What should be checked first when diagnosing a down fiber optic link?

When diagnosing a down fiber optic link, the first step should be to check physical connections. This involves ensuring that all cables are securely attached and properly aligned, as loose or improperly connected fiber can lead to significant signal loss or complete communication failure. Physical connections can be affected by various issues, such as accidental disconnections, damage to connectors or cables, and dirt or contamination on the connection points, which can all hinder the signal quality.

Ensuring that the physical connections are intact is a crucial first step, because if the connections are not secure, other aspects like wavelength compatibility or the integrity of components won't matter; the link will remain down until the connection issue is resolved. Once physical connections are confirmed to be sound, technicians can then proceed to evaluate other factors such as inspecting connectors for damage or verifying wavelength compatibility.