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SNR/Loop Att. recommendation

  • richardnaef
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22 Jan 2013 12:33 #74882 by richardnaef
SNR/Loop Att. recommendation was created by richardnaef
Hi,

What are the ideal/acceptable SNR and Loop Att. figures for ADSL2+ on a 2820 and ADSL on a 2600?

I had a check through Mikey's guide, but the only info I could find was http://www.draytek.co.uk/support/kb_adslstats.html and was identified as last updated "08 Jul 2105" and I'm stuck here in the 21st Century as my Tardis is undergoing essential maintenance atm after that unpleasant and messy event with the Face of Boe and a faulty Sonic Can-opener.

Live Long and Prosper!

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22 Jan 2013 17:09 #74891 by babis3g
Replied by babis3g on topic Re: SNR/Loop Att. recommendation
The Micky's guide is a basic information about adsl lines

Here some informations with my own words and not copy and paste

All lines are different, so to tell for a specific line what are best settings, you need to post line statistics from your modem (line synchronisation-mpbs or kbps,Loop Att, SNR etc, at Physical connection>>on line status) and describe your problem if is any

Each SNR is best to set according the line ( example adsl2+ short lines can do with lower snr but longer over 4-5 km needs higher the better ) and only your ISP can do that with out problems
Some times filters are very Important to terminate correct, an adsl/vdsl line but other factors as well can play important role but with small words is mainly the SNR can be adjusted to help solve problems

Are some modems (not with the drayteks) can adjust the SNR but are some cases the DLM (responsible for monitor errors in line) over writing the tweaked settings of the modem so problem still persist
Drayteks has the good think having firmware modem codes which helps stabilise the line (in a way line problems which is causing from different factors and few mentioned) ... according to dslam (at local exchange)

If you mean for VDSL and NOT adsl then can not really set SNR/Loop att at the moment even from ISP's (apart just reset the profile) because like adsl came out long years ago ... at first years was not allowed to make any tweaks as well (even with adsl)

So hoping got little more detailed infos, if you have problem with line may be better contact your ISP because we can only give advise and suggest firmwares codes here in the forum

Hope this helps

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23 Jan 2013 17:48 #74909 by richardnaef
Replied by richardnaef on topic Re: SNR/Loop Att. recommendation
OK, as requested here are stats from a 2820 router.

The history is that there have been many line drops on this line when using a combination of a 120 modem and 2955 Router. TalkTalk say the line is fine and it's our equipment. So to troubleshoot I have replaced the modem and 2955 with a 2820 - no there have been no line drops in the 2 days I've been running it BUT I notice the LA is now at 0 (it was 6 yesterday) - does anyone know if ) is very low or an error state and whether a 2820 might be more resilient that a 120/3300 combination?

ADSL Information ( ADSL Firmware Version: 232201_A)
ATM Statistics TX Cells RX Cells TX CRC errs RX CRC errs
3214328 207984 0 0
ADSL Status Mode State Up Speed Down Speed SNR Margin Loop Att.
ADSL2+(G.992.5) SHOWTIME 1020000 18671000 8 0


Model Name : Vigor2955
Firmware Version : v3.2.6
Build Date/Time : Wed Mar 17 16:13:48.9 2010

Model Name : Vigor2820
Firmware Version : 3.3.3_232201
Build Date/Time : Oct 23 2009 15:23:15
ADSL Firmware Version : 232201_A Hardware: Annex A

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23 Jan 2013 19:25 #74910 by babis3g
Replied by babis3g on topic Re: SNR/Loop Att. recommendation
Ok Thanks i am with TT as well

1st
Have to agree with TT that line seems ok because you are very very close to the TT LLU (exchange or dslam as i told you early) ... according to the stats you have provide (lucky you) so really can not be them wrong unless there is a fault at their equipment, which i dont think so

2nd
Loop attenuator is a measure feature to show how far your line length is
I have loop mainly around 29bd so this calculates that i am around 2.100m away from exchange
Your loop att from 0-6 is calculating that you are about 400m from exchange so just outside of it really
It is very very very good so not worry about it

3rd
your snr (8db) is fine but you need to focus with that at any modem
Perhaps if will fall down to 0,1 may give errors so have problem the connection but so close dont think will do give errors any more with the 2820
I am with snr 9 and when fall below 3db seems getting disconnected but i am 2.000m away (mentioned just to give you understand and i am not complaining because this is only happening winter with very very bad weather very rear times)

4th
Vigor 120 from what was reading around is a very good one but are some users complaining after 6 months of continues use fails
If they will connect it back after some time is fine again
So looks like by time something is wrong with continues use
I have mine because i find it special offer but only had it on (change firmware,give my own settings etc) only for 3 days and had no problems, but can not confirm cos did not use it for longer period to see if i will have same problem as others

Personal will blame the 120 modem

5th
I see your firmware is old
If you want you can go here (UK) http://www.draytek.co.uk/support/downloads.html
at right page will find your model and so download firmware 3.3.7.3 which is the latest
It may not help with speed but will have new features
You will need to use the rst file and do all settings from the begin manually (to avoid older firmware bugs)
But again if you ok how it works current firmware you dont need to upgrade.Just mentioned if you ever want in future

In summary it may was the 120 but I dont believe now with the 2820, you will have problem any more because is a solid good machine :)

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23 Jan 2013 21:27 #74911 by richardnaef
Replied by richardnaef on topic Re: SNR/Loop Att. recommendation
Babis3g

Thanks very much for your swift and detailed response.

I agree the 120 on the TT line is the main culprit. At the same site i also have a 120 on BT line and that has been working fine so I will now swap them over and see what happens.

I will update the firmware of the router when I am next on site.

Thanks again.

Richard

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25 Jan 2013 17:19 #74947 by babis3g
Replied by babis3g on topic Re: SNR/Loop Att. recommendation
Hi was looking something for my own interest and i find this about the update

IMPORTANT NOTE: Do not upgrade directly from 3.3.5 (and earlier) to 3.3.7.3.
Due to differences in the Web UI and functionality the router MUST first be
upgraded to 3.3.5.2 prior to upgrading to 3.3.7.3.

Upgrade your router to Version 3.3.5.2 first, and afterward upgrade the router
to Version 3.3.7.3.



Best take a look at release notes
http://www.draytek.co.uk/support/download/readme_v2820.txt

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