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Does the DLM always make the right decisions?

JayG
Aspiring Pro
Posts: 884
Thanks: 51
Fixes: 2
Registered: 30-10-2011

Does the DLM always make the right decisions?

After some serious stability problems over winter, my connection has been pretty well behaved all summer, running reliably with interleaving off, target SNRM's 6dB up and down despite there being occasional bursts of noise on the line, usually affecting the upstream more than the downstream.
On Monday of this week, the DLM applied interleaving on the DS, presumably in response to increased noise and errors (connection still quite stable.)
Dropped sync a couple of times yesterday evening, but reconnected with 6dB margins.
Powered everything off overnight, and reconnected as soon as it was light this morning, and found the DS SNRM target had been reduced to 3dB.
Did another graceful disconnect and resync - nope, DS target still 3dB with a correspondingly higher DS connection rate (bad news on my connection.).
My DS SNRM drops at least 2dB at night now the days are shortening, the US SNRM is already all over the place  a million FEC errors in one hour, so there isn't a snowflake's chance this target will prove to be stable after dark (or even before then.)
Current router stats:
Uptime: 0 days, 1:13:13

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 1,227 / 12,541

Data Transferred (Sent/Received) [kB/MB]: 878.03 / 4.89

Output Power (Up/Down) [dBm]: 12.7 / 0.0

Line Attenuation (Up/Down) [dB]: 16.6 / 37.0

SN Margin (Up/Down) [dB]: 5.6 / 3.1

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 0 / 0

Loss of Signal (Local/Remote): 0 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 87 / 0

FEC Errors (Up/Down): 6 / 1,015,257

CRC Errors (Up/Down): 1 / 100

HEC Errors (Up/Down): 1 / 257

It obviously begs the question as to how the DLM can reduce the target SNRM on a line to which it has already recently applied interleaving because it's starting to suffer noise problems.  Undecided
I'll let you know what happens next - I don't intend to resync manually or change anything in the immediate future.
8 REPLIES
Plusnet Staff
Plusnet Staff
Posts: 17,641
Thanks: 535
Fixes: 159
Registered: 05-04-2007

Re: Does the DLM always make the right decisions?

Hi,
Let us know if the line starts to become unstable, we can always set the target SNR up to 6db from here if needed.
If this post resolved your issue please click the 'This fixed my problem' button
 Chris Parr
 Plusnet Staff
JayG
Aspiring Pro
Posts: 884
Thanks: 51
Fixes: 2
Registered: 30-10-2011

Re: Does the DLM always make the right decisions?

Thanks Chris - one unforced resync at tea time on Friday - I think it's fair to say the connection has been hanging on grimly since then:  Roll eyes
Uptime: 1 day, 16:37:45

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 1,230 / 12,293

Data Transferred (Sent/Received) [MB/GB]: 792.94 / 1.64

Output Power (Up/Down) [dBm]: 12.9 / 0.0

Line Attenuation (Up/Down) [dB]: 16.7 / 37.0

SN Margin (Up/Down) [dB]: 4.9 / 3.0

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 9 / 0

Loss of Signal (Local/Remote): 1 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 27,580 / 0

FEC Errors (Up/Down): 831 / 174,054,885

CRC Errors (Up/Down): 186 / 93,551

HEC Errors (Up/Down): 289 / 337,473
Will revisit tomorrow when there are some CRT staff on duty - stats like this with a 3dB DS SNRM target are pretty unsustainable and still begs the question as to why the DLM should have opted to try it.  Undecided
JayG
Aspiring Pro
Posts: 884
Thanks: 51
Fixes: 2
Registered: 30-10-2011

Re: Does the DLM always make the right decisions?

