This topic

Is DLM stopping the SNR target dropping?

japage33 — Wed, 28 Jul 2021 19:08:36 GMT

Hi,

I had a problem with my Broadband earlier in the year where the Downstream SNR would slowly decrease over a few days to the point of causing the line to drop and retrain. This was resolved at the end of March 2021 by replacing the modem and removing the noise generating power adaptor that sat next to it. The connection has been rock solid ever since.

Since then the connection has remained fixed at 60,000kbps Downstream and 20,000kbps Upstream. I'm surprised that the target SNR on the Downstream has not dropped below 6dB despite the low error rate (i.e. 25 Errored Seconds and 6 Seriously Errored Seconds in the last 19 days). Back in December 2020, I was getting close to 72,000kbps on the Downstream, so I'd like to see if that is possible again.

Could this be because the line has been banded at 60,000kbps and so DLM sees no need to drop the target SNR? Line stats and results from the BT wholesale broadband checker below.

Line stats

Stats summary

Stats recorded 28 Jul 2021 20:01:17

DSLAM type / SW version:	BDCM:0xc190 (193.144) / v0xc190
Modem/router firmware:  	AnnexA version - A2pv6C038m.d24j
DSL mode:               	VDSL2 Profile 17a
Status:                 	Showtime
Uptime:                 	19 days 2 hours 14 min 2 sec
Resyncs:                	1 (since 08 Jul 2021 12:25:16)
			
				Downstream	Upstream
Line attenuation (dB):  	17.4		0.0
Signal attenuation (dB):	Not available on VDSL2		
Connection speed (kbps):	60000		20000
SNR margin (dB):        	6.5		7.0
Power (dBm):            	12.3		6.9
Interleave depth:       	16		1
INP:                    	48.00		0
G.INP:                  	Enabled		Not enabled
Vectoring status:       	5 (VECT_UNCONFIGURED)		

RSCorr/RS (%):          	0.1271		0.0000
RSUnCorr/RS (%):        	0.0000		0.0000
ES/hour:                	0.40		7.14

Connection stats

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:	0
Last initialization procedure status:	0
Max:	Upstream rate = 21889 Kbps, Downstream rate = 60384 Kbps
Bearer:	0, Upstream rate = 20000 Kbps, Downstream rate = 60000 Kbps
Bearer:	1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State:	L0
Mode:			VDSL2 Annex B
VDSL2 Profile:		Profile 17a
TPS-TC:			PTM Mode(0x0)
Trellis:		U:ON /D:ON
Line Status:		No Defect
Training Status:	Showtime
		Down		Up
SNR (dB):	 6.5		 7.0
Attn(dB):	 17.4		 0.0
Pwr(dBm):	 12.3		 6.9

Since Link time = 19 days 2 hours 15 min 1 sec
FEC:		628331		0
CRC:		315		1889
ES:		25		1501
SES:		6		19
UAS:		0		0
LOS:		0		0
LOF:		0		0
LOM:		0		0

BT wholesale broadband checker

Re: Is DLM stopping the SNR target dropping?

iniltous — Wed, 28 Jul 2021 19:19:32 GMT

Who is your ISP ?

Re: Is DLM stopping the SNR target dropping?

japage33 — Wed, 28 Jul 2021 19:20:50 GMT

BT Broadband

Re: Is DLM stopping the SNR target dropping?

samtheaspie — Wed, 28 Jul 2021 19:37:05 GMT

Im stuck with exactly the same.. I’ve left the router alone 😕 its bloody annoying! Roll on FTTP..

Re: Is DLM stopping the SNR target dropping?

imjolly — Wed, 28 Jul 2021 19:37:38 GMT

According to stats your max attainable is virtually the same as your connection speed of 60mb

Enter your phone number and post results remove number but leave exchange and can number

https://www.broadbandchecker.btwholesale.com/#/ADSL

Re: Is DLM stopping the SNR target dropping?

japage33 — Wed, 28 Jul 2021 19:42:31 GMT

Results from the checker below. Sorry, I thought that I'd included it in my original post, but it got lost somewhere. 😞

The maximum attainable was around 68,000kbps about a month ago. After a power failure it dropped to 60,000kbps again. What's odd is given all of the other stats I don't understand why DLM is not trying to reduce the target SNR.

Re: Is DLM stopping the SNR target dropping?

imjolly — Wed, 28 Jul 2021 19:48:55 GMT

You just need to leave connection and as long as it remains stable then DLM should activate G.INP whi h will reduce noise margin to about 3db and boost connection speed. This is automatic and cannot be activated manually

You are not in a banded profile

Re: Is DLM stopping the SNR target dropping?

japage33 — Wed, 28 Jul 2021 19:53:13 GMT

G.INP is already active on the Downstream.

For future reference, what are the banded speeds on the downstream side? I sometimes get asked this by friends who use me as free tech support.

Re: Is DLM stopping the SNR target dropping?

imjolly — Wed, 28 Jul 2021 20:01:25 GMT

If G.INP was activated then your noise margin would be down about 3db and not current 6db it was probably activated previously but then lost with your previous connection problems just need to be patient

Re: Is DLM stopping the SNR target dropping?

samtheaspie — Wed, 28 Jul 2021 20:06:15 GMT

Are you using a 3rd party router @japage33

Re: Is DLM stopping the SNR target dropping?

licquorice — Wed, 28 Jul 2021 20:12:03 GMT

@imjolly wrote:

If G.INP was activated then your noise margin would be down about 3db and not current 6db it was probably activated previously but then lost with your previous connection problems just need to be patient

G.Inp and 3dB margin are 2 separate mechanisms. G.Inp can be activated without 3dB margin being activated.

Re: Is DLM stopping the SNR target dropping?

licquorice — Wed, 28 Jul 2021 20:29:27 GMT

@japage33 wrote:

G.INP is already active on the Downstream.

For future reference, what are the banded speeds on the downstream side? I sometimes get asked this by friends who use me as free tech support.

Re: Is DLM stopping the SNR target dropping?

japage33 — Wed, 28 Jul 2021 20:30:02 GMT

I'm using a Huawei HG612 modem for the VDSL connection with an OpenWRT router connected to it.

Re: Is DLM stopping the SNR target dropping?

licquorice — Wed, 28 Jul 2021 20:34:50 GMT

Presumably you have 2 lines as your stats are different in your other thread.

Re: Is DLM stopping the SNR target dropping?

japage33 — Wed, 28 Jul 2021 20:36:52 GMT

Thanks for the info.

It's thoroughly frustrating waiting for DLM to do its thing. Is there anything that I can do to speed it up (e.g. request a DLM reset; restart modem on a weekly basis) or is just a case of leave it alone and waiting it out?

Re: Is DLM stopping the SNR target dropping?

licquorice — Wed, 28 Jul 2021 20:44:28 GMT

Definitely do not restart modem, as it will just make DLM think the fault still exists.

Unfortunately, as long as your sync speed is above the handback threshold you can't report a speed fault or get a DLM reset.

Re: Is DLM stopping the SNR target dropping?

japage33 — Wed, 28 Jul 2021 20:46:36 GMT

Yes, at different addresses:

The line in this thread is for my home address.
The line in the other thread is for my parent's address. I'm their tech support. 🙂 The DLM reset on that line has removed the banding and the downstream speed is now 30% higher than it was. Great result!