IPv6 GRE tunnels
IPv6 addresses can be used at both ends of a GRE tunnel in the same way as with IPv4. See GRE over IPsec for more information.
The configuration is similar to a tunnel for IPv4. However, when you configure the specific tunnel, you need to set the ip-version option to 6. This will enable IPv6-specific options for the tunnel.
To configure a GRE tunnel:
config system gre-tunnel
edit <name of tunnel>
set ip-version 6
set remote-gw6 <IPv6 address of the remote gateway>
set local-gw6 <IPv6 address of the local gateway>
next
end