Technical Tip: How to configure IKE version 1 or 2 in IPsec VPN FortiGate

[spathak]

Description
This article describes how to configure IKE version 1 or 2 in IPsec VPN FortiGate.

Solution
Internet Key Exchange (IKE) is the protocol used to set up SAs in IPsec negotiation.
Choose IKEv2 over IKEv1 is possible if a route-based IPsec VPN is configured.
IKEv2 simplifies the negotiation process, in that it provides no choice of Aggressive or Main mode in Phase 1.
IKEv2 also uses less bandwidth.

CLI command to configure IKE version in phase1.

# config vpn ipsec phase1-interface
   edit "TUNNEL_NAME"
        set type dynamic
        set interface "port1"
        set ike-version <Integer>   --It could be 1 or 2
end

IKE version will be configured under 'Authentication' section of phase1 in the VPN tunnel.