Planet Networking & Communication SGS-5220 User Manual page 351

On the Stack State Monitor web page, this is shown by "Reelect" being set to "Yes" for one of the switches in the stack.
Buttons
: Click to save changes.
: Click to undo any changes made locally and revert to previously saved values.
process.
This is done by clicking "Start Master Election", followed by "Save". This causes
the first two criteria to be ignored, thereby basing master election only on master
priority and MAC address. When master election is enforced, the first two criteria
are ignored for a period of 10-15 seconds.
Within a managed stack, one master switch (or just "master") must be elected.
Any switch not being master is a slave switch (or just "slave").
To elect a master, the following criteria are evaluated sequentially:
1. If any switch already claims to have been master for more than 30
seconds, then that switch will become master.
2. If multiple switches claim to have been master for more than 30
seconds, then the switch which has been master for the longest period
of time will become master.
3. The switch with the smallest master priority.
4. The switch with the smallest MAC address.
The above algorithm ensures that once a master has been elected and has been
master for more than 30 seconds, it will remain master. However in some cases
the user may want to enforce a new master election. This is done by clicking
"Start Master Election", followed by "Save". This causes the first two criteria to be
ignored, thereby basing master election only on master priority and MAC
address. When master election is enforced, the first two criteria are ignored for a
period of 10-15 seconds. On the Stack State Monitor web page, this is shown by
"Reelect" being set to "Yes" for one of the switches in the stack.
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User's Manual of SGS-5220 Series