Cisco Catalyst 2960 Series, Configuration Manual

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If you power on or reset an entire switch stack, some stack members might not participate in the active switch
election. Stack members that are powered on within the same 2-minute timeframe participate in the active
switch election and have a chance to become the active switch. Stack members that are powered on after the
120-second timeframe do not participate in this initial election and become stack members. For powering
considerations that affect active-switch elections, see the switch hardware installation guide.
As described in the hardware installation guide, you can use the ACTV LED on the switch to see if the switch
is the active switch.
A stack master retains its role unless one of these events occurs:
• The switch stack is reset.*
• The stack master is removed from the switch stack.
• The stack master is reset or powered off.
• The stack master fails.
• The switch stack membership is increased by adding powered-on standalone switches or switch stacks.*
In the events marked by an asterisk (*), the current stack master might be reelected based on the listed factors.
When you power on or reset an entire switch stack, some stack members might not participate in the stack
master election. Stack members that are powered on within the same 20-second time frame participate in the
stack master election and have a chance to become the stack master. Stack members that are powered on after
the 20-second time frame do not participate in this initial election and become stack members. All stack
members participate in reelections. For all powering considerations that affect stack-master elections, see the
“ Switch Installation ” chapter in the hardware installation guide.
The new stack master becomes available after a few seconds. In the meantime, the switch stack uses the
forwarding tables in memory to minimize network disruption. The physical interfaces on the other available
stack members are not affected during a new stack master election and reset.
After a new stack master is elected and the previous stack master becomes available, the previous stack master
does not resume its role as stack master.
For all powering considerations that affect stack-master elections, see the Catalyst 2960-X Switch Hardware
Installation Guide .
Switch Stack Configuration Files
The active switch has the saved and running configuration file for the switch stack. The standby switch
automatically receives the synchronized running configuration file. Stack members receive synchronized
copies when the running configuration file is saved into the startup configuration file. If the active switch
becomes unavailable, the standby switch takes over with the current running configuration.
The active switchstack master has the saved and running configuration files for the switch stack. All stack
members periodically receive synchronized copies of the configuration files from the active switchstack
master. If the active switchstack master becomes unavailable, any stack member assuming the role of active
switchstack master has the latest configuration files.
The configuration files record these settings:
• System-level (global) configuration settings such as IP, STP, VLAN, and SNMP settings that apply to
all stack members
• Stack member interface-specific configuration settings that are specific for each stack member
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
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Information About Switch Stacks