Upgrade to ADSL2+ - How quickly should DLM adapt?

Hi,

Early this morning I was switched from ADSL to ADSL2+ (different ISPs).
There was no problem resetting my router and since 9 am it has been
rock solid with these stats:

ADSL Status
Mode ADSL2+(G.992.5)
State SHOWTIME
Up Speed 1152000
Down Speed 18325000
SNR Margin 6
Loop Att. 27

Shortly before noon I did a BT speed test and got this:

Download speed achieved during the test was - 7298 Kbps
For your connection, the acceptable range of speeds is 1000-7150 Kbps.
Additional Information:
Your DSL Connection Rate :18324 Kbps(DOWN-STREAM), 1152 Kbps(UP-STREAM)
IP Profile for your line is - 7150 Kbps
The throughput of Best Efforts (BE) classes achieved during the test is
- 14.94:21.81:63.25 (SBE:NBE:PBE)

I presume the DLM takes time to adapt so round 5.30 pm I did another BT
speed test and got this:

Download speed achieved during the test was - 7341 Kbps
For your connection, the acceptable range of speeds is 1000-7150 Kbps.
Additional Information:
Your DSL Connection Rate :18324 Kbps(DOWN-STREAM), 1152 Kbps(UP-STREAM)
IP Profile for your line is - 7150 Kbps
The throughput of Best Efforts (BE) classes achieved during the
test is - 14.43:23.34:62.24 (SBE:NBE:PBE)

i.e. no difference in the profile.

Should there not have been at least a little increase in the profile by
now?

How quickly does the DLM usually adapt?

Thanks,

Kit

I use this speed and ping tester.

http://www.speedtest.net/

Regards
David

<090920101755529128%(E-Mail Removed)>, Kit <(E-Mail Removed)> wrote:

>
> ADSL Status
> Mode ADSL2+(G.992.5)
> State SHOWTIME
> Up Speed 1152000
> Down Speed 18325000
> SNR Margin 6
> Loop Att. 27
>
> Shortly before noon I did a BT speed test and got this:
>
> Download speed achieved during the test was - 7298 Kbps
> For your connection, the acceptable range of speeds is 1000-7150 Kbps.
> Additional Information:
> Your DSL Connection Rate :18324 Kbps(DOWN-STREAM), 1152 Kbps(UP-STREAM)
> IP Profile for your line is - 7150 Kbps

When I tested this morning there had been some change.

IP profile is now 16000 Kbps but SNR has zoomed up from 6 to 27 and DSL
connection rate dropped to 6852 Kbps. Loop Att is now 29.

Presumably that at least means that the DLM has started to adapt?

Kit

> IP profile is now 16000 Kbps but SNR has zoomed up from 6 to 27 and DSL
> connection rate dropped to 6852 Kbps. Loop Att is now 29.
>
> Presumably that at least means that the DLM has started to adapt?
>

I think that means 'something' happened which caused your SNR margin to
plummet meaning your router had to resync and you're now where you are. You
should get you router to resync with the exchange but its probably already
too late for your high profile. You'll need to wait for that to go back up
again once you're back at the higher sync speed which should *only* take a
few hours if BT are to believed as its a huge change.

--

WCZ

On Fri, 10 Sep 2010 08:59:34 +0100, Kit wrote:

>IP profile is now 16000 Kbps but SNR has zoomed up from 6 to 27 and DSL
>connection rate dropped to 6852 Kbps. Loop Att is now 29.

The two ends auto negotiate drops in sync rate due to noise but I don't
think they auto negotiate increases. If it was me I'd disconnect and
then reconnect and see if it goes up again. If it keeps dropping I'd be
thinking of regular monitoring to try and see when it drops.


--
Regards - Rodney Pont
The from address exists but is mostly dumped,
please send any emails to the address below
e-mail rpont (at) gmail (dot) com

On Fri, 10 Sep 2010 09:12:56 +0100 (BST), Rodney Pont wrote:

>>IP profile is now 16000 Kbps but SNR has zoomed up from 6 to 27 and DSL
>>connection rate dropped to 6852 Kbps. Loop Att is now 29.
>
>The two ends auto negotiate drops in sync rate due to noise but I don't
>think they auto negotiate increases. If it was me I'd disconnect and
>then reconnect and see if it goes up again. If it keeps dropping I'd be
>thinking of regular monitoring to try and see when it drops.

