Chapter 11 IPsec VPN for FortiOS 5.0 : IPv6 Configuration : IPv6 IPsec VPN : Site-to-site IPv4 over IPv6 VPN example : Configure FortiGate A IPsec settings
  
Configure FortiGate A IPsec settings
The phase 1 configuration is the same as in the IPv6 over IPv6 example.
config vpn ipsec phase1-interface
edit toB
set ip-version 6
set interface port2
set remote-gw6 fec0:0000:0000:0003:209:0fff:fe83:25c7
set dpd enable
set psksecret maryhadalittlelamb
set proposal 3des-md5 3des-sha1
end
The phase 2 configuration is the same as you would use for an IPv4 VPN. By default, phase 2 selectors are set to accept all subnet addresses for source and destination.
config vpn ipsec phase2-interface
edit toB2
set phase1name toB
set proposal 3des-md5 3des-sha1
set pfs enable
set replay enable
end