Viewing optical port and optical module information in Linux

You can view optical module information on Linux using the ethtool command to check port status, transceiver type, and diagnostic data.

Checking Network Port Status

To see the link status and configuration of a network interface:

ethtool <devname>

• <devname> is the network interface name (e.g., eth0, swp1, p4p1).
• This command displays link speed, duplex mode, port type (FIBRE), auto-negotiation status, and whether the link is detected .
• You can list all interfaces using ip link or ifconfig. Example output snippet:

Speed: 10000Mb/sDuplex: FullPort: FIBRELink detected: yesAuto-negotiation: on

Viewing Transceiver Identification and Diagnostics

To query the optical module (SFP/QSFP) for detailed information:

ethtool -m <devname>

• This command retrieves module type, vendor, serial number, wavelength, and Digital Diagnostic Monitoring (DDM) data such as Tx/Rx optical power, temperature, and voltage .
• Not all network cards support this command; if unsupported, the output may be empty or show an error. For more detailed module info, some systems support:

ethtool --module-info <devname>

• This provides module-specific pages and I²C data if the driver supports it .

Checking Loaded Kernel Modules

To see which drivers or kernel modules are loaded for network interfaces:

lsmod

• Lists all currently loaded kernel modules.
• To get detailed information about a specific module:

modinfo <module_name>

• Displays module version, dependencies, and supported devices .

Summary

1. Port status: ethtool <devname>
2. Transceiver details & DDM: ethtool -m <devname> or ethtool --module-info <devname>
3. Kernel modules: lsmod and modinfo <module_name> These commands allow you to monitor and troubleshoot optical modules on Linux, ensuring proper link operation and verifying transceiver health and specifications .