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[Hitman]

Hi,

I have been on a stable 72/19 (BT Infinity 2 80/20) connection for over 18 months (HG612 modem - Asus AC88U router) then suddenly I lost ~10 meg overnight a few months ago, I have a busy job and have only just started looking into this.

I unlocked my HG612 modem some years ago to the latest 08 GUI firmware and so I have reconnected to the HG612 modem and ran a xdslcmd stats command (results below), connection stats seems fine but on my router WAN - LAN, i'm only getting 63/17 instead of 72/19.

I have tried another cat5e cable between modem - router, no change.

Vectoring status:          5 (VECT_UNCONFIGURED)

Can anyone help as to what the issue maybe, also is G.IMP working correctly?

Any help appreciated, thanks.

Stats

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status:   0
Max:    Upstream rate = 25027 Kbps, Downstream rate = 70228 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 71215 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):        3.0             15.0
Attn(dB):        13.5            0.0
Pwr(dBm):        13.4            3.8
                        VDSL2 framing
                        Bearer 0
MSGc:           -6              26
B:              243             237
M:              1               1
T:              0               42
R:              10              16
S:              0.1091          0.3781
L:              18625           5374
D:              8               1
I:              254             127
N:              254             254
Q:              8               0
V:              0               0
RxQueue:                80              0
TxQueue:                20              0
G.INP Framing:          18              0
G.INP lookback:         20              0
RRC bits:               0               24
                        Bearer 1
MSGc:           154             -6
B:              0               0
M:              2               0
T:              2               0
R:              16              0
S:              6.4000          0.0000
L:              40              0
D:              3               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               2166608
OHFErr:         6               1692
RS:             120052376               3984235
RSCorr:         22393750                2591
RSUnCorr:       0               0
                        Bearer 1
OHF:            234496622               0
OHFErr:         0               0
RS:             2344965603              0
RSCorr:         2581            0
RSUnCorr:       0               0

                        Retransmit Counters
rtx_tx:         2256931         0
rtx_c:          374433          0
rtx_uc:         99              0

                        G.INP Counters
LEFTRS:         1               0
minEFTR:        71208           0
errFreeBits:    4090493878              0

                        Bearer 0
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    438881187               0
Data Cells:     4016777539              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:             2               1554
SES:            0               0
UAS:            23              23
AS:             3766696

                        Bearer 0
INP:            51.00           0.00
INPRein:        1.00            0.00
delay:          0               0
PER:            0.00            3.98
OR:             0.01            64.22
AgR:            71288.45        20063.54

                        Bearer 1
INP:            4.50            0.00
INPRein:        4.50            0.00
delay:          3               0
PER:            16.06           0.01
OR:             79.68           0.01
AgR:            79.68   0.01

Bitswap:        640470/640471           1339/1339

Total time = 1 days 14 hours 18 min 39 sec
FEC:            22393750                2591
CRC:            6               1692
ES:             2               1554
SES:            0               0
UAS:            23              23
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 15 minutes time = 3 min 39 sec
FEC:            155             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:            619             0
CRC:            0               1
ES:             0               1
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 1 day time = 14 hours 18 min 39 sec
FEC:            73777           36
CRC:            0               23
ES:             0               22
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 1 day time = 24 hours 0 sec
FEC:            1449695         84
CRC:            0               52
ES:             0               50
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Since Link time = 43 days 14 hours 18 min 15 sec
FEC:            22393750                2591
CRC:            6               1692
ES:             2               1554
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0

[johnson]

You said you were on 72/19 and lost 10mbits, but you are still synced at 70228/19999, where are you getting the 63/17 from? Actual speed tests?

[sotonsam]

Worth noting that it really isn't unusual to lose 10mb with this technology, sometimes even more, due to the presence of cross talkers (new subscribers over the last couple of months added to the cab for e.g.).

What are your estimated predictions on the BT Wholesale DSL checker? I’d imagine you’re still within your clean range as you’re still syncing at 70mb and that’s not bad really with 13.5 attenuation.

[Hitman]

You said you were on 72/19 and lost 10mbits, but you are still synced at 70228/19999, where are you getting the 63/17 from? Actual speed tests?

