Configuring The Time Parameters Of A Switch - 3Com 8800 Configuration Manual

3Com Switch 8800 Configuration Guide
Note:
The stp bridge-diameter command configures the switching network diameter and
determines the three MSTP time parameters (Hello Time, Forward Delay, and Max Age)
accordingly.

38.2.7 Configuring the Time Parameters of a Switch

The switch has three time parameters, Forward Delay, Hello Time, and Max Age.
Forward Delay is the switch state transition mechanism. The spanning tree will be
recalculated upon link faults and its structure will change accordingly. However, the
configuration BPDU recalculated cannot be immediately propagated throughout the
network. The temporary loops may occur if the new root port and designated port
forward data right after being elected. Therefore the protocol adopts a state transition
mechanism. It takes a Forward Delay interval for the root port and designated port to
transit from the learning state to forwarding state. The Forward Delay guarantees a
period of time during which the new configuration BPDU can be propagated throughout
the network.
The switch sends Hello packet periodically at an interval specified by Hello Time to
check if there is any link fault.
Max Age specifies when the configuration BPDU will expire. The switch will discard the
expired configuration BPDU.
You can use the following command to configure the time parameters for the switch.
Perform the following configuration in system view.
Table 38-9 Configure the time parameters of a switch
Configure Forward Delay on the
switch
Restore the default Forward Delay of
the switch
Configure Hello Time on the switch
Restore the default Hello Time on
the switch
Configure Max Age on the switch
Restore the default Max Age on the
switch
Every switch on the switching network adopts the values of the time parameters
configured on the root bridge of the CIST.
Operation
38-19
Chapter 38 MSTP Region-configuration
Command
stp timer forward-delay centiseconds
undo stp timer forward-delay
stp timer hello centiseconds
undo stp timer hello
stp timer max-age centiseconds
undo stp timer max-age