Configure Basic Functions of a Spanning Tree
Configuration Condition
None
Enable the Spanning Tree Function
After the spanning tree function is enabled, devices start to run the spanning tree protocol. The devices exchange BPDU packets to form a stable tree network topology, and network loops are eliminated.
Table 9-2 Enabling the Spanning Tree Function
|
Step
|
Command
|
Description
|
|
Enter the global configuration mode.
|
configure terminal
|
-
|
|
Enabling the spanning tree function globally.
|
spanning-tree enable
|
Mandatory.
By default, the spanning tree function is disabled globally.
|
|
Enter the L2 Ethernet interface configuration mode.
|
interface interface-name
|
Either
After entering the L2 Ethernet interface configuration mode, the subsequent configuration takes effect only on the current port. After entering the aggregation group configuration mode, the subsequent configuration takes effect only on the aggregation group.
|
|
Enter the aggregation group configuration mode.
|
interface link-aggregation link-aggregation-id
|
|
Enabling the spanning tree function on a port.
|
spanning-tree enable
|
Optional.
By default, the spanning tree function is enabled on a port.
|
Configure MST Regions
Dividing an entire network into multiple MST regions helps to shorten the network convergence time. VLAN packets are transmitted through the corresponding MSTIs in MST regions and transmitted through CSTs between MST regions.
Table 9-3 Configuring MST Regions
|
Step
|
Command
|
Description
|
|
Enter the global configuration mode.
|
configure terminal
|
-
|
|
Enter the MST region configuration mode.
|
spanning-tree mst configuration
|
-
|
|
Configure an MST region name.
|
region-name region-name
|
Mandatory.
By default, the name of an MST region is the MAC address of the local device.
|
|
Configure the MSTP revision level.
|
revision-level revision-level
|
Mandatory.
By default, the MSTP revision level is 0.
|
|
Configure a VLAN mapping table.
|
instance instance-id vlan
vlan-list
|
Mandatory.
By default, all VLANs are mapped to instance 0.
|
|
Activate MST region parameter configuration.
|
active configuration pending
|
Mandatory.
By default, MST region parameters do not take effect immediately after modification.
|
-
MST region parameters do not take effect immediately after they are modified. Instead, you need to run the active configuration pending command to activate the parameters and trigger re-calculation of the spanning tree. To cancel MST region parameter configuration, use the abort configuration pending command.
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