From: Chuck Church (cchurch@xxxxxxxxxxxx)
Date: Sun Oct 21 2001 - 19:49:40 GMT-3
Thanks Jay. Someone else mentioned using a chat script. That was the cure.
I don't know why the autoconfigure didn't work right. Occasionally it would
work right if I cleared the line, but the chat script works better.
Thanks again.
Chuck
P.S. Nuts are fine... (a typo)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Jay Hennigan
Sent: Sunday, October 21, 2001 4:45 PM
To: 'ccielab@groupstudy.com'
Subject: Re: HELP! Analog modems on aux ports
On Sun, 21 Oct 2001, Chuck Church wrote:
> Hey all,
>
> Sorry about yelling on the subject line, but I'm getting quite
> frustrated with my modems on aux ports. I've got a variety of 2500
routers,
> with rolled cables connecting to 2 USR 56kb modems. Autoconfigure for the
> modems keeps giving me 'deb confmodem' output like this:
>
> 01:40:56: TTY1: detection speed (300) response ---~# }}"%%}&'i}"'}"(X~---
> 01:40:56: TTY1: No modem found
> 01:40:43: TTY1: detection speed (1200) response ---~#
}}"%%}&'i}"'}"(X~---
> 01:40:56: TTY1: detection speed (300) response ---~# }}"%%}&'i}"'}"(X~---
> 01:40:56: TTY1: No modem found
[snippage]
I think I'd lose the autoconfig and go with a chat script. Modems will
usually set their DTE speed to whatever speed the last AT command was
received.
Try reverse telnet to the AUX port at a speed of 38400 and type ATZ,
see if you get back an "OK" from the modem. Then once you've got it
happy, guve the modem an "AT&W" to save it to the modem. If the AUX
port can go higher like to 57600 or 115200, then go with that. It sounds
as if hte router is trying to autonegotiate with the modem, and the modem
is also trying to auotnegotiate with the router, and neither is happy.
One thing that's puzzling is that the same garbage string comes back at
different speeds. I would expect it to be different.
> They worked once, and I was able to ping across the async ports, but
> when the call hung up, they started doing this again. Does anyone have
some
> tips on doing reliable DDR over modems, including dip switch settings on
the
> modems. They're Sportsters.
One way to do it is to set the modems DIP switches to give responses and
go with a chat script to parse those responses. Another way which won't
quite simulate ISDN because you won't have a dialer string is to set the
modem for DTR dialer so that when the router raises DTR, the modem dials
a number pre-programmed into the modem, and you suppress the modem output
back to the router so the router doesn't get confused by the status
messages from the modem. Not quite as nice for lab prep because you don't
have the dialer string.
I can't give exact advice on the dip switches, but things to check are
whether the modem echoes commands, and whether it gives response codes and
in what form. ATE? and ATQ? are at least two of what you want to play with,
or they may be replaced by dipswitches.
First configure things to reverse-telnet to the modem on the AUX port and
see if you can talk to it and get it to dial. Then get fancy.
> If I plug my PC into one of the modems, it
> responds to AT commands no problem. But the routers just get back
> gibberish. Since I got pings across once, I know my async interface
> settings are ok. It's just the configuration on the aux line. Any help
is
> appreciated. This is driving my nuts...
^^^^^^^^^^^^^^^^^^^^^^^^^^
Sounds painful.
-- Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net NetLojix Communications, Inc. - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323
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