It is primarily caused by physical layer attenuation—such as dirty connectors, fiber bending, or excessive link loss—rather than transceiver failure. If this is too low, your module's laser might be dying. Optical Receive Power (RX): The most critical metric. This tells you how much light is making it through the fiber cable to your switch. Thresholds (Alarm/Warn):. Monitoring optical power levels is essential because even slight deviations can significantly affect the stability, quality, and availability of optical transmission services. Optical networks rely on precise power balance—too much power can damage receivers or distort signals, while insufficient. If the transmit optical power remains low, replace the optical module or install it in another optical interface to check whether it is faulty. 10-30-2023. SFP Rx Power Low is a warning indicating that the received optical signal is below the SFF-8472 defined threshold (typically -11 dBm to -15 dBm depending on the standard). Run the display transceiver slot slot-id verbose command in the system view to check whether the receive power Rx Power of the.