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[sceptic-al]

I have Zen FTTC (Huawei), which has been working great for over 3 years with sync of ~80Mbit/sec / ~20Mbit/sec, and actual transfer around 76Mbit/sec / 18Mbit.

A few weeks ago I noticed speed tests were showing just 45Mbit/sec / 12Mbit/sec. Last night I got round to having a look and got the following stats (I had to flash the open HG612 firmware, hence no history).

Code: [Select]

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 32090 Kbps, Downstream rate = 83296 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 54999 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): 15.4 15.5
Attn(dB): 13.3 0.0
Pwr(dBm): 12.8 3.0
VDSL2 framing
Bearer 0
MSGc: -6 26
B: 227 237
M: 1 1
T: 0 42
R: 12 16
S: 0.1319 0.3781
L: 14562 5374
D: 4 1
I: 240 127
N: 240 254
Q: 4 0
V: 0 0
RxQueue: 132 0
TxQueue: 33 0
G.INP Framing: 18 0
G.INP lookback: 31 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 885088
OHFErr: 8292 12
RS: 1120204988 1254024
RSCorr: 3082126 40
RSUnCorr: 0 0
Bearer 1
OHF: 2307859 0
OHFErr: 0 0
RS: 18462381 0
RSCorr: 255983 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 217427491 0
rtx_c: 5050784 0
rtx_uc: 17628 0

G.INP Counters
LEFTRS: 3188 0
minEFTR: 53788 0
errFreeBits: 29864213 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 3765963191 0
Data Cells: 54565242 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: 2494 12
SES: 83 0
UAS: 28 28
AS: 37069

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: 55120.28 20063.54

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: 11440/11440 4/4

Total time = 10 hours 18 min 17 sec
FEC: 3082126 40
CRC: 8292 12
ES: 2494 12
SES: 83 0
UAS: 28 28
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 3 min 17 sec
FEC: 6521 0
CRC: 14 0
ES: 5 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: 29116 0
CRC: 45 0
ES: 23 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 10 hours 18 min 17 sec
FEC: 3082126 40
CRC: 8292 12
ES: 2494 12
SES: 83 0
UAS: 28 28
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 = 10 hours 17 min 47 sec
FEC: 3082126 40
CRC: 8292 12
ES: 2494 12
SES: 83 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0

The thing that stands out for me is: Bearer:   0, Upstream rate = 19999 Kbps, Downstream rate = 54999 Kbps

I'm afraid I'm not experienced in reading the stats to fully understand if this Bearer result is a cause or affect.

Can someone give me any pointers for investigating further or has Zen/Openreach simply capped my line?

[niemand]

Your line is banded. Neither Zen or Openreach have done anything but line conditions have triggered banding.

This is I believe covered extensively on this very site.

[j0hn]

The automated DLM system has capped/banded your line as CarlT points out.

It's usually due to too many resyncs/reconnections in a 24 hour period.

The DLM applies banding in stages.
It will have capped the line at 74Mb, then 70Mb, then 66Mb, etc (rough example).
To get your line all the way down to 55Mb you've either had a number of days with lots of resyncs or 1 VERY bad day.

If it's caused by resyncs often this isn't due to line instability but is due to your own actions.
Swapping modems frequently or persistent configuring/rebooting of your modem can cause banding.
The power in your home being turned on/off a number of times can also cause the line to keep resyncing which can trigger banding.
Reading this you may suddenly be aware of what the cause is.

Zen may be able to look at some of their tools and see when DLM applied the banding or see when the line kept resyncing.
That might help pinpoint the cause of the banding.

The DLM can take days, weeks or even months to remove banding. It often removes banding in stages similar to how it was added.
Zen can also attempt to get a DLM reset by OpenReach which would remove the banding right away.
The underlying issue that caused the banding should be fixed before getting a DLM reset or it could just reapply the banding.

[tubaman]

The stats don't look great even now - over 2400 errored seconds in 10 hours of uptime is not good. Have you tried a quiet-line test on the phone line to see if there is anything obviously the matter with it?