Chapter 9 High Availability for FortiOS 5.0 : HA and failover protection : Synchronizing kernel routing tables : Controlling how the FGCP synchronizes kernel routing table updates : Change the time the primary unit waits after receiving a routing update
  
Change the time the primary unit waits after receiving a routing update
Change the route-wait time to change how long the primary unit waits after receiving routing updates before sending the updates to the subordinate units. For quick routing table updates to occur, set route-wait to a relatively short time so that the primary unit does not hold routing table changes for too long before updating the subordinate units.
The route-wait range is 0 to 3600 seconds. The default route-wait is 0 seconds.
Normally, because the route-wait time is 0 seconds the primary unit sends routing table updates to the subordinate units every time its routing table changes.
Once a routing table update is sent, the primary unit waits the route-hold time before sending the next update.
Usually routing table updates are periodic and sporadic. Subordinate units should receive these changes as soon as possible so route-wait is set to 0 seconds. route-hold can be set to a relatively long time because normally the next route update would not occur for a while.
In some cases, routing table updates can occur in bursts. A large burst of routing table updates can occur if a router or a link on a network fails or changes. When a burst of routing table updates occurs, there is a potential that the primary unit could flood the subordinate units with routing table updates. Flooding routing table updates can affect cluster performance if a great deal of routing information is synchronized between cluster units. Setting route-wait to a longer time reduces the frequency of additional updates are and prevents flooding of routing table updates from occurring.