02-20-2016 08:47 PM - edited 03-08-2019 04:39 AM
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
02-22-2016 04:33 PM
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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