27.11.2 Checking multiple spanning tree status

Use the show spanning-tree command to check information about Multiple Spanning Tree. To check that the topology has been built properly, make sure that the following items are correct:

The region settings (Revision Level, Configuration Name, and VLAN Mapped for MST Instance)
The contents of Regional Root
The Status and Role for Port Information

The following figure shows the result of executing the show spanning-tree command.

Figure 27-15: Result of executing show spanning-tree command
> show spanning-tree mst Date 20XX/09/04 11:41:03 UTC Multiple Spanning Tree: Enabled Revision Level: 65535 Configuration Name: MSTP001 CIST Information VLAN Mapped: 1-99,151-4095 ..1 CIST Root Priority: 32768 MAC : 0012.e207.7200 External Root Cost : 2000 Root Port: 1/0/1 Regional Root Priority: 32768 MAC : 0012.e207.7200 Internal Root Cost : 0 Bridge ID Priority: 32768 MAC : 0012.e205.0900 Regional Bridge Status : Designated Port Information 1/0/1 Up Status:Forwarding Role:Root 1/0/2 Up Status:Discarding Role:Backup 1/0/3 Up Status:Discarding Role:Alternate 1/0/4 Up Status:Forwarding Role:Designated MST Instance 10 VLAN Mapped: 100-150 Regional Root Priority: 32778 MAC : 0012.e207.7200 Internal Root Cost : 2000 Root Port: 1/0/1 Bridge ID Priority: 32778 MAC : 0012.e205.0900 Regional Bridge Status : Designated Port Information 1/0/1 Up Status:Forwarding Role:Root 1/0/2 Up Status:Discarding Role:Backup 1/0/3 Up Status:Discarding Role:Alternate 1/0/4 Up Status:Forwarding Role:Designated >

Figure 27-15: Result of executing show spanning-tree command

> show spanning-tree mst
Date 20XX/09/04 11:41:03 UTC
Multiple Spanning Tree: Enabled
Revision Level: 65535  Configuration Name: MSTP001
CIST Information
  VLAN Mapped: 1-99,151-4095                                            ..1
  CIST Root      Priority: 32768       MAC      : 0012.e207.7200
  External Root Cost     : 2000        Root Port: 1/0/1
  Regional Root  Priority: 32768       MAC      : 0012.e207.7200
  Internal Root Cost     : 0
  Bridge ID      Priority: 32768       MAC      : 0012.e205.0900
  Regional Bridge Status : Designated
  Port Information
    1/0/1      Up   Status:Forwarding  Role:Root
    1/0/2      Up   Status:Discarding  Role:Backup
    1/0/3      Up   Status:Discarding  Role:Alternate
    1/0/4      Up   Status:Forwarding  Role:Designated
MST Instance 10  
  VLAN Mapped: 100-150
  Regional Root  Priority: 32778       MAC      : 0012.e207.7200
  Internal Root Cost     : 2000        Root Port: 1/0/1
  Bridge ID      Priority: 32778       MAC      : 0012.e205.0900
  Regional Bridge Status : Designated
  Port Information
    1/0/1      Up   Status:Forwarding  Role:Root       
    1/0/2      Up   Status:Discarding  Role:Backup     
    1/0/3      Up   Status:Discarding  Role:Alternate  
    1/0/4      Up   Status:Forwarding  Role:Designated 
>

Displaying instance mapping VLANs (VLAN Mapped)

The Switch supports VLAN ID from 1 to 4094, but VLAN ID used to set the region is 1 to 4095 according to the standard. The indication specifies 1 to 4095 so that VLAN ID1~4095 supported by the standard can be seen to belong to which instance.