3Com Switch 7750 Series
Command Reference Guide – MSTP Chapter 1 MSTP Configuration Commands
1-45
As 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 to
prevent 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 the
Hello 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 stp
bridge-diameter.
Example
# Set the Max age to 1,000 centiseconds.
<3Com> system-view
System View: return to User View with Ctrl+Z.
[3Com] stp timer max-age 1000
1.1.43 stp timer-factor Syntax
stp timer-factor number
undo stp timer-factor
View
System view
Parameter
number: Hello time factor. This argument ranges from 1 to 10 and defaults to 3.
Description
Use the stp timer-factor command to set the timeout time of MSTP protocol packets
on a switch in the form of a multiple of the Hello time. For example, with the number
argument 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 interval
specified by the Hello time parameter to test the links. Normally, a switch regards its
upstream switch faulty if the former does receive any protocol packets from the latter in
a period three times of the Hello time and then initiates the spanning tree regeneration
process.