Missing bandwidth can you find it?

when i moved at my property i had to wait for vdsl2 as the cab was full. Some couple of months later i got on vdsl2. For 2 years+ i sync at 80Mpbs with a full cabinit.

Just over 18 months ago i have noticed a degradation of my line. syncd at 74Mbps. Then for the last couple of months 66Mbps.

I have had 3-4 engineers out all of which can not find any problem. Engineers reported line length is 186M, there is no cross talk and no bridge taps. They mentioned that it could be to do with the thickness of the cables even though they could not tell me what my thickness was to the cab. The Best i can get is what i have and that the dsl checker needs updating to give a true reflection of actual attainable speeds.

Some little history, about a year into my first year on vdsl2 they built a new vdsl2 cab and moved the PCP next to the new dslam (huawei) , leaving the old eci cab where it was which is the one i am connected to. during this time there was no changes to my sync. I have no idea if this is a cause.

Any one care to find the missing bandwidth? Its a little mystery for me.

In reply to a post by RedBull2k14:

Engineers reported line length is 186M, there is no cross talk and no bridge taps.

No cross talk - rubbish. Unless you have a single pair running in its own duct away from everything else.


Can you find and list your router stats.

Can you please post your line stats from your router so that we can see how your line is performing. In particular upstream / downstream SNR and attenuation and any other line information your router provides, such as interleave depth etc...

You should be able to access it via the router's we interface

Thanks

Yes I can post them when I get home after work

As MHC says …. it’s crosstalk.

In reply to a post by RedBull2k14:

Engineers reported line length is 186M, there is no cross talk and no bridge taps.

Full cabs means more crosstalk than a single connection in a new cab.

In reply to a post by RedBull2k14:

They mentioned that it could be to do with the thickness of the cables even though they could not tell me what my thickness was to the cab.

The chances are, that they were the same thickness as when you were getting 80mbits.

Do post the stats regardless cos there may be a fault but its more likely to be crosstalk

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 28119 Kbps, Downstream rate = 65960 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 68810 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): 5.4 11.7
Attn(dB): 9.2 0.0
Pwr(dBm): -5.9 -5.8
VDSL2 framing
Bearer 0
MSGc: 18 150
B: 239 236
M: 1 1
T: 22 5
R: 0 16
S: 0.1110 0.3771
L: 17296 5410
D: 1 1
I: 240 255
N: 240 255
Counters
Bearer 0
OHF: 432415363 1077573
OHFErr: 538 490
RS: 0 2915576
RSCorr: 0 12869
RSUnCorr: 0 0

Bearer 0
HEC: 107 0
OCD: 5 0
LCD: 5 0
Total Cells: 2090373280 0
Data Cells: 1657615037 0
Drop Cells: 0
Bit Errors: 0 0

ES: 488 468
SES: 0 0
UAS: 24 24
AS: 795130

Bearer 0
INP: 0.00 0.00
INPRein: 0.00 0.00
delay: 0 0
PER: 1.83 6.15
OR: 104.41 202.87
AgR: 68914.80 20203.27

Bitswap: 389460/389460 1106/1121

Total time = 1 days 4 hours 52 min 34 sec
FEC: 0 12869
CRC: 538 490
ES: 488 468
SES: 0 0
UAS: 24 24
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 7 min 34 sec
FEC: 0 2
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: 0 4
CRC: 1 0
ES: 1 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 4 hours 52 min 34 sec
FEC: 0 105
CRC: 20 11
ES: 17 10
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 24 hours 0 sec
FEC: 0 655
CRC: 64 46
ES: 58 45
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 9 days 4 hours 52 min 9 sec
FEC: 0 12869
CRC: 538 490
ES: 488 468
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 28119 Kbps, Downstream rate = 65728 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 68810 Kbps

Discovery Phase (Initial) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (33,857) (1218,1959) (2795,4083)
Medley Phase (Final) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (41,857) (1218,1959) (2795,4083)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 28119 kbps 65728 kbps
Actual Aggregate Tx Power: - 5.8 dBm - 5.9 dBm
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4
D1 D2 D3
Line Attenuation(dB): 0.1 7.6 11.2 N/A N/A 5.1 10.6 17.7
Signal Attenuation(dB): 0.1 7.6 11.1 N/A N/A 6.1 10.6 17.8
SNR Margin(dB): 10.5 13.0 11.2 N/A N/A 5.4 5.4 5.4
TX Power(dBm): -10.4 -36.1 -7.9 N/A N/A 10.1 7.4 7.5

The proof is there ... crosstalk or noise.

SNR 5.4dB - so it is working to a 6dB margin and there is obviously a lot of crosstalk or noise on a short low attenuation line

Here's some background informatino to understand what's going on:
https://www.increasebroadbandspeed.co.uk/2014/vector...