User's Manual

266

Hello Time
：
The interval to send the configuration message to the designated port when theswitch functions
as the network root.

Forward Delay
：
Time that the port needs when it changes from the Blocking state to theLearning state and to the
Forwarding state in STP mode.

Max Age
：
The maximum live period of the configuration information about the spanningtree.
To reduce the shock of the network topology, the following requirements for the time parameters must be
satisfied:
 2 x (fwd_delay - 1.0) >= max_age
 max_age >= (hello_time + 1) x 2
Running the following command to set the time parameter of MSTP:
Command Purpose
spanning-tree mstp hello-time
seconds Resumes Hello Time to the default value.
seconds: value range: 1-10 seconds, Default value:
2 seconds
no spanning-tree mstp hello-time
Resumes the hello time to the default value.
spanning-tree mstp forward-time
seconds Sets the parameter Forward Delay.
seconds: value range from 4 to 30 seconds, the
default value is 15 seconds.
no spanning-tree mstp forward-time
Resumes Forward Delay to the default value.
spanning-tree mstp max-age
seconds Sets the parameter Max Age.
seconds: value range from 6 to 40 seconds, the
default value is 20 seconds.
no spanning-tree mstp max-age
Resumes the Max Age to the default value.
It is recommended to modify the time parameter of STP through setting the root or network diameter, ensuring
the rationality of the time parameter.
The newly-set time parameters are valid even if they do not comply with the previous formula’s requirements.
Pay attention to the notification on the console when you perform configuration.
36.3.8 Configuring network diameter
Network diameter stands for the maximum number of switches between two hosts in the network, representing
the scale of the network.
You can set the MSTP network diameter by running the command spanning-treemstp diameter net-diameter.
The parameter net-diameter is valid only to CIST. Afterconfiguration, three STP time parameters is
automatically updated to comparativelybetter values.
Run the following command to configure net-diameter:
Command Purpose
spanning-tree mstp diameter
net-diameter Configure net-diameter.
net-diameter: value range: 2-7; default value: 7