IPv4 and IPv6 ECMP load balancing

You can use the following command to configure the IPv4 ECMP load balancing method for a VDOM:

config system settings

set v4-ecmp-mode {source-ip-based | weight-based | source-dest-ip-based}

end

With VDOM-based session tables enabled, the FortiGate 7000E supports all IPv4 ECMP load balancing methods supported by FortiOS except usage-based.

See this link for information about how to support IPv6 ECMP load balancing: Technical Tip: ECMP – Load balancing algorithms for IPv4 and IPv6.