In conclusion, there are vpn implementations, above, including different types of vendors, Fortigate-to-Fortigate and Fortigate-to-Cisco ASA. Fortigate vpn connection that has same type of fortigate is straightforward, however, Cisco ASA and fortigate vpn connection should be paid attention compared to the first implementation regarding IPSec, encryption, Diffie-Hellman group, authentication method etc.