Mailing List Archive: AS5300 Dropped Calls

Hi all.

I have a situation where some customers may drop calls after a few
seconds-to-minutes of dial-up connection. In some cases, either the phone
line (noisy), modem or modem driver has been the cause, and problem
rectified.

In other cases, phone line's good (even less than <= 800m from CO), modem and
modem configuration are in order, but the line will still cut after a few
moments of connectivity.

The AS5300 has been configured for 56K access. I have tried different
modulation schemes to try and solve this problem, testing v.90 and v.92 (v.34
won't offer over 33.6Kbps, and some customers can support 52Kbps with no line
drops, but haven't tested it long enough to confirm problem resolution).

So I left the async lines to auto-negotiate line parameters with the customer
once they connect, but that doesn't seem to have solved the problem. What's
strange is that a previous purely analog NAS didn't have this problem (unless
the customer had an idle-timeout set).

Anyone have any idea how the AS5300 can be tuned to deal with this? PRI lines
have been delivered on HDSL/G.703, and D-channel interfaces on the AS5300
aren't reporting any line errors.

All help appreciated.

Mark.

Mark,

From my experience, there are just some customers that you're not
going to be able to get 56k, for whatever reason (bridged taps, etc.)

See if the problem is related to specific modems or specific
customers. Get some 'sho modem op' output and see if you can take a
look at the waveform printed out. One other thing that you mentioned,
they weren't having problems with the analog nas that was there
before? If it was analog, then they weren't doing 56k/v.9X, since you
have to have a digital facility on your end to accomodate that
speed/modulation std. So, past performance may not be totally
relevant.

make sure you're using the recommended modemcap and mica firmware:
http://cisco.com/en/US/tech/tk801/tk36/technologies_tech_note09186a008009491b.shtml

Eric

On Mon, 28 Mar 2005 14:00:56 +0200, Mark Tinka
<mtinka@africaonline.co.sz> wrote:
> Hi all.
>
> I have a situation where some customers may drop calls after a few
> seconds-to-minutes of dial-up connection. In some cases, either the phone
> line (noisy), modem or modem driver has been the cause, and problem
> rectified.
>
> In other cases, phone line's good (even less than <= 800m from CO), modem and
> modem configuration are in order, but the line will still cut after a few
> moments of connectivity.
>
> The AS5300 has been configured for 56K access. I have tried different
> modulation schemes to try and solve this problem, testing v.90 and v.92 (v.34
> won't offer over 33.6Kbps, and some customers can support 52Kbps with no line
> drops, but haven't tested it long enough to confirm problem resolution).
>
> So I left the async lines to auto-negotiate line parameters with the customer
> once they connect, but that doesn't seem to have solved the problem. What's
> strange is that a previous purely analog NAS didn't have this problem (unless
> the customer had an idle-timeout set).
>
> Anyone have any idea how the AS5300 can be tuned to deal with this? PRI lines
> have been delivered on HDSL/G.703, and D-channel interfaces on the AS5300
> aren't reporting any line errors.
>
> All help appreciated.
>
> Mark.
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>