Execute the following command to view detailed interface and optical module status: show interface <interface-type> <interface-number>Execute the following command to view detailed interface and optical module status: show interface <interface-type> <interface-number>When optical modules operate on a switch, it is usually necessary to read the module's internal information to understand its working status—such as connection status and real-time metrics like optical power and temperature. Additionally, identifying module information helps detect coding. This guide gives a practical, CLI-focused workflow for checking SFP health and diagnostics on Cisco switches, shows the exact commands you'll use, explains what the numbers mean, and compares OEM (Cisco) vs third-party modules so you can pick the right SFP module supplier for reliability and cost. The Cisco Small Business Series Switches allow you to plug in a Small Form-factor Pluggable (SFP) transceiver in their optical modules to connect fiber optic cables. Once the transceiver and fiber optic cable are plugged in properly in the switch optical module, you should be able to view the. Display diagnostics data and alarms for Gigabit Ethernet optical transceivers (SFP, SFP+, XFP, QSFP+, or CFP) installed in EX Series Switches or QFX Series Switches. The information provided by this command is known as digital optical monitoring (DOM) information. DDM is typically enabled by default, but you can verify this by checking the. Cisco IOS provides several useful CLI commands for viewing SFP information. Lists all detected hardware, including installed SFPs — displays Product ID (PID), Version ID (VID), and Serial Number. Displays full DDM metrics such as temperature.