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Catalyst 3650 Switch Hardware Installation Guide
OL-29734-01
Chapter2 Switch Installation
Planning a Switch Data Stack
•If two operating partial ring stacks are connected together using a stack cable, a stack merge can
occur. This situation reloads the whole stack (all switches in the stack).
•If some switches in the stack are completely separated from the stack, a stack split can occur.
•A stack split can 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 can occur in a partial ring stack if:
–
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 can cause a stack reelection or to manually elect the active switch, see the stacking
software configuration guide on Cisco.com at this URL:
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 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 change their stack member numbers to the lowest available numbers and use the stack
configuration of the newly elected active switch.
•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 configuration 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.
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.