Is The DLM Algorithm Becoming Less Harsh?

Hi all,

Yesterday, I was doing a lot of testing for the reasons in my FEC thread down in the technical section. I must've done at least 10 resyncs, so I expected today that the line would be banded, but no only the DS SNRM was increased from 3 to 4 dB and G.INP was re-enabled on the US.

I thought I'd share this, as if you're planning some work/testing that may involve resyncing the modem several times, you may not have to be as concerned about the result of the actions now...

Edited by deleted (Thu 07-Sep-17 13:58:23)

We�ve not been told it has changed, no.

I'm not aware that you can be told it has changed, as it stays within the realms of Openreach. It was just something I noticed, so wondered if anyone else had experienced this.

In reply to a post by WilliamGrimsley:

I'm not aware that you can be told it has changed, as it stays within the realms of Openreach. It was just something I noticed, so wondered if anyone else had experienced this.

It might depend on how long the modem was disconnected for.
Or as you only did the tests yesterday , the DLM might do the banding etc later.?
But I do not think that OR give out details relating to the DLM system unless they have to.

DLM would've banded the line 1st if it detected "severe" instability. It wouldn't of done the changes this morning, if it thought it wasn't enough.

In reply to a post by WilliamGrimsley:

DLM would've banded the line 1st if it detected "severe" instability. It wouldn't of done the changes this morning, if it thought it wasn't enough.

So it looks like you are correct in posting that the DLM is less harsh.
Or you just did not have the modem disconnected long enough at each re-sync for DLM to take any action.?
.

Ah, I'm talking only a few minutes at most between power down and power up. I think if it's longer than 15 minutes and/or longer than a 15 minute period DLM monitors, it doesn't count it as a resync. I could've done that, but the testing would've taken a lot longer!

You may just have been lucky. A single instance of DLM not intervening is not proof and as OR have made no announcements then we can't answer the question. We could all of course test it but that might result in a lot of people unhappy if DLM does kick in. So, unless someone has insider knowledge we probably won't know why yours survived the testing unscathed.

Yes, I agree there, Ian. The last thing I want is several people doing what I did, but that if similar actions are necessary, then they may also get away with it. DLM is an interesting topic, just a shame that we can't access the "behind the scenes" workings of it.

In reply to a post by WilliamGrimsley:

I'm not aware that you can be told it has changed, as it stays within the realms of Openreach. It was just something I noticed, so wondered if anyone else had experienced this.

You wouldn�t be told, but I�d like to think I would be told given I work for them and what my job is!