Your problem may be that the target router, the router with ip address
172.16.1.2, is getting encapsulation failure when it tries to reply to
the virtual IPv4 address, 172.16.1.20. You can test this by running
"debug ip packet". With both static and dynamic NAT-PT it is common for
the translating router NOT to reply to arps to the virtual IPv4
address. Try a static arp on the target router to the virtual IPv4
address. For example:
arp 172.16.1.20 0011.2222.3333 arpa
Netmasterclass offers a Class on Demand on IPv6 that covers both static
and dynamic NAT-PT.
--
Bob Sinclair CCIE 10427 CCSI 30427
www.netmasterclass.net