H3C Technologies H3C S3100 Series Switches - Manual (Page 186)

Operation Manual – MSTP
H3C S3100-52P Ethernet Switch
Chapter 1 MSTP Configuration
1-11
I. Specify the current switch as the root bridge of a specified spanning tree
Table 1-4 Specify the current switch as the root bridge of a specified spanning tree
Operation Command Description
Enter system view system-view —
Specify the current switch
as the root bridge of a
specified spanning tree
stp [ instance instance-id ] root
primary [ bridge-diameter
bridgenumber ] [ hello-time
centi-seconds ]
Required
II. Specify the current switch as the secondary root bridge of a specified
spanning tree
Table 1-5 Specify the current switch as the secondary root bridge of a specified
spanning tree
Operation Command Description
Enter system view system-view —
Specify the current switch
as the secondary root
bridge of a specified
spanning tree stp [ instance instance-id ] root
secondary [ bridge-diameter
bridgenumber ] [ hello-time
centi-seconds ]
Required
Using the stp root primary/stp root secondary command, you can specify the current
switch as the root bridge or the secondary root bridge of the spanning tree instance
identified by the instance-id argument. If the value of the instance-id argument is set to
0, the stp root primary/stp root secondary command specify the current switch as
the root bridge or the secondary root bridge of the CIST.
A switch can play different roles in different spanning tree instances. That is, it can be
the root bridges in a spanning tree instance and be a secondary root bridge in another
spanning tree instance at the same time. But in the same spanning tree instance, a
switch cannot be the root bridge and the secondary root bridge simultaneously.
When the root bridge fails or is turned off, the secondary root bridge becomes the root
bridge if no new root bridge is configured. If you configure multiple secondary root
bridges for a spanning tree instance, the one with the smallest MAC address replaces
the root bridge when the latter fails.