Re: Zero Address Set

I guess the key question here is whether there's
enough "bang for the buck" in this function for it
to be included in MOBIKE. Earlier we didn't see that
many people interested, but now we have some. In any
case, we need to consider the following:

- The benefit this feature offers is about "being
   a good citizen" (as you Bill put it) and not send
   unnecessary packets when we know the other end
   is down. Nevertheless, this is not a functional
   benefit in the sense that nothing breaks if we
   don't have it; just that extra packets are sent.

- We know we can not use this feature in all cases
   when the other end is down. We don't always know
   we are going outside coverage.

- We know there's some practical limits to how long
   this condition can be held and still be considered
   useful, such as applications on top starting to
   get timeouts.

- There may be some additional complexity for MOBIKE.
   For instance, assume A and B are talking to each other
   and that A now informs B that its offline. Now,
   normally in MOBIKE if B moves it can tell A immediately.
   But if zero-address set is supported then B must
   be able to queue this notification. And if all of
   B's addresses got changed, the situation is not
   recoverable.

--Jari