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835 posts

Ultimate Geek
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Topic # 31278 11-Mar-2009 14:09
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Hello

I have found that recently my modem fails dsl synchronisation typical once a day sometimes more

My modem has been synchronising for dsl2+ for quite a number of months so this issue is new. What is interesting is that when I force my modem back to g.dmt [dsl1] the problem does not occur.

Note I subscribe to a FS/128 plan so don't currently benefit from dsl2+ but this will  be an issue as soon as I upgrade to a FS/FS plan which I was considering

Could the issue be my local exchange is over subscribed for dsl2+ i.e. that frequency is overloaded ?

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8027 posts

Uber Geek
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  Reply # 200620 11-Mar-2009 14:44
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Is it your DSL connection or PPP session disconnecting?  Most routers have two lights one incidating DSL connection and another indicated an authentiated ppp session with your ISP.  Are you able to reconnect fairly quickly after the disconnection?  Is it random/intermittant or always around the same time of day?

Anyway could be any of these...

1:  Firmware problem in your modem/router
2:  Hardware problem in your modem/router
3:  Dodgy ADSL filters
4:  Dodgy internal phone wiring in your home
5:  Line issue or fault between the demarc at your house and the exchange or cabinet
6:  Dodgy port at the exchange/cabinet

It's fairly straight foward to rule out 1-4, eg: update the modem/routers firmware, try the router at a friends, try a different router.  Replace the adsl line filters or unplug analogue devices for a day see if you get disconnected.

For 5-6 you need to ring your ISP and get them to do some line tests etc.

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Master Geek


  Reply # 200690 11-Mar-2009 19:55
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I had a similar problem... if memory serves me correctly it was in the relatively brief period of time between my exchange going ADSL2+ capable and being cabinetised.  I also had to force G.DMT modulation to get a stable connection.  That was with a Netgear DG834Gv2 modem on Orcon FS/FS bitstream, with roughly 41 dB of downstream attenuation.  I was occasionally able to go for a few days with a stable ADSL2+ connection though, so it was somewhat intermittent.  One would expect ADSL2+ to be less stable than G.DMT as a general rule, since it utilises a wider band of frequencies, but it does depend on your port configuration. 

It may be that your config is simply too aggressive for your line quality... and your ISP should be able to assist with that... although obviously there's no point in sacrificing speed for stability if you end up worse off than you would be with G.DMT modulation.

Post more info on your modem and connection (stats like attenuation, etc.) to get more accurate advice.

 
 
 
 




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Ultimate Geek
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  Reply # 200703 11-Mar-2009 20:31
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Here is my stats whilst on g.dmt


Line ModeG.DMT Line StateShow Time  
Latency TypeInterleave Line Up Time00:14:42:54 
Line CodingTrellis On Line Up Count

StatisticsDownstreamUpstream
Line Rate7616 Kbps160 Kbps
Attainable Line Rate8960 Kbps1152 Kbps
Noise Margin14.8 dB31.0 dB
Line Attenuation26.0 dB13.0 dB
Output Power19.8 dBm11.6 dBm

and here are the stats for dsl2+


Line ModeADSL2+ Line StateShow Time  
Line Power StateL0 Line Up Time00:00:00:59 
Line CodingTrellis On Line Up Count

StatisticsDownstreamUpstream
Line Rate11594 Kbps166 Kbps
Attainable Line Rate14424 Kbps945 Kbps
Noise Margin12.2 dB41.0 dB
Line Attenuation28.5 dB13.1 dB
Output Power19.6 dBm12.2 dBm

When the dsl2+ only problem occurs the dsl lights goes off and only a soft or hard reset of the modem resolves the issue. On a good day I get just over 4Mbit download at peak times say 2.5Mbit.

I am also curious as to what I would get on a FS/FS plan



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Master Geek


  Reply # 200738 11-Mar-2009 22:14
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Your download rates would only be limited by your downstream sync rate on FS/FS, so you could expect an upper bound of just under 10 Mbps on ADSL2+.

If you search the Whirlpool forums, you'll find you're not the only one who has experienced ADSL2+ stability issues on an RTA1320 modem.  Whether your particular modem is faulty (e.g. one or more bad capacitors) remains to be verified, but I certainly wouldn't rule it out.  If you're able to borrow an ADSL2+ capable modem from someone else just to test, it wouldn't hurt to do so... your ISP might even be nice enough to lend you one, or at least advise you on the matter (they may have encountered similar cases before).  In any case, your modem seems the most likely culprit... it's not unheard of for them to deteriorate over time due to wear on the electrical components (exacerbated by poor cooling).

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  Reply # 200793 12-Mar-2009 11:47
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Yeah I would suspect the modem if it's requiring  hard reset to fix.  Try updating the firmware.

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