Switch 7700 Command reference Guide, v2.0

328 CHAPTER 8: USING STP COMMANDS
recommended to set the network diameter to get the other two time parameter
of the switch accordingly.
CAUTION: In a switching network, you can configure only one root bridge for
each STI and one or more secondary switches. Do not configure more than one
root bridge for an STI at the same time, otherwise, the calculation result will be
unpredictable.
After a switch is configured as primary root switch or secondary root switch, you
cannot modify the bridge priority of the switch.
Example
Designate the current switch as the root bridge of STI 1 and specifies the diameter
of the switching network as 4 and the Hello Time as 500 centiseconds:
[SW7700]stp instance 1 root primary bridge-diameter 4 hello-time 500
stp instance root
secondary
Syntax
stp instance instance-id root secondary [ bridge-diameter bridgenum
[ hello-time centi-seconds ] ]
undo stp instance instance-id root
View
System view
Parameter
instance instance-id: Specifies the spanning tree instance ID, ranging from 0
to 16. Specify it as 0 to configure CIST.
root secondary: Configure the current switch as the secondary root of the
designated STI.
bridge-diameter bridgenum: Specify the network diameter of the spanning
tree, ranging from 2 to 7.
hello-time centi-seconds: Specify the Hello Time of the spanning tree,
ranging from 100 to 1000 and measured in centiseconds.
Description
■ Use the stp instance root secondary command to configure the current
switch as the secondary root bridge of a specified STI.
■ Use the undo stp instance root command to cancel the current switch for
the secondary root bridge of a specified STI.
By default, the switch does not server as a secondary root bridge.
You can configure one or more secondary root bridges in an STI. If the primary
root is down or powered off, the secondary root will take its place. Among several
secondary root bridges, the one with the smallest MAC address takes the place of
the failed primary root.
When configuring the secondary root bridge, you may also specify the switching
network diameter and the Hello Time of the switch, so that the other two