About default address, there is an issue for apps that are using UDP and
are (miss?)configured with an unreachable literal IPv6 address. This is
typically the case for a DNS stub-resolver that is configured with a list
of literal addresses. We had to introduce an extra rule to take care of
that.
Could you elaborate a bit what you mean by that?
I have to take my previous statement back, I was a bit confused.
I meant to refer to the suggested rule 2.5 for address selection in
section "2.1 Problems with Default Address Selection for IPv6"
of draft-ietf-v6ops-v6onbydefault-03.txt
It essentially says that choosing a src address with different
reachability properties than the destination address (here src =
link local, dst = global, but there might be other bad combinations
with ULA) is a bad idea.