Testing an optical module involves verifying link status, reading transceiver details, monitoring optical parameters, and confirming compatibility with the switch.

Step 1: Verify Switch and Module Recognition

First, ensure the switch recognizes the module and the interface is operational. Use the CLI to check the switch model and software version with:

CodeCopyshow version

Then confirm the interface status:

CodeCopyshow interface status

If the port shows “connected”, the module is recognized; if it shows “notconnect”, the issue may be with the fiber cable, remote device, or the SFP module itself .

Step 2: Identify the Installed Transceiver

Check which SFP module is installed and its vendor information:

CodeCopyshow inventoryshow idprom interface <interface-id>

These commands display the part number, serial number, and vendor, helping verify that the correct module is used and compatible with the switch .

Step 3: Read Optical Diagnostics (DDM/DOM)

For deeper testing, read real-time optical parameters:

CodeCopyshow interfaces <interface-id> transceiver detail

or

CodeCopyshow interface transceiver detail

Key parameters include:

• Tx Power (dBm) – optical power transmitted
• Rx Power (dBm) – optical power received
• Temperature (°C) – module thermal status
• Voltage (V) – electrical health
• Laser Bias Current (mA) – laser operation Compare these values with the module datasheet to ensure they are within normal ranges.

Step 4: Check for Compatibility and Errors

If the module is third-party or unsupported, the switch may disable the port. Commands like:

CodeCopyno errdisable detect cause gbic-invalid

can allow operation with compatible third-party modules, but always verify MSA compliance and DOM support .

Step 5: Optional Advanced Testing

For critical links or high-speed modules (10G+), additional tests can be performed:

• Optical Power Measurement – using an optical power meter to verify Tx/Rx levels
• Bit Error Rate Testing (BERT) – to detect transmission errors and jitter
• Loopback Testing – using a loopback plug or second module to verify full-duplex operation
• Eye Diagram Validation – for QSFP28 or PAM4 modules to check signal clarity and jitter

Step 6: Monitor Logs

After inserting the module, check the switch logs for recognition messages:

CodeCopyshow logging

Successful identification confirms the module is accepted and operating at the correct data rate; errors indicate incompatibility or hardware issues .

Summary

Testing an optical module involves:

1. Confirming interface status and switch recognition
2. Identifying the installed transceiver and vendor
3. Reading DDM/DOM optical parameters
4. Verifying compatibility and resolving errors
5. Performing optional advanced tests for high-speed links
6. Monitoring switch logs for module acceptance Following these steps ensures the optical module is functioning correctly, the link is stable, and the switch operates within expected optical parameters .