Log in to the switch console to run the privileged EXEC mode of the Cisco switch, use the fiber-ports-optical-transceiver command. The Output Power (mWatt) field in the command output indicates the received power of the optical module, and the Input Power (mWatt) field indicates the. Monitoring the optical power of SFP (Small Form-factor Pluggable) modules is a critical step in maintaining stable network links. Even if an interface appears up, degraded Tx/Rx levels can cause intermittent flapping, packet loss, or err-disabled states. Checking optical power helps pinpoint issues. 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. 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. Here are the sample commands for checking the TX/RX optical power. Sample Output: IOS-router#show hw-module subslot 0/2 transceiver 2. Have you ever encountered a Cisco switch interface that constantly flaps (goes up and down) or suddenly enters an err-disabled state? Before you blame the switch or replace the cable, you need to look at the invisible data: the light levels. Additionally, identifying module information helps detect coding.
