2011/6/6 Jeroen Massar jeroen@unfix.org:
ULA would still require NAT66 if you want those hosts to be able to communicate to the outside, unless of course you want to firewall your internal machines based on the global prefix and update those firewall rules and all other dependencies all the time when your prefix changes... (the prefix change is why I mention NAT66 as renumbering is not funny, anywhere).
So, first of all we talk about sites that would have today a dynamic IPv4 address. That would be residential, mobile, and SOHO.
In the worst case, these sites can deal with LAN communication using ULA addresses, and then any public communication should be handled via public IPv6, which are at the moment all in 2000::/3, so clearly easy to identify and to put in a firewall. Readdressing the public addresses in the LAN is done easily with RAs, or DHCPv6-PD if the LAN is subdivided (an still in that case we've most likely left the normal SOHO, and we're in a bigger company that will have static v4 and most likely IPv6oE or in the home of a geek).
And finally, 6rd is a transition technology, and will be certainly removed in a few years to go to IPv6oE, once incompatible hardware will be phased out. Well, that's a wish, don't take it for granted :)
Guillaume