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I have two switches in a stack. One is master and the other is a slave. If I turn off the slave, the master will work with no problem. My questions:

  • if I turn off the master, will the slave still work, will the stack switch work normally, or I will have a downtime of the entire stack?
  • once the master switch that we turned off previously is turned on again, will be the master again?! I think it should be re-elected as master as the priority number of this switch is higher then the priority number of the slave.
  • Will the vlan database should not be affected by loosing the master?
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This is true of Cisco Catalyst and as far as I know all Cisco switches:

If you already have made both switches stack members, the slave switch should be elected to master if the current master becomes unavailable.

I believe the original master will be reelected upon a power cycle of the stack, or just the slave I suppose, assuming the original master is again online/available.

From cisco.com:

When is the stack master elected?

-When the whole switch stack is reset

-When the stack master is reset or powered off

Note: If you reset the stack master, it would reset the whole stack.

-When the stack master is removed from the stack

-When the stack master switch has failed

Within these events, the current stack master has a greater chance to get re-elected.

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  • 1
    Yes this is clear for me, but once the master switch that we turned off previously is turned on again, will be the master again?! I think it should be re-elected as master as the priority number of this switch is higher then the prioirity number of the slave. Also, the vlan database should not be affected, right ?!
    – ipermo
    Jan 16 '15 at 8:29
  • Please see edited answer above. Jan 16 '15 at 20:53
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Yes, you are correct on the priority number. As long as the master switch is set to a higher priority than the member, you should be fine when your master switch is powered on and comes back online in regards to VLAN database.

I am going to assume you have redundant uplinks configured on both switches A and B. If switch B doesnt have redundant uplinks and master switch A goes offline, switch B will be of no good.

HTH Rez

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