When you change the value of the Hello Time option, you change the time interval, in seconds, that the BIG-IP® system transmits spanning tree information (through BPDUs) to adjacent bridges in the network. The default value for this option is 2.
Although valid values are in the range of 1 to 10 seconds, F5 Networks highly recommends that you use the default value (2 seconds). This value is
optimal for almost all configurations.
Note that when running RSTP, you must maintain the following relationship between the Maximum Age and Hello Time options:
Maximum Age >= 2 * (Hello Time + 1)