3Com Switch 7750 SeriesCommand Reference Guide – MSTP Chapter 1 MSTP Configuration Commands1-45As for the configuration of the three time-related parameters (that is, the Hello time,Forward delay, and Max age parameters), the following formulas must be met toprevent network jitter.2 * (Forward delay – 1 second) >= Max age,Max age >= 2 * (Hello time + 1 second).You are recommended to specify the network diameter of the switched network and theHello time parameter by using the stp root primary or stp root secondary command.After that, the three proper time-related parameters are automatically determined.Related command: stp timer forward-delay, stp timer hello, and stpbridge-diameter.Example# Set the Max age to 1,000 centiseconds.<3Com> system-viewSystem View: return to User View with Ctrl+Z.[3Com] stp timer max-age 10001.1.43 stp timer-factorSyntaxstp timer-factor numberundo stp timer-factorViewSystem viewParameternumber: Hello time factor. This argument ranges from 1 to 10 and defaults to 3.DescriptionUse the stp timer-factor command to set the timeout time of MSTP protocol packetson a switch in the form of a multiple of the Hello time. For example, with the numberargument set to 3, the timeout time is three times of the Hello time.Use the undo stp timer-factor command to revert to the default Hello time factor.A switch regularly sends protocol packets to its neighboring devices at the intervalspecified by the Hello time parameter to test the links. Normally, a switch regards itsupstream switch faulty if the former does receive any protocol packets from the latter ina period three times of the Hello time and then initiates the spanning tree regenerationprocess.
