Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Pages: 1 2 3 [4] 5 6 ... 8

Author Topic: ADSL2 line problems  (Read 6387 times)

g3uiss

  • Reg Member
  • ***
  • Posts: 322
  • You never too old to learn
    • Midas Solutions
Re: ADSL2 line problems
« Reply #45 on: June 22, 2018, 08:36:40 AM »


What we currently do not know is whether the DP is aerial or underground. With an aerial DP, I would be very surprised for any significant quantity of water to accumulate . . . even more so for such water to fortuitously submerge the end of a cable sheath, thus setting up a "wet cable". However if it is an underground DP, whose closure was defective at some time in the past, then there is a distinct possibility of significant water ingress.

I wonder if Black Sheep has had any experience of such a fault or knows of an occurrence?
Underground DP and al cable all the way to the cab.

Another DLM at 0530 no significant changes except SNR reduced from 9.1 to 8.5. The only thing I hadnít seen before just before the re sync the DS SNRM dropped to below zero.  I recon this was on the DSL stats sample before the Re Sync.

Iíve just up loaded the stats to my web address. Very few errors I can see in this period

Tony
« Last Edit: June 22, 2018, 09:06:54 AM by g3uiss »
Logged
Zen FTTC and Plusnet ADSL HG612 modems with Vigor 2925

parkdale

  • Reg Member
  • ***
  • Posts: 272
Re: ADSL2 line problems
« Reply #46 on: June 22, 2018, 10:13:28 AM »

Looking at this post reminded me my dad had similar problem with Rodent damage to the underground cable feeding his circuit, BTOR had to replace the lot.....
Yes every time it rained errors went through the roof..
Logged

g3uiss

  • Reg Member
  • ***
  • Posts: 322
  • You never too old to learn
    • Midas Solutions
Re: ADSL2 line problems
« Reply #47 on: June 22, 2018, 10:26:22 AM »

Interesting thought. Is the DLM more sensitive following a fault rectification?

The so called training period ?

Iím not sure where to press the ISP as the current speed is acceptable and I wouldnít know about the re syncs if I didnít monitor the line :)
Logged
Zen FTTC and Plusnet ADSL HG612 modems with Vigor 2925

Black Sheep

  • Helpful
  • Kitizen
  • *
  • Posts: 4941
Re: ADSL2 line problems
« Reply #48 on: June 22, 2018, 12:16:15 PM »

I am aware that a "wet cable" can be seen by TDR but have never had any experience of such a situation. I have always assumed that it is water inside the outer sheath, water penetration as a result of protective sheath damage, that gives rise to the effect. Unfortunately payment is required to download a copy of the PDF file.

What we currently do not know is whether the DP is aerial or underground. With an aerial DP, I would be very surprised for any significant quantity of water to accumulate . . . even more so for such water to fortuitously submerge the end of a cable sheath, thus setting up a "wet cable". However if it is an underground DP, whose closure was defective at some time in the past, then there is a distinct possibility of significant water ingress.

I wonder if Black Sheep has had any experience of such a fault or knows of an occurrence?

Kitz PM'd me about this last night, and I have replied this morning stating how I'm as perplexed as yourselves with the missing tones ??
I did ask the question (as I had to speed-read the thread and wasn't 100% certain), if the OP was on an LLU service provider .... if so, then TAMS will play a part in the circuits make-up and may be a potential culprit ??

But, I have never witnessed graphs like that on either REIN or actual line faults  ???
« Last Edit: June 24, 2018, 11:48:59 PM by kitz »
Logged

g3uiss

  • Reg Member
  • ***
  • Posts: 322
  • You never too old to learn
    • Midas Solutions
Re: ADSL2 line problems
« Reply #49 on: June 22, 2018, 01:23:18 PM »

No Iím not on a LLU. May I ask what TAMS is. Not seen a reference to that before

Tony
Logged
Zen FTTC and Plusnet ADSL HG612 modems with Vigor 2925

Black Sheep

  • Helpful
  • Kitizen
  • *
  • Posts: 4941
Re: ADSL2 line problems
« Reply #50 on: June 22, 2018, 02:43:54 PM »

I thought I'd seen Talk-Talk mentioned ?? Like I say, I don't have the time read threads fully these days.

