3Com 5500-EI PWR, Справочное руководство

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Parameters
centi-seconds : Hello time to be set, in the range of 100 to 1,000 (in centiseconds).
Description
Use the stp timer hello command to set the hello time of the switch.
Use the undo stp timer hello command to restore the hello time of the switch to the default value.
By default, the hello time of the switch is 200 centiseconds.
A root bridge regularly sends out configuration BPDUs to maintain the stability of existing spanning
trees. If the switch does not receive BPDU packets in a specified period, spanning trees will be
recalculated because BPDU packets time out. When a switch becomes a root bridge, it regularly sends
BPDUs at the interval specified by the hello time you have configured on it. The other none-root-bridge
switches adopt the interval specified by the hello time.
As for the configuration of the three time-related parameters (namely, the hello time, forward delay, and
max age parameters), the following formulas must be met to prevent frequent 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 by
using the stp root primary or stp root secondary command. After that, the three proper time-related
parameters are automatically calculated by MSTP.
Related commands: stp timer forward-delay , stp timer max-age , stp bridge-diameter .
Examples
# Set the hello time to 400 centiseconds.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] stp timer hello 400
stp timer max-age
Syntax
stp timer max-age centi-seconds
undo stp timer max-age
View
System view
Parameters
centi-seconds : Max age to be set, in the range of 600 to 4,000 (in centiseconds).
Description
Use the stp timer max-age command to set the max age of the switch.
Use the undo stp timer max-age command to restore the default max age.
By default, the max age of a switch is 2,000 centiseconds.