Setting the Link Up Delay Period
When a member port in an aggregate/redundant becomes operationally up, be default it is considered as a viable port for aggregation/redundancy after 50ms. Increasing this delay can minimizing the effect of a flapping port by causing the FortiGate to wait longer before deciding if a port is considered viable. This option is available for both redundant and aggregate interfaces.
Syntax
config system interface
edit <name>
set type {aggregate | redundant}
set link-up-delay <time>
end
end