TAMS = Test Access Matrix System

A functionality that allows Openreach to test non-BT circuits.
Logged

g3uiss

  • Reg Member
  • ***
  • Posts: 322
  • You never too old to learn
    • Midas Solutions
Re: ADSL2 line problems
« Reply #51 on: June 22, 2018, 05:04:52 PM »

Thanks for that explanation. Iím pretty sure this plot has looked like that for some time, but couldnít say how long. I never took much notice of these stats until problems started in February. Is hardware ie modem a possible problem ?

Also itís not been power cycled for a long time but many re syncs since it was last. I havenít got a modem to try that has a Broadcom chipset to compare.

Error rate seems to have fallen dramatically over last 24 hours.

Current average ES is 17/hour.

Tony

Logged
Zen FTTC and Plusnet ADSL HG612 modems with Vigor 2925

kitz

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 31975
  • Trinity: Most guys do.
    • http://www.kitz.co.uk
Re: ADSL2 line problems
« Reply #52 on: June 22, 2018, 07:37:39 PM »

I need to do a longer reply.  Started last night but hands are bad today.

Thanks BS for the comments. 

Quote
I havenít got a modem to try that has a Broadcom chipset to compare.

I'll PM you.
Logged
Please do not PM me with queries for broadband help as I may not be able to respond.
-----
How to get your router line stats :: ADSL Exchange Checker

g3uiss

  • Reg Member
  • ***
  • Posts: 322
  • You never too old to learn
    • Midas Solutions
Re: ADSL2 line problems
« Reply #53 on: June 23, 2018, 11:30:02 AM »

1st night DLM left me alone Horray !
Logged
Zen FTTC and Plusnet ADSL HG612 modems with Vigor 2925

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 26175
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: ADSL2 line problems
« Reply #54 on: June 23, 2018, 06:08:50 PM »

Underground DP and al cable all the way to the cab.

Thank you for clarifying things.

With an underground DP and aluminium cabling there is the potential for mayhem following water ingress.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

g3uiss

  • Reg Member
  • ***
  • Posts: 322
  • You never too old to learn
    • Midas Solutions
Re: ADSL2 line problems
« Reply #55 on: June 23, 2018, 07:08:07 PM »

Thanks for that comment. Would those potential faults not show on the normal line tests done by ISP/OR, or cause a noisy line at my end 17070(2) .

It really follows, the Water problem cured a phone fault which started as intermittent, then one leg went. After that was fixed, the ADSL has been very erratic.

How do I get ISP/OR to look into that, any suggestions ?

Tony
« Last Edit: June 23, 2018, 07:10:28 PM by g3uiss »
Logged
Zen FTTC and Plusnet ADSL HG612 modems with Vigor 2925

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 26175
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: ADSL2 line problems
« Reply #56 on: June 23, 2018, 09:37:06 PM »

Would those potential faults not show on the normal line tests done by ISP/OR, or cause a noisy line at my end 17070(2) .

Yes, I would expect some sort of anomalous result to be obtained. 

Quote
It really follows, the Water problem cured a phone fault which started as intermittent, then one leg went. After that was fixed, the ADSL has been very erratic.

You really need someone like Black Sheep to be tasked with checking the circuit.

Quote
How do I get ISP/OR to look into that, any suggestions ?

The only suggestion I can make is persistence . . . Don't let your CP/ISP close the fault report.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

g3uiss

  • Reg Member
  • ***
  • Posts: 322
  • You never too old to learn
    • Midas Solutions
Re: ADSL2 line problems
« Reply #57 on: June 23, 2018, 09:44:28 PM »

Thanks @burakkucat. I think from BS earlier posts heís some what short of time. Iím doing my best to keep the fault open.

