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Stack Troubleshooting
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Stack Troubleshooting
If a stack fails to initialize or function, first check the following items:
• Check that all stacking cables are properly connected.
• Check if any stacking cables appear damaged.
• Check that only one Stack Master button is pressed in.
• Check that all switches in the stack are powered on.
After checking all items, reboot all the switches in the stack.
Switches in the stack may be configured using a ring- or line-topology. To ensure
minimal disruption in case a unit or stacking cable fails, always use a ring-topology.
When using ring-topology configuration and a switch fails, or a stacking cable is
disconnected, the stack continues normal operation using line-topology stacking
through the remaining stack connections.
If any changes occur to a slave unit, such as unit failure or insertion of a new unit,
operation of the other units in the stack are not affected. On the other hand, if the
master unit fails, the unit with the lowest MAC address is elected as the new master.
The stack reboots, discovers the new stack topology, assigns identifiers to each unit,
and checks the software images on each unit. This process make take up to two
minutes.
If you do not connect a wrap-around cable from the bottom unit back up to the top
unit in the stack, the failure of a single unit will cause the stack to break into two
separate stacks. In this case, a master unit will be elected for both of the stacks.
However, backup information inherited from the previous master unit will cause the
same IP address to be used by both master units in the two stacks. You must
therefore manually reconfigure the IP address of the management interface on one
of the master units.