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Unstable DSL connection

Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Unstable DSL connection

Hi Plusnet,
This issue has started Monday evening. I am getting constantly disconnected.
The reason of disconnect is always: "Loss of Signal Quality"
The router is a Asus DSL-N66U and it has been stable for the last months. Now from Monday I cannot even touch the internet connection without triggering a DSL renegotiation.
SNR data is constant. The real problem resides in the number of CRC errors:
adslphxcmd info --show
adslphxcmd: ADSL driver and PHY status
Status Showtime
Channel: Interleave, UpInterleavestream rate = 969 Kbps, DownInterleavestream rate = 16069 Kbps
Link Power State:      L0
Mode:                  ITU G.992.5(ADSL2PLUS)
Channel:                Interleave
Line Status:            Loss of Signal Quality
Training Status:        Showtime
                Down            Up
SNR (dB):      3.0            6.3
Attn (dB):      41.0            12.3
Pwr (dBm):      0.0            10.3
Max(Kbps):      18292          1088
Rate (Kbps):    16069          969
Intl Depth:    96              4
                        G.dmt framing
R:              0              0
S:              0              0
D:              0              0
                        ADSL2 framing
MSGc:          0              0
R:              12              8
S:              0.31            5.89
D:              96              4
                        Counters
RS:            342523456              18133074
RSCorr:        0              49767
RSUnCorr:      56273          0
HEC:            0              29003
OCD:            0              0
LCD:            0              0
Total Cells:    1013348292              32238
Drop Cells:    0              0
Bit Errors:    0              0
ES:            28210          0
SES:            14271          0
UAS:            1198            1198
CRC:            56273          0
FEC:            0              49767
The CRC (56273) counter is getting constantly reseted and the ES and SES numbers are atrocious.
The CRC counter is reseted at 65535 and that is happening every 8-9 seconds.
I had couple of disconnects over night but all of them are starting with:
2014-08-27 04:04:34 [Informational] kernel: Link State: PVC_0 PPPoE down.
2014-08-27 04:04:36 [Informational] kernel: Link State: DSL link down.
Please let me know if I can do something to help. The line seems quiet, no crackling noises or other artifacts.
21 REPLIES
DanHodby
Grafter
Posts: 248
Registered: ‎23-10-2013

Re: Unstable DSL connection

Hi Justinian,
It looks like the connection seems to drop at specific times of day, I've included a graph below.
<img src="http://community.plus.net/visualradius/generated/image14091424732312.png"/>
Is there anything in the property/just outside that seems to come on around these times?
Its worth raising a fault with us so we can take a look into this further Raise a fault  
Cheers,
Dan
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

That graph looks bad. There is nothing around my home which would produce something like this at that particular times or outside the time limits. It is probably happening at that time because I am trying to do traffic on that line and as soon as the CRC counters are going up the modem decides to shutoff the link. The fault is actually producing constantly bad CRC counters continuously during the day.
I will raise a fault, thanks for the quick reply.
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

The raised fault is #90672623
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

Just found another thing happening with the speed of transfers:
100 60.0M  100 60.0M    0    0  1449k      0  0:00:42  0:00:42 --:--:-- 1681k
  % Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 60.0M  100 60.0M    0    0  1486k      0  0:00:41  0:00:41 --:--:-- 1595k
  % Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 60.0M  100 60.0M    0    0  1341k      0  0:00:45  0:00:45 --:--:-- 1008k
  % Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 60.0M  100 60.0M    0    0  1249k      0  0:00:49  0:00:49 --:--:--  983k
  % Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 60.0M  100 60.0M    0    0  632k      0  0:01:37  0:01:37 --:--:--  819k
  % Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 60.0M  100 60.0M    0    0  737k      0  0:01:23  0:01:23 --:--:--  601k
  % Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 60.0M  100 60.0M    0    0  735k      0  0:01:23  0:01:23 --:--:--  859k
  % Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 60.0M  100 60.0M    0    0  840k      0  0:01:13  0:01:13 --:--:--  872k
The last number on every line is showing a progressive depreciation of the speed too during the last 10 minutes I was running the test.
The test is a simple:
while true; do curl http://edgecache902-manchester.se.csp999-998.cdd.bt.net/PT/Random4000x4000.jpg -o /dev/null ;done
which is using the same object used by the wholesale speed test.
redbull2k14
Grafter
Posts: 160
Thanks: 1
Registered: ‎29-01-2014

Re: Unstable DSL connection

there is a new beta firmware update. if you want to try that.
http://www.asus.com/uk/Networking/DSLN66U/HelpDesk_Download/
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

I am aware of a new beta available however the dsl layer was perfectly stable with 10.7.3. I will update the fw when the new bet will become mainstream, so far from the asus forums there seem to be some issues.
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