Hi,

Yes using speedtest.net and internet file download testing, was around 72/19 a few months ago, now it's down to 63/17.

Thanks.

[Hitman]

Worth noting that it really isn't unusual to lose 10mb with this technology, sometimes even more, due to the presence of cross talkers (new subscribers over the last couple of months added to the cab for e.g.).

What are your estimated predictions on the BT Wholesale DSL checker? I’d imagine you’re still within your clean range as you’re still syncing at 70mb and that’s not bad really with 13.5 attenuation.

Rechecking current BT Wholesale checker, the results have also lowered now 65DL and 17.5UL.

Seems strange that I was at a stable 72/19 for over 18 months then bam lost the 10meg overnight :O

[tubaman]

Perhaps your sync rate was nearer 80/20 before and you have lost speed due to a cross-talker.
Your download rate will never hit the sync rate as there are losses due to overheads - usually 5% or more.
 

[sotonsam]

Rechecking current BT Wholesale checker, the results have also lowered now 65DL and 17.5UL.

Seems strange that I was at a stable 72/19 for over 18 months then bam lost the 10meg overnight :O

So you've probably had a couple of new subscribers (or even one) added to the cab. Your SNR probably fell, along with your attainable and the SNR may have fell low enough to force a resync, which would have resynced you back to the new attainable rate of 70.

Not sure there’s really a great deal of margin for improvement on this one. Just have to hope you lose a couple of subscribers on the cab! Or G.Fast comes into town...

[Hitman]

Ok, thanks for the info guy's, appreciated!

One other thing have noticed is Vectoring is showing as unconfigured (I have rebooted the modem this afternoon to cause a resync) and only just noticed i'ts showing as Vectoring - 5 (VECT_UNCONFIGURED) in DSLstats.

I have a Broadcom based modem/FTTC cab and vectoring should be enabled, will vectoring become enabled on it's own after some uptime?

Thanks again.

[johnson]

As far as I know vectoring is rare to non-existent outside of BDUK areas. Have you had vectoring before?

Edit: also your stats since resync may be useful. 

[j0hn]

What makes you think that Vectoring should be enabled?
Vectoring is incredibly rare in the UK.
It is only enabled on a few specific BDUK cabinets, usually cabinets where most users are a good distance from the cabinet.
It's enabled to help push users above Superfast targets (24Mb/s) so even less likely if most on your cabinet achieve similar speeds to you.

You've likely lost most of your speed from crosstalk, neighbouring lines joining after you and the interference they cause lowers your sync.

You have working G.INP (aka retransmission)
You are on retransmission high which means your throughput (download speed) is only around 91% of the sync speed.
You were likely on retransmission low before which has a throughput of around 97% of sync speed.

So the missing speed you are seeing is likely a combination of crosstalk and retransmission overhead.

You probably lost more than that but your line has lowered to a 3dB SNRM target which will have recovered some of this.

[Hitman]

Thanks jOhn, Johnson.

Edit: also your stats since resync may be useful. 

New stats....

Stats recorded 10 Jun 2018 15:09:17

DSLAM type / SW version:   BDCM:0xa48c (164.140) / v0xa48c
Modem/router firmware:     AnnexA version - A2pv6C038m.d24j
DSL mode:                  VDSL2 Profile 17a
Status:                    Showtime
Uptime:                     0 hour 49 min 24 sec
Resyncs:                   1 (since 10 Jun 2018 13:32:37)
         
            Downstream   Upstream
Line attenuation (dB):     13.7      0.0
Signal attenuation (dB):   Not monitored      
Connection speed (kbps):   70975      19999
SNR margin (dB):           3.2      15.2
Power (dBm):               13.5      4.1
Interleave depth:          8      1
INP:                       51.00      0
G.INP:                     Enabled      Not enabled
Vectoring status:          5 (VECT_UNCONFIGURED)      

RSCorr/RS (%):             0.0026      0.0001
RSUnCorr/RS (%):           0.0000      0.0000
ES/hour:                   0      1.58

