Hi!
> > rtr1 runs frr, has full route, either with or without default route.
>
> If that makes no difference then something else is wrong.
I agree, but we have to find out, what is wrong...
> > > (b) At the time this happens does rtr1 have a route to z.z.z.z ?
> > > route -4 get z.z.z.z
> > Yes.
>
> And that is not pointing back to the interface rtr2 is on but out
> on an interface towards inet?
Technically, some of the routes point out to the same interface,
but a different IP (like x.x.x.5), and some point out to the wan interface.
Here's the small network layout again:
inet ------ wan:rtr1:lan ------ rtr2 ------ wan:host
x.x.x.1 y.y.y.1
--
p...@freebsd.org +49 171 3101372 Now what ?
