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. During use, reading optical module information helps understand its real-time operating status, enabling faster troubleshooting of link abnormalities. It contains configuration commands, troubleshooting methods, power-check commands. Huawei: How to use debugging on CLI using SSH or telnet? For more in-depth troubleshooting, debugging on the CLI (Telnet or SSH) can be very helpful. The activation of debugging is done in a few steps.