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Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

ExtremeZero
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Registered: 10-05-2016

Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

I seem to have noticed that my download bandwidth on a current line speed of 6.5 Mb on ADSL-Max has taken a drop from the usual 5500-6500kbps range towards the range of 4500-3000kbps just a few/couple of days ago. As a result I am wondering what caused the sudden drop.

 

  Link Information
       
Uptime: 2 days, 13:43:59
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 416 / 4,512
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 11.5 / 19.5
Line Attenuation (Up/Down) [dB]: 18.0 / 32.0
SN Margin (Up/Down) [dB]: 5.0 / 14.0
Vendor ID (Local/Remote): TMMB / P
Loss of Framing (Local/Remote): 13 / 0
Loss of Signal (Local/Remote): 36 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 54 / 0
FEC Errors (Up/Down): 1 / 361,152
CRC Errors (Up/Down): 1 / 950
HEC Errors (Up/Down): 2 / 864

 

Now I have noticed that my FEC Errors are a lot higher then they usually were (Est: 2000-3000 range) and that both CRC/HEC Errors which I barely got have also slightly increased as a result. I am not fully sure but I'm not too keen on the SN Margin being 14.0dB on the download side either. I have no idea what it was previously but considering the results of the errors being displayed, I wouldn't put it past that the decibles may have risen as a result but I may also be wrong and it was always like that to begin with.

Now with that being said. I need to clarify that there is what appears to be work at the side of the phone exchange building on the road which is literally next to the Green BT exchange box. I'm not sure if the work there is related towards the exchange itself or that they are fixing just the road itself but the road has been dug up a bit and is barricaded off. I think the work has been going on for over a week now.

I'm not sure what's going on over there and as a result, can't be too clear if the problem is coming from that or not. I suppose contacting what's going on over there would be a start but I got a feeling that even if I knew what to do to contact them, I doubt I get an answer if it's confidential information.

70 REPLIES
Superuser
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Hi,

You've done a good analysis of the stats.  The slower speed is a consequence of the elevated SNRM, which will have been raised by the DLM to address the error rate.

14dB does imply that there is interference on the line, it should be a multiple of 3dB.  You are going to need to do some step by step tests.

Please perform a quiet line test - dial 17070 select option 2 using a corded phone plugged into the test socket behind the face plate of the master socket. It should be silent. A noisy phone line (or no dial tone) will have a marked adverse impact on the performance of broadband.

If the line is noisy or there is no dial tone, then a PHONE LINE fault needs to be raised with your phone provider. If this is PlusNet, you can report a fault on line using the button below.

 

Also follow the guidance in the speed issues topic - see the link below.

ExtremeZero
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

I did the quiet line test and there didn't seem to be any problem with the line.

 

I actually rechecked my stats again and it appears to have gone back to almost normal.

 

  Link Information
       
Uptime: 0 days, 2:54:55
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 6,784
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 19.5
Line Attenuation (Up/Down) [dB]: 18.0 / 31.0
SN Margin (Up/Down) [dB]: 22.0 / 5.5
Vendor ID (Local/Remote): TMMB / P
Loss of Framing (Local/Remote): 24 / 0
Loss of Signal (Local/Remote): 37 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 67 / 0
FEC Errors (Up/Down): 0 / 16,180
CRC Errors (Up/Down): 0 / 61
HEC Errors (Up/Down):

0 / 56

 

Now I went to the phone exchange to see in more detail whats going on. It's definitely work relating to the Exchange.This is what I found out when seeing it. No idea what's going on though unless you guys know what is happening by the pictures alone.

MLWlbq0

rjB1dxpe09eepH4KoZxyTtzDiWJYtyPvrpK

 

spBsxJq

Superuser
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Interesting!  You look rather rural.  ADLS (not ADSL2/2+) however your speed is still a little slow.

Please use the following links to check the services available and their estimated speeds. From the first link, please record and report back the distance from the exchange. The second link advises of which fibre services (if any) are available on your line and their anticipated speed.

