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Author Topic: Line issues  (Read 12783 times)

burakkucat

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Re: Is my line banded?
« Reply #45 on: October 11, 2017, 03:33:46 PM »

Hmm . . . perhaps ignore it for a day or two, then look closely.
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j0hn

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Re: Is my line banded?
« Reply #46 on: October 11, 2017, 05:16:28 PM »

It doesn't look promising. The line appears to still be showing the plummeting snrm prior to each resync.
That's certainly not normal behaviour.

The line also jumped in attenuation by 0.9dB after the last resync. All the waiting in the world won't fix that. The attenuation should not change like that.

edit: Looking further each time the snrm crashes there is 10,000's of CRCs. Fortunately it's only a small amount of ES. However such high error rates and subsequent resyncs may see the line banded in time.
« Last Edit: October 11, 2017, 05:23:58 PM by j0hn »
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WWWombat

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Re: Is my line banded?
« Reply #47 on: October 11, 2017, 05:50:02 PM »

DLM seems to be having some fun with my connection today, had 4 resyncs all "Remote Defect Indicator/DLM" but not sure why  :no:

It seems to me that the majority of people see this reason, and immediately discard the "remote defect indicator" as being a valid cause.

A "Remote Defect Indicator" is a bit in the OH frames sent between modem and DSLAM; if the DSLAM triggers a resync because of an RDI it is because it has seen the RDI bit set to 0 in the incoming OH bitstream from the end-user modem. In turn, the end-user modem chooses to set RDI to 0 when it has detected a flaw in the synchronisation of the incoming bitstream from the DSLAM (labelled officially as a "sever errored frame").

So an RDI becomes a valid possibility when the end-user modem could be receiving a particularly bad bitstream.

It always struck me that, on a line with bad faults or noise, even if only intermittent, an RDI could be a more likely explanation than DLM.

DLM should only be suspected if there is also a significant change to other framing parameters. In older times, that would be just the INP and delay parameters, but now we need to also watch for target SNRM adjustments. It hasn't happened here, so I would discount DLM.

edit: Looking further each time the snrm crashes there is 10,000's of CRCs. Fortunately it's only a small amount of ES.

Something that causes tens of thousands of CRCs in a few seconds would be just the kind of thing that will bring out a "sever errored frame" and a consequent "remote defect indicator".

It doesn't look promising. The line appears to still be showing the plummeting snrm prior to each resync.
That's certainly not normal behaviour.

The line also jumped in attenuation by 0.9dB after the last resync. All the waiting in the world won't fix that. The attenuation should not change like that.

Definitely still something wrong...
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tbailey2

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Re: Is my line banded?
« Reply #48 on: October 11, 2017, 05:59:04 PM »

It always struck me that, on a line with bad faults or noise, even if only intermittent, an RDI could be a more likely explanation than DLM.
The actual response AFAIAA is just 'Remote Defect Indicator' - I added the '/DLM' part back in 2014 when this all first ran on the assumption that the RDI triggered the DLM system to act.

I'll remove it preferred if that isn't what is happening.
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WWWombat

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Re: Is my line banded?
« Reply #49 on: October 11, 2017, 06:18:06 PM »

There certainly looks to be times when it *does* indicate a DLM intervention, so it is probably OK to leave that indication in there. The only thing that has gone wrong is where people assume it only means DLM.

I've often wondered how DLM triggers the resync; forcing an RDI would indeed be one way, but I haven't seen how in a MIB.
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jt999

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Re: Is my line banded?
« Reply #50 on: October 11, 2017, 09:33:22 PM »

You're all far too clever for me  :(

Is there anything I can try to do to help it? Or are we talking another BT visit?
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WWWombat

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Re: Is my line banded?
« Reply #51 on: October 11, 2017, 11:01:04 PM »

I tend to think that if the attenuation is varying, and we've already ruled out internal stuff (wiring, filters, routers) then it is something that can only bend to the call of the copper whisperers.
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burakkucat

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Re: Is my line banded?
« Reply #52 on: October 11, 2017, 11:12:20 PM »

. . . then it is something that can only bend to the call of the copper whisperers.

b*cat approves of that turn of phrase.  :)
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jt999

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Re: Is my line banded?
« Reply #53 on: October 12, 2017, 10:53:11 AM »

To be safe I've switched to my ECI modem from the Huawei one to see if it helps, although it does mean I lose my monitoring so I'll have to hope I catch the outages manually. If I still see them I'll get back onto Zen.

Thanks again for your help everyone! :)
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jt999

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Re: Is my line banded?
« Reply #54 on: October 12, 2017, 11:05:30 PM »

I switched back to my Huawei modem as had a drop on the ECI, but touch wood things are back to normal.

Is it possible DLM was reset and was trying to work out how my line was?
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burakkucat

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Re: Is my line banded?
« Reply #55 on: October 12, 2017, 11:24:06 PM »

Is it possible DLM was reset and was trying to work out how my line was?

That would have been done when the technician concluded his work on the circuit. I very much doubt that you were "blessed" with another "circuit recalc" (to use the Openreach turn of phrase).
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j0hn

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Re: Is my line banded?
« Reply #56 on: October 13, 2017, 06:15:20 AM »

Definitely not.
The attenuation should NEVER change between resyncs like it did. This indicates your problem is not completely fixed. The plummeting snrm confirms this.

Keep the HG612 connected with DslStats uploading to MyDSLWebStats so you can show the ISP of it continues to happen.
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jt999

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Re: Is my line banded?
« Reply #57 on: October 13, 2017, 10:33:26 AM »

OK will do, thanks again.

I seem to have bursts of ES, oddly about the same time as yesterday. Will keep logging for a few weeks to see if there is a pattern  :)
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jt999

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Re: Is my line banded?
« Reply #58 on: October 13, 2017, 12:02:37 PM »

Zen can't find a line fault, and have asked for me to collect stats for longer (which is understandable) to see if this is a pattern - I can probably live with it for a few weeks (I'm away for a week in a week, so that'll help). Will let you know how it goes I guess  :)

They also mentioned this site by name, so that's something cool  ;D
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jt999

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Re: Line issues
« Reply #59 on: October 13, 2017, 05:30:07 PM »

Just tried the quiet line test again, no noises, but it did again cause my DSL to drop and come back fast. I'm just going to move house  :lol:

This time the reason for the drop was:
  4 MIS: CReverb1Misdetection
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