Switching Notes

Switch with the lowest priority is the root Hard-code as much as possible, priorities, router-ids?
The path with the lowest cost to root is in forwarding state.
Duplicates, and higher cost to the root are in blocking state.
spanning-tree VLAN 56 root primary Configures the switch as primary root for this spanning tree, priority = 24576
spanning-tree VLAN 2 root primary A switch can be a primary root more for more than 1 VLAN [same effect as priority 0] as recommended as the official way in Cisco's DOC
spanning-tree VLAN 2 priority 0 Set switch & VLAN to be the root [same effect as root primary, but is preferred]
Better use priority 0 to make sure that it becomes the root of the spanning tree.
In case the switch MUST be always root switch.
ALWAYS, ALWAYS set the switch priority when there is more than 1 switch.