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[jimmyca69]

Evening all,

I have been running DSLstats for the past 24hrs after successfully setting up a VMG8924-B10a as a bridged modem alongside my Sky SR203 router.

Backstory to this is since moving into new house 18 months ago my connection (on Sky Superfast FTTC 80-20 with min speed guarantee of 42mb) went from around 55mb/20mb, steadily down to 44/20 where it has been for last 3-4 months (DLM sync randomly at night would bring a drop and always sync'd at likes of 43999/19999 to show it was banded). I recently attempted to replace the Sky SR203 router with a TP-Link VR2800 - not to fix the line issues but for better Wi-Fi. However after initially sync'ing the same as the sky router, DLM kicked in each of the first 3 nights and dropped it down each night eventually to 34999/19999 which it is now. After this I changed the firmware back a version and it seemed to steady up and remained same for a week with little errors shows in basic router stats.

I tried to get DSLstats working with the TP-Link but failed, TP-Link support was awful and so I decided to return the TP-Link and put the Sky Router back in. As the speed dropped below min guaranteed i was able to do online tests to confirm and the automated system said I need an engineer visit, which is booked for the 28th October.

In the meantime thanks to help on here I identified the best setup was probably to get a dedicated modem and then look at a wireless router. I then realised the SR203 would be ok to use in WANoE mode with a modem so i bought a VMG8924-B10a. I plan to replace the SR203 but only after the engineer visit and hopefully a DLM reset to get me back to better speeds.

So here we are, my stats are below and I am keen to understand if this shows anything that I can raise with the engineer, the banding of the line previously hints at something which would be good to address. So anything that jumps out here would be good to know about.

Thanks

Code: [Select]

xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    0
Last initialization procedure status:   0
Max:    Upstream rate = 22875 Kbps, Downstream rate = 62916 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 34999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State:       L0
Mode:                   VDSL2 Annex B
VDSL2 Profile:          Profile 17a
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        14.6            7.5
Attn(dB):        17.8            0.0
Pwr(dBm):        12.4            7.4

                        VDSL2 framing
                        Bearer 0
MSGc:           -6              26
B:              170             237
M:              1               1
T:              0               42
R:              12              16
S:              0.0000          0.3781
L:              9421            5374
D:              16              1
I:              183             127
N:              183             254
Q:              16              0
V:              4               0
RxQueue:                20              0
TxQueue:                10              0
G.INP Framing:          18              0
G.INP lookback:         10              0
RRC bits:               0               24
                        Bearer 1
MSGc:           90              -6
B:              0               0
M:              2               0
T:              2               0
R:              16              0
S:              10.6667         0.0000
L:              24              0
D:              1               0
I:              32              0
N:              32              0
Q:              0               0
V:              0               0
RxQueue:                0               0
TxQueue:                0               0
G.INP Framing:          0               0
G.INP lookback:         0               0
RRC bits:               0               0

                        Counters
                        Bearer 0
OHF:            0               1251554
OHFErr:         0               64
RS:             2277549152              3586141
RSCorr:         3911            344
RSUnCorr:       0               0
                        Bearer 1
OHF:            5530147         0
OHFErr:         0               0
RS:             33180514                0
RSCorr:         6               0
RSUnCorr:       0               0

                        Retransmit Counters
rtx_tx:         479207863               0
rtx_c:          138             0
rtx_uc:         0               0

                        G.INP Counters
LEFTRS:         4               0
minEFTR:        35006           0
errFreeBits:    47391246                0

                        Bearer 0
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    1683658681              0
Data Cells:     547588993               0
Drop Cells:     0
Bit Errors:     0               0

                        Bearer 1
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    0               0
Data Cells:     0               0
Drop Cells:     0
Bit Errors:     0               0

ES:             0               53
SES:            0               0
UAS:            34              34
AS:             88854

                        Bearer 0
INP:            47.00           0.00
INPRein:        0.00            0.00
delay:          0               0
PER:            0.00            3.98
OR:             0.01            64.22
AgR:            35075.90        20063.54

                        Bearer 1
INP:            2.50            0.00
INPRein:        2.50            0.00
delay:          0               0
PER:            16.06           0.01
OR:             47.81           0.01
AgR:            47.81   0.01

Bitswap:        2720/2720               41/41

Total time = 1 days 41 min 28 sec
FEC:            3911            344
CRC:            0               64
ES:             0               53
SES:            0               0
UAS:            34              34
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 15 minutes time = 11 min 28 sec
FEC:            11              0
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:            93              14
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 1 day time = 41 min 28 sec
FEC:            164             14
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 1 day time = 24 hours 0 sec
FEC:            3747            330
CRC:            0               64
ES:             0               53
SES:            0               0
UAS:            34              34
LOS:            0               0
LOF:            0               0
LOM:            0               0
Since Link time = 1 days 40 min 53 sec
FEC:            3911            344
CRC:            0               64
ES:             0               53
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0

[RealAleMadrid]

The only thing that jumps out is that your line is banded at 35Mbps, that is what needs to be addressed in the first case.

