Modifying SNR on my 8800NL R2

My modem has been up for 50 days, and since I started recording with dlstats on 20 May I've had 29 resyncs.

The resyncs frequently occur during the day. I'm about 600m from the cabinet

The line stats are:

DSLAM type / SW version: BDCM:0xc190 (193.144) / v0xc190
Modem/router firmware: AnnexA version - A2pvI042j1.d26q_rc1a
DSL mode: VDSL2 Profile 17a
Status: Showtime
Uptime: 18 hours 18 min 9 sec
Resyncs: 0 (since 09 Jun 2022 14:43:28)

Downstream Upstream
Line attenuation (dB): 21.9 0.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 45338 9898
SNR margin (dB): 5.0 6.1
Power (dBm): 11.7 7.3
Interleave depth: 4 1
INP: 55.00 0
G.INP: Enabled Not enabled
Vectoring status: 5 (VECT_UNCONFIGURED)


adsl info --stats
adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 9898 Kbps, Downstream rate = 45444 Kbps
Bearer: 0, Upstream rate = 9898 Kbps, Downstream rate = 45338 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): 5.0 6.1
Attn(dB): 21.9 0.0
Pwr(dBm): 11.7 7.3

VDSL2 framing
Bearer 0
MSGc: -6 26
B: 227 237
M: 1 1
T: 0 46
R: 10 16
S: 0.1599 0.7642
L: 11904 2659
D: 4 1
I: 238 127
N: 238 254
Q: 4 0
V: 0 0
RxQueue: 110 0
TxQueue: 22 0
G.INP Framing: 18 0
G.INP lookback: 22 0
RRC bits: 0 24

Total time = 50 days 21 hours 29 min 19 sec
FEC: 1071106459 486924
CRC: 95755 5452
ES: 6608 1503
SES: 1627 208
UAS: 3000 1317
LOS: 64 0
LOF: 205 0
LOM: 612 0
Retr: 44
FailedRetr: 0
FailedFastRetr: 0

Latest 1 day time = 21 hours 29 min 19 sec
FEC: 2573293 41957
CRC: 2617 422
ES: 79 72
SES: 43 11
UAS: 99 59
LOS: 3 0
LOF: 11 0
LOM: 0 0
Retr: 2
FailedRetr: 0
FailedFastRetr: 0

Previous 1 day time = 24 hours 0 sec
FEC: 8738246 61527
CRC: 8115 687
ES: 210 132
SES: 141 32
UAS: 269 145
LOS: 8 0
LOF: 18 0
LOM: 43 0
Retr: 5
FailedRetr: 0
FailedFastRetr: 0

Since Link time = 18 hours 18 min 9 sec
FEC: 1511783 15289
CRC: 26 210
ES: 10 31
SES: 0 4
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
FailedRetr: 0
FailedFastRetr: 0


The line is quiet. AFAIK, for downstream the "exchange" sets the SNR, and the modem can accept it, or using the Billion I can choose a specific value. The Billion has no control of the upstream SNR.

Would manually selecting a SNR on my modem provide a more stable line or am I barking up the wrong tree? I'm thinking of trying a SNR of 6 to see what happens. I'd be happy with 40 down and a reduced amount of resyncs.

IIRC the SNR adjustment on Billion routers is only applicable to ADSL and has no effect on a VDSL connection so is probably irrelevant to your problem.

@GonePostal,

You are correct. The Billon forum says the same.

Ummmmm….

I got Billion 8800NL as I can confirmed SNR modifying will NOT work on any FTTC,

As mentioned above the setting of the downstream SNRM target only works on ADSL on any Broadcom chipset modem.

You can however manually cap the sync rate which will increase the current SNRM, although not the target.

To set a 40 down 10 up limit you run the command

adsl configure --maxDataRate 40000 10000 100000

In reply to a post by j0hn83:

As mentioned above the setting of the downstream SNRM target only works on ADSL on any Broadcom chipset modem.

You can however manually cap the sync rate which will increase the current SNRM, although not the target.

To set a 40 down 10 up limit you run the command

adsl configure --maxDataRate 40000 10000 100000

Some people who have become locked on re-transmission high do that at a significantly lower speed than the line will support. The backroom systems eventually work out the the line is stable and runs with a high SNRM and drop things back to re-transmission low. Once that is done the user can remove the manually applied cap and with any luck get back to a higher full speed with re-transmission low rather than high.

Thanks @j0hn83, @GonePostal,

Google is wonderful when you know what to ask it but it would be nothing without all the people that provide the info. I've found a bit of a discussion on another BB forum - not sure if I can mention on this forum but it starts with a k and ends with a z. I think @j0hn83 was researching the impact of the capping command with the help of others.

I think I understand that G.INP and retx are one of the same thing, but not sure what is considered a low value or high value. I think I shouldn't mess with the upstream rate even though I see some errors. I think it will take several days/weeks to see any changes.

