ethtool command enables you to query or control the network driver and hardware settings. It takes the device name (like swp1) as an argument. When the device name is the only argument to
ethtool, it prints the current settings of the network device. See
man ethtool(8) for details. Not all options are currently supported on switch port interfaces.
Monitor Interface Status Using ethtool
To check the status of an interface using
The switch hardware contains the active port settings. The output of
ethtool swpXX shows the port settings stored in the kernel. The
switchd process keeps the hardware and kernel in sync for the important port settings (speed, auto-negotiation, and link detected) when they change. However, many of the fields in
ethtool, like Supported Link Modes and Advertised Link Modes are not updated based on the actual module inserted in the port and therefore are incorrect or misleading.
To query interface statistics:
View and Clear Interface Counters
Interface counters contain information about an interface. You can view this information when you run
cat /proc/net/dev. You can also use
cl-netstat to save or clear this information:
Copies and clears statistics. It does not clear counters in the kernel or hardware.
Deletes saved statistics, either the
|-D||Deletes all saved statistics.|
|-l||Lists saved tags.|
|-r||Displays raw statistics (unmodified output of |
|-t <tag name>||Saves statistics with |
Monitor Switch Port SFP/QSFP Hardware Information Using ethtool
To see hardware capabilities and measurement information on the SFP or QSFP module installed in a particular port, use the
ethtool -m command. If the SFP/QSFP supports Digital Optical Monitoring (that is, the
Optical diagnostics support field in the output below is set to Yes), the optical power levels and thresholds are also printed below the standard hardware details.
In the sample output below, you can see that this module is a 1000BASE-SX short-range optical module, manufactured by JDSU, part number PLRXPL-VI-S24-22. The second half of the output displays the current readings of the Tx power levels (
Laser output power) and Rx power (
Receiver signal average optical power), temperature, voltage and alarm threshold settings.