You’ve probably heard that IPv6 doesn’t have any NAT in it, and you’ve heard correctly—sort of. By itself, IPv6 doesn’t have a NAT implementation. But that’s only a technicality because there is a transition strategy known as NAT protocol translation (NAT-PT). Just know that you really only use this approach as a last resort because it’s not that great of a solution. With it, your IPv4 hosts can only communicate with other IPv4 hosts, and those that are native IPv6, with other IPv6 hosts. What do I mean by that? Well, with a tunneling approach we took IPv6 packets and disguised them as IPv4 packets. With NAT-PT there is no encapsulation—the data of the source packet is removed from one IP type and repackaged as the new destination IP type. Even though being able to configure NAT-PT is beyond the scope of the CCNA objectives, I still want to explain it to you. And just as it is with NAT for IPv4, there are a couple of ways to implement it.
Static NAT-PT provides a one-to-one mapping of a single IPv4 address to a single IPv6 address (sounds like static NAT). There is also Dynamic NAT-PT, which uses a pool of IPv4 addresses to provide a one-to-one mapping with an IPv6 address (sounding kind of familiar). Finally, there is Network Address Port Translation (NAPT-PT), which provides a many-toone mapping of multiple IPv6 addresses to one IPv4 address and a port number (well, glad we have that cleared up from NAT).
As you can see, we are not using NAT to translate a public and private IPv6 address as we did with IPv4, but rather between IPv4 and IPv6. Again, this should be used as an absolute last resort. In most cases a tunneling approach will work much better and without the headache of this configuration and system overhead.
Static NAT-PT provides a one-to-one mapping of a single IPv4 address to a single IPv6 address (sounds like static NAT). There is also Dynamic NAT-PT, which uses a pool of IPv4 addresses to provide a one-to-one mapping with an IPv6 address (sounding kind of familiar). Finally, there is Network Address Port Translation (NAPT-PT), which provides a many-toone mapping of multiple IPv6 addresses to one IPv4 address and a port number (well, glad we have that cleared up from NAT).
As you can see, we are not using NAT to translate a public and private IPv6 address as we did with IPv4, but rather between IPv4 and IPv6. Again, this should be used as an absolute last resort. In most cases a tunneling approach will work much better and without the headache of this configuration and system overhead.
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