[arin-ppml] The role of NAT in IPv6

David Farmer farmer at umn.edu
Thu Apr 15 12:48:37 EDT 2010

Gary Giesen wrote:

> Yes, NAT is an ugly beast that we wish would disappear...

Yes, NAT is ugly, it would be nice to leave it behind in the IPv4 world.

However, there are other equally ugly problems that IPv6 has not solved 
and are not being left behind in IPv4 world.

- IPv6 doesn't fundamentally solve the routing table growth problem, 
large initial allocation will help some, but it doesn't solve it

- IPv6 doesn't eliminate the renumbering problem, it is not as bad, but 
again it is not solved

- IPv6 doesn't eliminate the motivation to do NAT, I believe there 
should be less and more people should have other options, but it doesn't 
eliminate it

I think NAT is ugly, heck I think it is an abomination, but I think 
telling other people how to run there network is much more ugly thing 
than NAT.  And how much ever I dislike NAT, it has been an effective way 
to run a network for a lot of people.  How effective have you been in 
telling other people how to run (or not run) there network?

> Since we have abundant globally unique addresses, and no equivalent to
> RFC1918 in IPv6, it has reached the end of its usefulness...

Yes, there is abundant address space in IPv6.  But, please read RFC 
4193, which is fundamentally the IPv6 replacement for RFC 1918 in IPv4. 
  Since IPv6 has abundant address space it is possible to provide 
private address space in a much better ways than the simple solution 
chosen for RFC 1918.  So unfortunately, no NAT has not reached the end 
of its usefulness at least for everyone.

David Farmer               Email:farmer at umn.edu
Networking & Telecommunication Services
Office of Information Technology
University of Minnesota	
2218 University Ave SE	    Phone: 612-626-0815
Minneapolis, MN 55414-3029   Cell: 612-812-9952

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