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Author Topic: Interpreting VDSL2 numbers  (Read 1969 times)

tommy45

  • Reg Member
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  • Posts: 627
Re: Interpreting VDSL2 numbers
« Reply #15 on: August 30, 2022, 10:56:14 PM »

Yes it's somewhat relevant.

The policy picked determines the thresholds used before applying specific DLM profiles.

A line on the Standard policy might need to be a little more stable than a line on the Speed policy before applying a lower SNR target.

They all use the exact same DLM profiles though and can all lower the SNR target.

What you have quoted is also specific to Talktalk retail, not all Talktalk based services.
There are providers who use Talktalk backhaul that use the Speed profile.

It was also written nearly 10 years ago and I wouldn't bet on it being accurate as to what providers use what specific policy.
My understanding of the DLM stability  policies  is there were 3 that isp's could choose from,  Zen use the Speed policy  by default, At 1 point due to them switching me from WBMC to TT backhaul  that speed policy got changed  But was corrected  due to  DLM putting me on a RE TX High profile  Not sure how that happened  but it had been put on  a stable policy
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mbrijun

  • Just arrived
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  • Posts: 4
Re: Interpreting VDSL2 numbers
« Reply #16 on: September 02, 2022, 10:40:33 PM »

The router has been up since Monday afternoon. I see that the SNR margin has reduced to 5.3dB for download, remains ~6dB for upload. I suspect the line has dropped a few times. I would be grateful if someone could please point out the markers that indicate how stable (or unstable) the line is.

Thank you.

Code: [Select]
engineer>xdslctl --stats info
/usr/bin/xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    1
Last initialization procedure status:   0
Max:    Upstream rate = 5883 Kbps, Downstream rate = 35303 Kbps
Bearer: 0, Upstream rate = 5883 Kbps, Downstream rate = 34651 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):        5.3             5.9
Attn(dB):        22.1            0.0
Pwr(dBm):        11.7           -5.6

                        VDSL2 framing
                        Bearer 0
MSGc:           -6              26
B:              227             175
M:              1               1
T:              0               38
R:              10              8
S:              0.2093          0.9491
L:              9098            1551
D:              4               1
I:              238             92
N:              238             184
Q:              4               0
V:              0               0
RxQueue:                84              0
TxQueue:                12              0
G.INP Framing:          18              0
G.INP lookback:         12              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               18016022
OHFErr:         0               268
RS:             3092440636              684461912
RSCorr:         1788            181
RSUnCorr:       0               0
                        Bearer 1
OHF:            10112186                0
OHFErr:         0               0
RS:             60672747                0
RSCorr:         1               0
RSUnCorr:       0               0

                        Retransmit Counters
rtx_tx:         842             0
rtx_c:          517             0
rtx_uc:         0               0

                        G.INP Counters
LEFTRS:         0               0
minEFTR:        34660           0
errFreeBits:    185801943               0

                        Bearer 0
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    2233662413              0
Data Cells:     526761884               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:             20              553
SES:            20              0
UAS:            108             88
AS:             162426

                        Bearer 0
INP:            59.00           0.00
INPRein:        1.00            0.00
delay:          0               0
PER:            0.00            9.05
OR:             0.01            28.28
AgR:            34727.27        5911.17

                        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:        3268/3287               1528/1528

Total time = 4 days 5 hours 27 min 33 sec
FEC:            7191            464
CRC:            0               602
ES:             20              553
SES:            20              0
UAS:            108             88
LOS:            2               0
LOF:            1               0
LOM:            0               0
Retr:           2
HostInitRetr:   0
FastRetr:       0
FailedRetr:     0
FailedFastRetr: 0
Latest 15 minutes time = 12 min 33 sec
FEC:            0               0
CRC:            0               1
ES:             0               1
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Retr:           0
HostInitRetr:   0
FastRetr:       0
FailedRetr:     0
FailedFastRetr: 0
Previous 15 minutes time = 15 min 0 sec
FEC:            8               3
CRC:            0               4
ES:             0               3
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Retr:           N/A
HostInitRetr:   N/A
FastRetr:       N/A
FailedRetr:     N/A
FailedFastRetr: N/A
Latest 1 day time = 5 hours 27 min 33 sec
FEC:            408             14
CRC:            0               37
ES:             0               32
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Retr:           0
HostInitRetr:   0
FastRetr:       0
FailedRetr:     0
FailedFastRetr: 0
Previous 1 day time = 24 hours 0 sec
FEC:            915             124
CRC:            0               154
ES:             0               138
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Retr:           0
HostInitRetr:   0
FastRetr:       0
FailedRetr:     0
FailedFastRetr: 0
Since Link time = 1 days 21 hours 7 min 5 sec
FEC:            1788            181
CRC:            0               268
ES:             0               245
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Retr:           0
HostInitRetr:   0
FastRetr:       0
FailedRetr:     0
FailedFastRetr: 0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0
engineer>
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tubaman

  • Senior Kitizen
  • ******
  • Posts: 12669
Re: Interpreting VDSL2 numbers
« Reply #17 on: September 03, 2022, 11:04:12 AM »

Looks like G.INP has started its good work and dropped your DS SNR from 6dB to 5dB and in doing so has increased the sync rate from 32Mbps to 34Mbps.
I'd just leave it alone and hopefully in the next few days you'll see it go to 4dB and then 3dB with further sync rate increases. Each one of these changes will trigger a resync, usually in the early hours.
The rest on the stats look fine to me for an uptime of 4 days or so. The one I particularly look at is 'Errored Seconds (ES) and that is fine on the DS and US sides. US will often be higher as G.INP doesn't usually operate on that side.
« Last Edit: September 03, 2022, 11:13:12 AM by tubaman »
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j0hn

  • Kitizen
  • ****
  • Posts: 4100
Re: Interpreting VDSL2 numbers
« Reply #18 on: September 03, 2022, 10:37:40 PM »

The router has been up since Monday afternoon. I see that the SNR margin has reduced to 5.3dB for download, remains ~6dB for upload.

The upstream is always on a 6dB SNR target. Unfortunately that can't be lowered to gain more speed on the upstream.

Quote
I would be grateful if someone could please point out the markers that indicate how stable (or unstable) the line is.

As Tubaman says ES is the main error counter the DLM monitors. 0 since the last resync after nearly 48 hours. Can't be any better than 0.
LEFTERS is like a retransmission (G.INP) error. That's 0 again.

Hopefully the DLM will lower the target to 4dB in the next day or so, then 3dB a few days later.

You will not have noticed any increase in throughput on speed tests. Although you are connected at 2Mb higher than before the DLM has also changed you from Retx Low to Retx High.
This lowers the percentage of throughput compared to sync.
Once the DLM has settled your line on hopefully 3dB we'll work on getting you back to Retx Low.

In short Retx Low gives you about 96.7% of sync speed in useable bandwidth.
Retx High only gives around 91-92% of the sync speed as useable bandwidth.
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Talktalk FTTP 550/75 - Speedtest - BQM
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