Real World NAT64 deployments

Thu Mar 3 16:20:47 CST 2011

6in4 is IPv6 encapsulated in IPv4 = protocol 41, typically used in manual
tunnelling configuration and also in tunnel brokers and some other type of

6to4 is an automatic transition mechanism that uses 6in4 to automatically
create IPv6 tunnels using a special IPv6 prefix 2002::/16, appending the
IPv4 public address to obtain a /48 for each IPv4 public address. It works
very well for peer-to-peer, but it requires 6to4 relays for connecting to
end-sites using any other kind of IPv6 connectivity (anything not-6to4).



-----Mensaje original-----
De: Hammer <bhmccie at>
Responder a: <bhmccie at>
Fecha: Thu, 3 Mar 2011 16:01:29 -0600
Para: William Herrin <bill at>
CC: <nanog at>
Asunto: Re: Real World NAT64 deployments

>A little better. So what's the difference between 6to4 and 6in4? Isn't
>what HE uses?
> -Hammer-
>"I was a normal American nerd."
>-Jack Herer
>On Thu, Mar 3, 2011 at 3:54 PM, William Herrin <bill at> wrote:
>> On Thu, Mar 3, 2011 at 3:41 PM, Hammer <bhmccie at> wrote:
>> > I need a cheat sheet.
>> >
>> > nat64
>> > 6to4nat
>> > 6in4nat
>> > etc...
>> 6to4 and 6in4 are not NAT. They're tunnels (VPNs) that allow two IPv6
>> nodes to talk to each other via an IPv4 backbone.
>> nat64 is NAT. It allows IPv6 endpoints to communicate with IPv4
>> nat44 is the IPv4 NAT you're used to.
>> nat444 is carrier NAT (translated once by the customer and once again
>> by the ISP, get it?)
>> --
>> William D. Herrin ................ herrin at  bill at
>> 3005 Crane Dr. ...................... Web: <>
>> Falls Church, VA 22042-3004

IPv4 is over
Are you ready for the new Internet ?
The IPv6 Company

This electronic message contains information which may be privileged or confidential. The information is intended to be for the use of the individual(s) named above. If you are not the intended recipient be aware that any disclosure, copying, distribution or use of the contents of this information, including attached files, is prohibited.

More information about the NANOG mailing list