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Author Topic: Strange upstream attenuation figure  (Read 4366 times)

curls

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Strange upstream attenuation figure
« on: January 18, 2007, 07:47:56 PM »

I've asked about this elsewhere but not been able to get an answer. Fingers crossed. :)

The readings below are from my 3Com 3CRWDR100A-72 router. Note the 63dB for the upstream attenuation

Data Rate
Stream Type   Actual Data Rate
Up Stream   288 (Kbps.)
Down Stream   2272 (Kbps.)


Operation Data
Operation Data    Upstream    Downstream
Noise Margin   23 dB   16 dB
Attenuation   63 dB   31 dB

Defect Indication
Indicator Name    Near End Indicator    Far End Indicator
Fast Path FEC Correction   0   0
Interleaved Path FEC Correction   0   0
Fast Path CRC Error   35   60
Interleaved Path CRC Error   0   0
Loss of Signal Defect   0   ---
Fast Path HEC Error   0   0
Interleaved Path HEC Error   0   0


Statistics
Received Cells   83653938
Transmitted Cells   7982184

I get around 240kB/s download and 30kB/s upload, which is what I would
expect with a two meg connection. I am with Pipex.

The 63dB attenuation figure stays the same no matter what I do. The others
have changed practically every time I check them, as I would expect.
That 16dB download noise margin is normally about 26 to 30dB and seems to
come down to 16-17db when it is raining. The figures don't change much whether
I have the router plugged into the master socket, the test socket, or at the end
of two 5 metre extension leads. I am about 1.3km from the exchange by road.

Can anyone tell me what's happening here with that 63dB attenuation figure,
and if it's going to affect me if I move to Be, expecting a 24 meg connection?
(I'm not *really* expecting that  speed. :) )
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roseway

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Re: Strange upstream attenuation figure
« Reply #1 on: January 19, 2007, 08:09:02 AM »

Hi curls, welcome to the forum.

I don't know the answer, but it looks like a router firmware bug to me (i.e. incorrect reporting). If there is a firmware upgrade it might be worth installing it.

Eric
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  Eric

kitz

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Re: Strange upstream attenuation figure
« Reply #2 on: January 19, 2007, 11:57:15 AM »

Hi and welcome

As you say the high attenuation is unusual.. normally downstream is the higher of the 2.
Attenuation is normally related to the length of your line and remains static... normally only affected by line length, quality of line (eg aluminium joints) or a general line fault.

On top of that the maximum figure that most routers will report is 63dB and aside from the high upstream those figures look ok.  Out of curiousity is it possible to borrow another router to rule out that its not the router thats recording the stats incorrectly?
Also follow roseways advice - check for firmware updates.


The only possible clue could be
>> and seems to come down to 16-17db when it is raining.
This could indicate a fault on your physical phone line, but the problem you have is trying to get BT to act on something that they would deem to currently work ok.

Do you have any noise on your phone line.
Try doing a "quiet line phone test" by dialling 17070 and selecting the relevant option (2).

All your other stats (few CRC errors in view of data transferred and downstream) would point to you being able to get approx 4Mb on maxdsl.  Your current upstream figures on max may well just about scrape through without taking anything away from your downstream speeds.
How your line would cope on adsl2+ (be*) I really dont know, the higher available upstream bandwidth could impact on your downstream... but then again adsl2+ will give you more leaway on your downstream... therefore  you certainly shouldnt be any worse off.
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curls

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Re: Strange upstream attenuation figure
« Reply #3 on: January 19, 2007, 02:38:12 PM »

Thanks for the replies.

I just checked and I have the latest firmware for the router. I don't know anyone else with a router that I could borrow, so that's out too. My only option is to connect my old Alcatel Speedtouch USB "stingray" and see if I can get stats from that with Dr Speedtouch.

Quote
Try doing a "quiet line phone test" by dialling 17070 and selecting the relevant option (2).
I can hear, but only just, a very faint buzzing, but that could easily be the wireless phone I suppose. Heh, I only binned my old phone last week.

If it looks like I can only get 4Mb, I'll stay as I am seeing as my 2 meg line is stable.

Thanks again.
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kitz

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Re: Strange upstream attenuation figure
« Reply #4 on: January 20, 2007, 12:42:40 AM »

>> my old Alcatel Speedtouch USB "stingray" and see if I can get stats from that with Dr Speedtouch

worth a try. :)
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curls

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Re: Strange upstream attenuation figure
« Reply #5 on: January 21, 2007, 11:02:57 AM »

It's definitely looking healthier from the old Alcatel Speedtouch USB:

ReceiveAttenuation_dB= 31
ReceiveMargin_dB= 28
SendAttenuation_dB= 31
SendMargin_dB= 24

I might be going to Be after all.
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roseway

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Re: Strange upstream attenuation figure
« Reply #6 on: January 21, 2007, 11:17:54 AM »

Those figures look quite reasonable, and you should get a much faster connection with Be LLU. With BT Max you would probably get the full 8192 kbps.

Eric
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mr_chris

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Re: Strange upstream attenuation figure
« Reply #7 on: January 22, 2007, 09:53:21 AM »

I'd say you'd almost definitely get the full 8Mb from BT Max, and from ADSL2+ you may even see around 10-12Mbps ;D
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Chris

kitz

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Re: Strange upstream attenuation figure
« Reply #8 on: January 22, 2007, 07:01:44 PM »

Much better stats.
 
the SNR Margin is also very much better and things are now looking good.

Looks like it was your router Im afraid :/
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