Planning A Stackpower Stack; Stackpower Stacking Guidelines - Cisco Catalyst 3850 Hardware Installation Manual

Planning a StackPower Stack

• If two operating partial ring stacks are connected together using a stack cable, a stack merge can take
• 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:
• A stack split can occur in a partial ring stack if:
• In a split stack, depending on where the active and standby switches are located, either two stacks might
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:
catalyst-3850-series-switches/products-installation-and-configuration-guides-list.html.

Planning a StackPower Stack

StackPower Stacking Guidelines

You can configure a StackPower stack for either power sharing or redundancy. In power-sharing mode, the
power of all the power supplies in the stack is aggregated and distributed among the stack members.
In redundant mode, when the total power budget of the stack is calculated, the wattage of the largest power
supply is not included. That power is held in reserve and used to maintain power to switches and attached
devices when one power supply fails. Following the failure of a power supply, the StackPower mode becomes
power sharing.
Note
Power-sharing mode is the recommended configuration for Cisco Catalyst 3850 Series Switches .
For general concepts and management procedures for switch power stacks, see the Software Configuration
Guide on Cisco.com.
Catalyst 3850 Switch Hardware Installation Guide
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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 can occur:
place. This situation reloads the whole stack (all switches in the stack).
• More than one running switch is removed without powering down.
• More than one stack cable is removed without powering down.
• A switch is removed without powering down.
• A stack cable is removed without powering down.
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.
http://www.cisco.com/c/en/us/support/switches/
Switch Installation
OL-26779-05