Huawei Quidway S3000 Series Operation Manual page 41

Operation Manual - STP
Quidway S3000 Series Ethernet Switches
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.
Table2-9 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 switch of the CIST.
Caution:
The Forward Delay configured on a switch depends on the switching network diameter. Generally, the
Forward Delay is supposed to be longer when the network diameter is longer. Note that too short a
Forward Delay may redistribute some redundant routes temporarily, while too long a Forward Delay may
prolong the network connection resuming. The default value is recommended.
A suitable Hello Time ensures the switch to detect the link fault on the network but occupy moderate
network resources. The default value is recommended. If you set too long a Hello Time, when there is
packet dropped over a link, the switch may consider it as link fault and the network device will recalculate
the spanning tree accordingly. However, for too short a Hello Time, the switch frequently sends
configuration BPDU, which adds its burden and wastes the network resources.
Too short a Max Age may cause the network device frequently calculate the spanning tree and mistake the
congestion as link fault. However, if the Max Age is too long, the network device may not be able to
discover the link fault and recalculate the spanning tree in time, which will weaken the auto-adaptation
capacity of the network. The default value is recommended.
Operation
2-17
Chapter 1 RSTP 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