Chapter 1
  |  Initial Switch Configuration
Stack Operations
ā  71  ā
failover events, you should include port members on several units within the 
primary VLAN used for stack management. 
Resilient Configuration
If a unit in the stack fails, the unit numbers will not change. This means that when 
you replace a unit in the stack, the original configuration for the failed unit will be 
restored to the replacement unit. This applies to both the Master and Slave units.
Renumbering
the Stack
The startup configuration file maps configuration settings to each switch in the 
stack based on the unit identification number. If the units are no longer numbered 
sequentially after several topology changes or failures, you can reset the unit 
numbers using the System > Stacking (Renumber) menu in the web interface or the 
switch all renumber command in the CLI. Just remember to save the new 
configuration settings to a startup configuration file prior to powering off the stack 
Master.
Ensuring Consistent
Code is Used Across
the Stack
Consistent Runtime Code in Each Switch ā The main board runtime firmware 
version for each unit in the stack must be the same as the Master unitās runtime 
firmware. After Auto-ID assignment is completed, the Master unit checks the image 
versions for consistency. If the firmware versions (i.e., runtime code) configured for 
bootup on any slave units are not the same as those on the Master unit, the stack 
will operate in Special Stacking Mode in which all backup units are disabled as 
described below:
ā The master unit starts normal operation mode in standalone mode.
ā The master unit can see all units in the stack and maintain stack topology.
ā None of the other units can function (all ports will be disabled).
ā All user-initiated commands to configure the non-functioning units are 
dropped. The master unit, however, will be able to communicate the following 
information to the non-functioning units:
ā 
Image downloads
ā 
Stack topology information
ā 
System configuration information already stored on the master.
In Special Stacking mode, the master unit displays warning messages whenever 
you log into the system through the CLI that inform you that an image download is 
required. 
You can use the CLI, web or SNMP to download the runtime image from an FTP or 
TFTP server to the master unit. The master unit stores the image as its āNext boot