Change STP VLAN priorities and implement STP root Guard

'
I created the change below to correct our STP load balancing between the primary core switch and the secondary core switch. Previous implementation incorrectly set the VLAN STP priorities and we have to implement this change before we can add root STP root guard on all uplink ports going to the edge switches. This is done to project our core switches from taking over as the root of our STP domain from any one who will configure a switch connected to the edge with lower priority.

 With this implementation we can make sure that only the two core switches (primary and secondary) can only be elected as the root bridge.

----------------------------------------------------
                    | CoreSW1001 | CoreSW1002
---------------+----------------+-----------------
Odd VLAN   | 8192                 | 16384
---------------+----------------+-----------------
Even VLAN | 16384              | 8192
----------------------------------------------------

CoreSW1001:

conf t
spanning-tree vlan 215 priority 8192

spanning-tree vlan 202 priority 16384

CoreSW1002:

conf t
spanning-tree vlan 215 priority 16384

spanning-tree vlan 202 priority 8192

-------------------------
enabling STP Root Guard
-------------------------

CoreSW1001:

cont t
int r "all uplink interface"
spanning-tree guard root
end
wr mem

CoreSW1002:

conf t
int r "all uplink interface"
spanning-tree guard root
end
wr mem

STP VLAN root primary|secondary 2nd post

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I just find out today from my lead that we are not really using the command above as part of our VLAN creation steps instead we statically set VLAN priority to 8192 for the root bridge and 16384 for the secondary root bridge.
We just try to use the Cisco macro command root primary and root secondary because our boss insisted on using it. Now we know that this command give's/set 24576 and 28372 priority value to the root and the secondary root bridge respectively.
I don't really see any problem in using the macro command or setting the priority value by your self as long as your being consistent and not mix the two command in a single setup.

STP VLAN root primary|secondary

'
I just was testing this on live network. We are trying to find out how this Cisco Macro command will be able to set the STP priority. We expect that we get a priority of 8192 for the primary root bridge and 16384 for the secondary root bridge, but after we created a new VLAN and implemented the commands on our primary core switch as the primary root and secondary core as the secondary root and we get the following setting below:

Core1:

Core1#sh run | i span

Spanning-tree vlan 999 priority 24576

Core2:

Core2#sh run | i span

Spanning-tree vlan 999 priority 28372

We really don’t know why this priority setting is deferent from the previous VLAN STP implementations done on the same core switches.

I’ll be posting the answers if I can find out the explanation behind this.