correct, prove the point.

LLU DLMs all operate, I believe, in different ways. I think TT and Sky operate 24/7 but O2/BE only operate in the initial few days of a new connection and is then turned off. So it is a pointless exercise trying to compare different LLU users or even comparing LLU to IPStream/WBC.

The other aspect is I thought that BT were making technical changes to the way their DLM functioned in respect of how it manages the recovery after a noise incident.

[strontium90]

The other aspect is I thought that BT were making technical changes to the way their DLM functioned in respect of how it manages the recovery after a noise incident.

Apparently it will be 88.2% of the sync speed but I'm not sure if it's 21CN exchanges only...but someting seems to be going wrong at the moment as the BT forum is full of people with stuck profiles like myself....

On a side note, does anyone know of ANY instance of when DLM rectified target SNR from, say 15dB< to 6dB in ANY timescale as from my experience the whole thing is a lie used to cap EU's bandwidth...Someone really should explain this "complicated algorthim"

[roseway]

On a side note, does anyone know of ANY instance of when DLM rectified target SNR from, say 15dB< to 6dB in ANY timescale as from my experience the whole thing is a lie used to cap EU's bandwidth...Someone really should explain this "complicated algorthim"

My target margin has been up to 15 dB and back down to 6 dB over a period of months without any manual intervention. And I know at least one other member here has also been though it - in his case he deliberately tweaked his target noise margin up to reduce the error rate, and this does seem to have speeded up the process of noise margin reduction.

[strontium90]

My target margin has been up to 15 dB and back down to 6 dB over a period of months without any manual intervention. And I know at least one other member here has also been though it - in his case he deliberately tweaked his target noise margin up to reduce the error rate, and this does seem to have speeded up the process of noise margin reduction.

Thanks for that...so DLM isn't like "the Tooth Fairy"?...however, I have to question if this "period of months" isn't in the interests of capping End-Users through-puts, rather than stability, as the time-scale you refer to is surely a bit draconian?...

Many rural customers (like myself) will struggle to maintain a connection for a period of months as high winds and storms can cause frquent electrical outtages..I do use a netgear to tweak it, but there is something afoot with BTwholesales system for profiles at the minute as it seems beyond co-incidence that so many customers are having stuck profile issues..

[roseway]

I agree that DLM in the form it's taken to date has been too harsh on the user - it does make it feel as though you're being punished for something you haven't done. Whether it was done that way with the deliberate intention to reduce throughput I really can't say.

There does seem to be some adjustment taking place at the moment. DLM on ADSL2+ works a bit differently anyway, and maybe they're updating DLM on ADSL to work the same way.

[waltergmw]

Gentlefolk,

I also concur that something has changed with the line management functions on the BT Wholesale 7 km ADSL (1) 21CN rural line with an average attenuation of about 79 dB that I'm monitoring.
Since the change-over date of 15 March 2011 there have, remarkably, been no power outages. (I know this as the 2Wire clears down the diagnostic data after a power fail or a system soft-reset.)  The line re-synced after change-over from 576 Kbps up to 896 Kbps and then twice on 7 May to 960 Kbps and 5 times on 19 May up to 1056 Kbps and back down to 960 Kbps but has since remained absolutely stable. Given the otherwise stable line it could well be human intervention caused the 19 May multiple resyncs. I am unable to say how much of this is due to the new Infineon line card in the exchange and the Infineon chip in the 2Wire 2700HGV and how much is due to the possibly different line management functions. However I think we can deduce that the synchronisation logic possibly together with monitoring function outputs have changed since the BT line speed tester now reports both up and downstream speeds and IP profiles and the numerical values of the IP Profile steps are different.

Conversely others have reported a deterioration in 21CN ADSL2+ stability.

If one considers all the possible permutations I suggest it will be a significant challenge to define how observations on even a few lines can define precisely how BT's line management functions work.

Please note in this context I have deliberately not used the DLM acronym as some of these observations could be the result of other algorithms. Hence my suggestion that detailed specifications would provide a far more satisfactory solution albeit that is probably wishful thinking.

