Line Quality for 2 MBits?

Hi Guys,

I wonder if someone more knowledgeable could clarify the following line
stats for me?

A customer reports that following an regrade to a 2 Mbit service they are no
longer able to connect via their fairly ancient router (connexant access
runner based).

The symptoms are basically a failure to authenticate with their ISP. The ISP
is not reporting any issues their end. However just prior to the regarade
everything was reported as operating correctly and they were not
experiencing any Internet or ADSL connectivity issues.

Their router reports the following line stats:

SNR Margin: Downstream -> 34 / 35 dB (fluctuates between these values)
SNR Margin Upstream -> 27 dB
Line Attenuation Downstream: 8.3 dB
Line Attenuation Upstream: 8.0 dB

We should probably conclude that these figures may be inaccurate but they
are hopefully not to far off the correct values.

Would these stats indicate that their phone line might not be good enough to
support 2 Mbit? From what I have read they should be good enough however
can someone confirm this for me?

Kind Regards

Simon

On Sat, 11 Feb 2006, Simon Zerafa wrote:

> A customer reports that following an regrade to a 2 Mbit service
> they are no longer able to connect via their fairly ancient router
> (connexant access runner based).
>
> The symptoms are basically a failure to authenticate with their ISP.

Is this via a BT line? There's a BT test account which can be used in
order to eliminate any problems with one's ISP, and pin a fault down
more accurately.

See e.g http://usertools.plus.net/tutorials/id/10 , or Google suggests
http://www.more-solutions.co.uk/supp...test-user.html and
http://www.adslguide.org.uk/hardware...oyager2100.asp

I'm assuming that if you're capable of posting to this newsgrope, then
you do at least have some way to peruse those URLs. (It's as well to
get the basic troubleshooting advice *on paper* in preparation for the
kind of situation where one really can get *no* access to the 'net,
IMHO)

> The ISP is not reporting any issues their end. However just prior to
> the regarade everything was reported as operating correctly and they
> were not experiencing any Internet or ADSL connectivity issues.

It's been reported on this group at least once before, that someone's
ISP account details got reset when their ADSL speed was changed.
Maybe that's happened to you? Just a random hunch - YMMV.


AFAIK, if your line quality was inadequate, you wouldn't get as far as
failing to authenticate to the ISP - you would still be waiting for
the ADSL line to synchronise.

Simon Zerafa wrote:

> SNR Margin: Downstream -> 34 / 35 dB (fluctuates between these values)
> SNR Margin Upstream -> 27 dB
> Line Attenuation Downstream: 8.3 dB
> Line Attenuation Upstream: 8.0 dB
>
> these figures may be inaccurate but they are hopefully not too far off...

> Would these stats indicate that their phone line might not be good enough to
> support 2 Mbit? From what I have read they should be good enough however
> can someone confirm this for me?

At first glance I'd say there should be no problems, but have you done
anything to check error rates... I'd almost expect the SNR and loss
figures the other way around (in which case there could be problems
because of low SNR). Have you tried another router on the line ?

Here are some figures from a friend's Connexant-based Dabs router...

ADSL STATUS
ADSL Startup Attempts: 2
Elapsed Time: 67 days 2 hours 32 minutes 12 seconds

Downstream Upstream
SNR Margin 36.9 31.0 dB
Line Attenuation 36.8 22.0 dB
Errored Seconds 252 10
Loss of Signal 1 1
Loss of Frame 0 0
CRC Errors 142 6
Data Rate 576 288 kbps

Hi Alan,

Thanks for confirming what I has suspected.

The ISP has now confirmed issues at their end (which they denied 2 days ago)
so that would appear to be the probable cause of the authentication issues.

It has and remains suspecious that the fault appeared at the same time as
the regrade but it may be that is was coincidental.

Kind Regards

Simon

Hi Peter,

I have retested with a USB ADSL Modem and this also is giving authentication
failures.

I have verified that the users logon details are correct so it would appear
to be an ISP issue.

Kind Regards

Simon

On Sat, 11 Feb 2006, Simon Zerafa wrote:

> Hi Alan,
>
> Thanks for confirming what I has suspected.

Hang on - in the interests of other readers, as well as myself, did
you actually /try/ any of the suggested BT tests? - and if so,
please share the result?

(Usenet works best with a bit of co-operative feedback.)

--

Most folks would think a Referer header is something you smoke.
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