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[aesmith]

Hi,

When a Max line is reset to learn MSR/FTR over the famous 10 day learning period, does DLM force re-synchs during that time?  If so, are these triggered by any sort of event, like so many hours or something?   I'm wondering whether I can avoid ours re-synching during the night when it's likely to connect at a lower speed.

Thanks,  Tony S

[kitz]

Not that Im aware of. 
The only time it would force a resync is if it decided it needed to adjust your profile to say apply interleaving.
These resyncs were traditionally done overnight, but especially on fttc line they can now happen at practically any time of the day.

[Weaver]

Is this also called the "training phase"? or "SNR reset"? Or am I getting various things mixed up.

[Weaver]

How would I know if something is a "forced resync", as opposed to just a failure of the connection because of too much change in the line conditions for bitswap to be able to cope?

[Weaver]

A few weeks ago I did a "SNR reset" to change downstream target SNRM from 6 dB to 3 dB (21CN ADSL2). It still left the MSR at 2272 - rather lower than the current d/s sync rate (> 2800). The FTR is the usual fraction of the MSR, at ~1800, if memory serves. What is going on here? The truth of the current actual downstream sync is being ignored in setting the MSR, or am I misunderstanding?

[Weaver]

Oh and during this period, 21CN ADSL2, I did get the impression that resyncs were taking place, although I'm not sure how to tell for certain. (Kitz, I hear you.)

[ejs]

Setting the target SNRM on 21CN does not need to start a new 10 day training period, depending on how it is done (although if done that way, the DLM may quickly change things back again).

[Weaver]

@ejs - thanks. So maybe there's a question for the ISP then, if I want to understand properly?

[William Grimsley]

These resyncs were traditionally done overnight, but especially on fttc line they can now happen at practically any time of the day.

This isn't quite correct. Only positive DLM resync's will be made during the day.

[sevenlayermuddle]

I don't think it is unusual for MSR to be lower than typical connection speed. 

When a line is left to itself with no manual resets, any loss of sync is likely to occur at night when interference is highest, hence the subsequent sync speed will also be lower.   If you manually resync in daytime you might get a higher rate, and it might even sustain that rate, but the line parameters (as judged by DLM) when aggregated over 24 hours, may not meet the criteria for 'stable', hence it would not qualify as an 'MSR'.

See also from..

http://www.kitz.co.uk/adsl/maxdsl2.htm

The MSR is set from the lowest achieved rate over this 10 day period rounded down to the nearest 0.5Mb. A notification after this period is sent to the RAP profile and your ISP.

Just my understanding, though I'm a bit rusty on DLM and related topics these days.

[roseway]

These resyncs were traditionally done overnight, but especially on fttc line they can now happen at practically any time of the day.

This isn't quite correct. Only positive DLM resync's will be made during the day.

What makes you believe that?

[William Grimsley]

What makes you believe that?

On FTTC, DLM does not work on the fly. It only makes DLM retrains away from night hours only if it's a positive change. DLM will not intervene negatively on the fly like ADSL.

[ejs]

And what makes you believe that? There's not really much point having DLM if it can't do something when necessary!

[William Grimsley]

And what makes you believe that? There's not really much point having DLM if it can't do something when necessary!

Oh, really? Come on! Like you know, I did some DLM testing when I had my BT Home Hub 5 (Type B) and did nearly 30 line retrains in one day and DLM did not act negatively until the early hours of the next day!

[ejs]

I think the not banding the speed until later may have been overlooked, but with the HH5b, you may not have been able to see all the steps the DLM made.