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[Weaver]

At 0905 Line 3 went down and stayed down. In the early afternoon, I belatedly noticed an automatic (KCI - Keeping Customer Informed) alert email from my ISP AA telling me that it had gone down and not come back up, so I asked AA to look into it. When they ran their usual remote diagnostics, it somehow kicked the thing back into life. No-one knows how it came about.

So all’s well. Unfortunately not quite, as it’s now about 200kbps slower than before, and for the life of me I just can’t see why. I can’t see anything obvious in the stats and unfortunately I don’t have a recent stats’ snapshot for comparison. (Although I can post say line 1 stats instead.)

Can you see anything odd?

— Current line 3 stats now, after slight slowdown :
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:   20
Last initialization procedure status:   0
Max:   Upstream rate = 312 Kbps, Downstream rate = 3068 Kbps
Bearer:   0, Upstream rate = 392 Kbps, Downstream rate = 2776 Kbps

Link Power State:   L0
Mode:         ADSL2 Annex A
TPS-TC:         ATM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    2.7       6.0
Attn(dB):    65.0       40.2
Pwr(dBm):    17.3       12.4

         ADSL2 framing
         Bearer 0
MSGc:      54      11
B:      18      5
M:      8      16
T:      5      8
R:      16      16
S:      1.7231      7.6581
L:      780      117
D:      1      4

         Counters
         Bearer 0
SF:      1422199      389461
SFErr:      17      3
RS:      53332491      3476147
RSCorr:      7107      486
RSUnCorr:   92      0

ReXmt:      913      0
ReXmtCorr:   893      0
ReXmtUnCorr:   92      0

         Bearer 0
HEC:      112      5
OCD:      5      0
LCD:      5      0
Total Cells:   151343222      21407230
Data Cells:   9280931      1523754
Drop Cells:   0
Bit Errors:   3444      494

ES:      198489      238
SES:      4213      2
UAS:      44777      42155
AS:      23115

         Bearer 0
INP:      29.00      2.00
INPRein:   0.00      0.00
delay:      8      8
PER:      16.15      16.27
OR:      29.71      8.35
AgR:      2793.37   399.58

Bitswap:   6589/6589      280/280

Total time = 57 days 7 hours 39 min 18 sec
FEC:      21769337      82964
CRC:      610077      277
ES:      198489      238
SES:      4213      2
UAS:      44777      42155
LOS:      274      0
LOF:      682      0
LOM:      139      0
Latest 15 minutes time = 9 min 18 sec
FEC:      277      1
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 15 minutes time = 15 min 0 sec
FEC:      1307      9
CRC:      2      0
ES:      2      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Latest 1 day time = 7 hours 39 min 18 sec
FEC:      7107      486
CRC:      17      3
ES:      10      2
SES:      0      0
UAS:      4443      4443
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 1 day time = 24 hours 0 sec
FEC:      0      0
CRC:      0      0
ES:      15      5
SES:      11      2
UAS:      19828      19828
LOS:      0      0
LOF:      9      0
LOM:      8      0
Since Link time = 6 hours 25 min 15 sec
FEC:      7107      486
CRC:      17      3
ES:      10      2
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0

[burakkucat]

No, I can't see anything obvious. 

I would, however, be tempted to power off the relevant modem for a 30 minute rest . . .

[Weaver]

It happened again. Down for x hours until I noticed and then when I ran an AA remote ‘copper line test’ that fixed it, brought the link back up. AA staff are not seeing anything obvious.

How do these BT OR remote tests manage to wake things up again?

[burakkucat]

How do these BT OR remote tests manage to wake things up again?

To be able to answer the question we would need to know exactly how those tests operate.

[Weaver]

Our good friend might know? I’m guessing that there must be hardware in the exchange (or an FTTC cab?) that is remote controlled and can inject test signals into the line and get results back. Like a cheapo mini-JDSU ?

[Alex Atkin UK]

Still trying to get my head around how my deafeningly crackly line passed the automated tests when the engineers equipment immediately saw the fault.  Though granted, it had gotten a lot worse to the point of not being able to maintain dial tone at that point.

[Weaver]

Good point. We just don’t know how the remote tests work and what their capabilities are.

[burakkucat]

Our good friend might know? I’m guessing that there must be hardware in the exchange (or an FTTC cab?) that is remote controlled and can inject test signals into the line and get results back. Like a cheapo mini-JDSU ?

A "test-head", yes. There are such items located at an exchange.

[Weaver]

See https://forum.kitz.co.uk/index.php/topic,25659.msg431373.html#msg431373

[Weaver]

Line 3 has now, yes you guessed it, gone bad again: downstream sync rate crashed to 160k due to DLM pushing SNRM up to a crazy amount. Emailed A & A too late on friday afternoon and so missed the whole weekend :-(

Once again, when this gets fixed, by an OR engineer call-out or however, we won’t know how it gets fixed, that’s my bet.

[Weaver]

AA looking into it now, talking to BTW.

Noticed this in the AA log: "Note Intermittent sync and below sync rate for download rate, repeat issue caused by overhead cabling damaged by wind"

I didn’t know that, must have missed it.

It also says: "escalation" and "review" and something like "repeat fault", which is very true - so good for them.

[Weaver]

It turns out that the wind thing was some kind of technological nonsense / trickery and isn’t correct.

OR booked for tomorrow morning (Tuesday).

[Weaver]

OR engineer came here this morning all the way from Spean Bridge in the Great Glen on the mainland, must be 75 miles. Sorted the problem extremely quickly but I’ve no idea how and Janet can’t tell me. Line looks perfect now.

[Black Sheep]

Still trying to get my head around how my deafeningly crackly line passed the automated tests when the engineers equipment immediately saw the fault.  Though granted, it had gotten a lot worse to the point of not being able to maintain dial tone at that point.

Remote test voltages are low .... therefore they can pass through a high-resistance joint that the nominal working voltage would maybe struggle to bridge ... ergo the audible crackling noise.

[Black Sheep]

A "test-head", yes. There are such items located at an exchange.

Just seen this thread, apologies.

Testing and the science behind it, is a mammoth subject.

In a nutshell, there is such a thing as a TSC (Test system controller) .... based on the inventory build of the circuit in question, it will send the required test to the appropriate test-head in the correct Exchange.

For example, if the circuit is SMPF, we have the ability to test from Exchange to NTE through our in-house test system. If the circuit is MPF, then it has to go through the LLU TAM in order to test out to the NTE. This is just two of the varied systems available.