I repeat my comment from when I first saw Mike O'Dell's original 8+8
proposal: "It's architected NAT." I think anything that massages
locators,
whether it's in the host stack or in a proxy, comes down to
architected
NAT. Which means there is going to be state, so that the massage can
be
reversed, so that the ULP always sees the same e2e identifier. It's a
design choice whether that state is in hosts, proxies, or both.
Actually, we're kidding ourselves if we don't admit that this is what
we are going to end up doing.
I think that it is vitally important that we all understand this and
how we got here. If we want a host to respond flexibly to
multiple addresses, then either (a) the protocol stack needs to know
about
the various addresses and can swap between them on the fly, OR
(b) something NATty outside of the protocol stack has to "fool" the
protocol
stack into responding consistently.
Years ago, we rejected (a) on the grounds that it would change IPv6.