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Catalyst 3650 Switch Hardware Installation Guide
OL-29734-01
Chapter2 Switch Installation
Planning a Switch Data Stack
Figure 2-4 shows an example of a stack of Catalyst 3650 switches with incomplete StackWise cabling
connections. This stack provides only half bandwidth and does not have redundant connections.
Figure2-4 Example of a Data Stack with Half Bandwidth Connections
Figure 2-5 and Figure2-6 show data stacks of Catalyst 3650 switches with failover conditions. In
Figure 2-5, the StackWise cable is bad in link 2. Therefore, this stack provides only half bandwidth and
does not have redundant connections. In Figure2-6, 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.
Figure2-5 Example of a Data Stack with a Failover Condition
Figure2-6 Example of a Partitioned Data Stack with a Failover Condition
Power-On Sequence for Switch Data 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
active switch and the standby switch.
•There are two ways to elect an active switch:
–
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 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:
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PWR-C2-250WAC PWR-C2-640WAC