Changing MST and STP priority values

[johnlloyd_13]

hi,

i'll be replacing a pair of core switches to a new hardware.

i plan to run a temporary trunk between old and new CSW1 before doing cable migration (to downstream SW and CPE devices) and change MST and STP priority values between old and new CSW1 and CSW2 switches.

would this be a straightforward change and will i lose remote access if i change around these values?

does anyone configure the same and has similar steps/plan?

CSW1-OLD

spanning-tree mst 0-2 priority 24576   <<< CHANGE TO 4096

spanning-tree vlan 1-4094 priority 24576   <<< CHANGE TO 4096

CSW2-OLD

spanning-tree mst 0-2 priority 28672   <<< CHANGE TO 8192

spanning-tree vlan 1-4094 priority 28672   <<< CHANGE TO 8192

-----

pre-configure values below and connect a trunk between CSW1-OLD and CSW1-NEW

CSW1-NEW

spanning-tree mst 0-2 priority 12288

spanning-tree vlan 1-4094 priority 12288

CSW2-NEW

spanning-tree mst 0-2 priority 16384

spanning-tree vlan 1-4094 priority 16384

during the migration of ports/cables from old to new CSW1 and CSW2:

CSW1-OLD

spanning-tree mst 0-2 priority 20480    <<< "FLOAT" MST AND STP VLAN PRIORITY"

spanning-tree vlan 1-4094 priority 20480

CSW2-OLD

spanning-tree mst 0-2 priority 24576    <<< "FLOAT" MST AND STP VLAN PRIORITY"

spanning-tree vlan 1-4094 priority 24576

-----

CSW1-NEW

spanning-tree mst 0-2 priority 4096    <<< LOWER DOWN MST AND STP VLAN PRIORITY VALUES

spanning-tree vlan 1-4094 priority 4096

CSW2-NEW

spanning-tree mst 0-2 priority 8192   <<< LOWER DOWN MST AND STP VLAN PRIORITY VALUES

spanning-tree vlan 1-4094 priority 8192

then remove temporary trunk link between CSW1.

[paul driver]

Hello
Why do you need to change the stp priority’s, The old core will still be the active core until you have migrated everything over so why not keep the values as they are?

As for the migration, I would say perform this migration in a 2-step approach,
1- all layer 2 connection (distribution/access)
2- L3

[johnlloyd_13]

hi paul,

i would need to change STP priority values to make way for the new CSW1 and CSW2.

the current  primary STP priority is 24576 and secondary is 28672 so there's no room left for the new CSW since default is 32768 which will make it equal to other downstream/access SW. do you recommend changing all STP priority values on the migration day itself?