Spanning-Tree VLAN Root Primary
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.
Swith(cconfig)#spanning-tree vlan <vlan range> root primary
Now we will configure SW1 to become root for Vlan 10.
We can see that SW1 is now root for Vlan 10. Notice the priority is now 24576.