> with PPP routing:  yesterday, I couldn't ping my own PPP address from the
> NetBSD system

This is known behaviour.

Ethernet interfaces add a loopback route to their local address when
configured. Point to point interfaces don't do that (they could, but I'm
not aware of any driver doing it right now).

You can simply add the missing route yourself in the ip-up script, if you
realy need it. I never missed it myself.

Martin