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Any benefit of ADSL2 for long line? Advice please

maranello
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Any benefit of ADSL2 for long line? Advice please

My connection was moved from 20CN to 21CN, still on ADSL1. This gave me an increase in speed from around 1.75 to 2.5Mbps. Downstream attenuation, as reported by the router, changed from 63.5dB to 60.5dB. My connection remains stable, with an uptime in excess of 45 days.
Would there be any further improvement possible on ADSL2 (G.992.3)?
Are there any potential downsides?
My other car isn't a Ferrari
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Re: Any benefit of ADSL2 for long line? Advice please

It's possible you might see an improvement, but it could also make the line unstable. I think you are going to have to try it and accept you might need to move back if it doesn't pan out.
jelv (a.k.a Spoon Whittler)
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maranello
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Re: Any benefit of ADSL2 for long line? Advice please

What could cause the instability?
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Re: Any benefit of ADSL2 for long line? Advice please

When you switch ADSL mode it changes the frequencies used. It may be that on higher frequencies it gets a lot of errors forcing more resyncs and possibly a higher target noise margin.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
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Re: Any benefit of ADSL2 for long line? Advice please

What if you set your modem to ADSL2 and not ADSL2+? Then it would use the same frequency range as ADSL1.
Do all the tones with no bits allocated to them really cause that much trouble? On a long line, there probably won't be any bits allocated to any of the highest frequency tones in the ADSL1 range.
PeeGee
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Re: Any benefit of ADSL2 for long line? Advice please

ADSL2 may be a benefit - ADSL2 with 3.5dB SNRM and 60dB attenuation is giving me 3.8Mbps; tones from 147 to 178 are 4 bits or less Roll eyes
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link Archer VR600 modem-router.
Plusnet Help Team
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Re: Any benefit of ADSL2 for long line? Advice please

@maranello
If you wish to give it a try we don't mind changing you over, then back again if you weren't happy. Each order we need to place should only take one working day to complete.
Adam
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
maranello
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Re: Any benefit of ADSL2 for long line? Advice please

Yes please Adam.
Up until now, the response I've received from Plusnet staff on the forum has always been to state that the policy was not to move customers with long lines onto ADSL2+ due to instability issues, but no mention of ADSL2.
Router is currently configured to automatically connect using the detected modulation (if that's the correct terminology). Do I need to change it to ADSL2 only to ensure it doesn't attempt to connect using ADSL2+?  I would like to avoid this possibility as it could appear as an unstable line so that target noise margin is increased
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Re: Any benefit of ADSL2 for long line? Advice please

I am a little late to this but in my case with a not very long line 49dB attenuation I have a more stable line on ADSL1 than ADSL2 both with uncapped upstream - so suck it and see is the best advice
The one thing is that with ADSL1 you are stuck with a 6dB minimum noise margin whereas on ADSL2 I believe it can drop to 3dB with an improvement in speed. My line just won't stand that but some may and the only way mine would improve is replacement of the main inter connectors from the exchange to the primary cab and possibly from the primary cab to the secondary cab (not many people have those but it is because of the dispersed properties in my area)
PeeGee
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Re: Any benefit of ADSL2 for long line? Advice please

Quote from: maranello
Do I need to change it to ADSL2 only to ensure it doesn't attempt to connect using ADSL2+?

I would, at least, start by "forcing" ADSL2 as you suggest and see how it goes. It may be beneficial to log the bit loading information (on the 585v7 it is the telnet command  "xdsl debug bitloadinginfo" ) whilst using ADSL1, then with ADSL2. It will probably stop well before tone 256, tailing off from about 150 (max is 15 bits) - so the additional ADSL2+ tones would have no beneficial effect.
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Re: Any benefit of ADSL2 for long line? Advice please

It should go to ADSL2 automatically - you can easily check by looking here http://192.168.1.254/cgi/b/dsl/dt/?ce=1&be=0&l0=1&l1=0 under DSL Type assuming that you have a Plusnet router
ITU-T G.992.1 is ADSL1
ITU-T G.992.3 is ADSL2
ITU-T G.992.5 is ADSL2+
PeeGee
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Re: Any benefit of ADSL2 for long line? Advice please

Quote from: Oldjim
It should go to ADSL2 automatically

Yes ... and no Shocked It's some time since I selected ADSL2 instead of Auto, but ISTR that every now and again it would switch to ADSL2+ for a couple of hours and then fall back to ADSL2, dropping the sync speed. A couple of those and you are down from a reasonably stable 32.5Mbps to 1.6Mbps and double figures SNRM Cry I must admit that I haven't tried ADSL2+ since my line was repaired as I'm happy with a stable 3.8Mbps and an indicated SRNM of 3.5 +- 0.5dB  Cheesy
Edit: just spotted a trypo Shocked
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
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Re: Any benefit of ADSL2 for long line? Advice please

Mine always did on a 49dB line
maranello
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Re: Any benefit of ADSL2 for long line? Advice please

Thanks for the advice.
@Oldjim - allowing the router to autoselect would be the most convenient, I didn't know if Plusnet could change my connection to ADSL2 specifically.
@PeeGee 
Quote
telnet command  "xdsl debug bitloadinginfo"
I haven't a clue how to do this. I have the Plusnet supplied TG582n router.
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Re: Any benefit of ADSL2 for long line? Advice please

Easier way - install routerstats and you will get it automatically in graphical format http://www.vwlowen.co.uk/internet/files.htm