H3C Technologies H3C S12500 Series Switches - Manual (Page 86)

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Step Command Remarks
1. Enter system view. system-view N/A
2. Enter MST region view. stp region-configuration N/A
3. Configure the MST region
name.
region-name name
Optional.
The MST region name is the MAC
address by default.
4. Configure the
VLAN-to-instance mapping
table.
• instance instance-id vlan
vlan-list
• vlan-mapping modulo modulo
Optional.
Use either command.
All VLANs in an MST region are
mapped to the CIST (or MSTI 0) by
default.
5. Configure the MSTP revision
level of the MST region.
revision-level level
Optional.
The default setting is 0.
6. Display the MST region
configurations that are not
activated yet.
check region-configuration Optional.
7. Activate MST region
configuration manually.
active region-configuration N/A
8. Display the activated
configuration information of
the MST region.
display stp region-configuration [ |
{ begin | exclude | include }
regular-expression ]
Optional.
Available in any view.
Configuring the root bridge or a secondary root
bridge
The root bridge of a spanning tree is determined through spanning tree calculation. Alternatively, you
can specify the switch as the root bridge or a secondary root bridge.
A switch has independent roles in different spanning trees. It can act as the root bridge in one spanning
tree and as a secondary root bridge in another. However, a switch cannot be the root bridge and a
secondary root bridge in the same spanning tree.
A spanning tree can have one root bridge only. If two or more switches are selected as the root bridge
in a spanning tree at the same time, the switch with the lowest MAC address is selected.
When the root bridge of an instance fails or is shut down, the secondary root bridge (if you have
specified one) can take over the role of the primary root bridge. However, if you specify a new primary
root bridge for the instance then, the secondary root bridge will not become the root bridge. If you have
specified multiple secondary root bridges for an instance, when the root bridge fails, the secondary root
bridge with the lowest MAC address is selected as the new root bridge.