Comparing 2x line stats? new and old? faster maybe?

first line stats:

DSL
Line Status:Connected
DSL Modulation Type:VDSL2
Annex Type:Annex A/L
Upstream Downstream
Current Rate (Kbps) 18972 62153
Max Rate (Kbps) 18961 61754
SNR Margin (dB) 5.8 2.6
Line Attenuation (dB) 26.5 12.4
Errors (Pkts) 0 0

Second line stats:

Line Status:
Connected

DSL Modulation Type:
VDSL2

Annex Type:
Annex A/L

Upstream Downstream
Current Rate (Kbps) 14933 48566
Max Rate (Kbps) 14933 49854
SNR Margin (dB) 6.2 6.3
Line Attenuation (dB) 22.5 10.7
Errors (Pkts) 0

im going to assume when the line drops to a 3db noise ratio in theory the second line is the better quality line?

also when openreach installed the line his machine esitimated the line at about 230m long or so if that helps?

It is a lower loss line which could be down to length or cable gauge.

If noise levels are the same then yes, it could be better, however noise levels can vary between lines even when the follow the same route.

Now, look at the upstream figures: The first is 18.9Mbps on a 26.5 dB attenuation, and the second has a lower attenuation at 22.5 which should given a higher rate, but it does not, the speed being significantly lower at 14.9 Mbps If the Margin was similar, 5.8:6.2, then the figures could be a little closer but not significantly.

You will need to wait and see if the new line gets near to the older one.

A drop from 6dB to 3dB is worth roughly 11-12Mb on a good short line that makes good use of the D3 band.

I'd expect line 1 to sync very slightly higher if both were on 3dB despite the higher attenuation.

The upstream is considerably better on line 1. It won't improve on line 2.

Edited by j0hn83 (Sat 09-Jan-21 23:08:02)

how long does DLM take to drop SNR on a new line? the upload would prob be more beneficial really so maybe the first line might be worth keeping as better speed, also first line seems better but we have the second line on vodafone which seems to have contention issues.

As short as a few days after a line goes live for the 1st drop to 5dB.
It can be on 3dB within a week.

Some lines will never drop SNRM despite appearing stable.

Agreed, have, I believe, from memory, seen 5 days.

Gut feel is that the second will fall short if it does drop to 3dB and it may try lowering but revert. It does appear to be a noisy line.


The downstream attenuations of 12 & 10 dB and 230m line. With max attainable at 3 dB being around 62Mbps - that is LOW, I would expect to see something well above 80 and potentially 90. Similarly, I would be looking for upstream above 20. It does suggest that there is a high level of noise on both lines.

Edited by MHC (Sun 10-Jan-21 11:59:25)

i assume thats 2 copper pairs going back to the cabinet and both have noise on them, what could be the culprit or could it be alluminium on some of the network? its just the vdsl line connected and no telephone.

also dsl checker info:

Featured Products Downstream Line Rate(Mbps) Upstream Line Rate (Mbps) Downstream Handback
Threshold(Mbps) WBC FTTC Availability Date WBC SOGEA Availability Date
High Low High Low
VDSL Range A (Clean) 73.1 52.2 20 13.8 46 Available Available
VDSL Range B (Impacted) 71.2 49 19.8 12.3 40 Available Available

Edited by MagicUK (Sun 10-Jan-21 12:50:48)

tonight DLM adjusted and issues a new IP:

Line Status:
Connected

DSL Modulation Type:
VDSL2

Annex Type:
Annex A/L

Upstream Downstream
Current Rate (Kbps) 16486 50451
Max Rate (Kbps) 16486 49192
SNR Margin (dB) 5.2 5.6
Line Attenuation (dB) 22.6 10.7
Errors (Pkts) 0 0

May not have been the DLM. My guess would be it wasn't.

The downstream SNRM lowered a little but not as much as the DLM lowers it.
The upstream SNRM also lowered which the DLM doesn't ever lower.

The DSLAM may have rebooted which is why your downstream sync is above the attainable and the SNRM dropped.

The attainable rate almost always increases when the SNRM is lowered.

Edited by j0hn83 (Tue 12-Jan-21 11:32:57)

L
Upstream Downstream
Current Rate (Kbps) 19142 58711
Max Rate (Kbps) 17270 50406
SNR Margin (dB) 3.3 3.4
Line Attenuation (dB) 22.5 10.7
Errors (Pkts) 0 0
WAN