Link status: Check the link status of the fiber ports. Look for the fiber ports and check if they are showing "up" or "down" status. I know that "show cable-diag tdr int [slot/port]" command can check 10/100/1000 etherent link. for example WS-X6724-SFP Is there no command to check fiber link?? Thank you 04-01-2009 10:48 PM It's got. If you run fiber or copper uplinks in a small office, home lab, or data closet, SFPs (and SFP+) are the little parts that keep your links alive. This guide gives a practical, CLI-focused workflow for checking SFP health and diagnostics on Cisco switches, shows the exact commands you'll use. Look for interfaces with "Fiber" or "Gi" (Gigabit Ethernet) in their names, as these are likely to be fiber ports. By checking module health, compatibility, and digital diagnostics, you can quickly confirm correct installation, detect optical problems, and maintain accurate hardware. 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. Digital Optical Monitoring (DOM) is a feature that allows for the real-time monitoring of various physical and operational parameters of fiber optic transceivers, such as transmit power, receive power, temperature, laser bias current, and voltage. DOM is supported on MS120, MS125, MS130, MS210.
