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Catalyst 3650 Switch Hardware Installation Guide
OL-29734-01
Chapter 2 Switch Installation
Planning a Switch Data Stack
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If you want a particular switch to become the active switch, power on that switch first. This
switch remains the active switch until a re-election is required. After 2 minutes, power on the
other switches in the stack. If you have no preference as to which switch becomes the active
switch, power on all the switches in the stack within 1 minute. These switches participate in the
active switch election. Switches powered on after 2 minutes do not participate in the election.
If changes are made to the stack without powering down the switches, the following results might occur:
•
If two operating partial-ring stacks are connected together using a stack cable, a stack merge might
occur. This situation reloads the whole stack (all the switches in the stack).
•
If some switches in the stack are completely separated from the stack, a stack split might occur.
•
A stack split might occur on a full-ring stack if:
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More than one running switch is removed without powering down.
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More than one stack cable is removed without powering down.
•
A stack split might occur in a partial-ring stack if:
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A switch is removed without powering down.
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A stack cable is removed without powering down.
•
In a split stack, depending on where the active and standby switches are located, either two stacks
might be formed (with the standby taking over as the new active switch in the newly formed stack),
or all the members in the newly formed stack might reload.
Note
These results depend on how the switches are connected. You can remove two or more switches
from the stack without splitting the stack.
For conditions that may cause a stack re-election or to manually elect the active switch, see the switch’s
software configuration guide at:
http://www.cisco.com/go/cat3650_docs
Changes to Switch Stack Membership
If you replace a stack member with an identical model, the new switch functions with exactly the same
configuration as the replaced switch, assuming that the new switch (referred to as the provisioned
switch) is using the same member number as the replaced switch.
The operation of the switch stack continues uninterrupted during membership changes unless you
remove the active switch or you add powered-on standalone switches or switch stacks.
Note
A switch stack always has one active switch and one standby switch. The active switch contains the
saved and running configuration files for the switch stack. If the active switch becomes unavailable, the
standby switch assumes the role of the active switch, and continues to the keep the stack operational.
For powered-on switches:
•
Adding powered-on switches (merging) causes all the switches to reload and elect a new active
switch from among themselves. The newly elected active switch retains its role and configuration.
All the other switches change their stack member numbers to the lowest available numbers and use
the stack configuration of the newly elected active switch.
