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Author Topic: Weird message from "PSTN test" on two out of three lines  (Read 984 times)

Weaver

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Weird message from "PSTN test" on two out of three lines
« on: March 27, 2017, 10:05:31 PM »

I accidentally hit "PSTN Test" in clueless.aa.net.uk today, and this is what I got for line cwcc@a.1 = BBEU20700042:
Quote
WLR3Test WLR3_CIDT_Test cbs00556dat03:61518000: Pass Line Test OK. Dial tone OK ServiceLevel:2.5, MainFaultLocation:OK, FaultReportAdvised:N, AppointmentRequired:N, LineStability:Unstable, NetworkStability:Stable, StabilityStatement:Unstable - Line may test OK but recent routine tests indicate possible fault. Openreach diagnostic testing has determined the need for an Engineer investigation, where possible test and demonstrate with EU. Routine test & fault data available at Customer Diagnostic Tool on INFORMe under MIS>Artisan>CDT. If no fault is found please close as FNF. If a fault is found close using the appropriate clear code. Do not close as RWT as a possible fault has been detected   cwcc@a

I wonder what this is about, is it real or a red herring? Asked AA what they thought about it, but it's a bit late in the day for any humans to be around. Also there was a similar report for line cwcc@a.4 = BBEU20709519 :
Quote
WLR3Test WLR3_CIDT_Test hws00556dat01:61584563: Pass Line Test OK. Dial tone OK ServiceLevel:2.5, MainFaultLocation:OK, FaultReportAdvised:N, AppointmentRequired:N, LineStability:Unstable, NetworkStability:Stable, StabilityStatement:Unstable - Line may test OK but recent routine tests indicate possible fault. Openreach diagnostic testing has determined the need for an Engineer investigation, where possible test and demonstrate with EU. Routine test & fault data available at Customer Diagnostic Tool on INFORMe under MIS>Artisan>CDT. If no fault is found please close as FNF. If a fault is found close using the appropriate clear code. Do not close as RWT as a possible fault has been detected

The remaining line, cwcc@a.3, showed no weirdness at all. I wondered if it might be moaning about the _intentionally_ low SNRM but then all the lines are the same in that respect.
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aesmith

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #1 on: March 28, 2017, 09:55:35 AM »

What does the Copper Line Test show?   Just wondering if for a DSL only line whether you might get some weirdness if they're testing PSTN function.
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Weaver

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #2 on: March 28, 2017, 11:32:58 AM »

Copper line test is success currently. Just retested it.
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burakkucat

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #3 on: March 28, 2017, 05:51:01 PM »

The second string from the beginning of both reports shows "WLR3_CIDT_Test". So I read it as you have performed Copper Integrated Demand Testing on both circuits.

A very brief synopsis of the Openreach document PHME 62559, dated 2011, is "CIDT is an optional service for CPs which will detect High Resistance (HR) faults and many underlying broadband performance faults."
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Weaver

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #4 on: March 29, 2017, 04:35:49 AM »

What is your opinion of the significance of this?

Andrews and Arnold said in their opinion it was a red herring given the length of the line and the low SNRM. However it is only true for two out of the three lines. Maybe it's simply that they don't have any other tools at their disposal, and there are no significant symptoms apart from very occasional flecks of packet loss which have been seen for months.
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burakkucat

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #5 on: March 29, 2017, 05:32:53 PM »

What is your opinion of the significance of this?

Either the code being executed is defective or this is some "corner case" which rules out those two circuits.

Quote
Andrews and Arnold said in their opinion it was a red herring given the length of the line and the low SNRM. However it is only true for two out of the three lines. Maybe it's simply that they don't have any other tools at their disposal, and there are no significant symptoms apart from very occasional flecks of packet loss which have been seen for months.

All I can go on is that the test output states (having inserted new line characters to aid readability) --

Quote
LineStability:Unstable,
NetworkStability:Stable,
StabilityStatement:Unstable - Line may test OK but recent routine tests indicate possible fault.
Openreach diagnostic testing has determined the need for an Engineer investigation, where possible test and demonstrate with EU.
Routine test & fault data available at Customer Diagnostic Tool on INFORMe under MIS>Artisan>CDT.
If no fault is found please close as FNF.
If a fault is found close using the appropriate clear code.
Do not close as RWT as a possible fault has been detected

Looked at again, we see that it consists of statements based on possibility. To the best of that diagnostic's ability your two circuits appear to be unstable. (However the stable/unstable criteria has not been defined.)

