3Com 8807 Command Reference Manual page 204

202 C 13: MSTP C C
HAPTER ONFIGURATION OMMANDS
undo stp [ instance instance-id ] root
View
System view
Parameter
instance instance-id: Specifies the spanning tree instance ID, ranging from 0 to
48. Specify it as 0 to configure CIST.
root secondary: Configures the current switch as the secondary root of the
designated MSTI.
bridge-diameter bridgenum: Specifies the network diameter of the spanning
tree, ranging from 2 to 7.
hello-time centi-senconds: Specifies the Hello Time of the spanning tree, which is
in the range from 100 to 1000 and is measured in centiseconds.
Description
Use the stp root secondary command to configure the current switch as the
secondary root bridge of a specified MSTI.
Use the undo stp root command to cancel the current switch for the secondary
root bridge of a specified MSTI.
Only when the instance-id parameter is set to 0, can its following parameters take
effect.
By default, the switch does not server as a secondary root bridge.
You can configure one or more secondary root bridges in an MSTI. 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
parameters, Forward Delay and Max Age, of the switch can be determined. To
configure the current switch as the root bridge of CIST, simply specify instance-id
as 0. You can configure only one root bridge for an MSTI and one or more
secondary root bridges for it.
After a switch is configured as a primary root bridge or a secondary root bridge,
users cannot modify the bridge priority of the switch.
Example
# Configure the current switch as the secondary root bridge of MSTI 0 and specify
the diameter of the switching network as 5 and the Hello Time of the switch as
300 centiseconds.
<SW8800>system-view
System View: return to User View with Ctrl+Z.
[SW8800] stp instance 0 root primary bridge-diameter 5 hello-time 30
0