How to use teredo protocol in Windows 7

In Windows 7 Microsoft have configured DNS so that the system will never resolve any name to an IPv6 address, as long as the system only has link-local and Teredo IPv6 addresses. The trick is to provide windows with a 6to4 address reducted from your private IPv4 address. Use the following link to create an IPv6 address from your IPv4 address and go to your LAN properties to give this IPv6 static address to your TCP/IPv6 component. In my case the address is 2002:c0a8:3709:: and the prefix is always 48. Do not assign a default gateway address.
Open an elevated command prompt and enter the command
netsh int ipv6 show route
to print the ipv6 routing table. You will see the index of the teredo tunneling interface. In my case the index is 16, so I enter the following command to create a default route through this interface:
netsh interface ipv6 add route ::/0 interface=16
Try to ping ipv6.google.com to see if it's working.
Enter this command to check if teredo is enabled
netsh int teredo show state
If state is offline then enter this command to activate teredo
netsh int teredo set state type=client
and then
netsh interface ipv6 delete route ::/0 interface=16
netsh interface ipv6 add route ::/0 interface=16
We assume here that the interface index is 16.
Windows 7 deactivates this route if there is no ipv6 traffic for a certain period of time. To disable this functionality use the local group policy:
Run gpedit.msc and navigate to Computer Configuration -> Administrative Templates -> Network -> TCPIP Settings -> IPv6 Transition Technologies
Double click the "Teredo Default Qualified" setting, change it from "Not Configured" to "Enabled", and click OK, then close gpedit.msc
From an elevated command prompt enter the command gpupdate /force to force a refresh of the group policy.
In a windows domain environment teredo is always disabled. You must use the command
netsh int teredo set state type=enterpriseclient
to bypass this restriction
You must also open in your router/firewall the IPv4 udp port 3544 to the traffic travelling from your internal network to the Internet because this port is used from teredo protocol
For more info take a look at http://yorickdowne.wordpress.com/2008/01/26/ipv6-at-home-part-1-overview-teredo/