Active-passive WAN optimization requires an active WAN optimization policy on the client-side FortiGate unit and a passive WAN optimization policy on the server-side FortiGate unit. The server-side FortiGate unit also requires a security policy with the wanopt tunnel interface as the Incoming Interface.

You can use the passive policy to control WAN optimization address translation by specifying transparent mode or non-transparent mode. See “WAN optimization transparent mode”. You can also use the passive policy to apply security profiles, web caching, and other FortiGate features at the server-side FortiGate unit. For example, if a server-side FortiGate unit is protecting a web server, the passive policy could enable web caching.

A single passive policy can accept tunnel requests from multiple FortiGate units as long as the server-side FortiGate unit includes their peer IDs and all of the client-side FortiGate units include the server-side peer ID.