Telnet Stats
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Last initialization procedure status:   0
Max:   Upstream rate = 25441 Kbps, Downstream rate = 70412 Kbps
Bearer:   0, Upstream rate = 19999 Kbps, Downstream rate = 70975 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):    3.2       15.2
Attn(dB):    13.7       0.0
Pwr(dBm):    13.5       4.1
         VDSL2 framing
         Bearer 0
MSGc:      -6      26
B:      243      237
M:      1      1
T:      0      42
R:      10      16
S:      0.1095      0.3781
L:      18562      5374
D:      8      1
I:      254      127
N:      254      254
Q:      8      0
V:      0      0
RxQueue:      80      0
TxQueue:      20      0
G.INP Framing:      18      0
G.INP lookback:      20      0
RRC bits:      0      24
         Bearer 1
MSGc:      154      -6
B:      0      0
M:      2      0
T:      2      0
R:      16      0
S:      6.4000      0.0000
L:      40      0
D:      3      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      723935
OHFErr:      0      2
RS:      104569136      327092
RSCorr:      2655      1
RSUnCorr:   0      0
         Bearer 1
OHF:      178925      0
OHFErr:      0      0
RS:      1788638      0
RSCorr:      5      0
RSUnCorr:   0      0

         Retransmit Counters
rtx_tx:      2257915      0
rtx_c:      6      0
rtx_uc:      0      0

         G.INP Counters
LEFTRS:      0      0
minEFTR:   70959      0
errFreeBits:   3111174      0

         Bearer 0
HEC:      0      0
OCD:      0      0
LCD:      0      0
Total Cells:   392235057      0
Data Cells:   206479      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      2
SES:      0      0
UAS:      25      25
AS:      2874

         Bearer 0
INP:      51.00      0.00
INPRein:   1.00      0.00
delay:      0      0
PER:      0.00      3.98
OR:      0.01      64.22
AgR:      71047.32   20063.54

         Bearer 1
INP:      4.50      0.00
INPRein:   4.50      0.00
delay:      3      0
PER:      16.06      0.01
OR:      79.68      0.01
AgR:      79.68   0.01

Bitswap:   162/162      0/0

Total time = 48 min 19 sec
FEC:      2655      1
CRC:      0      2
ES:      0      2
SES:      0      0
UAS:      25      25
LOS:      0      0
LOF:      0      0
LOM:      0      0
Latest 15 minutes time = 3 min 19 sec
FEC:      173      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:      761      0
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 = 48 min 19 sec
FEC:      2655      1
CRC:      0      2
ES:      0      2
SES:      0      0
UAS:      25      25
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 1 day time = 0 sec
FEC:      0      0
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Since Link time = 47 min 53 sec
FEC:      2655      1
CRC:      0      2
ES:      0      2
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
#

[johnson]

I think the others analysis is probably correct, its likely you were syncing at the full 80/20 before and added noise from crosstalkers have brought it down some.

One thing I note is that you have some CRCs on the upstream after less than an hour, this is no problem and you would need huge amounts more to trigger any kind of intervention based on it, but it at least suggests the line has some noise on it.

[michty_me]

Also, I woukdnt be doing too many resyncs on the line either. You don't want to trigger the DLM to further reduce your speeds.

[Weaver]

The point about doing a lot of resynchs within a short space of time is an important one. You may well get away with it if you just order your modem to resynch, or reboot it, so it shuts down in a controlled way. But pulling the power may or may not get you into trouble and pulling the dsl cable out certainly will. It all depends on whether or not your modem informs the network that it is bringing the link down. Iirc some kitizens have told me they have their doubts about the accuracy of this idea in some cases though.

DLM could drop your speed if it becomes angered or scared and then you will have to do penance for a period.

[j0hn]

The point about doing a lot of resynchs within a short space of time is an important one. You may well get away with it if you just order your modem to resynch, or reboot it, so it shuts down in a controlled way. But pulling the power may or may not get you into trouble and pulling the dsl cable out certainly will. It all depends on whether or not your modem informs the network that it is bringing the link down. Iirc some kitizens have told me they have their doubts about the accuracy of this idea in some cases though.

DLM could drop your speed if it becomes angered or scared and then you will have to do penance for a period.

The OpenReach DLM takes no notice of a modems "dying gasp".
A controlled resync and pulling the power cable are both treated equally as a retrain.