7-16
To do...
Use the command...
Remarks
instance
instance-id
vlan
vlan-list
Configure the VLAN-to-instance
mapping table
vlan-mapping modulo
modulo
Optional
Use either command.
All VLANs in an MST region are
mapped to MSTI 0 (that is, the
CIST) by default.
Configure the MSTP revision level
of the MST region
revision-level
level
Optional
0 by default
Display the MST region
configurations that are not
activated yet
check region-configuration
Optional
Activate MST region configuration
manually
active region-configuration
Required
Display the configurations of
currently activated MST regions
display stp region-configuration
The
display
command can be
executed in any view.
z
Two or more MSTP-enabled bridges belong to the same MST region only if they are configured to
have the same format selector (0 by default, not configurable), MST region name, the same
VLAN-to-instance mapping entries in the MST region and the same MST region revision level, and
they are interconnected via a physical link.
z
The configuration of MST region–related parameters, especially the VLAN-to-instance mapping
table, will cause MSTP to launch a new spanning tree calculation process, which may result in
network topology instability. To reduce the possibility of topology instability caused by configuration,
MSTP will not immediately launch a new spanning tree calculation process when processing MST
region–related configurations; instead, such configurations will take effect only after you activate
the MST region–related parameters using the
active region-configuration
command, or enable
MSTP using the
stp enable
command in the case that MSTP is not enabled.
Configuring the Root Bridge or a Secondary Root Bridge
MSTP can determine the root bridge of a spanning tree through MSTP calculation. Alternatively, you
can specify the AP as the root bridge or a secondary root bridge by using the commands provided by
the system.
Note that:
z
A bridge has independent roles in different MSTIs. It can act as the root bridge or a secondary root
bridge of one MSTI while being the root bridge or a secondary root bridge of another MSTI.
However, a bridge cannot be the root bridge and a secondary root bridge in the same MSTI at the
same time.
z
There is only one root bridge in effect in a spanning tree instance. If two or more bridges have been
designated to be root bridges of the same spanning tree instance, MSTP will select the bridge with
the lowest MAC address as the root bridge.
