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Author Topic: Technical question on bit swapping  (Read 5724 times)

Oldjim

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Technical question on bit swapping
« on: September 21, 2010, 06:37:50 PM »

Apologies if this is in the wrong place
A bit of history
On Saturday evening my connection went bad with very high error rates for about 2 hours.
It then settled down but at about 1:00am the error rate went so high it lost sync and the rate dropped from 4256 to 3776 kbps.
The odd thing was that while this was happening there was no downstream bit swapping at all taking place. Note that this lack of bit swapping started after a resync on Saturday morning for no obvious reason..
I rebooted the router on Sunday afternoon (4384kbps).
Since then there has been significant bit swapping and the line has been stable.
My question is whether the lack of bit swapping (which almost certainly caused the high error rates and very low noise margin - about 3dB)) was likely to be due to an exchange problem or the router.
The router is a Netgear DG834G v4 and the bit swapping is monitored by Routerstats
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Jim
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jeffbb

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Re: Technical question on bit swapping
« Reply #1 on: September 21, 2010, 10:37:12 PM »

Hi
I cannot be 100% sure but It may well be a router problem. I believe the router requests bit swapping and its agreed by the dslam which channel and time . I had a similar problem with my DG834gt. After some time hours/days the bitswap would stop working .The main difference is that my line was very quiet anyway and it did not seem to create a problem. I then swapped back to my dg834 v4 and had no further loss of bit swapping .

you can try using telnet     :adslctl configure --bitswap on  (with thanks to Roseway)

Regards Jeff
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Oldjim

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Re: Technical question on bit swapping
« Reply #2 on: September 21, 2010, 10:52:15 PM »

Thanks Jeff
If it happens again I will try the telnet command to see if that fixes it
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Jim
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Oldjim

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Re: Technical question on bit swapping
« Reply #3 on: September 22, 2010, 01:25:05 PM »

Just to add - the router just decided to resync twice in quick succession for no apparent reason so I have ordered a Netgear DG834G (presumably v5) from Amazon and will see how that works.
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Jim
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jeffbb

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Re: Technical question on bit swapping
« Reply #4 on: September 22, 2010, 06:47:57 PM »

Hi

The V5 cannot be tweaked ! its not the same chip set .
edit :I am not  sure it will work with DMT? can someone confirm

see http://www.kitz.co.uk/routers/DMTv8.htm

Regards Jeff
« Last Edit: September 22, 2010, 07:02:09 PM by jeffbb »
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Oldjim

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Re: Technical question on bit swapping
« Reply #5 on: September 22, 2010, 08:08:37 PM »

I will be using Routerstats to monitor it
I am not bothered about tweaking at the moment as I have a 6dB default noise margin
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Jim
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jeffbb

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Re: Technical question on bit swapping
« Reply #6 on: September 22, 2010, 10:08:57 PM »

Hi
I use Routerstats on my v4 ,its very good .very good .

Regards Jeff
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Azzaka

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Re: Technical question on bit swapping
« Reply #7 on: September 24, 2010, 10:16:23 AM »

The v5 works best under 2km from the exchange. Anything over that it is a relatively hit and miss affair.
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Oldjim

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Re: Technical question on bit swapping
« Reply #8 on: September 24, 2010, 02:21:36 PM »

If it is much worse it will be going back to Amazon  ;D
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Jim
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Oldjim

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Re: Technical question on bit swapping
« Reply #9 on: September 25, 2010, 10:44:43 AM »

Definitely a miss
Reported attenuation up from 51dB to 53.5dB
Speed down from 4416kbps at 6.3dB noise margin to 3956kbps at 6dB noise margin
I hope it hasn't had time to drop my IP profile  :(
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Jim
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Azzaka

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Re: Technical question on bit swapping
« Reply #10 on: October 06, 2010, 05:13:21 PM »

Put the other back on and Monitor. If you're interested in getting a tad bit more speed, try a DGN1000. I know its not a Broadcom chip but you would be surprised how well it works.
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Oldjim

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Re: Technical question on bit swapping
« Reply #11 on: October 06, 2010, 05:26:50 PM »

The v4 is running quite happily at 4000kbps 3,500 IP profile  (I tweaked it down to that as anything over 4400kbps has massive errors over night when the noise margin drops below 3.5dB)
Why do you say I would be surprised - I read the reviews on Amazon and there seems to be quite a few problems with that router although, to be fair, not in relation to connection speed
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Jim
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Azzaka

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Re: Technical question on bit swapping
« Reply #12 on: October 20, 2010, 09:12:55 AM »

The issues are with the wireless and not the connection speeds themselves. I have noted the reviews and hence I said you would be suprised.
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