I said I was done with this discussion, but I think Melinda
deserves a response here.
Melinda Shore <mshore@cisco.com> writes:
> > I'm not sure what you mean by routing above. Are you suggesting there's
> > some negative externality in that NAT makes the routing infrastructure
> > more complicated? If so, what is it?
>
> If you're multihomed and your route changes, your address
> changes. (Yes, this happens).
Agreed.
> I am profoundly weirded out by reading an IAB member argue
> that something that's got broad market acceptance is
> tautologically okay. I agree that there's a real problem
> here that NAT is trying to solve, but I certainly wouldn't
> treat it as a given that NAT is the best, or even a good,
> solution.
I can understand how this would bother you, and I think
part of the problem is that I haven't been writing as clearly
as I could have. A series of e-mail replies isn't a good
way to elucidate your position.
Here's what I mean to be arguing:
(1) There are some set of problems that users have or
believe they have.
(2) NAT solves at least some of those problems, at some
cost (say Cn), both financial and operational and
that solution has benefit Bn.
(3) The fact that a large number of people have chosen
to use NAT is a strong argument that B>C. (Here's
where the invocation of revealed preference comes in).
(4) It may well be the case that some other solution S
would have some other costs Cs and benefit Bs such
that (Bs - Cs) > (Bn - Cn). It may be that S doesn't
exist yet, in which case it would be good for us
to design and build it.
(5) It's also possible that at some time in the future
Cn will exceed Bn, in which case I would expect people
to stop using NAT and (probably) demand something else.
(6) The argument that I thought I heard people (though not
you) making is that Cn > Bn. I don't think that this
is likely to be the case. In that sense, I think
NAT is OK. I think that if we believe this, it will likely
lead to us designing a long series of S'es that are
inferior to NAT (in the sense that users do not
prefer them because (Bs - Cs) < (Bn - Cn). That's a waste
of time.
Does this seem like a weird position for an IAB member to take?
I don't think so.
There certainly are cases where it's appropriate for the IETF to say
that something users want to do is not OK. Most of those cases are
ones where their behavior has negative external effects on everyone
else. I don't think a strong argument has been made that this is
such a case.
-Ekr
--
[Eric Rescorla ekr@rtfm.com]
Web Log: http://www.rtfm.com/movabletype