Current router stats:
Uptime: 2 days, 17:05:39

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 1,230 / 12,293

Data Transferred (Sent/Received) [MB/GB]: 804.27 / 1.69

Output Power (Up/Down) [dBm]: 12.9 / 0.0

Line Attenuation (Up/Down) [dB]: 16.7 / 37.0

SN Margin (Up/Down) [dB]: 5.4 / 3.4

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 9 / 0

Loss of Signal (Local/Remote): 1 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 59,528 / 0

FEC Errors (Up/Down): 1,225 / 341,210,419

CRC Errors (Up/Down): 256 / 302,113

HEC Errors (Up/Down): 418 / 1,464,644
+ +
So, still hanging on by the skin of its teeth, with overnight SNR down to 1.2dB.
Would Chris or someone else from CRT change the DS SNRM target to 6dB please?
Will this be a fixed or minimum target?
Plusnet Help Team
Plusnet Help Team
Posts: 519
Thanks: 51
Fixes: 18
Registered: 02-03-2015

Re: Does the DLM always make the right decisions?

Hi, I have reset the SNR top a 6db profile and this take effect shortly for you
If this post resolved your issue please click the 'This fixed my problem' button
 Ben Babinski
 Plusnet Help Team
JayG
Aspiring Pro
Posts: 884
Thanks: 51
Fixes: 2
Registered: 30-10-2011

Re: Does the DLM always make the right decisions?

Thanks Ben - just hope the DLM regards it as a slap on the wrist and keeps its interfering mitts in its pocket from now on... Wink

New DSL stats after reset SNRM target:

Uptime: 0 days, 0:06:36

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 1,235 / 11,005

Data Transferred (Sent/Received) [MB/GB]: 807.22 / 1.72

Output Power (Up/Down) [dBm]: 12.8 / 0.0

Line Attenuation (Up/Down) [dB]: 16.7 / 37.0

SN Margin (Up/Down) [dB]: 6.0 / 6.3

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 26 / 0

Loss of Signal (Local/Remote): 3 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 60,056 / 0

FEC Errors (Up/Down): 0 / 4,444

CRC Errors (Up/Down): 0 / 0

HEC Errors (Up/Down): 0 / 0
Plusnet Help Team
Plusnet Help Team
Posts: 519
Thanks: 51
Fixes: 18
Registered: 02-03-2015

Re: Does the DLM always make the right decisions?

Hahaha no problems, just keep us up to date if you need any further assistance and we'll be more than happy to help.  Cool
If this post resolved your issue please click the 'This fixed my problem' button
 Ben Babinski
 Plusnet Help Team
jem16
Grafter
Posts: 874
Registered: 27-10-2014

Re: Does the DLM always make the right decisions?

Quote from: JayG
Thanks Ben - just hope the DLM regards it as a slap on the wrist and keeps its interfering mitts in its pocket from now on... Wink

BT's DLM seems to have a mind of its own which doesn't necessarily follow reason in my experience.
JayG
Aspiring Pro
Posts: 884
Thanks: 51
Fixes: 2
Registered: 30-10-2011

Re: Does the DLM always make the right decisions?


Quote from: JayG
Thanks Ben - just hope the DLM regards it as a slap on the wrist and keeps its interfering mitts in its pocket from now on... Wink

In the event DLM only managed to restrain itself for about 2 hours, resynching soon after with a DS SNRM target of 9db.  Sad
Couple of evening and overnight drops since then, but I resynched and rebooted manually yesterday morning to reset the stats and try to get a DS rate of above rather than below 10Mbps.
Obviously not happy that a connection which behaved itself all spring and summer with a 6dB DS target and no interleaving now has interleaving and a 9dB target, but at least I can understand the logic of the DLM's actions this time, and up to now the connection seems to be generating few errors.
I fear a repeat of last winter's erratic behaviour, which started around this time (hopefully not - time will tell no doubt.)

Current DSL stats:

Uptime: 1 day, 0:04:49

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 1,227 / 10,049

Data Transferred (Sent/Received) [MB/MB]: 10.28 / 86.87

Output Power (Up/Down) [dBm]: 12.9 / 0.0

Line Attenuation (Up/Down) [dB]: 16.6 / 37.0

SN Margin (Up/Down) [dB]: 5.6 / 8.4

System Vendor ID (Local/Remote): TMMB / ----

Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 0 / 0

Loss of Signal (Local/Remote): 0 / 0

Loss of Power (Local/Remote): 0 / 0

Loss of Link (Remote): -

Error Seconds (Local/Remote): 102 / 0

FEC Errors (Up/Down): 423 / 163,682

CRC Errors (Up/Down): 104 / 142

HEC Errors (Up/Down): 150 / 1,156