If there are CRC and input errors on a particular port, follow the below procedure:
Possible SFP issue:
- Change the SFP on one side and check if the errors stop.
- If errors are still present, change the SFP on the other end and check for errors.
- If above steps don't help check for cable/fiber issue.
Possible fiber/cable issue:
- If the errors are still present and the port is a fiber port, then clean the fiber end on both sides.
- If the CRC and input errors are still present then use optic cleaning swabs or spray air to clean the optic and reconnect the fiber.
- Connect a new fiber strand and see the errors still stays or not.
- Move the fiber/cable to a different port and see if the errors follow. If they do, then it is cable/fiber strand issue.
- If the above steps don't resolve the issue check for possible patch panel port issue. If the customer doesn't use patch panel then check for port issues.
Possible patch-panel port issue:
- If the customer has a patch panel between the two devices, then check the optics on the patch-panel ports. Change the optics to see it resolves the issue.
- If the issue is not resolvesed, check the cable connected on the patch-panel ports. Change it to see it stops the errors seen on the ports.
- If the errors are still seen then change the patch-panel ports to a known good port to rule out port issue on the patch-panel.
- If the input errors are still seen after changing the patch panel port then check for possible port issue on both end.
Possible port issue:
- Move the cable and SFP to a known good port (with no errors) on one end and check if you still see the errors. If you don't then it could be a port issue.
- If the errors still persists after the above step then move the cable and SFP on the other end to a known good port and check for errors on the interface. If you don't see them then it could be a port issue.