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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 5 Managing Switch Stacks Configuring the Switch Stack
the previous stack master does not rejoin the stack during this period, the switch stack takes the MAC
address of the new stack master as the stack MAC address.You can also configure stack MAC persistency
so that the stack never switches to the MAC address of the new stack master.
Note When you enter the command to configure this feature, a warning message appears containing the
consequences of your configuration. You should use this feature cautiously. Using the old stack master
MAC address elsewhere in the same domain could result in lost traffic.
You can configure the time period as 0 to 60 minutes.
• If you enter the command with no value, the default delay is 4 minutes. We recommend that you
always enter a value. If the command is entered without a value, the time delay appears in the
running-config file with an explicit timer value of 4 minutes.
• If you enter 0, the stack MAC address of the previous stack master is used until you enter the no
stack-mac persistent timer command, which immediately changes the stack MAC address to that
of the current stack master. If you do not enter the no stack-mac persistent timer command, the
stack MAC address never changes.
• 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.
Note If the entire switch stack reloads, it uses the MAC address of the stack master as the stack MAC address.
Beginning in privileged EXEC mode, follow these steps to enable persistent MAC address. This
procedure is optional.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 stack-mac persistent timer [0 |
time-value]
Enable a time delay after a stack-master change before the stack MAC
address changes to that of the new stack master. If the previous stack
master rejoins the stack during this period, the stack uses that MAC
address as the stack MAC address.
• Enter the command with no value to set the default delay of
approximately 4 minutes. We recommend that you always configure
a value.
• Enter 0 to continue using the MAC address of the current stack
master indefinitely.
• Enter a time-value from 1 to 60 minutes to configure the time period
before the stack MAC address changes to the new stack master.
Note When you enter this command, a warning states that traffic
might be lost if the old master MAC address appears elsewhere
in the network domain.
If you enter the no stack-mac persistent timer command after a new
stack master takes over, before the time expires, the switch stack moves
to the current stack master MAC address.
Step 3 end Return to privileged EXEC mode.