Re: [v4v6interim] [BEHAVE] [46translation] Proposal for new BEHAVEcharter

On Monday 20 October 2008 14:06:38 ext marcelo bagnulo braun, you wrote:
> Rémi Denis-Courmont escribió:
> > On Monday 20 October 2008 13:37:05 ext Iljitsch van Beijnum, you wrote:
> >> Interestingly, I did a small survey about whether people _expect_
> >> there to be NAT66 in the future and the majority said "yes".
> >>
> >> On the one hand we can do nothing and if all goes well there will be
> >> no IPv6 NAT so we're all happy because not doing anything made the
> >> right thing happen. (Although I've used a NAT66 implementation myself
> >> some years back, so there is at least one out there.)
> >>
> >> But if we do nothing, we run the risk that someone will do a quick
> >> search and replace on their NAT44 code and create a port overloading
> >> NAT66. The port overloading is 90% of the harmful stuff that NAT boxes
> >> do.
> >>
> >> What we could do is come up with a stateless, transport-agnostic 1-
> >> to-1 NAT66 spec so we at least avoid the port overloading and nothing
> >> much breaks except referrals.
> >
> > I share your analysis that, _assuming_ we have NAT66, it should be
> > transport-agnostic. IPv6 has a large enough address space, and we are
> > painfully aware of the problems of transport-dependent NAT(44).
> >
> > However, when I look at the reasons for deploying NAT:
> > 1/ address space shortage
> > 2/ inbound firewalling
> > 3/ topology hiding
> > 4/ prefix delegation "bypass"
> >
> > (1) is a non-issue for IPv6. (2) is solved with stateful firewalling and
> > does not require NAT. 1:1 NAT fails to solve (3) as it does hide the
> > subnetting scheme, but fails to hide individual hosts. This leaves only
> > (4). Did I miss anything?
>
> I think one main reason would be provider independence (ie. no need to
> renumber)  for small sites that cannot afford to have thier own PI
> address block allocated

That's prefix delegation/routing bypass.

-- 
Rémi Denis-Courmont
Maemo Software, Nokia Devices R&D
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