Cisco Systems 3750E Stack Master Election and Re-Election

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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter5 Managing Switch Stacks
Understanding Switch Stacks
Figure5-2 Adding a Standalone Switch to a Switch Stack
Stack Master Election and Re-Election
The stack master is elected or re-elected based on one of these factors and in the order listed:
1. The switch that is currently the stack master.
2. The switch with the highest stack member priority value.
Note We recommend assigning the highest priority value to the switch that you prefer to be the
stack master. This ensures that the switch is re-elected as stack master if a re-election occurs.
3. The switch that is not using the default interface-level configuration.
4. The switch with the higher priority feature set and software image combination. These combinations
are listed from highest to lowest priority:
– Advanced IP services feature set and the cryptographic universal sof tware image
– Advanced IP services feature set and the noncryptographic so ftware image
– IP services feature set and the cryptographic software image
– IP services feature set and the noncryptographic software image
– IP base feature set and the cryptographic software image
– IP base feature set and the noncryptographic software image
During the stack master switch election, differences in start-up times between the feature sets
determine the stack master. The switch with the shorter start-up time becomes the stack master.
For example, a switch running the IP services feature set and the cryptographic software image has
a higher priority than the switch running the IP base feature set and the noncryptogra phic image, but
the switch running the IP base feature set becomes the stack master because the other switch takes
10 seconds longer to start. To avoid this problem, upgrade the switch running the IP base feature set
to same feature set and software image as the other switch, or manually start the master switch and
wait at least 8 seconds before starting the new member switch that running the IP base feature set.
5. The switch with the longest system up-time.
6. The switch with the lowest MAC address.
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Stack member 1
Stack member 2
and stack master
Stack member 3
Stack member 4
Stack member 1
Stack member 2
and stack master
Stack member 3
Stack member 1