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[Weaver]

Here we go again: downstream sync rate of line 4 down to 1.278 Mbps. Have contacted AA

[Weaver]

It wasn’t reliable at 3 dB SNRM downstream, so I changed it to 6 dB; that brought the downstream sync rate down to 0.963 Mbps 

Code: [Select]

xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 8000
Last initialization procedure status: 0
Max: Upstream rate = 515 Kbps, Downstream rate = 1068 Kbps
Bearer: 0, Upstream rate = 560 Kbps, Downstream rate = 963 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): 5.7 6.0
Attn(dB): 65.5 41.6
Pwr(dBm): 18.0 12.4

ADSL2 framing
Bearer 0
MSGc: 59 13
B: 30 62
M: 4 1
T: 1 1
R: 16 14
S: 3.9576 3.5402
L: 283 174
D: 1 8

Counters
Bearer 0
SF: 11791 11483
SFErr: 12 2
RS: 191604 217969
RSCorr: 848 429
RSUnCorr: 12 0

ReXmt: 1652 0
ReXmtCorr: 1651 0
ReXmtUnCorr: 13 0

Bearer 0
HEC: 6 7
OCD: 0 0
LCD: 0 0
Total Cells: 433813 251913
Data Cells: 11612 7587
Drop Cells: 0
Bit Errors: 1023 0

ES: 805889 1593
SES: 1862 1
UAS: 131703 130487
AS: 194

Bearer 0
INP: 27.00 2.50
INPRein: 0.00 0.00
delay: 8 7
PER: 16.07 16.81
OR: 32.34 9.03
AgR: 990.67 567.23

Bitswap: 30/30 5/5

Total time = 87 days 15 hours 2 min 27 sec
FEC: 34198733 2870825
CRC: 1347699 1668
ES: 805889 1593
SES: 1862 1
UAS: 131703 130487
LOS: 90 0
LOF: 481 0
LOM: 51 0
Latest 15 minutes time = 2 min 27 sec
FEC: 666 417
CRC: 9 2
ES: 9 1
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 15648 872
CRC: 1335 4
ES: 540 3
SES: 11 0
UAS: 60 49
LOS: 1 0
LOF: 9 0
LOM: 0 0
Latest 1 day time = 15 hours 2 min 27 sec
FEC: 277085 31655
CRC: 12709 6
ES: 6854 4
SES: 21 0
UAS: 120 99
LOS: 2 0
LOF: 18 0
LOM: 0 0
Previous 1 day time = 24 hours 0 sec
FEC: 115311 63313
CRC: 637 28
ES: 656 22
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 3 min 13 sec
FEC: 848 429
CRC: 12 2
ES: 12 1
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0


[burakkucat]

It wasn’t reliable at 3 dB SNRM downstream, so I changed it to 6 dB; that brought the downstream sync rate down to 0.963 Mbps 

Remember that the default target SNRM is 6 dB, hence the circuit's degraded performance should be reported relative to that target and not with your tweaked setting.

Looking at it slightly differently, with the default 6 dB SNRM target the circuit is clearly faulty and so, hopefully, Donald, Hamish or Malcolm will resolve the problem quite quickly. (Until the next attack by the haggis on the cables or joints.)

[Weaver]

I usually keep everything at 3dB so as to compare like with like. Perhaps I should change to 6dB when reporting sync rates to AA.

It wasn’t happy at 6dB downstream SNRM either, not completely, so now it’s up to 9dB downstream and a miserable 598k downstream sync rate.

[burakkucat]

I usually keep everything at 3dB so as to compare like with like. Perhaps I should change to 6dB when reporting sync rates to AA.

Yes, that would be sensible.

[Weaver]

AA got back to me. They are going to book an SFI engineer and get the drop cable replaced. Lines 4 and 2, the two problem lines, share that drop cable.

I have heard the term SFI engineer so many times, but nevertheless I have no idea what an SFI engineer does or what their expertise is. Can someone give me a definitive explanation ?

[Weaver]

Openreach coming on the 25th

[burakkucat]

AA got back to me. They are going to book an SFI engineer and get the drop cable replaced. Lines 4 and 2, the two problem lines, share that drop cable.

Ah, now that is interesting. I wonder if the fault is due to that very close lightening strike earlier this year?

I have heard the term SFI engineer so many times, but nevertheless I have no idea what an SFI engineer does or what their expertise is. Can someone give me a definitive explanation ?

Special Fault Investigation and Special Fault Investigation 2

Here follows a brief list (in chronological order) of forum threads where SFI (or SFI2) is mentioned --

May 03, 2015
July 15, 2015
August 17, 2016
January 15, 2017
September 08, 2020

I think you might recognise the contributors to the above. 

[Weaver]

My memory frequently embarrasses me; it’s shocking. The past is all simply - gone. Looking back, I didn’t understand our Sheep’s post.

[burakkucat]

Looking back, I didn’t understand our Sheep’s post.

He was just detailing the basic steps which apply when visiting an end-user, on behalf of an ISP/CP who has ordered the SFI service.

One thought came to me overnight. I believe the "high level" pole was classified as dangerous at its last inspection (hence the D label affixed to it) and is listed for eventual replacement. As a consequence, any pole-top access will have to be done from the platform of a hydraulic hoist. So the replacement of the second drop cable will need to be a two person task.

[Weaver]

I didn’t understand what the skills and abilities of an SFI engineer are.

[Weaver]

Burrakucat- you were spot on about the D - the engineer moaned about that fact. Well why didn’t they give him a hoist? They must know. I have mentioned the D to AA in case it holds things up on some future occasion.

The moaning engineer said there was nothing wrong with the line. He put in his conclusion: "internet congestion". I’m lost for words!

   However, he fixed both line 4 and line 2 some how (even though not booked to fix line 2). Speeds are now superb on both lines, and SNR curves are boringly normal. I shall await the notes coming back.

Live sync rates:
  #1: down 2765 kbps, up 522 kbps
  #2: down 2865 kbps, up 515 kbps
  #3: down 2979 kbps, up 379 kbps
  #4: down 2881 kbps, up 557 kbps

[burakkucat]

I didn’t understand what the skills and abilities of an SFI engineer are.

Oh, I see. The answer is quite simple . . . Just clone Black Sheep, divide the clone into two and then you have two SFI engineers. 

[burakkucat]

Here is another one of my "overnight" thoughts.

Certain lines are occasionally damaged by nearby lightning strikes. Just like the big zap, some months ago, which resulted in the replacement of (an) underground cable(s) at Harrapul. I believe one (or more) of your four lines required some of their joints to be remade, as the gel-crimps were smoke-blackened, nasty and defective.

We know that a basic NTE5 contains a series connected 1.8 micro Farad capacitor and 470k Ohm resistor as a shunt across the pair. When a line has suffered lightning damage, I would be very suspicious of the condition of both the capacitor and the resistor in the NTE5. So much so that I would be inclined to replace the NTE5 . . . 

[Weaver]

I understand. I can’t replace them myself and Janet’s hands aren’t good enough. Is that a job for AA?

I do get very good results on the lines. When they’re working properly, that is. Does that tell us anything regarding the state of the components?

I don’t know if a local electrician would want to touch the forbidden territory that is the NTE5?