3Com 7700 Configuration Manual page 176

168 C 8: STP O
HAPTER PERATION
state and resume data frame forwarding. This delay ensures that the new
configuration BPDU has been propagated throughout the network before the
data frame forwarding is resumed.
Perform the following configurations in system view.
Table 7 Set the Forward Delay for a Bridge
Operation
Set forward delay of a specified
bridge
Restore the default forward delay
of specified bridge
The forward delay of the bridge is related to the diameter of the switching
network. As a rule, the larger the network diameter, the longer the forward delay.
Note that if the forward delay is configured too short, occasional path redundancy
can occur. If the forward delay is configured too long, the restoration of the
network connection can take a long time. The default setting is recommended.
By default, the bridge forward delay is 15 seconds.
Setting the Hello Timer of the Specified Bridge
A bridge transmits a hello packet regularly to the adjacent bridges to check if there
is a link failure.
Perform the following configurations in system view.
Table 8 Set the Hello Timer of the Specified Bridge
Operation
Set Hello Time of the specified
bridge
Restore the default Hello Time of
the specified bridge
The appropriate hello timer can ensure that the bridge can detect the link failure in
the network in time without occupying too many network resources. If the hello
timer is too long, it will result in spanning tree recalculation because the bridge
mistakes due to the frame dropping of the link for link failure. If the hello timer is
too short, it will result in the frequent transmission of configuration BPDUs by the
bridge and an undue increase in the switch load and waste of network resource.
By default, the hello time of the bridge is 2 seconds.
Setting the Max Age of the Specified Bridge
Max Age is a parameter to judge whether the configuration BPDU has timed out.
Users can configure it according to the actual network situation.
Perform the following configurations in system view.
Table 9 Set Max Age for a Bridge
Operation
Set Max Age for a bridge
Command
stp timer forward-delay centiseconds
undo stp timer forward-delay
Command
stp timer hello centiseconds
undo stp timer hello
Command
stp timer max-age centiseconds