@ Colin S,
Spot on with your assumption !
We might also suggest that the execrable subcontractor practice of commissioning VDSL services without the vital ability to perform full pair quality and VDSL line tests should be ceased immediately as it must surely contravene the sale of goods and services act.
Were that the case, perhaps Walter's wheelbarrow would not burn quite so much rubber !
Kind regards,
Walter
I wasnt sure what you meant but looking back I assume you mean this
Have I got that right, and am I right in guessing that your point is that even 'bad' lines (that perhaps might have merited activation in a 'stable' profile) are still activated in an open one?
Personally I find it fair that all accounts are provisioned on an open profile. Yes there may be some instability for a few days whilst the DLM kicks in, but at least it gives a long line the opportunity of getting the best speeds it can in the long term. There may be some longer lines which run pretty stable this way. We all know of the used phrase "Give the line up to 10 days to settle in" really means give the DLM chance to find the best level.
Whilst I agree with you on the use of subcontractors, that is a matter separate from the DLM. Even with a BToR install and all his kit, he would not be able to second guess how the variance of SNRm will affect the line over a period of hours, nvm over a longer period. Things could get even more interesting with the advent of self install FTCC, but again a different topic.
What this thread has disclosed is the DLM being able to identify & mark 'very poor' lines. These are fast tracked through the DLM penalties and therefore they should stabilise much quicker.
The reason I agree with the open profile, is the alternative system is much worse. In the early days of Max dsl, how many good lines got stuck at 2Mb and would have sat there forever not able to reach its full potential. That said my favourite DLM of all time is that of Be* Broadband. It had a KISS approach.. but regretfully I fear that even this may be too complicated for non-technical users. It may also have worked fine on adsl2+ but its doubtful whether it would have been quite so straight forward with all the additional vdsl frequency bands, and they too may have had to come up with an alternative dlm if they ever had gone down the vdsl route.