Cisco Catalyst 2960-XR

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If you enter a time delay of 1 to 60 minutes, the stack MAC address of the previous stack master is used
until the configured time period expires or until you enter the no stack-mac persistent timer command.
When you enter the stack-mac persistent timer command with or without keywords, a message appears
warning that traffic might be lost if the old master MAC address appears elsewhere in the network domain.
You should use this feature cautiously.
Note
If you enter the no stack-mac persistent timer command after a switchover, before the time expires, the
switch stack moves to the current stack master MAC address.
If the whole stack reloads, when it comes back up, the MAC address of the stack master is the stack MAC
address.
Examples
This example shows how to configure the persistent MAC address feature, with the warning messages for
each configuration. It also shows how to verify the configuration:
Switch(config)# stack-mac persistent timer
WARNING: Use of an explicit timer value with the command is recommended.
WARNING: Default value of 4 minutes is being used.
WARNING: The stack continues to use the base MAC of the old Master
WARNING: as the stack-mac after a master switchover until the MAC
WARNING: persistency timer expires. During this time the Network
WARNING: Administrators must make sure that the old stack-mac does
WARNING: not appear elsewhere in this network domain. If it does,
WARNING: user traffic may be blackholed.
Switch(config)# stack-mac persistent timer 0
WARNING: Stack MAC persistency timer value of 0 means that, after a
WARNING: master switchover, the current stack-mac will continue
WARNING: to be used indefinitely.
WARNING: The Network Administrators must make sure that the old
WARNING: stack-mac does not appear elsewhere in this network
WARNING: domain. If it does, user traffic may be blackholed.
Switch(config)# stack-mac persistent timer 7
WARNING: The stack continues to use the base MAC of the old Master
WARNING: as the stack-mac after a master switchover until the MAC
WARNING: persistency timer expires. During this time the Network
WARNING: Administrators must make sure that the old stack-mac does
WARNING: not appear elsewhere in this network domain. If it does,
WARNING: user traffic may be blackholed.
Switch(config)# end
Switch(config)# show switch
Switch/Stack Mac Address : 0cd9.9624.dd80
Mac persistency wait time: 7 mins
H/W Current
Switch# Role Mac Address Priority Version State
----------------------------------------------------------
*1 Master 0cd9.9624.dd80 1 4 Ready
You can verify your settings by entering either of two privileged EXEC commands:
• show running-config—If enabled, stack-mac persistent timer and the time in minutes appears in the
output.
• show switch—If enabled, Mac persistency wait time and the number of minutes appears in the output.
Catalyst 2960-XR Switch Stack Manager Command Reference, Cisco IOS Release 15.0(2)EX1
OL-29435-01 33
Stack Manager Commands
stack-mac persistent timer