You mean aside from applications understaning that an ICMP Destination
Unreachable / Administratively Prohibited response from the site firewall?
For that matter, IPv6 machines arguably could try their Site Local address
and be given that same feedback from the border router or firewall
how does any party - the host, border router or firewall - know whether the SL
address is from that site or some other site? SLs are inherently ambiguous.
, and use
the response as an indication to go use their assigned global address.
if the destination has a global address, it should *always* be used in
preference to the site local, at least in the absence of external
configuration.
We have the problem of scoped addresses whether the "site local" mechanism
is retained or not.
I disagree, or at least, I think it's misleading to use the term "scoped
addresses" to cover all filtering, because this is conflating two things - use
of filtering on one hand and use of ambiguous addresses on the other. It's
useful to be able to refer to a host even if you can't send traffic there.
Keith