Master Selection Process; Stack Changes - Cisco 350 Series Administration Manual
Managed switches
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8
Master Selection Process
NOTE
Stack Changes
123
The master unit is selected from the master-enabled units (1 or 2). The factors in selecting the
master unit are taken into account in the following priority:
•
System Up Time—The master-enabled units exchange up-time, which is measured in
segments of 10 minutes. The unit with the higher number of segments is selected. If
both units have the same number of time segments, and the unit ID of one of the units
was set manually while the other unit's unit ID was set automatically, the unit with the
manually-defined unit ID is selected; otherwise the unit with the lowest unit ID is
selected. If both units IDs are the same, the unit with the lowest MAC address is
chosen.
The up time of the backup unit is retained when it is selected as master in the
NOTE
switch failover process.
•
Unit ID—If both units have the same number of time segments, the unit with the
lowest unit ID is selected.
•
MAC Address—If both units IDs are the same, the unit with the lowest MAC address
is chosen.
For a stack to operate, it must have a master unit. A master unit is defined as the active unit that
assumes the master role. The stack must contain a unit 1 and/or unit 2 after the master selection
process. Otherwise, the stack and all its units are partially shut down, not as a complete power-
off, but with traffic-passing capabilities halted.
This section describes various events that can cause a change to the stack. A stack topology
changes when one of the following occurs:
•
One or more units are connecting and/or disconnecting to and from the stack.
•
Any of its stack ports has a link up or down.
•
The stack changes between ring and chain formation.
When units are added or removed to and from a stack, it triggers topology changes, master
election process, and/or unit ID assignment.
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4
Administration: Stack Management
Master Selection Process
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