Command
Spanning-Tree VLAN Root Primary
Use
This command sets the switch to become root for a given VLAN. It works by lowering the priority of the switch until it becomes root. Once the switch is root, it will not prevent any other switch from becoming root.
Syntax
Swith(cconfig)#spanning-tree vlan <vlan range> root primary
Example
In the below example we will configure SW1 to become the root for VLAN 10. Currently, we see that SW1 is not root for vlan 10. Notice the priority is currently 32768
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SW1(config)#do show spanning vlan 10 VLAN0010 Bridge ID Priority 32778 (priority 32768 sys-id-ext 10) Interface Role Sts Cost Prio.Nbr Type Interface Role Sts Cost Prio.Nbr Type Fa0/19 Desg FWD 19 128.19 P2p |
Now we will configure SW1 to become root for Vlan 10.
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SW1(config)#spanning vlan 10 root primary |
We can see that SW1 is now root for Vlan 10. Notice the priority is now 24576.
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SW1(config)#do show spanning vlan 10 VLAN0010 Bridge ID Priority 24586 (priority 24576 sys-id-ext 10) Interface Role Sts Cost Prio.Nbr Type Interface Role Sts Cost Prio.Nbr Type Fa0/20 Desg FWD 19 128.20 P2p |
