[arin-ppml] The role of NAT in IPv6

Gary T. Giesen ggiesen at akn.ca
Thu Apr 15 18:37:16 EDT 2010

I'd argue that the collective costs of implementing and supporting NAT
far outweigh the costs of more routing slots (though neither is a small
number, I'd argue NAT is at least an order of magnitude higher).

Also, IPv6 adoption, despite my best optimism, will be rather slow, and
IPv4 will be with us for some time to come. That gives router vendors
time to increase the size of their TCAMs, and ISP's time to upgrade on
their normal refresh schedules.

Enterprises will be the last to adopt IPv6 regardless of what we do,
should we hold up the show for them? Or should we take a leadership
position, show them that IPv6 can be done without NAT (and more
effectively and cheaply)?


On Thu, 2010-04-15 at 18:22 -0400, William Herrin wrote:
> On Thu, Apr 15, 2010 at 3:08 PM, Gary T. Giesen <ggiesen at akn.ca> wrote:
> > If you think it's wrong to use IP allocation policy as a tool for a
> > prescriptive approach to NAT in IPv6 (or lack thereof), we're already
> > using it as a measure to constrain BGP table growth, which like NAT, is
> > a cost shared mostly not by the route originator (read: NAT
> > implementer), but by everyone else.
> Respectfully Gary, that doesn't follow.
> Route announcements have a direct, real cost. Your route announcement
> consumes resources in tens of thousands of routers, compelling those
> routers' owners to spend money. Use of NAT has, at worst, an
> opportunity cost. Because someone uses NAT, you lose the opportunity
> to vend an incompatible product or service.
> Shall we use ARIN policy to require registrants to wear pink dresses
> because you might have trouble selling them pink dresses if we don't?
> > As Owen has pointed out many times, the cost of supporting NAT is rarely
> > borne by the person implementing it. It's borne by everyone else trying
> > to sell services to the the NAT'd customer.
> The cost of your breathing is borne by everyone else who has to muddle
> through with that much less oxygen. Shall I object? Perhaps you should
> hold your breath.
> Regards,
> Bill Herrin

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