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MSTP Configuration Advice

My goal is to establish specific root bridges for certain VLAN traffic. I have 1 core switch that will be the root bridge for about half the VLANs and the secondary bridge for the rest of the VLANs. There are 3 distribution switches which will serve as the root bridge for certain VLANs. Does this look like a good configuration?

Core Switch
Root bridge for VLANs 10,20,30-31,50,70-71
Secondary bridge for VLANs 32,60-61,80-82,90-91,100

spanning-tree mst configuration
name campus
revision 3
instance 1 vlan 10,20,30-31,50,70-71
instance 2 vlan 32,80,82,90,91,100
instance 3 vlan 60-61
instance 4 vlan 81

spanning-tree mst 0 priority 20480
spanning-tree mst 1 priority 24576
spanning-tree mst 2-4 priority 28672

Distribution Switch 1
Root bridge for VLANs 32,80,82,90,91,100

spanning-tree mst configuration
name campus
revision 3
instance 1 vlan 10,20,30-31,50,70-71
instance 2 vlan 32,80,82,90,91,100
instance 3 vlan 60-61
instance 4 vlan 81

spanning-tree mst 2 priority 24576

Distribution Switch 2
Root bridge for VLANs 60-61

spanning-tree mst configuration
name campus
revision 3
instance 1 vlan 10,20,30-31,50,70-71
instance 2 vlan 32,80,82,90,91,100
instance 3 vlan 60-61
instance 4 vlan 81

spanning-tree mst 3 priority 24576

Distribution Switch 3
Root bridge for VLAN 81

spanning-tree mst configuration
name campus
revision 3
instance 1 vlan 10,20,30-31,50,70-71
instance 2 vlan 32,80,82,90,91,100
instance 3 vlan 60-61
instance 4 vlan 81

spanning-tree mst 4 priority 24576

Access Switches

spanning-tree mst configuration
name campus
revision 3
instance 1 vlan 10,20,30-31,50,70-71
instance 2 vlan 32,80,82,90,91,100
instance 3 vlan 60-61
instance 4 vlan 81

Everyone's tags (3)
1 REPLY 1
Collaborator

Hello,

Hello,

I am not sure why you have not got any answer so far. You should repeat spanning tree mst command in all switches to avoid being depending on default value. If your core switch goes down for any reason, you access switches may become root bridge with your current configuration.

For example,

Switch 1:

spanning-tree mst 1 priority 28672

spanning-tree mst 2 priority 24576

spanning-tree mst 3 priority 28672

spanning-tree mst 4 priority 28672

Access switches:

spanning-tree mst 0-4 priority 32768

Hope it helps,

Masoud

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