This document describes how to check the switch interface or port status and how to locate an interface physically down fault and restore the interface to the up state. Hardware failures:. This section describes the insertion loss and reflection requirements of optical links and the method of checking the quality of optical links for the application of 50G optical modules with the PAM4 coding technology. To check if there are any packet errors and negotiation modes on ports, you can use the command display interface. During use, reading optical module information helps understand its real-time operating status, enabling faster troubleshooting of link abnormalities. Run the display transceiver [interface interface-type interface-number | slot slot-id], to view the information on.