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address, which is called the stack bridge MAC address. Typically, a stack uses the bridge MAC address 
of the master device as the stack bridge MAC address. 
You are recommended to configure the preservation time of stack bridge MAC address properly, 
otherwise, network problems will occur: 
z  If a master leaves a stack to join another stack or to operate independently and the stack is 
configured to preserve the bridge MAC address permanently, bridge MAC address collision occurs 
and thus causes network communication problem.  
z  If the master leaves the stack because of reboot or link failure and the stack is configured to change 
the stack bridge MAC address as soon as the master leaves, the unnecessary switch of bridge 
MAC address occurs and thus causes flow interruption. 
Therefore, configure the preservation time stack bridge MAC address according to your network status: 
z  Preserve for six minutes: After the master leaves, the bridge MAC address will not change within 
six minutes. If the master does not come back after six minutes, the stack system will use the 
bridge MAC address of the newly elected master as that of the stack. 
z  Preserve permanently: No matter the master leaves the stack or not, the stack bridge MAC 
address remains unchanged. 
z  Not preserved: As soon as the master leaves, the system will use the bridge MAC address of the 
newly elected master as that of the stack. 
Follow these steps to specify preservation time of stack bridge MAC address: 
To do…  Use the command…  Remarks 
Enter system view 
system-view 
— 
Configure the stack bridge MAC 
address to be preserved permanently 
after the master leaves 
irf mac-address persistent 
always 
Specify the preservation time of the 
stack bridge MAC address as 6 
minutes after the master leaves 
irf mac-address persistent timer 
Configure that the stack bridge MAC 
address changes as soon as the 
master leaves 
undo irf mac-address persistent 
Optional 
By default, stack 
bridge MAC 
address is 
preserved for 6 
minutes after the 
master leaves. 
 
 
The change of the bridge MAC address may cause a temporary flow interruption. 
 
Enabling Auto Upgrade of Boot Files 
If this function is disabled, when the boot files of slaves and that of the master are in different versions, 
the new member or the member with a low priority will not boot normally. You need to update the device 
version manually and add the device into the stack again.  
If this function is enabled, as soon as a device is added into a stack, the system compares its software 
version with that of the master. If the versions are not consistent, the device downloads the boot file