FortiControllers act as load balancers for FortiGate-5000s operating as workers in Session Aware Load Balancing Clusters (SLBCs) installed in FortiGate-5000 chassis. All traffic is directed to the FortiController front panel interfaces and then the FortiControllers load balance traffic to the workers. SLBC load balances TCP and UDP sessions. As a session-aware load balancer, the FortiController includes DP processors that maintain state information for all TCP and UDP sessions. The DP processors are capable of directing any TCP or UDP session to any worker installed in the same chassis. This session-awareness means that all TCP and UDP traffic being processed by a specific worker continues to be processed by the same worker. Session-awareness also means that more complex networking features such as network address translation (NAT), fragmented packets, complex UDP protocols, and complex protocols such as SIP that use pinholes, can be load balanced by the cluster.
