1/ Set your stack master priority:
Cisco recommends that you assign the highest priority value to the switch that you prefer to be the stack master. This ensures that the switch is re-elected as stack master if a re-election occurs.
How do you change the priority value?
From the global configuration mode, issue the command switch stack-member-number priority new-priority-value .
From the bootloader switch: prompt, issue the command set SWITCH_PRIORITY new-priority-value .
Even though the priority value applies immediately to the member, it will not affect the status of the current stack master. New priority value will play a role in the next stack-master election.
2/ Get rid of the phantom switches
Remove a Provisioned Switch from the Stack
If a switch stack runs Cisco IOS Release 12.2(20)SE or later and you remove a provisioned switch from the switch stack, the configuration associated with the removed stack member remains in the running configuration as provisioned information. In order to delete all configuration information associated with the removed switch (a stack member that has left the stack), apply the no switch provision command in global configuration mode.
In this example, switch number 2 was removed from a stack. The model number of the switch is WS-C3750-48TS:
3750(config)# no switch 2 provision ws-c3750-48ts
3750(config)# exit
3750# write memory
Note: In order to avoid the receipt of an error message, you must remove the specified switch from the switch stack before you use the no form of this command to delete a provisioned configuration.
3/ Renumber the higher-numbered stack members to lower numbers:
Go to global configuration mode.
Issue the command switch current-stack-member-number renumber new-stack-member-number .
Return to the privileged EXEC mode and reload the member with the command reload slot current-stack-member-number .
After the member boots up, issue the command show switch to verify the stack member number. If the number is used by another member in the stack, the switch selects the lowest available number in the stack.
If you move a stack member to a different switch stack, the stack member retains its number only if the number is not used by another member in the stack. If it is used by another member in the stack, the switch selects the lowest available number in the stack. The switch is able to retain the stack member number as an environment variable. You can also renumber a switch from the bootloader switch: prompt with the command set SWITCH_NUMBER stack-member-number .