>
> 
> Neil J. McRae writes:
>  > I can't see how you can do demand dialing without know the IP addresses,
>  > otherwise everytime you do anykind of network traffic it would dial up.
> 
> 	I think it should be feasible to have a ppp setup that brings
> up a ppp link if there is a routing failure - this assumes that the
> ppp link would carry the default route. Possibly with a tunnel device
> that starts up a ppp link if there is any traffic; the tunnel device
> would have the default route when the ppp link was down, and the
> default route would be moved to the ppp link later. 

I've setup a demand-dial ppp setup on a FreeBSD i386 machine at work using
the program ppp.  It uses the tun0 device, and will negotiate a new IP
address every time you connect.  The catch is that 1) you have to give
the tun0 device a valid default IP (0.0.0.0 causes TCP/IP to ignore that
route), and 2) the first socket connection out every time you reconnect
will fail.  (your-IP.Socket# <--> their-IP.Socket# becomes invalid when
your-IP changes).  Not generally a problem if the first connection is to
a nameserver, and you have more than one nameserver in the list.

jf
-- 
John Franklin
jfrankli@bev.net