Subject: Re: PPP message: serial line looped
To: Jell-O <>
From: Bill Studenmund <>
List: current-users
Date: 06/05/1996 09:37:24
On Tue, 4 Jun 1996, Jell-O wrote:

> Hi,
> I had to rebuild a couple of things recently, included /etc because I 
> screwed-up bigtime.  Anyway, now that things are back to "normal", I'm
> trying to use pppd.  I'm using the same script as I was before, except
> now I'm getting a message about the serial line getting looped when I
> dial and connect.  I seem to connect and I can run through the chat script
> okay.  After that point, I get the message and DTR drops.  
> I believe I'm using the May 5 or May 7 distribution.  I'm on the mac68k 
> platform.  What's this message caused by?  

The problem source depends on the sequence of events. Sounds like it is:

1) chat finishes
2) loopback warning
3) modem drop

where the problem is that the chat script is not leaving the remote end
with pppd running. You have some tty left on, which is echoing to pppd
what it's sending. pppd is specifically written to notice this through a
magic number arbitration, which echoing will fail.

For this case, I'd suggest turning on the debug option in chat. You can
basically make it dump everything to the log files. Then you can see
exactly what's going on. The last thing chat should do is type ppp or
pppd; it should exit with the line running ppp.

Take care,