Planning for IPv6 Migration

Migrating your existing IPv4-based network infrastructure to IPv6 requires an understanding of different IPv6 transition technologies that you can use to achieve your goal. Windows 7, Windows Vista, and Windows Server 2008 support three transition technologies in particular:

• ISATAP An address assignment and automatic tunneling technology defined in RFC 4214 that you can use to provide unicast IPv6 connectivity between IPv6/IPv4 hosts (hosts that support both IPv6 and IPv4) across an IPv4-based intranet (a private network whose infrastructure hardware, such as routers, supports only IPv4, not IPv6).
• 6to4 An address assignment and automatic tunneling technology defined in RFC 3056 that you can use to provide unicast IPv6 connectivity between IPv6/IPv4 hosts and sites across the IPv4-based public Internet. 6to4 enables you to assign global IPv6 addresses within your private network so that your hosts can reach locations on the IPv6 Internet without needing a direct connection to the IPv6 Internet or an IPv6 global address prefix obtained from an IPv6-supporting ISP. (Communication between a 6to4 site and a node on the IPv6 Internet requires the use of a 6to4 relay, however.)
• Teredo An address assignment and automatic tunneling technology defined in RFC 4380 that you can use to provide unicast IPv6 connectivity between IPv6/IPv4 hosts across the IPv4 public Internet, even when the IPv6/IPv4 hosts are located behind zero or more NATs. Teredo provides similar functionality to 6to4 but without needing edge devices that support 6to4 tunneling.

Note For more information on IPv4/IPv6 transition technologies, see the white paper, "IPv6 Transition Technologies," at http://www.microsoft.com/downloads/details.aspx?FamilyID=afe56282-2903-40f3-a5ba-a87bf92c096d&DisplayLang=en.

These three IPv6 transition technologies are supported by Windows 7, Windows Vista, Windows Server 2008, Windows XP SP2, and Windows Server 2003 SP1. Of the three, ISATAP is the primary transition technology that you should use for migrating an existing IPv4-based intranet to IPv6; it is discussed further in the following sections. Teredo is primarily useful in SOHO networking environments, where NAT-enabled broadband routers provide Internet connectivity for users. (Think of Teredo as a transition technology of last resort, because as IPv6 connectivity becomes ubiquitous, the need for NAT traversal will decline until Teredo is no longer needed.)