I would probably go with A&A's opinion . . .
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Weaver

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #6 on: March 29, 2017, 07:54:01 PM »

And 'unstable' simply means either (a) too many uncorrected errors, or (b) too many resyncs?

And 'agreed'. I am very much indeed inclined to go with AA's opinion. I am trying to understand BT's robot brain, because understanding might mean less of my wasting AA's time with needless whimpering. This was a purely accidental discovery anyway. I don't believe it's a good idea to be wielding these tools which AA has trustingly made available to the user, after all, they didn't have to, and it's a mark of respect for their customers which I thinks speaks well of their attitude.
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anfield_92

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #7 on: March 29, 2017, 09:02:08 PM »

And 'unstable' simply means either (a) too many uncorrected errors, or (b) too many resyncs?

The copper line test is just that - it does not take into account any data about broadband performance. An unstable line test means that although the line tests ok now, historic data (28 days i think) for that line shows at least one failed test. I think you posted on here recently about a fault on one or more of your lines, so that explains the unstable result (I work for openreach btw).
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Weaver

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #8 on: March 29, 2017, 09:31:36 PM »

A very warm welcome to the forum. Extremely glad to have you here, not just for your expertise.

So do we think it's just a recap on history? Although it doesn't explain why the result is a fail on some of the lines but not on others as no repair work was carried out on the _line_ cwcc@a.4 apart from the good man replacing the front plate which the surly man had broken. And the only reason I asked for that NTE5 to be replaced anyway was a just-in-case after the lightning strike, which had taken out the modem on a different line (all at the one site though) not that line. But perhaps any kind of engineer activity counts in the database, not just mending a line itself, although presumably leaving aside engineer callouts on a wild goose chase.)

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anfield_92

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #9 on: April 01, 2017, 09:15:01 PM »

A very warm welcome to the forum. Extremely glad to have you here, not just for your expertise.

So do we think it's just a recap on history? Although it doesn't explain why the result is a fail on some of the lines but not on others as no repair work was carried out on the _line_ cwcc@a.4 apart from the good man replacing the front plate which the surly man had broken. And the only reason I asked for that NTE5 to be replaced anyway was a just-in-case after the lightning strike, which had taken out the modem on a different line (all at the one site though) not that line. But perhaps any kind of engineer activity counts in the database, not just mending a line itself, although presumably leaving aside engineer callouts on a wild goose chase.)

Thankyou for the warm welcome, I have actually been a member for a while but I am happy to read usually and only contribute if i have something useful to say :)

With regards to your query about one line not being worked on, there are routine line tests automatically carried out overnight regardless of whether a fault has been reported or not and the data is stored for a while, this is used to identify areas of the network that might need attention if for example there are several lines served off the same DP showing a failed line test. I seem to recall that each line is tested around once every two months although I cannot remember where i read this.

I think you posted that the recent line faults you had were battery contact faults, so assuming all of your lines are fed via the same cable then it is likely that they have all have tested faulty at some point regardless of whether you have raised a fault or not so that could explain the unstable test results. It is also not unsual to get red herring results anyway so I wouldnt be concerned as long as you are satisfied the lines are working as they normally should.
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Weaver

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Re: Weird message from "PSTN test" on two out of three lines
« Reply #10 on: April 01, 2017, 10:03:25 PM »

That is really really helpful, and I didn't know about the proactive tests - an excellent idea.

The only real symptoms are occasional very short bursts of packet loss (as reported by loss of PPP LCP echo request test packets sent by CQM servers). And these have got quite a bit better.

Then something that has been going on for so long that it became normal, and I never realised that I had a fault: this is the upstream performance loss of >30%, which recently vanished, and which is discussed in another thread.

My outpouring of welcomes was caused by the fact that your username is marked as 'just arrived'.
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