Given my current stats,

adsl info --stats
adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 9760 Kbps, Downstream rate = 47101 Kbps
Bearer: 0, Upstream rate = 9778 Kbps, Downstream rate = 48774 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): 4.3 5.7
Attn(dB): 21.8 0.0
Pwr(dBm): 11.9 7.2

VDSL2 framing
Bearer 0
MSGc: -6 26
B: 227 237
M: 1 1
T: 0 45
R: 10 16
S: 0.1487 0.7735
L: 12806 2627
D: 4 1
I: 238 127
N: 238 254
Q: 4 0
V: 0 0
RxQueue: 115 0
TxQueue: 23 0
G.INP Framing: 18 0
G.INP lookback: 23 0
RRC bits: 0 24
Bearer 1
MSGc: 122 -6
B: 0 0
M: 2 0
T: 2 0
R: 16 0
S: 8.0000 0.0000
L: 32 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 3823216
OHFErr: 0 14
RS: 891324064 171982294
RSCorr: 6920097 2368
RSUnCorr: 0 0
Bearer 1
OHF: 2070723 0
OHFErr: 0 0
RS: 16565291 0
RSCorr: 3359 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 151065 0
rtx_c: 149504 0
rtx_uc: 1 0

G.INP Counters
LEFTRS: 0 0
minEFTR: 48728 0
errFreeBits: 3202362536 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 3117608309 0
Data Cells: 17539394 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: 6629 1516
SES: 1647 209
UAS: 3049 1346
AS: 33261

Bearer 0
INP: 54.00 0.00
INPRein: 1.00 0.00
delay: 0 0
PER: 0.00 8.73
OR: 0.01 29.30
AgR: 48880.79 9807.76

Bearer 1
INP: 2.00 0.00
INPRein: 2.00 0.00
delay: 0 0
PER: 16.06 0.01
OR: 63.75 0.01
AgR: 63.75 0.01

Bitswap: 16162/16790 1344/1352

Total time = 51 days 21 hours 45 min 30 sec
FEC: 1079604426 489831
CRC: 96929 5473
ES: 6629 1516
SES: 1647 209
UAS: 3049 1346
LOS: 66 0
LOF: 209 0
LOM: 612 0
Retr: 45
FailedRetr: 0
FailedFastRetr: 0
Latest 15 minutes time = 30 sec
FEC: 10633 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
FailedRetr: 0
FailedFastRetr: 0
Previous 15 minutes time = 15 min 0 sec
FEC: 392793 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: N/A
FailedRetr: N/A
FailedFastRetr: N/A
Latest 1 day time = 21 hours 45 min 30 sec
FEC: 8328907 2906
CRC: 1174 21
ES: 21 13
SES: 20 1
UAS: 49 29
LOS: 2 0
LOF: 4 0
LOM: 0 0
Retr: 1
FailedRetr: 0
FailedFastRetr: 0
Previous 1 day time = 24 hours 0 sec
FEC: 2742353 41958
CRC: 2617 422
ES: 79 72
SES: 43 11
UAS: 99 59
LOS: 3 0
LOF: 11 0
LOM: 0 0
Retr: 2
FailedRetr: 0
FailedFastRetr: 0
Since Link time = 9 hours 14 min 19 sec
FEC: 6920097 2368
CRC: 0 14
ES: 0 5
SES: 0 1
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
FailedRetr: 0
FailedFastRetr: 0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0
>


could someone advise if I have low/high retx and what I should see after issuing the "configure" command?

During the last two years (lockdown) the line was perfect during the day with reysncs in the early hours. However my wife is complaining that her calls are dropping. I say "go to the office" but I'm told there is no one in the office and/or the background noise from the open plan makes it difficult to concentrate. My wife has been spoilt working alone in her "conservatory office"

I am an amateur bodger and do not have the expert knowledge of many of the helpful people around these parts so this may be nonsense. I picked up somewhere that if the INPRein value for Bearer 0 is 1 or greater then the line is set to retx high. Scrolling down through your stats I think you are on retx high.

You're on Retx High.

If you cap the downstream to something around 40Mb (the less the better to be honest) then the DLM should hopefully nudge you to Retx Low.
That will increase throughput from circa 91% of the sync speed to 96.7% of the sync speed.

It takes between 2 to 8 days depending on the lines history and the current error levels.

In reply to a post by GonePostal:

Some people who have become locked on re-transmission high do that at a significantly lower speed than the line will support. The backroom systems eventually work out the the line is stable and runs with a high SNRM and drop things back to re-transmission low. Once that is done the user can remove the manually applied cap and with any luck get back to a higher full speed with re-transmission low rather than high.

I'm very aware of that

I'm pretty sure I was the 1st person to document the DLM beheading in that way, changing from Retx High to Retx Low as a result of capping the sync speed. There's an old thread dedicated to it on the kitz forum from a number of years ago.

The same cap method can remove interleaving and also help the DLM lower the SNRM target below 6dB.