 

Works: It looks as though a FTTC cabinet is being installed outside of the exchange so that FTTC can be provided on what are presently exchange only lines.

ExtremeZero
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Interesting!  You look rather rural

It is rural but it's not far away from the nearest town which is almost less then a mile away.

 

Works: It looks as though a FTTC cabinet is being installed outside of the exchange so that FTTC can be provided on what are presently exchange only lines.

By exchange only lines, you mean lines connected from the exchange towards premises with copper wire  (I.E. FTTC) or just exclusive to the exchange itself.

Exchange: ---- BT Code: -----
Location: ---- ----
Distance:- Direct:    1.84 km
  (appx)* By Road: 1.9 km
  Status  
ADSL enabled: November 7, 2005
DSL Max enabled: March 31, 2006
21CN WBC (ADSL2+) Not available
  21CN due : (PSTN) Info N/A
FTTC Not available
SDSL enabled : Not Enabled
Broadband Access Market Broadband Access Market 1
BT price band BTw Pricing Band Band E
Fixed ADSL:  2048 kbps (2 Mb)
DSL Max:   6500 kbps (6.5 Mb)
ADSL 2+ : Not Available  
FTTC is unavailable in your area.
  Speed Max Min
  DownStream N/A N/A
  UpStream N/A N/A
Fixed: 1Mbps and 2Mbps available
radsl: 512Kbps and 256Kbps available
MAX: ADSL Max is available
TPON: TPON/Fibre not recorded
Check: The check identified another service on your line which may prevent you from ordering a new ADSL connection. Examples are : Existing adsl connection, DACs, LLU, TPON etc

ADSL Products

Downstream Line Rate(Mbps)

Upstream Line Rate(Mbps)

Downstream Range(Mbps)

Availability Date

 

Left in Jumper

ADSL Max Up to 6.5 -- 5.5 to 7.5 Available -- --
Fixed Rate 2 -- -- Available --

--

 

Superuser
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Registered: 22-08-2007

Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

OK everything except the synch speed stacks up.

There is no ADSL2/2+ available on your line.

Attenuation of 31-32dB suggest a line length of 2.2-2.3km which matches the mapping information.

The last synch speed is around 1Mbps slower than that expected for your attenuation (7.7Mbps) that could be down to the interleaving.

I suggest that you keep a watch on the line noise - it can come and go.  You might have an intermittent line fault.  Watch out for the internet dropping when you use the phone and for noise during calls.  If you get drops when using the phone, try changing the filter.  If you get this issue consider buying a good quality new one if you do not have a Mk3 faceplate.  I recently had a friend try 3 filters (two new ones) before BB drop on call start / finish problem was eliminated.

ExtremeZero
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

I suppose if FTTC is actually being installed (If that's what is happening) then ADSL2/2+ is kind of pointless to begin with.

It is possible that it is interleaving as it is on and I do have spare filters to try out. though I haven't experienced any drops when the phone is in use nor noise during calling as well. I rather not disconnect the modem from the master socket too many times considering the Exchange may change the sync speed.

So how would I know that FTTC is avaliable to begin with. I don't have too much confidence on BT sending a notifcation stating such nor do I expect websites to be updated when checking the amount of availability for the exchange.

ExtremeZero
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

I seem to have narrowed down the problem a bit.

Five hours ago the modem router lost connection to the exchange and reconnected and as a result the SN Margin has risen to 11.0.

Uptime: 0 days, 5:54:12
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 4,960
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 19.5
Line Attenuation (Up/Down) [dB]: 18.5 / 32.0
SN Margin (Up/Down) [dB]: 6.0 / 11.0
Vendor ID (Local/Remote): TMMB / P
Loss of Framing (Local/Remote): 16 / 0
Loss of Signal (Local/Remote): 20 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 68 / 0
FEC Errors (Up/Down): 0 / 51,997
CRC Errors (Up/Down): 0 / 420
HEC Errors (Up/Down): 0 / 362

 

Now I disconnected from the line again and reconnected and now the SN margin is back to 5.0. I changed the filter while I was at it but I don't think it holds relevence to what's been going on.

