Primarily used for STP, the Forward Delay option specifies the amount of time, in seconds, that the system blocks an interface from forwarding network traffic when the spanning tree algorithm reconfigures a spanning tree. The default value is 15, and the valid range is 4 to 30.
This option has no effect on the BIG-IP® system when running in RSTP or
MSTP mode, provided that all bridges in the spanning tree use the RSTP or MSTP protocol. However,
if the addition of legacy STP bridges causes neighboring bridges to fall back to running the STP
protocol, then the spanning tree algorithm uses the Forward Delay option when reconfiguring the
Note that when running RSTP, you must maintain the following relationship between the Forward Delay and Maximum Age options:
Maximum Age <= 2 * (Forward Delay - 1)