To be sure, the migration of IPv4 to IPv6 will be a long process and some details of migration have yet to be determined. As a general methodology, to migrate from IPv4 to IPv6 you must perform the following steps:
Windows Sockets applications must be changed to use new application programming interfaces (APIs) so that name resolution and socket creation is independent of whether IPv4 or IPv6 is being used. For more information about Windows Sockets API changes, see Appendix B.
The DNS infrastructure might need to be upgraded to support the new AAAA records (required) and PTR records in the IP6.INT reverse domain (optional).
Hosts must be upgraded to use a dual IP layer or dual IP stack. DNS resolver support must also be added to process DNS query results that contain both IPv4 and IPv6 addresses
Routers must be upgraded to support native IPv6 routing and IPv6 routing protocols. For more information on IPv6 routing protocols, see Chapter 10, "IPv6 Routing."
IPv6/IPv4 nodes can be upgraded to be IPv6-only nodes. This should be a long-term goal because it will take years for all current IPv4-only network devices to be upgraded to IPv6-only. For those IPv4-only nodes that cannot be upgraded to IPv6/IPv4 or IPv6-only, employ translation gateways or proxies as appropriate so that IPv4-only nodes can communicate with IPv6-only nodes.