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Re: Access to the IPv4 net for IPv6-only systems, was: Re: WG Action: Conclusion of IP Version 6 (ipv6)

  • From: John Curran
  • Date: Mon Oct 01 08:10:36 2007

At 9:30 PM +0200 9/30/07, Iljitsch van Beijnum wrote:
>On 30-sep-2007, at 5:10, John Curran wrote:
>>The irony is that the I* rationale for moving NAT-PT to historic
>>was "to restore the end-to-end transparency of the Internet"
>>and yet the only real chance we have to restore end-to-end
>>transparency is to first have a transition to the IPv6 (using
>>dual-stack, NAT-PT, and every other tool at our disposal) and
>>then over time let present IPv4 destination sites add IPv6 for
>>end-to-end transparency based on their actual need for it.
>>Instead, central planning may have effectively killed the very
>>tool that's needed to allow providers to provision new Internet
>>customers over a pure IPv6-only model, and create the right
>>motivation for existing Internet sites to go dual-stack and
>>actually gain "end to end transparency" via IPv6.
>In my opinion, the mistake the IETF made was to "deprecate" NAT-PT without coming up with an alternative first.

Agreed.  Lucklily, it got spec'd and it's now a question of what ISP's
want and what vendors feel like making money.

>Originally, my thinking was "sure, NAT-PT doesn't work with everything unless you have ALGs for a good number of protocols, but it gives you 80% of what you need so it's a good start". But I've come to see how having IPv6 applications expect end-to-end IPv6 connectivity and then have that rug pulled from under them will inevitably lead to the same lack of end-to-end transparency in IPv6 that we currently have with IPv4. And once that can is open, it's unlikely we can get the worms to crawl back inside later.

I disagree with that view...  There's no reason why NAT-PT for access
to legacy IPv4 sites implies anything about the connectivity model for
IPv6.   As noted above, it's *lack* of NAT-PT that will cause ISP's to
avoid a connecting customers with a pure IPv6 model, since that isn't
enough for full Internet connectivity in the absence of NAT-PT.