Uptime: 0 days, 0:00:47
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 6,816
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 19.5
Line Attenuation (Up/Down) [dB]: 18.0 / 32.0
SN Margin (Up/Down) [dB]: 21.0 / 5.0
Vendor ID (Local/Remote): TMMB / P
Loss of Framing (Local/Remote): 28 / 0
Loss of Signal (Local/Remote): 23 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 70 / 0
FEC Errors (Up/Down): 0 / 185
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0

 

Again I'm not sure if it's the work being done at the exchange that's possibly been doing this. I don't happen to know when and what days they appear to be working at the exchange but maybe it's at 8:00AM if they disconnect all the lines towards the exchange while working? I'm not sure, it's not really a field I'm knowledgeable in.

Superuser
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Hi,

11dB is not a 'target' SNRM, so it certainly did not 'connect' at that level.  I suspect that at the time of the connection, there was noise present (cause of the disconnect) and the connection happened at a slower speed at 6dB.  By the time you grabbed the stats, the noise had gone and thus the SNRM rose accordingly.

When you next connected, there was no noise and thus at 6dB )normal target) you got a higher synch rate.

If you look at the router log, it should indicate the SNRM and synch speed at the point of connection.  Can you please remind me which router you have?

ExtremeZero
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Well right now I am using the ASUS DSL-N55U Router. I was using the Thompson TG585 v7 till I got another drop with the same result again so I changed to the ASUS in case it was a Router problem which I doubted.

At the very least the Router comes with a spectrum for signal to noise ratio. I did a quick check and then rebooted and did another one after.

Before Reboot

Capture.JPG

After Reboot

Capt2ure.JPG

Modulation : G.Dmt
Annex Mode : Annex A/L
Line State : up
Lan Tx : 163941
Lan Rx : 88174
ADSL Tx : 33241
ADSL Rx : 62833
CRC Down : 0
CRC Up : 0
FEC Down : 0
FEC Up : 1013
HEC Down : 0
HEC Up : 0
SNR Up : 21.0
SNR Down : 2.5
Line Attenuation Up : 16.0
Line Attenuation Down : 37.0
Data Rate Up : 448
Data Rate Down : 7520

So I think I narrowed down to these possiblities.

  1. Work at the Exchange/Cabinet has done something to affect the quality of the phone line, possibly due to recent working of introducing FTTC as you stated townman.
  2. The phone line itself is the one having the problems and the work isn't the cause of it.
Superuser
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Oh I just love graphs and that first one is so pretty!! Cool smiley

The second one (bits per bin) is very much what one would expect: Bell curve on the US, with a gap between US & DS, the DS having a falling bits per bin (and SNRM) as the bin number increases.

The first one is very odd.  The dips are even spaced, which rather implies a harmonic interference someone (like @ejs) might have an informed view on what's happening here - I'm not familiar with that router.  I would suspect that the plotting might be borked - no SNRM below bin 170 (approx.) just does not make sense.  The absence of a gap between US & DS equally does not make sense.

Community Veteran
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

I would concur with the "harmonics" thought. I'd guess some sort of interference was present when that sync occurred, it's certainly strange, especially if there has been work going on at the exchange. Other than that, If it doesn't re-occur, I wouldn't give it much further thought. Just put it down to one of those things.

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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Just a few comments on the observations on the initial stats. The DS SNRM won't always be a multiple of 3dB. It depends when the sync occurred - the uptime suggests it was daytime and that stats were posted well after dark, so there can be an element of interference from MW/AM propagation.

Now the fact that there is work going on at the exchange also suggest the possibility of the line/connection being disturbed and very likely sync was achieved during such disturbance. The only way to get a better idea of what was going on, would be a graceful resync. The 2nd lot of stats imply the connection was disturbed again (hence a resync) but this time back to around normal 6dB Target SNRM.