So far whatever happened yesterday the connection has been more stable however the CRC is still much higher than before.
adslphxcmd info --show
adslphxcmd: ADSL driver and PHY status
Status Showtime
Channel: Interleave, UpInterleavestream rate = 972 Kbps, DownInterleavestream rate = 16314 Kbps
Link Power State:      L0
Mode:                  ITU G.992.5(ADSL2PLUS)
Channel:                Interleave
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):      2.1            6.7
Attn (dB):      41.0            12.3
Pwr (dBm):      0.0            10.3
Max(Kbps):      18556          1080
Rate (Kbps):    16314          972
Intl Depth:    96              4
                        G.dmt framing
R:              0              0
S:              0              0
D:              0              0
                        ADSL2 framing
MSGc:          0              0
R:              12              6
S:              0.30            5.88
D:              96              4
                        Counters
RS:            639610432              33446610
RSCorr:        0              2113
RSUnCorr:      17220          0
HEC:            0              18831
OCD:            0              0
LCD:            0              0
Total Cells:    1892273339              1020337
Drop Cells:    0              0
Bit Errors:    0              0
ES:            214            4
SES:            34              0
UAS:            78              78
CRC:            17220          0
FEC:            0              2113
ES and SES are still unacceptable high.
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

Hi guys, my case is still ongoing, it seems that it will require an engineer visit. In the meantime I am posting the spectrum analyzer results on my line in the hope that this will ease the debug process.
Please let me know if there is anything else I can help with.
Superuser
Superuser
Posts: 12,978
Thanks: 4,275
Fixes: 26
Registered: ‎22-08-2007

Re: Unstable DSL connection

@CRT,
Do we believe those router stats are true and have not been tweaked?  A 41dB attenuated line at 6dB SNRM should deliver 8.6Mbps according to recognised calculators.  The above stats report 16Mbps at 2dB SNRM.  Something looks not quite right here!  Has the DLM's arm been twisted here with a tweaked router, thereby giving rise to an elevated error rate and consequential instability?
What is the DLM's target SNRM for this line?  What is the BTOR estimate for this line?
Kevin
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

The router is not tweaked in any way. I was also wondered the 41db atten and I was trying to work with asus to fix that reading. BT estimate was between 12 and 18 and it is in that area. The line has just passed a 3db test.
Forcing the SNRM to 6 - 9 or even 12 is NOT lowering the error rate in any way.
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

Latest readings adslphxcmd info --show
adslphxcmd: ADSL driver and PHY status
Status Showtime
Channel: Interleave, UpInterleavestream rate = 440 Kbps, DownInterleavestream rate = 12939 Kbps
Link Power State:      L0
Mode:                  ITU G.992.5(ADSL2PLUS)
Channel:                Interleave
Line Status:            Loss of Signal Quality
Training Status:        Showtime
                Down            Up
SNR (dB):      2.7            23.2
Attn (dB):      41.0            12.3
Pwr (dBm):      0.0            11.3
Max(Kbps):      14808          576
Rate (Kbps):    12939          440
Intl Depth:    64              8
                        G.dmt framing
R:              0              0
S:              0              0
D:              0              0
                        ADSL2 framing
MSGc:          0              0
R:              14              8
S:              0.45            4.00
D:              64              8
                        Counters
RS:            468132416              53447152
RSCorr:        0              21197
RSUnCorr:      62021          0
HEC:            0              7264
OCD:            0              0
LCD:            0              0
Total Cells:    1630958408              5317612
Drop Cells:    0              0
Bit Errors:    0              0
ES:            6406            0
SES:            135            0
UAS:            1862            1862
CRC:            62021          0
FEC:            0              21197

The up snrm used to be 7 db before the line has been tested for 24 hours by plusnet or their providers.
A fritz.box router on the same line is showing a attenuation of 30-32 as a linksys one too. The ES and SES error rates are consistent on all routers.
Superuser
Superuser
Posts: 12,978
Thanks: 4,275
Fixes: 26
Registered: ‎22-08-2007

Re: Unstable DSL connection

Hi Justinian,
That is a really useful information - thank you.  The synch speeds are completely in line with a 30dB attenuated line.  That makes the synch speed "sensible".  It does though start to cast doubt over the dependability of the router (and validity of its stats), given what the other two report.
@CRT what stats do the copper tests report - 30dB or 41dB?
Kevin
Justinian
Grafter
Posts: 59
Thanks: 8
Registered: ‎02-07-2013

Re: Unstable DSL connection

The quality of the adsl hardware driver used by asus for this router is a shady one. I cannot open the router without breaking the warranty to know which actually adsl driver chip they are using.
These atten readings have been like this from the start.
Also the software framework they are using is, i think, based on the trendnet one. The software adsl driver is: FwVer:5.4.11.26_A_TC3095 HwVer:T14.F7_0.0 probably not of much help.
Copper initial results atten was 30.
Acassim
Grafter
Posts: 1,075
Thanks: 1
Registered: ‎11-06-2007

Re: Unstable DSL connection

Hi folks,
Just to check on this, is the account you're referencing the one that's linked to your forum login?
Just checking that account it seems you have a fault open and running further tests fails due to an open fault on the phone line so I wasn't able to see stats for some of the tests (including the copper line test) due to this phone fault.