Subject: Re: pppd's routes aren't getting created reliably
To: Manuel Bouyer <>
From: Dr. Bill Studenmund <>
List: tech-net
Date: 12/08/1998 11:40:07
On Tue, 8 Dec 1998, Manuel Bouyer wrote:

> On Dec 7, Ignatios Souvatzis wrote
> > Hm... maybe the route add operation in pppd should do a replace operation?
> > 
> I guess it should, yes ... If you have the same IP on the ethernet and ppp,
> you're going to loose on way or the other. If you add a route to the
> new ppp interface, you should at last be able to log on the ppp server
> (via telnet, ssh or anyhting else) and see what's wrong.

I've been following this thread off and on, and I've been wondering what
is up.

As I understand it, the original poster has a local, non-routed network. 
There are at least two machines involved. Machine A is the server, where
the routing problems are happening. Machine B is on the other end of the
ppp link.

The problem is that the IP address given to machine B is within the
netmask of the ethernet, and pppd is having trouble setting up the routes
to the other end of the link.

I don't think this is a bug in pppd, I think its a bug in the network
configuration. I don't understand why the ppp link addresses were chosen
within the netmask of the ethernet - they shouldn't be there! Every IP
address within the ethernet's netmask should be reachable via the
ethernet. That's the definition (I thought).

What I'd suggest is that the original poster pick two IP addresses outside
the ethernet netmask and give them to the ppp link. That way there's no
such question about routing spaces.

For instance, I have tanis, vespasia, and pokey. They have IP addresses,, and on a net. I also
have tanis-ppp, vespasia-ppp, and pokey-ppp (,, and respectivly) for when I'm doing ppp links. 

If machine B is supposed to be visable on the ethernet, then I think IP
NAT combined with an alias address can make the machine appear to be on
the net when it's really on the other end of the ppp link.

Total aside, the only time I'd love to see pppd do a route replace instead
of add is when it's setting up the default route.

Take care,