R0106-HP MSR Router Series Layer 2 - LAN Switching Configuration Guide(V7)

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instability, the MST region configuration takes effect only after you activate it by doing one of the
following:
• Use the active region-configuration command.
• Enable a spanning tree protocol by using the stp global enable command if the spanning tree
protocol is disabled.
In STP, RSTP, or PVST mode, MST region configurations do not take effect.
To configure an MST region:
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
The default setting is the MAC
address.
4. Configure the
VLAN-to-instance mapping
table.
• instance instance-id vlan
vlan-id-list
• vlan-mapping modulo modulo
Use one of the commands.
By default, all VLANs in an MST
region are mapped to the CIST (or
MSTI 0).
5. Configure the MSTP revision
level of the MST region.
revision-level level The default setting is 0.
6. (Optional.) Display the MST
region configurations that are
not activated yet.
check region-configuration N/A
7. Manually activate MST region
configuration.
active region-configuration N/A
Configuring the root bridge or a secondary root
bridge
You can have the spanning tree protocol determine the root bridge of a spanning tree through
calculation. You can also specify the current device as the root bridge or as a secondary root bridge.
A device 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, one device cannot be the root bridge and a
secondary root bridge in the same spanning tree.
A spanning tree can have only one root bridge. If two or more devices can be selected as the root bridge
in a spanning tree, the device with the lowest MAC address is selected.
When the root bridge of an instance fails or is shut down and no new root bridge is specified:
• If you specify only one secondary root bridge, it becomes the root bridge.
• If you specify multiple secondary root bridges for the instance, the secondary root bridge with the
lowest MAC address is given priority.
• If you specify no secondary root bridge, a new root bridge is calculated.
You can specify one root bridge for each spanning tree, regardless of the device priority settings. Once
you specify a device as the root bridge or a secondary root bridge, you cannot change its priority.