Configuring IPsec VPN load balancing

FortiGate 7000F IPsec load balancing is tunnel based. You can set the load balance strategy for each tunnel when configuring phase1-interface options:

config vpn ipsec phase1-interface

edit <name>

set ipsec-tunnel-slot {auto | FPM3 | FPM4 | FPM5 | FPM6 | FPM7 | FPM8 | FPM9 | FPM10 | FPM11 | FPM12 | master}

end

auto the default setting. All tunnels started by this phase 1 are load balanced to an FPM slot based on the src-ip and dst-ip hash result. All traffic for a given tunnel instance is processed by the same FPM.

FPM3 to FPM12 all tunnels started by this phase 1 terminate on the selected FPM.

master all tunnels started by this phase 1 terminate on the primary FPM.

Even if you select master or a specific FPM, new SAs created by this tunnel are synchronized to all FPMs.

If the IPsec interface includes dynamic routing, the ipsec-tunnel-slot option is ignored and all tunnels are terminated on the primary FPM.