The more recent data (graphs) suggest there's a lot of interference being generated whilst this work is being done. As long as Quiet Line Tests don't show a bad connection, then as long as the sync and SNRM return to near normal outside of the hours that the work is being carried out, then there's probably little to worry about.

However those last set of stats are not too nice! The increased line attenuation (but that could be a combination of different modem/router and the sync speed), the rather high sync speed and low SNRM suggest the line synced at a moment when there was less than the normal amount of noise (possibly less cross-talk) - hence the higher speed. Now the noise is back to normal, everybody else's lines are now synced - the SNRM has gone down a bit too low for 20CN.

If the connection doesn't actually drop overnight - well even if it does (post the stats first) but then I would do a daytime graceful resync.  Log into the modem/router, and click on the Disconnect button to drop the PPP session if you have one on the Asus. Wait about 30 seconds and then pull the mains plug on it. Stay off-line for about 15 minutes then power it up again, check and post the new stats.

I would always advocate doing "graceful" resyncs/disconnects -  but certainly in the current circumstances where disconnects and errors are/might be occurring as a result of the work, then DLM may not need too much further provocation to raise the Target SNRM.

Hope that helps.

ExtremeZero
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Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

My assumption that the disconnection appears to be done at the exchange & cabinet around 6AM-8AM seems about right now that I've noticed there is a pattern.

May 21 06:22:09 pppd[345]: Serial link appears to be disconnected.
May 21 06:22:14 WAN Connection: Fail to connect with some issues.
May 21 06:22:14 stop_nat_rules: apply the redirect_rules!
May 21 06:22:15 pppd[345]: Connection terminated.
May 21 06:22:15 pppd[345]: Modem hangup
May 21 06:22:19 WAN Connection: Ethernet link down.
May 21 06:22:25 pppd[345]: Connected to 00:aa:bb:01:23:45 via interface eth2.1.1
May 21 06:22:25 pppd[345]: Connect: ppp0 <--> eth2.1.1
May 21 06:22:55 pppd[345]: LCP: timeout sending Config-Requests
May 21 06:22:55 pppd[345]: Connection terminated.
May 21 06:22:55 pppd[345]: Modem hangup
May 21 06:23:05 pppd[345]: Connected to 00:aa:bb:01:23:45 via interface eth2.1.1
May 21 06:23:05 pppd[345]: Connect: ppp0 <--> eth2.1.1
May 21 06:23:35 pppd[345]: LCP: timeout sending Config-Requests
May 21 06:23:35 pppd[345]: Connection terminated.
May 21 06:23:35 pppd[345]: Modem hangup
May 21 06:23:45 pppd[345]: Connected to 00:aa:bb:01:23:45 via interface eth2.1.1
May 21 06:23:45 pppd[345]: Connect: ppp0 <--> eth2.1.1
May 21 06:24:15 pppd[345]: LCP: timeout sending Config-Requests
May 21 06:24:15 pppd[345]: Connection terminated.
May 21 06:24:15 pppd[345]: Modem hangup
May 21 06:24:25 pppd[345]: Connected to 00:aa:bb:01:23:45 via interface eth2.1.1
May 21 06:24:25 pppd[345]: Connect: ppp0 <--> eth2.1.1
May 21 06:24:55 pppd[345]: LCP: timeout sending Config-Requests
May 21 06:24:55 pppd[345]: Connection terminated.
May 21 06:24:56 pppd[345]: Modem hangup
May 21 06:25:06 pppd[345]: Connected to 00:aa:bb:01:23:45 via interface eth2.1.1
May 21 06:25:06 pppd[345]: Connect: ppp0 <--> eth2.1.1
May 21 06:25:36 pppd[345]: LCP: timeout sending Config-Requests
May 21 06:25:36 pppd[345]: Connection terminated.
May 21 06:25:36 pppd[345]: Modem hangup
May 21 06:25:46 pppd[345]: Connected to 00:aa:bb:01:23:45 via interface eth2.1.1
May 21 06:25:46 pppd[345]: Connect: ppp0 <--> eth2.1.1
May 21 06:26:16 pppd[345]: LCP: timeout sending Config-Requests
May 21 06:26:16 pppd[345]: Connection terminated.
May 21 06:26:16 pppd[345]: Modem hangup
May 21 06:26:26 pppd[345]: Connected to 00:aa:bb:01:23:45 via interface eth2.1.1
May 21 06:26:26 pppd[345]: Connect: ppp0 <--> eth2.1.1
May 21 06:26:30 pppd[345]: CHAP authentication succeeded
May 21 06:26:30 pppd[345]: peer from calling number 00:AA:BB:01:23:45 authorized
May 21 06:26:30 pppd[345]: local IP address -----------------
May 21 06:26:30 pppd[345]: remote IP address -------------
May 21 06:26:30 pppd[345]: primary DNS address ---------------
May 21 06:26:30 pppd[345]: secondary DNS address --------------
May 21 06:26:30 start_nat_rules: apply the nat_rules(/tmp/nat_rules_ppp0_eth2.1.1)!
May 21 06:26:30 rc_service: ip-up 1718:notify_rc stop_upnp
May 21 06:26:30 miniupnpd[432]: received signal 15, good-bye
May 21 06:26:30 rc_service: ip-up 1718:notify_rc start_upnp
May 21 06:26:30 miniupnpd[1747]: HTTP listening on port 53239
May 21 06:26:30 miniupnpd[1747]: Listening for NAT-PMP traffic on port 5351
May 21 06:26:31 WAN Connection: WAN was restored.

