NAT, apart from security reasons, was used in IPv4 to cope up with the exhaustion of IPv4 addresses. Using NAT one can use same addresses behind NAT while talking inside a network(nust be unique within that network), but when these IPv4 addresses want to communicate to outside world NAT translate these IPv4 ambiguous addresses to unambiguous unique global IPv4 address.
Now in case of IPv6, there is no scarcity of IP addresses :). So, ideally NAT is not needed in IPv6 network.
answered 19 Nov '11, 17:15
There is, with NATv6, though there is basically no use for this except possibly security.
answered 17 Nov '11, 23:08