You really don't know what IPv6 boxes are capable of. Below is the start of a netstat of the active IPv6 connections. The first connection is a internal connection. The stack automatically choose to use the ULA address (fd92) over the non-ULA address as it was a connection to a internal host. Both machines have ULA and non ULA addresses. The other connections are all to external servers. They use the non-ULA address. That address could be changed at anytime the same as your IPv4 is being changed. The IPv6 hosts don't care. You also don't need NAT66 to achieve this. Active Internet connections (including servers) Proto Recv-Q Send-Q Local Address Foreign Address (state) tcp6 0 0 fd92:7065:b8e::6.50942 fd92:7065:b8e::2.22 ESTABLISHED tcp6 0 0 2001:470:1f00:82.50941 2001:4860:8005::.80 ESTABLISHED tcp6 0 0 2001:470:1f00:82.50940 2001:4860:4001:8.80 ESTABLISHED tcp6 0 0 2001:470:1f00:82.50286 2001:4860:4001:8.80 CLOSE_WAIT tcp6 0 0 2001:470:1f00:82.49833 2001:4f8:4:d::8.5223 ESTABLISHED This is done using machines that you can walk down to the local computer store and pick up today. I didn't have to configure anything to achieve this other than have the router advertise a second ULA prefix. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@xxxxxxx _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf