To run stack-port diagnostics:
- Run disable stacking node-address <mac_addr> for the node being tested.
- Disconnect the stacking cables from that node.
- Take a known-working stacking cable and connect it between S1 and S2 (in a loop) on the disconnected node.
- Console into the disconnected node and type "run diagnostics stack-port".
- The switch will reboot and run diagnostics. When diagnostics are complete, it will reboot again.
- Console in to the node again and type "enable stacking".
- Re-connect the stacking cable to the other stack nodes.
- Type "reboot" in the console. The node should rejoin the stack once the reboot is complete.