power cut in the area brought speed improvements forced DLM

Ooh.
Moved in a few weeks ago.
previous owner was on ADSL after presumably getting 10megs on VDSL due to internal wiring. Wholesale checkers says VDSL estimate was ~32 - 35, but last observed on this line was 10, back in January, then it showed ADSL observed of 8 just before we moved in. There were phone extensions *everywhere*.. junction box with 5 extensions above the doorframe, around the staircase, upstairs, downstairs, everywhere.
(see here for original discussion before we moved in: https://forums.thinkbroadband.com/fibre/t/4661638-mo... )

The estimates for the line were about 36/7 down/up.

Ripped all the cabling out, got FTTC with Plusnet 12 days ago, and saw 36 megs down and 7.6 up from day one, which I was happy about. I'm using an unlocked HG612 and I could see the SNR was at 6.1 down and 5.6 up. I was hoping and waiting for it to DLM down to 3dB.

Over the last 12 days it hasn't changed though.

We just had an area-wide power outage - much of CW6, WA6, and parts of Chester.

It was out for 20 minutes. I presume that means the FTTC cab will have lost power as well, or would it ?

Either way, power has come back on, and now I'm on a 4dB line with a line rate of 40 down and 9.2 up, although the attainable rate / throughput hasn't changed so dramatically, but I'm intrigued to see what happens over the next week or so.

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 8003 Kbps, Downstream rate = 35488 Kbps
Bearer: 0, Upstream rate = 9223 Kbps, Downstream rate = 40000 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): 4.0 2.2
Attn(dB): 25.5 0.0
Pwr(dBm): 11.8 5.0
VDSL2 framing
Bearer 0
MSGc: -6 26
B: 138 239
M: 1 1
T: 0 50
R: 8 0
S: 0.1101 0.8272
L: 10684 2321
D: 16 1
I: 147 120
N: 147 240
Q: 16 0
V: 12 0
RxQueue: 27 0
TxQueue: 9 0
G.INP Framing: 18 0
G.INP lookback: 9 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 107262
OHFErr: 3 24
RS: 40144400 1067410
RSCorr: 108395 0
RSUnCorr: 0 0
Bearer 1
OHF: 69105 0
OHFErr: 0 0
RS: 414257 0
RSCorr: 3 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 51036 0
rtx_c: 207 0
rtx_uc: 3 0

G.INP Counters
LEFTRS: 5 0
minEFTR: 39989 0
errFreeBits: 676994 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 85337583 0
Data Cells: 3608595 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: 1 22
SES: 0 0
UAS: 25 25
AS: 1110

Bearer 0
INP: 45.00 0.00
INPRein: 0.00 0.00
delay: 0 0
PER: 0.00 10.38
OR: 0.01 24.66
AgR: 40252.99 9247.87

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: 797/797 85/86

Edited by deleted (Wed 25-Nov-20 15:31:42)

Guessing you are on a 40/10 package so isn't likely to get much faster without a package change and even then not much difference.

Also, your IP profile may not have caught up with the increased sync so actual speeds may not yet be any faster.

12 days is, in my expereince, too soon for a stepped improvement from 6 to 3dB.

What I believe has happened is when power came back up, the modem could see a nice clean noise free line and synced at 6dB with over 40Mbps attainable. You are on a 40/10 profile so it capped at 40. Then as more electrical and electonic equipment powered up in te neighbourhood, more noise is seen and the SNR dropped to 4dB.


One give away is that yoiur achievable is 35.5.


If you were to do a resync now you would probably come back with a max of 35-36 and sync 34-35 with a 6dB margin.

The line is still on a 6dB target.
Nothing on the DLM will have changed.

The DSLAM lost power, everyone disconnected.
The DSLAM came back up and you resynced before some neighbouring lines(crosstalkers).
As you synced before the other lines you synced higher than usual, at the target SNRM of 6dB.
As the crosstalkers connected the noise they create brought down your current SNRM to 4dB (the target is still 6dB).

If you resynced at the moment it would resync roughly at the reported "Max Downstream rate" of 35.4Mb/s.

A common occurrence and often mistaken as the DLM lowering the SNRM target.

If it was the DLM lowering the target SNRM then it would also increase the max attainable rate that's reported.
The DLM can also only change the target SNRM in 1dB increments. It can't jump from a 6dB to a 4dB target.

The line looks like it's handling the increased sync just fine.

In reply to a post by MHC:

12 days is, in my expereince, too soon for a stepped improvement from 6 to 3dB.

What I believe has happened is when power came back up, the modem could see a nice clean noise free line and synced at 6dB with over 40Mbps attainable. You are on a 40/10 profile so it capped at 40. Then as more electrical and electonic equipment powered up in te neighbourhood, more noise is seen and the SNR dropped to 4dB.


One give away is that yoiur achievable is 35.5.


If you were to do a resync now you would probably come back with a max of 35-36 and sync 34-35 with a 6dB margin.

