Chapter 11 IPsec VPN for FortiOS 5.0 : IPv6 Features : IPv6 in dynamic routing
  
IPv6 in dynamic routing
Unless otherwise stated, routing protocols apply to IPv4 addressing. This is the standard address format used. However, IPv6 is becoming more popular and new versions of the dynamic routing protocols have been introduced.
As with most advanced routing features on your FortiGate unit, IPv6 settings for dynamic routing protocols must be enabled before they will be visible in the GUI. To enable IPv6 configuration in the GUI, enable it in System > Config > Features. Alternatively, you can directly configure IPv6 for RIP, BGP, or OSPF protocols using CLI commands.