From: Len Tucker (tuckerfamily2@xxxxxxxxx)
Date: Sun Oct 21 2001 - 18:09:53 GMT-3
You shouldn't be using rolled cables unless you are using a rolled db25 to
RJ45 adapter.
The connection should be straight through from the router to the modem (DTE
to DCE).
Len Tucker
----- Original Message -----
From: "Jay Hennigan" <jay@west.net>
To: <ccielab@groupstudy.com>
Sent: Sunday, October 21, 2001 4:44 PM
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
This archive was generated by hypermail 2.1.4 : Thu Jun 20 2002 - 22:33:23 GMT-3