Network troubleshooting Question

[bhireg0]

Hello all,

I’ve recently been working on a switch using fiber cable. Is there a command to make the switch send pulses of light down a specific port for troubleshooting/identify purposes, I don’t know which ports go where inside the building and I’m trying to avoid shutting off and turning on random ports. I don’t have the switch model number atm but was more so looking for some food for thought of how to trace this fiber from the switch port to the wall port so I can properly label them in the switch configs.

[balaji.bandi]

There is no command available like that to identify the port - if the port connected and working, you can use CDP neighbour to detect peer (if other side supported)

if not you need to use fiber Light tools or other tools available in the market to trace the cables.

If this is critical link you can not remove to troubleshoot, then you need to physical trace all the way.

[Leo Laohoo]

Were you even using laser safety glasses?

[fratpoly]

You can use the command switchport monitor on many managed switches to send a pulse of light down a specific port for troubleshooting and identification. This way, you can trace the fiber from the switch port to the wall port without disrupting other connections. Just ensure to replace 'switchport' with the actual command for your switch model when you find it.

[MHM Cisco World]

Check beacon command it can led specific port you need.

[mazedarjourney]

If you're working with a fiber switch and need to identify ports without randomly toggling them, consider using the switch's port blinking or flashing feature. This feature sends pulses of light down a specific port for troubleshooting. Access the switch interface, identify the target port, and use a command like "test cable-diagnostics tdr interface <interface-id>" (replace <interface-id> with the port). Observe the blinking port on the switch and trace the fiber cable from there to the wall port for proper labeling. Check your switch's documentation for specific commands if needed#dairyqueenlunch

[Leo Laohoo]

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@mazedarjourney wrote:

If you're working with a fiber switch and need to identify ports without randomly toggling them, consider using the switch's port blinking or flashing feature. This feature sends pulses of light down a specific port for troubleshooting. Access the switch interface, identify the target port, and use a command like "test cable-diagnostics tdr interface <interface-id>" (replace <interface-id> with the port). Observe the blinking port on the switch and trace the fiber cable from there to the wall port for proper labeling. Check your switch's documentation for specific commands if needed.

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The above is an incorrect information generated by ChatGPT. 

Cisco does not support OTDR and the port "blinking" feature is only available in Nexus switches.  Catalyst 9k switches have LED flash that will only flash the blue LED (but not flash the port LED).