IBM Partner Pavilion Vitrual Switch Extension BMD00082 Benutzerhandbuch

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SmartConnect User’s Guide
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  Chapter 4: Stacking
BMD00082, February 2009
Only the Designated Master can change the backup bit. So it is necessary to bring back the 
original Designated Master in order to make this change (/c/stack/backup). Because of 
the backup bit setting, the result of merging two stacks will always result in one Master and 
one Member at all times. 
Master and Backup Behavior
When a group of switches are rebooted in stacking mode, the Designated Master switch 
becomes the Master of the stack. If the Designated Master switch is not present, then all 
switches in the stack are placed in a WAITING state until a Master appears. During this WAIT-
ING period, all external and server ports of these Member switches are placed into operator-
disabled state. Without the Master, a stack cannot respond correctly to a networking event.
When the Master switch is present, it controls operation of the stack. The configuration of the 
Master is pushed to the other switches in the stack. 
If the Master switch fails, the Backup switch becomes the new Master and the stack continues 
to operate normally. If the Backup switch is not available, all the switches in the stack reboot 
and wait for a new stack to form. 
After the Designated Master switch reboots, if another Master is already present in the stack, 
the Designated Master does not become the stack Master. Instead, the Designated Master 
becomes the Backup if instructed by the Current Master. It can become the Master only if the 
Current Master fails.