Cisco Catalyst 3650 Series User Manual

stack-mac persistent timer
To enable the persistent MAC address feature, use the stack-mac persistent timer command in global
configuration mode on the switch stack or on a standalone switch. To disable the persistent MAC address
feature, use the no form of this command.
stack-mac persistent timer [0| time-value]
no stack-mac persistent timer
Syntax Description
(Optional) Continues using the MAC address of the current active switch indefinitely,
even after a new active switch takes over.
0
(Optional) Time period in minutes before the stack MAC address changes to that of
the new active switch. The range is 1 to 60 minutes.
time-value
Command Default
Persistent MAC address is disabled. The MAC address of the stack is always that of the first active switch.
Command Modes
Global configuration
Command History
ModificationRelease
This command was introduced.Cisco IOS XE 3.3SECisco IOS XE 3.3SE
Usage Guidelines
By default, the stack MAC address will always be the MAC address of the first active switch, even if a new
active switch takes over. The same behavior occurs when you enter the stack-mac persistent timer command
or the stack-mac persistent timer 0 command.
When you enter the stack-mac persistent timer command with a time-value, the stack MAC address will
change to that of the new active switch after the period of time that you entered whenever a new switch
becomes the active switch. If the previous active switch rejoins the stack during that time period, the stack
retains its MAC address for as long as the switch that has that MAC address is in the stack.
If the whole stack reloads the MAC address of the active switch is the stack MAC address.
If you do not change the stack MAC address, Layer 3 interface flapping does not occur. This also means
that a foreign MAC address (a MAC address that does not belong to any of the switches in the stack) could
be the stack MAC address. If the switch with this foreign MAC address joins another stack as the active
switch, two stacks will have the same stack MAC address. You must use the stack-mac update force
command to resolve the conflict.
Note
Command Reference, Cisco IOS XE Everest 16.5.1a (Catalyst 3650 Switches)
875
stack-mac persistent timer

Cisco Catalyst 3650 Series Specifications

General

RAM	4 GB
Flash Memory	4 GB
Ports	24 or 48 10/100/1000 Ethernet ports
Uplinks	4 x 1G SFP or 4 x 10G SFP+ (depending on model)
Stacking	Up to 9 switches with StackWise-160
Layer Support	Layer 2, Layer 3
Software	Cisco IOS Software
Power Supply	Internal power supply; optional redundant power supply available
Storage Temperature	-40°F to 158°F (-40°C to 70°C)