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Training period on moving to 21CN on Value

Community Veteran
Posts: 38,460
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Registered: ‎15-06-2007

Training period on moving to 21CN on Value

I have another thread running on my changeover http://community.plus.net/forum/index.php/topic,87054.16.html but thought it would be useful to split this question out for more general viewing
When you are transferred from 20CN to 21CN (not ADSL2) does the 10 day training period restart
If it restarts does it change the default noise margin back to 6dB or does it carry something over from the old connection (mine has increased from 9dB to 12dB)
During the training period is it better to avoid tweaking the default noise margin.
Effect on IP profile - since changing I no longer have a standard IP profile of 2500kbps but an assured rate IP profile of 2742kbps
24 REPLIES
jojopillo
Grafter
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Registered: ‎16-06-2010

Re: Training period on moving to 21CN on Value

Hi there,
there would be a 10 day training period but  shouldn't reset the SNR. As for tweaking the noise margin we would not recommend that you do this at all. the DLM could do allsorts because of this and if any tweaking took place it could lead to banded profiles and increased noise margins which are much harder to change on 21cn.
Jojo Smiley
Community Veteran
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Re: Training period on moving to 21CN on Value

Jojo,
Can you read my post again.
I am on Value hence ADSL
There are no banded profiles on ADSL even on 21CN
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: ‎18-07-2007

Re: Training period on moving to 21CN on Value

Hi Jim,
It's the same deal with ADSL1 on 21CN so Jojo's advice is spot on - granted there's no banded profiles but there's no doubt playing with the SNR during the training period will lead to profile oddness.
Community Veteran
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Re: Training period on moving to 21CN on Value

Matt,
What was actually said was
Quote
As for tweaking the noise margin we would not recommend that you do this at all. the DLM could do allsorts because of this and if any tweaking took place it could lead to banded profiles and increased noise margins which are much harder to change on 21cn.

I will leave the tweaking until the 10 day period runs out on the assumption that it might sort itself out.
How does the noise margin get carried forward when the line has been moved to a different piece of equipment and surely the start of a new training period should start back at the default settings
Can you comment on the funny IP profile
jojopillo
Grafter
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Registered: ‎16-06-2010

Re: Training period on moving to 21CN on Value

Hi, well, I've no idea where that odd figure come from. Your account shows 2500 and the same 2500 profile with BT
We use an option called modified FTR which carries the DLM line profile across from 20 to 21CN so you get the same snr and interleave status, the aim is to reduce faults because you don't move people from, say, stable 15dB interleave to 6dB fast
Community Veteran
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Re: Training period on moving to 21CN on Value

Thanks,
That clears one point up.
As there were two resyncs in rapid succession at the time of changeover that may have been when the noise margin was increased.
Will the training period dynamically alter the noise margin during the 10 days to find the optimum conditions or will it still use the 3 to 4 weeks at a stable rate before dropping it
Community Veteran
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Re: Training period on moving to 21CN on Value

Are we sure that there is actually a new training period when using "modified FTR" this is my latest stats after over 6 days continuous connection
jojopillo
Grafter
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Re: Training period on moving to 21CN on Value

Hi oldjim,
the modified FTR is carried over so there is no need for a training period. As the training period is used to establish the DLM profile, it is not necessary to define a new one, as your old one was carried over.
Jojo Smiley
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Re: Training period on moving to 21CN on Value

Jojo,
Not wishing to be picky - well yes I am  Grin
Quote
When you are transferred from 20CN to 21CN (not ADSL2) does the 10 day training period restart
Quote
there would be a 10 day training period but  shouldn't reset the SNR
Quote
It's the same deal with ADSL1 on 21CN so Jojo's advice is spot on - granted there's no banded profiles but there's no doubt playing with the SNR during the training period will lead to profile oddness
Quote
the modified FTR is carried over so there is no need for a training period
jojopillo
Grafter
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Registered: ‎16-06-2010

Re: Training period on moving to 21CN on Value

Hi oldjim,
ok, having double-checked I was not quite accurate in my last post. What happens is the line is still monitored during the first ten days but as the DLM profile is carried over there is no expected instability. So in a way, there is a training period but nothing like the initial one we would see with a new install.
Jojo Smiley
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Re: Training period on moving to 21CN on Value

So I assume that the system is such that I won't be able to request a full retrain until the 10 day period is past.
To save you checking my posts in another thread the move to 21CN which involves a change of equipment in the exchange has fixed a long standing problem which numerous fault reports and BT visits failed to identify or fix.
The obvious difference between before and after is in the bit loading values - bits per tone - as shown in this picture - note the change from tones 104 to 200
jojopillo
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Re: Training period on moving to 21CN on Value

Hi oldjim,
Yes, you wouldn't be able to request a reset until the 10 days had elapsed. A request for this would have to be done through the faults process and there is no guarantee it would get done; or if it did and the SNR was to increase, they would not reset it again. That said, we are hoping towards the end of the year to be able to reset this from our end.
Jojo Smiley
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Re: Training period on moving to 21CN on Value

In which case I will wait for the 10 day period to end and then do it myself  Cool
jojopillo
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Re: Training period on moving to 21CN on Value

Definitely the easiest route Smiley