BT DLM Firmware update?

Ok so I'm pretty close to my cab and have healthy stats anyway.

My line doesn't ever drop sync or gets any errors on the line.

So I checked my BBQ monitor today and see a massive blotch of red just at 6am,

I thought odd and checked the stats on my modem and there is been a forced resync at that

time and now my connection is slightly different in that the upload is now connecting at 19999 and download is the same at 79999.

Not a massive issue I know but I thought it was a bit strange so I rebooted the modem a few times now and still the upload is 19999 and the other stats are pretty much the same.



Path 0


Downstream Upstream
Line rate (kbit/s) 79999 19999
CRC errors 0 0
FEC errors 0 0
HEC errors 0 0

The uptime has been on since about half 6 this morning.

Seeing as we don't know what the upload was before, it just looks normal now . But a few reboots of the modem wasn't a good idea. What did you hope to achieve seeing as it's at the maxima?

Firmware update?

I think DLM has just done something to your line. Maybe interleaving, or a banded profile. That's what it does.

The red patch at 6am on your TBBQM could be down to something internal to your isp like a routing issue, or even maintenance work which could possibly cause a loss of service

Edited by tommy45 (Tue 16-Jul-13 15:26:03)

I have recently noticed that my upload sync has changed from 20000 to 19999, down sync is unchanged at 79999. I have also noticed changes in my upload snr, over the last year it has fallen from 22dB to around 15dB, however after the change in upstream sync it is now at 21.5dB. Curiously the upstream attainable rate has not changed much whether the snr was 15 or 22dB.

In reply to a post by RobertoS:

Seeing as we don't know what the upload was before, it just looks normal now . But a few reboots of the modem wasn't a good idea. What did you hope to achieve seeing as it's at the maxima?

The upload was 20000 now it's 19999. Rebooting the modem has ZERO affect on DLM (from what I have experienced), before I moved house I did an experiment and rebooted the modem 35 times in the morning and again in the evening and the DLM did not make a peep. I tried to get the DLM to intervien but it didn't.

In reply to a post by BatBoy:

Firmware update?

I think DLM has just done something to your line. Maybe interleaving, or a banded profile. That's what it does.

The only thing has changed is upload from 20000 to 19999.

In reply to a post by tommy45:

The red patch at 6am on your TBBQM could be down to something internal to your isp like a routing issue, or even maintenance work which could possibly cause a loss of service

I thought that too but there was an event on the sync side of things and doesn't look like a routing issue.

Edited by lockyatlrg (Tue 16-Jul-13 20:39:24)

In reply to a post by TheHorseman:

I have recently noticed that my upload sync has changed from 20000 to 19999, down sync is unchanged at 79999. I have also noticed changes in my upload snr, over the last year it has fallen from 22dB to around 15dB, however after the change in upstream sync it is now at 21.5dB. Curiously the upstream attainable rate has not changed much whether the snr was 15 or 22dB.

Yep I have seen the exact same thing on mine, mine dropped from 24 to 15.5 but no change in attainable rate.

The only times I have seen this kind of "rounding error" difference in the actual sync *change* is when there's been a shift in the bands (ie frequency bands, not speed bands). As the modem radically changes the bit loading, that perhaps isn't a surprise.

So perhaps something has happened to your line to make a big change in the bit loading shape. Have you been keeping the graphed logs?

The SNR change suggests this too, so I wonder if BT have introduced some power changes to your line, maybe with an upstream power backoff mechanism. This is a feature that happens to short lines, to allow longer lines to be heard well.

Or perhaps they've changed the PSD masks.

I do have the before and after, the attainable rate on both of these graphs is roughly the same give or take a few kps.

http://img268.imageshack.us/img268/1900/xig2.png

the dates are on the graph.


And this is one I took a few moments ago.

http://img835.imageshack.us/img835/1420/mn7y.png

0 crc errors, fast path.

stats in sig.

Edited by lockyatlrg (Tue 16-Jul-13 20:49:24)