ADSL Uptime 0 days 15 hours 18 minutes 48 seconds

Modulation : G.Dmt
Annex Mode : Annex A/L
Line State : up
Lan Tx : 6151933
Lan Rx : 3106216
ADSL Tx : 523305
ADSL Rx : 1062335
CRC Down : 26
CRC Up : 637
FEC Down : 35
FEC Up : 58297
HEC Down : 13094
HEC Up : 26
SNR Up : 20.0
SNR Down : 4.0
Line Attenuation Up : 16.0
Line Attenuation Down : 37.5
Data Rate Up : 448
Data Rate Down : 7456

Capture.JPG

 

So I did the 'Graceful' resync as you asked and nothing appears to of changed that much.

ADSL Uptime 0 days 0 hours 2 minutes 33 seconds

Modulation : G.Dmt
Annex Mode : Annex A/L
Line State : up
Lan Tx : 1809
Lan Rx : 1534
ADSL Tx : 399
ADSL Rx : 359
CRC Down : 0
CRC Up : 0
FEC Down : 0
FEC Up : 1505
HEC Down : 0
HEC Up : 0
SNR Up : 21.0
SNR Down : 3.5
Line Attenuation Up : 16.0
Line Attenuation Down : 37.0
Data Rate Up : 448
Data Rate Down : 7456

Capture.JPG

So from what I gathered. It seems the modem reconnected with the exchange after four minutes when it was disconnected at 6:22AM. Now four minutes as work on introducing FTTC dosen't seem right unless they only disconnected the lines once they were sorting something and reconnected them and continued to work from there or something is triggering it automatically and I would have no idea what would cause that.

I suppose the only way to fully know for sure is to check the log during Sunday and Monday. Though I don't know if Morrison Utility Service/BT Openreach work on a Sunday at around 6AM but knowing if they do or not would determine if the issue appears to be related to any work during the issue or it's something else triggering the disconnection at 6AM.

I'm probably thinking ahead way too much but I rather identify the cause to see if it's human activity related with the introducing of the FTTC cabinet or an automated issue.

Superuser
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Registered: 22-08-2007

Re: Phone Line issue. Not sure what's causing the issue that appeared a few days ago.

Looking at the variability of the SNRM figure, I'd be looking for a source of rein.  4 minutes to establish resynch is a bit long.

You might want to look at RouterStats (link below) to establish persistent monitoring.  Works well with the TG routers, not sure about your other one.  See links below.