How to check the optical module of a switch

You can check an optical module on a switch using either the web-based utility or CLI commands to view status, diagnostics, and transceiver details.

Using the Web-Based Utility

1. Log in to your switch's web interface.
2. Navigate to Status and Statistics > Diagnostics > Optical Module Status (example: Cisco SG350X-48MP) .
3. Select the switch and port where the SFP is installed.
4. Click Go to view details such as:
   • Port: Port number of the SFP.
   • Description: Type of optical transceiver.
   • Serial Number / PID / VID: Identification of the module.
   • Temperature, Voltage, Current: Operating conditions.
   • Output/Input Power: Transmit and receive optical power.
   • Transmitter Fault / Loss of Signal / Data Ready: Operational status indicators. This method provides a quick overview of the module's health and helps identify link issues.

Using CLI Commands

1. SSH or console into the switch.
2. Run the following commands to check module status and diagnostics:
   • show interface status — Confirms if the port is up and connected .
   • show inventory — Lists installed SFPs with part number, vendor, and serial number .
   • show interfaces <interface-id> transceiver detail — Displays Digital Optical Monitoring (DOM/DDM) data including Tx/Rx power, temperature, voltage, and bias current .
   • show idprom interface <interface-id> or show idprom transceiver extended — Reads EEPROM/vendor information for the SFP .
3. Analyze the output:
   • Link status: UP indicates normal operation.
   • Optical power: Ensure Tx/Rx values are within the module's specifications.
   • Temperature and voltage: Check for abnormal readings that may indicate failure.
   • Transceiver identification: Verify the correct module is installed and compatible.

Best Practices

• Always verify module compatibility with your switch to avoid unsupported transceivers .
• Use DOM/DDM readings to proactively monitor for potential failures.
• If a port shows “notconnect” or errors, check the fiber cable, remote device, and SFP module itself .
• Regularly check optical modules during maintenance or when troubleshooting link issues. By combining GUI and CLI methods, you can efficiently monitor, verify, and troubleshoot optical modules on your switch, ensuring reliable fiber-optic connectivity.