[siofjofj]

I concur that there is nothing obvious jumping out from those stats. Please could you post the Hlog and QLN plots too (you'll need to enable the monitoring of these in the DSLstats configuration).

I note however you are getting some 4000 FEC errors per day, which normally wouldn't be a cause for concern as these are errors which have been corrected, however these errors could be CRCs if the DLM had not applied interleaving to your line which, for this quantity, would result in the DLM taking corrective action. Perhaps someone with a known good VDSL service could post the number of FECs they get per day. On my ADSL2+ service I get around 400 per day.

There are some rumours that the DLM pays attention to the number of FECs on lines that have G.INP enabled (as yours does), so this could explain why the DLM is not relenting.

[jimmyca69]

Thanks both

Hopefully these work:




Relating to FEC errors i noted this morning a big jump that must have occurred overnight as now at over 30k....

Code: [Select]

xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    0
Last initialization procedure status:   0
Max:    Upstream rate = 22929 Kbps, Downstream rate = 61837 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 34999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State:       L0
Mode:                   VDSL2 Annex B
VDSL2 Profile:          Profile 17a
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        14.3            7.5
Attn(dB):        17.8            0.0
Pwr(dBm):        12.4            7.3

                        VDSL2 framing
                        Bearer 0
MSGc:           -6              26
B:              170             237
M:              1               1
T:              0               42
R:              12              16
S:              0.0000          0.3781
L:              9421            5374
D:              16              1
I:              183             127
N:              183             254
Q:              16              0
V:              4               0
RxQueue:                20              0
TxQueue:                10              0
G.INP Framing:          18              0
G.INP lookback:         10              0
RRC bits:               0               24
                        Bearer 1
MSGc:           90              -6
B:              0               0
M:              2               0
T:              2               0
R:              16              0
S:              10.6667         0.0000
L:              24              0
D:              1               0
I:              32              0
N:              32              0
Q:              0               0
V:              0               0
RxQueue:                0               0
TxQueue:                0               0
G.INP Framing:          0               0
G.INP lookback:         0               0
RRC bits:               0               0

                        Counters
                        Bearer 0
OHF:            0               455089
OHFErr:         0               94
RS:             3916706592              1422131
RSCorr:         33537           505
RSUnCorr:       0               0
                        Bearer 1
OHF:            9510163         0
OHFErr:         0               0
RS:             57060607                0
RSCorr:         7               0
RSUnCorr:       0               0

                        Retransmit Counters
rtx_tx:         479207999               0
rtx_c:          267             0
rtx_uc:         0               0

                        G.INP Counters
LEFTRS:         7               0
minEFTR:        35006           0
errFreeBits:    81498439                0

                        Bearer 0
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    1691472815              0
Data Cells:     1075321048              0
Drop Cells:     0
Bit Errors:     0               0

                        Bearer 1
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    0               0
Data Cells:     0               0
Drop Cells:     0
Bit Errors:     0               0

ES:             0               80
SES:            0               0
UAS:            34              34
AS:             152801

                        Bearer 0
INP:            47.00           0.00
INPRein:        0.00            0.00
delay:          0               0
PER:            0.00            3.98
OR:             0.01            64.22
AgR:            35075.90        20063.54

                        Bearer 1
INP:            2.50            0.00
INPRein:        2.50            0.00
delay:          0               0
PER:            16.06           0.01
OR:             47.81           0.01
AgR:            47.81   0.01

Bitswap:        2720/2720               70/70

Total time = 1 days 18 hours 27 min 15 sec
FEC:            33537           505
CRC:            0               94
ES:             0               80
SES:            0               0
UAS:            34              34
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 15 minutes time = 12 min 15 sec
FEC:            29              2
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:            32              5
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 1 day time = 18 hours 27 min 15 sec
FEC:            29790           175
CRC:            0               30
ES:             0               27
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 1 day time = 24 hours 0 sec
FEC:            3747            330
CRC:            0               64
ES:             0               53
SES:            0               0
UAS:            34              34
LOS:            0               0
LOF:            0               0
LOM:            0               0
Since Link time = 1 days 18 hours 26 min 41 sec
FEC:            33537           505
CRC:            0               94
ES:             0               80
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0


[siofjofj]

I'd say your Hlog and QLN look absolutely fine.

