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Downstream SNR Target - Reset to 6dB please

RTNI
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Registered: 28-04-2014

Downstream SNR Target - Reset to 6dB please

Hi @Gandalf

 

Ive noticed that our connection is dropping more than usual over the last number of days and that the reason for this appears to be a reduction in the SNR margin downstream from the usual 6dB.

 

Given that we are in a rural location and the length of the line could you please reset the target SNR for downstream to 6dB to give us a bit more "margin" and increased stability?

 

Thank you.

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RTNI
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Registered: 28-04-2014

Re: Downstream SNR Target - Reset to 6dB please

Opening up to other staff members also to do this?

Plusnet Help Team
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Re: Downstream SNR Target - Reset to 6dB please

Hi there.

 

Given that we are in a rural location and the length of the line could you please reset the target SNR for downstream to 6dB to give us a bit more "margin" and increased stability?

We can't reset fibre lines I'm afraid. Though it doesn't look like you're on a target SNR of 3db.

Profile Name 0.128M-40M Downstream, Error Protection Off - 0.128M-10M Upstream, Error Protection Off

 

Testing your line isn't finding the cause of the drops.

 

Is your router in the optimal position, i.e. the test socket?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
am77
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Registered: 26-03-2013

Re: Downstream SNR Target - Reset to 6dB please

I may be wrong but it's not possible on Fibre to change the target margin manually via the ISP as you can if you were on ADSL(2).  Basically the DLM (automated system) will take care of line margins and if "it" thinks it's safe to reduce it then it will do so, if it's not then "it" will increase it.  

 

An engineer can also do this but usually only to clear a fault. 

 

If your connection is unstable perhaps check to see if there are no faults on your voice side i.e no crackles, hiss, etc and if there aren't any then go through the faults procedure to see if it picks anything up. 

 

=)

 

Edit: I was beaten to it but I'll leave this up 

RTNI
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Re: Downstream SNR Target - Reset to 6dB please

Speed on the line has been increasing from 20MB to now 30MB which is clearly too fast for the line to support and the SNR was recorded at 4.4dB last night (see below)

 

5. DSL uptime:

0 days, 00:28:44

6. Data rate:

6649 / 31562

7. Maximum data rate:

6649 / 34057

8. Noise margin:

6.1 / 4.5

9. Line attenuation:

31.3 / 27.1

10. Signal attenuation:

31.0 / 24.5

 

It has been stable for weeks now.  What can be done to provide more stability on the line?  Reduce the data rate?  To be clear the length of the line is circa 1600m as I recall to the cabinet.

am77
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Registered: 26-03-2013

Re: Downstream SNR Target - Reset to 6dB please

4.4dB should be fine, in fact there is slow rollout from BT in that if your line can support 3dB then it'll run at that speed.

 

 

Again it's up to the DLM systems in place, if it thinks it's unstable i.e too many errors or frequent drop outs it'll try adding interleaving to the line & / or increasing the SNRm back towards 6dB or higher.

 

This DLM process is constantly on (unless it gets stuck, which is fairly rare) and your line will adjust over a period of weeks unless there is a sudden fault.  

So if there is no fault on your line or with your equipment then suffer the stability problems for a couple of days whilst the DLM is doing it's thing and it'll go back to being stable without you noticing it. 

bluewhale
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Re: Downstream SNR Target - Reset to 6dB please

out of interest are you using the plusnet hub one on it's own, ie as the vdsl modem

have you done a quiet line test yet?

RTNI
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Re: Downstream SNR Target - Reset to 6dB please

Yes it's the hub one by itself and just done a quiet line test via corded phone and all appears to be fine. 

 

Its clearly no coincidence that the drops have started when the DL speeds have increased by 33% on a line of some 1600m that I was told could only support 20MB at best!

Moderator's note by Mike (Mav): Full quote of preceding post removed as per Forum rules.

RTNI
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Registered: 28-04-2014

Re: Downstream SNR Target - Reset to 6dB please

Just had another drop. Saw this in the logs:

 

(1855601.940000) PPP LCP Send Termination Request [User request]

 

I didnt request a termination though?

 

Can my IP profile be changed to a lower speed (say 20MB)?

Plusnet Help Team
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Re: Downstream SNR Target - Reset to 6dB please

We’ve got no tools to remotely change fibre lines I’m afraid. Is your router in the test socket?
If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
RTNI
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Re: Downstream SNR Target - Reset to 6dB please

No the router is in the new filtered faceplate fitted by BT engineer a few months ago. 

 

Its clearly a case of the line being overstretched. The router seems to take a good while to reconnect (circa 90 seconds) not sure if that's normal?

 

Do you want the router connected to the test socket and if so what will that let you do?

Plusnet Help Team
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Re: Downstream SNR Target - Reset to 6dB please

The test socket will fully rule out your internal wiring from affecting your connection.
If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
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RTNI
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Re: Downstream SNR Target - Reset to 6dB please

Ok it's now in the test socket behind the front face of the 5C filtered faceplate still showing a 4 dub SNR

 

1. Product name: Plusnet Hub
2. Serial number: +081441+NQ72611058
3. Firmware version: Software version 4.7.5.1.83.8.237.2.2 Last updated 21/09/17
4. Board version: Plusnet Hub One
5. DSL uptime: 0 days, 00:03:06
6. Data rate: 6743 / 34080
7. Maximum data rate: 6743 / 36239
8. Noise margin: 6.0 / 4.2
9. Line attenuation: 31.1 / 27.1
10. Signal attenuation: 30.9 / 24.1
11. Data sent/received:

Plusnet Help Team
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Re: Downstream SNR Target - Reset to 6dB please

Thanks for that. I’d leave it in that position overnight if you can and I’ll check your connection tomorrow to see if the drops have become less frequent.
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 Anoush Mortazavi
 Plusnet Help Team
Plusnet Help Team
Plusnet Help Team
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Re: Downstream SNR Target - Reset to 6dB please

It looks like your connection is stable since last night:

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 Anoush Mortazavi
 Plusnet Help Team