Measuring Optical Attenuation on Huawei Switches

Use the display transceiver and display transceiver diagnosis commands to view optical attenuation and module diagnostics on Huawei switches.Viewing Optical Module InformationTo check optical attenuation and related parameters, Huawei switches provide commands that display both general and diagnostic information of the optical module:Basic Module Information Run the command:CodeCopydisplay transceiver [ interface interface-type interface-number | slot slot-id ] [ verbose ] This command shows the optical module type, vendor, wavelength, transfer distance, and current transmit (TX) and receive (RX) power levels. Using the verbose option provides detailed information including optical attenuation, voltage, current, and temperature readings .Diagnostic Monitoring (DDM) Information For real-time diagnostics, execute:CodeCopydisplay transceiver diagnosis interface [ interface-type interface-number ] This displays Digital Diagnostic Monitoring (DDM) data, including:TX Power (dBm) – current transmitted optical powerRX Power (dBm) – current received optical powerHigh/Low Thresholds – alarm limits for optical powerBias Current (mA) – laser drive currentVoltage (V) and Temperature (°C) – operational status of the module By comparing the TX and RX power values with the expected link budget, you can determine the optical attenuation and verify if it is within acceptable limits.Checking Optical AttenuationOptical attenuation can be inferred from the difference between the transmit power of the sending module and the receive power of the receiving module. Huawei switches report these values in the DDM output. If the RX power is significantly lower than expected, it may indicate excessive attenuation due to fiber length, connectors, or inline attenuators .Ensuring Module CertificationHuawei recommends using Huawei-certified optical modules to ensure accurate readings and reliable operation. Non-certified modules may not report correct DDM values, can cause data bus errors, or damage interfaces . Certified modules can be identified by:Vendor Name showing HUAWEI in display transceiver outputManufactured date later than 2013-07-01Switch software version V200R001C00 or later SummaryTo check optical attenuation on Huawei switches:Use display transceiver for general module info and optical power.Use display transceiver diagnosis for detailed DDM parameters.Compare TX and RX power to calculate attenuation.Ensure modules are Huawei-certified for accurate readings and stable operation . These steps allow network administrators to monitor optical link performance, troubleshoot issues, and maintain reliable switch operation.