Modifying some of the Spanning Tree Protocol parameters allows the operator to balance STP between resiliency and speed of convergence extremes. Modifying particular parameters, as follows, must be done in the constraints of the following two formulas:
2 x (Bridge_Forward_Delay - 1.0 seconds) ≥ Bridge_Max_Age Bridge_Max_Age ≥ 2 x (Bridge_Hello0_Time + 1.0 seconds)
The following STP parameters can be modified at VPLS level:
STP always uses the locally configured values for the first three parameters (Admin State, Mode, and Priority).
For the parameters Max Age, Forward Delay, Hello Time, and Hold Count, the locally configured values are only used when this bridge has been elected root bridge in the STP domain; otherwise, the values received from the root bridge are used. The exception to this rule is: when STP is running in RSTP mode, the Hello Time is always taken from the locally configured parameter. The other parameters are only used when running mode MSTP.