3Com 7700 Configuration Manual page 234

226 C 8: STP O
HAPTER PERATION
Specifying the Switch as
Primary or Secondary
Root Switch
Configuring the MST Region
Perform the following configuration in MST region view.
Table 19 Configure the MST region for a switch
Operation
Configure MST region name
Restore the default MST region name
Configure VLAN mapping table
Restore the default VLAN mapping table
Configure the MSTP revision level of MST
region
Restore the MSTP revision level of MST region undo revision-level
An MST region can contain up to 49 spanning tree instances, among which
Instance 0 is an IST and instances 1 through 48 are MSTIs. Upon the completion of
this configurations, the current switch is put into a specified MST region. Note that
two switches belong to the same MST region only if they have been configured
with the same MST region name, STI-VLAN mapping tables of an MST region, and
the MST region revision level.
Configuring the related parameters, especially the VLAN mapping table, of the
MST region, will lead to the recalculation of spanning tree and network topology
flapping. To reduce such flapping, MSTP triggers to recalculate the spanning tree
according to the configurations only if one of the following conditions is met:
The user manually activates the configured parameters related to the MST
■
region, using the active region-configuration command.
The user enables MSTP, using the stp enable command.
■
By default, the MST region name is the first switch MAC address, all the VLANs in
the MST region are mapped to the STI 0, and the MSTP region revision level is 0.
You can restore the default settings of MST region, using the undo stp
region-configuration command in system view.
Activating the MST Region Configuration,and Exit the MST Region View
Perform the following configuration in MST region view.
Table 20 Activate the MST Region Configuration and Exit the MST Region View
Operation
Show the configuration information of the
MST region under revision (from MST region
view)
Manually activate the MST region
configuration (from MST region view)
Exit MST region view (from MST region view)
MSTP can determine the spanning tree root through calculation. You can also
specify the current switch as the root, using the command provided by the switch.
You can use the following commands to specify the current switch as the primary
or secondary root of the spanning tree.
Command
region-name name
undo region-name
instance instance-id vlan vlan-list
undo instance
revision-level level
Command
check region-configuration
active region-configuration
quit