Itís odd because the DLM is acting to reduce speed by raeducing the SNRM but the errors are well below what I believing should trigger that. The only issue is the ISP  recons they reset line on the 15th so Iím in the 10 training period.

At the moment Iím syncing below their MGALS.

I think sometimes they are not happy with comments from users with some degree of Tecnical knowledge.

Tony
« Last Edit: June 23, 2018, 10:56:40 PM by g3uiss »
Logged
Zen FTTC and Plusnet ADSL HG612 modems with Vigor 2925

kitz

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 31975
  • Trinity: Most guys do.
    • http://www.kitz.co.uk
Re: ADSL2 line problems
« Reply #58 on: June 24, 2018, 12:29:19 AM »

I strongly suspect its the number of LOFs which is upsetting the DLM, not the Err Secs..  which may also explain why its increasing the TNM rather than INP.

This is the reply I started the other night but didn't finish.   I'm mega busy for the next few days and then I go AWOL for a while so I may as well post it now.

----------


It's looking like the LOFs can cause DLM action.  But we have to be a bit careful if deciding whether an LOF could count towards DLM as you'd need to take note of the last retrain reason
According to your stats  "Retrain Reason:   1" which we generally take to indicate that the resync was caused by DLM  - see here here RDI detector code linky

This sparks a few other questions, the main ones being
Is DLM using RDI codes for calculation of MBTR or ignoring any RDIs?
Do Line tests cause an RDI?

We may also have to be careful when distinguishing between retrain reason = 1 being an RDI and the RDI indicator mentioned in the ITU specification
RDI's only occur when an LOF is initiated at the DSLAM without a SEF defect.


LOF between the modem and DSLAM direction are highly likely to be counted towards MBTR.
Linestats show SFErrors but don't record what could be SEFs so we may not always know which downstream LOFs are being counted by DLM
   


From ITU G.992.1

Quote

D.2.1 LOF-rs: Loss of ADSL frame synch/resync event. This event occurs when some algorithm,
which may be vendor-specific, determines that a resync attempt is required. Note that this LOF-rs
event is probably (but not required to be) related to the SEF (severely errored frame) defect defined
for operations and maintenance (see 9.3).

So now lets look up the relevant sections relating to SEFs which trigger a LOF

Quote
9.3.1.3  ADSL line related near-end defects  [path from the modem to DSLAM]
Severely errored frame (SEF) defect: An SEF defect occurs when the content of two
consecutively received ADSL synchronization symbols does not correlate with the expected
content over a subset of the tones. An SEF defect terminates when the content of two
consecutively received ADSL synchronization symbols correlate with the expected contents
over the same subset. The correlation method, the selected subset of tones, and the threshold
for declaring these defect conditions are implementation discretionary.

9.3.1.4 ADSL line related far-end defects [path from DSLAM to modem]
Far-end Remote defect indication (RDI): An RDI defect is an SEF defect detected at the
far-end and is reported once per superframe by the RDI indicator. The RDI indicator
(see 7.4.1.1) shall be coded "1" to indicate that no SEF defect is present in the previous
superframe and shall be coded "0" to indicate that an SEF defect is present in the previous
superframe. An RDI defect occurs when a received RDI indicator is set to "0". An RDI
defect terminates when a received RDI indicator is set to "1".

Logged
Please do not PM me with queries for broadband help as I may not be able to respond.
-----
How to get your router line stats :: ADSL Exchange Checker

ejs

  • Kitizen
  • ****
  • Posts: 1938
Re: ADSL2 line problems
« Reply #59 on: June 24, 2018, 06:16:01 AM »

It is completely normal to see LOS and LOF counts like that every time the ADSL drops and reconnects (retrains). It seems the ADSL is dropping a lot.

Note that "resync" in the ITU documents does not mean what we usually call a resync.

I think sometimes it does not help to get bogged down in minute details of stats while losing sight of whatever the actual symptoms of the problem are.
Logged
Pages: 1 2 3 [4] 5 6 ... 8