Subject: Re: pppd's routes aren't getting created reliably
To: Dr. Bill Studenmund <>
From: Ignatios Souvatzis <>
List: tech-net
Date: 12/08/1998 21:16:02
On Tue, Dec 08, 1998 at 11:40:07AM -0800, Dr. Bill Studenmund wrote:

> 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).

while in his configuration he could avoid this, you can't always.
Thats what proxy arp is about.  pppd better should know that it might need
to replace the arp entry, instead of just trying to add it.

> 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.
> 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.

no. you need proxy arp. Nothing else needed.

> 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.

This is a separate issue, but worth considering, I thing. However, you might
even need to talk a routing protocol in this case...