Power-On Sequence For Switch Stacks - Cisco Catalyst C3850 Series Hardware Installation Manual

Switch Installation
Figure 21: Example of a Data Stack with Half Bandwidth Connections
The figures below show data stacks of switches with failover conditions. In this figure, the StackWise cable
is bad in link 2. Therefore, this stack provides only half bandwidth and does not have redundant connections.
Figure 22: Example of a Data Stack with a Failover Condition
In this figure, link 2 is bad. Therefore, this stack partitions into two stacks, and the top and bottom switches
become the active switch in the stack. If the bottom switch is a member (not active or standby switch), it
reloads.
Figure 23: Example of a Partitioned Data Stack with a Failover Condition

Power-On Sequence for Switch Stacks

Consider these guidelines before you power on the switches in a stack:
• The sequence in which the switches are first powered on might affect the switch that becomes the stack
• There are two ways to elect an active switch:
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master.
• If you want a particular switch to become the active switch, configure it with the highest priority.
Among switches with same priority, the switch with the lowest MAC address becomes the active
switch.
• If you want a particular switch to become the active switch, power on that switch first. This switch
remains the active switch until a reelection 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
Power-On Sequence for Switch Stacks
Catalyst 3850 Switch Hardware Installation Guide
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