MacOSX IPv6 Networking Knowhow

They can operate as a direct IPv6 gateway if your ISP supports IPv6, or it can operate as a tunneling device. To configure the tunneling option, follow these steps (courtesy of James Woodyatt):

1. Launch AirPort Utility.
2. Select your device from the sidebar and choose Manual Setup.
3. Select the [Internet] pane of the configuration window.
4. Select the TCP/IP tab.
5. At the “Configure IPv4″ pop-up, choose the “Manually” option.
6. Enter the statically assigned IPv4 WAN configuration parameters for your device:
+ IP Address
+ Subnet Mask
+ Router Address
+ DNS Servers
+ Domain Name [optional]
7. Select the [Advanced] pane of the configuration window.
8. Select the IPv6 tab.
9. At the “IPv6 Mode” pop-up, choose the “Tunnel” option.
10. At the “Configure IPv6″ pop-up, choose the “Manually” option.
11. Enter the statically assigned IPv6-in-IPv4 configuration parameters for your tunnel:
+ Remote IPv4 Address
+ Local IPv6 Address
+ Remote IPv6 Address
…also…
+ Enter the IPv6 address for a /64 LAN with a prefix that was assigned with your tunnel.
12. Click [Update] and wait for the AirPort/Time-Capsule to restart.