Interesting about the bursts of errors though. It might be worth enabling the monitoring of absolutely everything in DSLstats (no real disadvantage to doing this). That will then give you a plot showing the times the FEC bursts occur which you could perhaps start trying to correlate with things like the central heating switching on etc.

Other than that, it will probably just be a matter of seeing what the attending Openreach engineer does. As I said in your other thread, it's likely that the remote tests have identified something amiss so hopefully they will be able to find and repair it.

[burakkucat]

Regarding the Hlog and QLN plots . . . What you have shown is truncated. You will need to adjust the configuration of DSLstats, to allow for the full width of 4096 sub-carriers of a VDSL2 circuit.

[jimmyca69]

Thanks both

Show further stats, I changed the hlog and qln for VDSL2, graphs below. I also turned on all the other config settings and have posted up the FEC error to show spikes there overnight. Not sure if other info might show more on these.

Thanks again

[siofjofj]

Hlog and QLN still look good (thanks for spotting that burakkucat, I'm too used to seeing ADSL2+ ones for me to notice they were truncated) . There seems to just be a general high background of FEC errors for some reason, the spikes don't seem to be too significant. Probably worth seeing if the larger spikes reoccur at similar times each day. Could also try picking up and/or ringing the phone to see if anything changes in the stats.

Other than that, probably just to have wait and see what Openreach say.

[jimmyca69]

Hlog and QLN still look good (thanks for spotting that burakkucat, I'm too used to seeing ADSL2+ ones for me to notice they were truncated) . There seems to just be a general high background of FEC errors for some reason, the spikes don't seem to be too significant. Probably worth seeing if the larger spikes reoccur at similar times each day. Could also try picking up and/or ringing the phone to see if anything changes in the stats.

Other than that, probably just to have wait and see what Openreach say.

Thanks again! Yes i'll leave it running and see if anything obvious changes, useful to have the info from it for when the engineer shows up at least. Moving forward it is good to have access to this info after years on the Sky Router.

Thanks again for you help on this and my other thread, much appreciated 

[GigabitEthernet]

Hello fellow high FEC experiencer!

I get millions of FECs a day, it's never caused me any issue, I've always just ignored it.

[j0hn]

That isn't high FEC!

I almost always received 10,000 FEC per min on my VDSL2 line.
For a long time period i received 100,000 FEC per min with zero issues.

Occasionally the DSLAM would go bonkers and FEC would get stuck at 1,000,000+ per min.
If i wasn't monitoring stats i would never have noticed because the line runs perfect even with 1M+ FEC every single minute.

[siofjofj]

Interesting. Do you think perhaps there could be a significant difference between defects which cause FEC errors on an non-interleaved line, and defects that cause FEC errors on an interleaved line that would be CRCs on a non-interleaved line?

If not, then there doesn't seem to be any evidence in the stats for what it was that caused the DLM to apply interleaving and banding to this line. Hopefully following a DLM reset everything will just be fine with no further work needed.

[GigabitEthernet]

I've had 527539 FECs in the last 10 minutes @j0hn, I would call that quite high.

In response to the question above, I thought I had read on here previously that it is possible DLM now looks at FECs. Something for somebody more knowledgable than me to explain, Kitz herself perhaps?

[j0hn]

I was referring to the graph above, and the mention of millions per my day. Neither is very high.

Half a million in 10 mins is on the higher side but in no way would i call that very high.

I received 100,000+ FEC per minute for months with no negative affect on the line, error rates or throughput.
If i wasn't looking at stats i would never have known

Kitz is (or has previously been) of the opinion FEC isn't involved all at in the DLM.

I'm of the opinion FEC isn't used when taking negative action on a line but that it might be used when taking positive actions.

For example i believe FEC is used when deciding to remove interleaving or Retx High but not when deciding to add them.

FEC are corrected errors and nothing to worry about.

[jimmyca69]

Just as a follow up to this, a Sky Engineer attended today. He replaced the external nte and requested a DLM reset on the line. He said the line showed no issues and by replacing the NTE connection it saw some stats improvement also so then requested the DLM reset, he says I should see around 60mb once that takes place.