Kind regards,
Walter

[razpag]

I'm sorry RP, but you're crossing the line there and making this a personal issue. It isn't as far as I'm concerned, nor do I believe that it's personal for Walter. And we're not involved in any joining of forces, but each expressing our views, based on our individual experiences and knowledge.

If anyone has anything further to contribute I would like to hear it, but this sniping has got to stop.

WHAT Hells bells Eric, tad sensitive aren't we ??

How on gods earth am I making it personal ?? You say switching the hub off at night has no effect on speed, I say it does. It's called a difference of opinion, not a personal attack. Just because I posted up "Admit defeat graciously", followed by blatantly obvious emoticons to show it was meant in a jokey fashion, doesn't warrant you suggesting "I've crossed the line".

Likewise the comment about Walter, I genuinely meant that as a moment of mirth and would like to think everbody else reading this thread thought so too ??

You've got it sooo wrong there Eric. I like to post not only informatively, but also as a person would speak in a face-to-face situation. Not - just - posting - like - a - robot - without - any - sense - of - humour. 

[strontium90]

RE: my problems with DLM...just got a resync on my router and see the target SNR is 6dB again...also got an email from one of the mods on their forum that
"occasionally lines can be set outside of DLM control following a difficult fault. It is possible that this was done previously with your connection and left this way."

Does anyone know how often this is the case?

[burakkucat]

Being a academic research scientist earlier in my life taught me many things. (Fortunately I haven't yet forgotten everything. )

From practical experience gained over 45 years (minimum) I have discovered that GPO, BT & now OR Engineering staff are extremely knowledgeable people who, if they have the time to spare, are more than willing to discuss the technology involved in their daily work. (b*cat raises his paw to salute Messrs Razpag, Ezzer & Gumble (His Lordship thereof), to name just a few.)

If it came down to having to decide upon advice provided by an ISP's CS representative versus that provided by an OR employee, the latter would always have higher status. For my particular case -- which is LLU -- both are in agreement. As of yesterday, I started a crude experiment -- I did not power off my DG834Gv5 last night. I intend to leave it alone and just check its vital statistics once per day. Obviously until I complete my rewiring job, my situation is not optimal. (The DG834Gv5 is fed by a RJ11 plug to RJ11 socket extension lead from the ADSL socket on the filtered faceplate at the NTE5A. Oops. ) However I still hope that some information may be forthcoming.

[razpag]

Thank you for vote of confidence B*Cat. But all I try to do is share first hand experience with others, regarding my day-to-day work.

I'm not some sort of deity that knows it all, far from it in fact as somebody pointed out on a REIN thread on this DG, where one of my comments was incorrect.
I will always stand corrected as I'm not (nor is anybody) perfect. I got the REIN situation slightly wrong due to not being trained in that particular area, but am due to be at the end of this month.
But, for this rather emotive subject of switching the router off, I do have knowledge of its effect and this is backed up by every ISP's technical people that I speak with on a daily basis. I don't have reams of paper backing up each individuals router stats taken over a month, nor do I have the circit diagram of the DLM's inner workings. I do however have a Field Log Book detailing umpteen EU visits where the cause of their 'slow-speeds' has indeed been due to switching off ones router. There has not been a single re-visit on these jobs that I am aware of, since making the EU conscious of the need to leave the router powered up 24/7.

Another common thread to these type of jobs is they are usually (but not always for the pedants  ) what we would calss as 'Early Life failures' (ELF's), as the EU will have reported a problem with their circuit within the first month of connection. There are no underlying electrical fault conditions, only the fact they switch their router off every evening.

Columbo I am not, but if it looks like a penguin and it walks like a penguin, then there's a good chance it is a penguin !!  Yes, that's jokingly aimed at you Eric. No hard feelings please, I genuinely wasn't making this a personal thing in any way, it just happened to be your good-self that had the 'other point-of-view', and thats why my postings were mainly addressed to you. 

[roseway]

Thank you RP, we'll shake hands and agree not to come to blows. But I do still disagree with you.