Cisco Catalyst 2960 Series, Configuration Manual

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• Adding powered-on switches (merging) causes all switches to reload and elect a new active switch from
among themselves. The newly elected active switch retains its role and configuration. All other switches
retain their stack member numbers and use the stack configuration of the newly elected active switch.
Adding powered-on switches (merging) causes the stack masters of the merging switch stacks to elect
a stack master from among themselves. The reelected stack master retains its role and configuration as
do its stack members. All remaining switches, including the former stack masters, reload and join the
switch stack as stack members. They change their stack member numbers to the lowest available numbers
and use the stack configuration of the reelected stack master.
• Removing powered-on stack members causes the switch stack to divide (partition) into two or more
switch stacks, each with the same configuration. This can cause:
• An IP address conflict in your network. If you want the switch stacks to remain separate, change
the IP address or addresses of the newly created switch stacks.
• A MAC address conflict between two members in the stack. You can use the stack-mac update
force
command to resolve the conflict.
If a newly created switch stack does not have an active switch or standby switch, the switch stack will reload
and elect a new active switch.
Make sure that you power off the switches that you add to or remove from the switch stack.
After adding or removing stack members, make sure that the switch stack is operating at full bandwidth
. Press the Mode button on a stack member until the Stack mode LED is on. The last two right port LEDs
on all switches in the stack should be green. Depending on the switch model, the last two right ports are
10-Gigabit Ethernet ports or small form-factor pluggable (SFP) module ports (10/100/1000 ports). If one
or both of these LEDs are not green on any of the switches, the stack is not operating at full bandwidth.
It may take upto 4 seconds for stack convergence when a new stack member is added to the existing switch
stack.
Note
If you remove powered-on members but do not want to partition the stack:
• Power off the switches in the newly created switch stacks.
• Reconnect them to the original switch stack through their stack ports.
• Power on the switches.
For cabling and power considerations that affect switch stacks, see the Catalyst 2960-X Switch Hardware
Installation Guide .
Stack Member Numbers
The stack member number (1 to 8) identifies each member in the switch stack. The member number also
determines the interface-level configuration that a stack member uses. You can display the stack member
number by using the
show switch EXEC command.
A new, out-of-the-box Switch (one that has not joined a Switch stack or has not been manually assigned a
stack member number) ships with a default stack member number of 1. When it joins a Switch stack, its
default stack member number changes to the lowest available member number in the stack.
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
721
Information About Switch Stacks