Planning for IPv6 Transition Technologies

You will need to use one or more IPv6 transition technologies during the IPv6 migration process. The below provide planning information for ISATAP, 6to4, and Teredo.

ISATAP
By default, ISATAP hosts will obtain the IPv4 address of the ISATAP router by using DNS and other IP name resolution techniques to resolve the name ISATAP to an IPv4 address. Once the host has identified the ISATAP router’s IP address, it uses IPv4 unicast messages to acquire autoconfiguration information from the router. To ensure that clients can find the ISATAP router, plan to use one of the following techniques:

• If the ISATAP router is a computer, configure the computer name as ISATAP.
• Create a DNS entry for every DNS domain.
• Add an entry to the Hosts file.
• Create a static WINS record.
• Run a netsh command on all ISATAP hosts.


6to4
6to4 allows you to access the IPv6 Internet by using your existing IPv4 Internet connection. 6to4 requires you to have a 6to4 router and a public IPv4 address (such as an address assigned by your ISP). IPv4-only routers cannot act as 6to4 routers. Therefore, if you are currently using an IPv4-only router for your Internet access, you will need to upgrade or replace your router. Before investing in upgrades to support 6to4 or Teredo, evaluate whether the benefits of connecting to the IPv6 Internet outweigh the costs. Unless you need to access a specific resource on the IPv6 Internet that is not accessible on the IPv4 Internet, there might be no practical benefit to connecting to the IPv6 Internet. Generally, public IPv6 Internet resources (such as Web sites) are also available on the IPv4 Internet.


Teredo
You can use Teredo to provide hosts with IPv6 Internet connectivity when you do not have a 6to4 router with a public IPv4 address. For best results with Teredo, choose cone or restricted NATs that support UDP port translation, and avoid symmetric NATs. While implementing Teredo, you might discover that you need to change the NAT or firewall configuration. Therefore, you should be prepared to work with network administrators to provide the connectivity you require. You can use Microsoft’s Internet Connectivity Evaluation Tool to determine whether your current NAT supports Teredo. To use the online tool, open http://www.microsoft.com/windows/using/tools/igd/ in Microsoft Windows Internet Explorer, and follow the prompts.

Source of Information : Microsoft Press Windows Server 2008 Networking and Network Access Protection NAP