You were pretty much right. It did settle back down slower. Ended up at about 38 - 39 down and 7.6 up. It's been like that for a good while now, however I never see more than 35.5 through the line.
It's enough, but of course if there's 10% extra to be had, it's silly not to get it.

Yesterday the Internet died, lost sync. I looked out the window and could see our phone and power cable goes through trees, but nothing obviously out of line. I went for a drive in the direction that I believe the cabinet is. I have no idea where the cabinet is, but I know that a few houses down the road can't get FTTC at all, so I know which direction it is. Anyway Openreach had closed the road and were replacing a big multi cored cable because the trees were rubbing through it. Apparently it gets done periodically. It was a twin cable.. one side being large diameter multi-cored and what looked like a narrower cable alongside it, shotgun style.

Since reconnection - about 25 hours ago, guess what.. more speed ! Well, more bigger numbers on the modem stats anyway! 42.5mbps down and 8.4mbps up.

I did a BTW advanced speed test to see what the IP Profile is, and the profile is 37.5mbps which is a bit frustrating. Also I don't know why (or even if it is) a 40 meg service - it's Plusnet's unlimited fibre extra whatever package. Surely Openreach don't have VDSL1-only cabinets/services any more do they ? I'd like the extra 2.5 megs if I can have it. Oh, I can see from the modem that it's VDSL2. Would a 40meg package show as VDSL1 ?

Here's the modem stats today. Like I said, it's been more than 25 hours since they replaced that big multi-core cable.
Generally, the line seems to exceed Openreach's expectations.
I want my downstream rate to start with a 4!

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 8410 Kbps, Downstream rate = 42724 Kbps
Bearer: 0, Upstream rate = 8302 Kbps, Downstream rate = 39999 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): 5.5 5.4
Attn(dB): 25.8 0.0
Pwr(dBm): 11.8 4.8
VDSL2 framing
Bearer 0
MSGc: -6 26
B: 162 245
M: 1 1
T: 0 37
R: 8 8
S: 0.1295 0.9412
L: 10564 2159
D: 4 1
I: 171 127
N: 171 254
Q: 4 0
V: 0 0
RxQueue: 135 0
TxQueue: 27 0
G.INP Framing: 18 0
G.INP lookback: 27 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 948092
OHFErr: 0 412
RS: 2834904824 742138
RSCorr: 4167695 581
RSUnCorr: 0 0
Bearer 1
OHF: 5736155 0
OHFErr: 0 0
RS: 34416561 0
RSCorr: 16 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 281348 8213
rtx_c: 5672413 3780
rtx_uc: 270625 67

G.INP Counters
LEFTRS: 430 118
minEFTR: 40005 8488
errFreeBits: 10109128 34093699

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 2603113282 0
Data Cells: 247259107 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: 147 18015
SES: 76 27
UAS: 5347 5274
AS: 92139

Bearer 0
INP: 55.00 0.00
INPRein: 1.00 0.00
delay: 0 0
PER: 0.00 8.73
OR: 0.01 29.29
AgR: 40122.38 8331.45

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: 69889/69889 2052/2059

Total time = 1 days 2 hours 46 min 55 sec
FEC: 264496315 154770
CRC: 4236 25594
ES: 147 18015
SES: 76 27
UAS: 5347 5274
LOS: 7 0
LOF: 57 0
LOM: 0 0
Latest 15 minutes time = 1 min 55 sec
FEC: 13111 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: 93676 3
CRC: 0 8
ES: 0 8
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 2 hours 46 min 55 sec
FEC: 1275540 131
CRC: 0 74
ES: 0 47
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 24 hours 0 sec
FEC: 2988074 519
CRC: 548 368
ES: 11 265
SES: 10 0
UAS: 3243 3233
LOS: 1 0
LOF: 7 0
LOM: 0 0
Since Link time = 1 days 1 hours 35 min 37 sec
FEC: 4167695 581
CRC: 0 412
ES: 0 309
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0

Edited by deleted (Sat 23-Jan-21 14:11:11)

What YOU want and what you get will be totally different.

In reply to a post by broadband66:

What YOU want and what you get will be totally different.

How, erm.. enlightening. Thank you!

It's an upto service and always will be depending on usage by others.

Slightly different cable lay and maybe a high level interferer has moved away from your pair or a damaged pair has been repaired dropping the noise from those.

IF, and it is a big IF, you could get a regrade to 80/20 then you might see the max achievable moving up to 45 to 48 wit a 3dB profile. Getting your provider to agree to a regrade when you will see just a marginal increase - you may have a battle.


The shotgun style you refer to is a combination of a multipair - maybe 50 or 100, cable paired with a steel strain or support cable.

I used to love a powercut when I had my HG612.

Not had a modem sync as fast as the HG612 since. They simply beat the routers to sync and you have little to zero crosstalk.

My line used to hold up quite well but eventually would end up resyncing due to crosstalk.