Load balancing and other FortiOS features
Flow-based and proxy-based security features such as virus scanning, IPS, DLP, application control, and web filtering can be applied to load balanced sessions. This includes SSL offloading and multiplexing. Applying these UTM features to load balancing traffic may reduce load balancing performance.
Authentication is not supported for load balancing sessions. Usually FortiGate load balancing is used to allow public access to services on servers protected by a FortiGate unit. Authentication is not generally not required for this kind of configuration.
Features such web proxying, web caching, and WAN optimization also do not work with load balanced sessions. However, most other features that can be applied by a security policy are supported.