The next MP problem when using route entries are stale ifas.
Stale ifas exist because we do not purge corresponding route entries
when we remove an ifa. Instead we try to 'fixup' such routes when
we found them later on. This happens in two places when cloning
a route, inside rtalloc(9), or when
I really like this. It will allow us to move forward. While I was for a
long time holding the opinion that static routes should not disapear from
the routing table because the interface address changes I came to the
conclusion that this is causing more harm and so it is better to remove
all routes