This explains what happens:
http://www.thinkbroadband.com/files/...nd-legends.pdf

--
Regards - Rodney Pont
The from address exists but is mostly dumped,
please send any emails to the address below
e-mail rpont (at) gmail (dot) com

In article <(E-Mail Removed) t.me.uk>,
Rodney Pont <(E-Mail Removed)> wrote:

> On Fri, 10 Sep 2010 09:12:56 +0100 (BST), Rodney Pont wrote:
>
> >>IP profile is now 16000 Kbps but SNR has zoomed up from 6 to 27 and DSL
> >>connection rate dropped to 6852 Kbps. Loop Att is now 29.
> >
> >The two ends auto negotiate drops in sync rate due to noise but I don't
> >think they auto negotiate increases. If it was me I'd disconnect and
> >then reconnect and see if it goes up again. If it keeps dropping I'd be
> >thinking of regular monitoring to try and see when it drops.
>
> This explains what happens:
> http://www.thinkbroadband.com/files/...nd-legends.pdf

Thanks for this.

The IP profile has now dropped from 16000 Kbps to 5500 Kbps and SNR is
still high (27).

Am I correct in thinking the drop in connection rate from about 18000
Kbps yesterday to about 6600 Kbps today is caused by the huge increase
in SNR from 6 to 27? Is there anything I can do about that?

I looked at the above linked document and to be honest I'm still
confused by all the alphabet soup of initials. For example, I thought
one shouldn't turn off or disconnect the modem/router during the
training period, but in the document it says:
QUOTE
Does my modem automatically retrain to a higher line rate?
No, currently the end user will have to force a retrain by turning the
modem off and back on, or via the GUI to retrain to a higher speed.
UNQUOTE

So doesn't that mean that if I'm now on this low line rate with high
SNR then I'll have to switch off the modem in order to get it to go
back to its initial high rate and low SNR?

Kit

On Fri, 10 Sep 2010 11:37:13 +0100, Graham J wrote:

>The change in SNR margin is a response, not a cause. There was some noise
>event, and the SNR margin was increased in response. Consequently the data
>rate reduced. These two actions together ensure that the connection remains
>stable.

It also possible that the noise caused the SNR margin to fall so it
retrained slower to get the SNR margin back up again. Then the noise
cleared up so the SNR margin rose. You have to resync to raise the
speed and get a lower SNR margin.

--
Regards - Rodney Pont
The from address exists but is mostly dumped,
please send any emails to the address below
e-mail rpont (at) gmail (dot) com

In article <4c8a0a54$0$2501$(E-Mail Removed)>, Graham J
<graham@invalid> wrote:


> The change in SNR margin is a response, not a cause. There was some noise
> event, and the SNR margin was increased in response. Consequently the data
> rate reduced. These two actions together ensure that the connection remains
> stable.

Thanks for this. I guess that to go overnight from SNR of 6 to SNR of
27 the 'noise event' must have been pretty drastic!

> If you reboot the router the new connection may negotiate a lower SNR margin
> and a higher data rate. But the figures will change for the poorer next
> time there is a noise event.
>
> The resolution is to remove the cause of the noise event.

Perhaps I should say that For over a year I had very stable ADSL with
SNR between 6 and 9, Attenuation around 25, connection rate around 8000
Kbps and IP profile of about 7150 Kbps. Yesterday I migrated to
ADSL2+.

I'm using the same modem/router now (in ADSL2+ mode) and nothing else
on my side of the socket has changed. The initial connection rate was
18325 Kbps with SNR 6 and Att 27, but the IP profile remained at 7150
Kbps and those stats remained pretty constant up until I went to bed
last night.

Early his morning the connection rate was 6652 Kbs with SNR 27, Att 30
and IP profile of 16000 Kbps.

Now the connection rate is still 6652 Kbps with SNR 26, Att 27 and IP
profile now down to 5500 Kbps.

> Remove all possible cause of problems with your house wiring by fitting a
> faceplate filter on the master socket, and following all other good
> practises, as described elsewhere in the NG.

The ADSL comes in to a master socket fitted by BT. The only connections
to that socket are the modem/router and one phone (no extensions). All
is exactly the same as it has been for the past year when SNR were
always between 6 and 9. There is no new equipment in my house

> Listen for noise on the line using the BT "quiet line" test, and get any
> noise corrected by your telephony provider.

Just tried that and the line sounds very quiet to me.

FWIW the migration was from entanet ADSL to IDNet ADSL2+. I'm not sure
if you consider either of those to be professional! :-)

Thanks again for your input.

Kit

In article <4c8a1715$0$2539$(E-Mail Removed)>, Graham J
<graham@invalid> wrote:

> The ADSL2+ technology requires a greater available bandwidth, and it may be
> that there is noise in the part of the spectrum that wasn't used by the
> older ADSL system. But it surprises me that such circumstances would reduce
> the speed below what you had previously.

From 9 am (immediately after ADSL2+ activation) until after 9 pm
yesterday the connection was solid with connection rate 18324 Kbps and
SNR 6. Would SNR not have jumped up sooner if the cause was the noise
was in the higher ADSL2+ spectrum?

Thanks again,

Kit