Chapter 9 High Availability for FortiOS 5.0 : HA and load balancing
  
HA and load balancing
FGCP active-active load balancing distributes network traffic among all of the units in a cluster. Load balancing can improve cluster performance because the processing load is shared among multiple cluster units.
This chapter describes how active-active load balancing works and provides detailed NAT/Route and Transparent mode packet flow descriptions.
This chapter contains the following sections:
Load balancing overview
Configuring load balancing settings
NAT/Route mode active-active cluster packet flow
Transparent mode active-active cluster packet flow