Hi Jeroen,


In IPv6 every enduser should have enough IP's simply
because of the simple rule [...]

Nevertheless customers should never have any need whatsoever for NAT.
If there once is a need for it IPv6 'failed' as it didn't get up to
the primary need for IPv6: More addressspace so that everything can be
e2e.

Unfortunately, there is another reason why enterprises use NAT that has not been addressed in IPv6: provider independence.

Enterprises do not want to be "held hostage" to a particular ISP based
on their address usage -- they want it to be cheap to move between ISPs
to gain rate advantages, and they don't want to be adversely affected
by ISP closures, mergers, etc.  By using internal addresses inside of
their network, and using NAT to reach the global Internet, only a few
systems need to be renumbered when ISP-provided global addresses change.

So, if we don't come up with a way to allow provider-independent address
allocation in IPv6, we will probably get IPv6<->IPv6 NAT.

Unfortunately, we don't have a proven/accepted method for doing provider
independent address allocation that will scale -- the most obvious
methods would all result in much larger core routing tables, and won't
scale to Internet proportions.  There are folks working on solutions
to this problem (both in the IETF and the IRTF), and those solutions
are the best hope that we have to avoid NAT.

In the meantime, though, I wouldn't object to a statement in the IPv6
node requirements that says that you MUST NOT translate source or
destination addresses in forwarded packets...  even though I don't
think that it will actually stop anyone.

Margaret




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