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Standard User MagicUK
(learned) Sat 09-Jan-21 21:38:54
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Comparing 2x line stats? new and old? faster maybe?


[link to this post]
 
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?
Standard User MHC
(sensei) Sat 09-Jan-21 22:10:52
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
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.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User j0hn83
(fountain of knowledge) Sat 09-Jan-21 23:07:14
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
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)


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Standard User MagicUK
(learned) Sun 10-Jan-21 09:03:08
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MHC] [link to this post]
 
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.
Standard User j0hn83
(fountain of knowledge) Sun 10-Jan-21 11:27:32
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
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.
Standard User MHC
(sensei) Sun 10-Jan-21 11:53:19
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: j0hn83] [link to this post]
 
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.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit

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

Standard User MagicUK
(learned) Sun 10-Jan-21 12:44:58
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MHC] [link to this post]
 
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)

Standard User MagicUK
(learned) Tue 12-Jan-21 05:35:44
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
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
Standard User j0hn83
(fountain of knowledge) Tue 12-Jan-21 11:30:49
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
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)

Standard User Magicuk27
(regular) Fri 15-Jan-21 01:04:49
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: j0hn83] [link to this post]
 
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
Standard User j0hn83
(fountain of knowledge) Fri 15-Jan-21 01:12:15
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: Magicuk27] [link to this post]
 
There's been a local power cut or a DSLAM reboot.

Check how low the max rates are which is where the line would resync right now.

The increase in sync you see is a result of you reconnecting before other lines.
Standard User MagicUK
(learned) Fri 15-Jan-21 02:12:19
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: j0hn83] [link to this post]
 
powercut at about midnight for about a second so your correct, so looks like il be getting 58mb max on sync and about the 3.3db on the upstream, is that alound on openreach cabinets as i thought it was only downstream that could drop and the upstream should always stay at 6?
Standard User j0hn83
(fountain of knowledge) Fri 15-Jan-21 02:49:53
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
There's a target SNRM set by the DLM and there's the current SNRM. Also known as the target noise margin and current noise margin.

Your line has a target of 6dB (up and down) but it's running lower than that.

You connected at the 6dB target before other lines on the cabinet. As those lines weren't there you synced higher.
The other lines connected after you (likely within a minute). The noise the other lines create (known as crosstalk) knocks the current SNRM (noise margin) down.

The max rate reported knows the target SNRM is 6dB so the max rate is still low.
If/when the DLM lowers the SNRM target to 5dB the max rate will increase.

Your line jumping straight from 6dB to 3dB and the max data rate staying low suggests a power cut or the cabinet rebooting.
The DLM only ever moves the target SNRM in 1dB steps.

The upstream is always a fixed 6dB target (some modems target 6.3dB)
Standard User MagicUK
(learned) Sat 16-Jan-21 09:51:52
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: j0hn83] [link to this post]
 
Little update, another resync this morning and back to default 6db but have adjusted to fastpath as latency has dropped on broadband quality monitor:

Line Status:
Connected

DSL Modulation Type:
VDSL2

Annex Type:
Annex A/L

Upstream Downstream
Current Rate (Kbps) 17343 48077
Max Rate (Kbps) 17343 49421
SNR Margin (dB) 6.1 6.4
Line Attenuation (dB) 22.5 10.7
Errors (Pkts) 0 0

My Broadband Ping

Edited by MagicUK (Sat 16-Jan-21 09:56:07)

Standard User j0hn83
(fountain of knowledge) Sat 16-Jan-21 10:14:15
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
Not so sure of that myself.

Interleaving adds a minimum 8ms latency and knocks about 10% of the potential sync.
With interleaving enabled the max rate reported is exaggerated and incorrect.

If the line went to fastpath sync should go up, max rate down, latency would drop by 8ms.

Only the latency changed, by what looks like less than 8ms (hard to tell on a BQM).

It could just be a change of routing from the ISP.

Does your modem have any more stats?
Standard User MagicUK
(learned) Mon 18-Jan-21 07:53:20
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: j0hn83] [link to this post]
 
no further stats as using a 9970 modem, line dropped at 3am and SNR on downstream dropped to 5:

Line Status:
Connected

DSL Modulation Type:
VDSL2

Annex Type:
Annex A/L

Upstream Downstream
Current Rate (Kbps) 15175 51192
Max Rate (Kbps) 15175 53372
SNR Margin (dB) 6 5.4
Line Attenuation (dB) 22.5 10.7
Errors (Pkts) 0 0
Standard User MagicUK
(learned) Mon 15-Feb-21 20:59:43
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Re: Comparing 2x line stats? new and old? faster maybe?


[re: MagicUK] [link to this post]
 
switched back to my huewei 3b modem, line seems to have improved, no g.inp on upstream yet and at 4db snr on down stream also!

DSLAM type / SW version: BDCM:0xa4a1 (164.161) / v0xa4a1
Modem/router firmware: AnnexA version - A2pv6C038m.d24j
DSL mode: VDSL2 Profile 17a
Status: Showtime
Uptime: 11 hours 22 min 56 sec
Resyncs: 1 (since 14 Feb 2021 07:28:49)

Downstream Upstream
Line attenuation (dB): 17.7 0.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 61571 17763
SNR margin (dB): 4.1 6.0
Power (dBm): 13.5 7.6
Interleave depth: 4 1
INP: 52.00 0
G.INP: Enabled Not enabled
Vectoring status: 5 (VECT_UNCONFIGURED)

RSCorr/RS (%): 0.0018 0.1561
RSUnCorr/RS (%): 0.0000 0.0000
ES/hour: 1.19 2.43
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