If possible, remove and reinstall the optical modules to check whether the fault is rectified. 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. Check whether the information is consistent with the optical module specifications provided in the product documentation. Check if the switch is powered on and if. This is for Layer 1 connectivity, if the link shows "up/up," but expected traffic is not passing, other configuration issues may be present. For example. 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. Even if an interface appears up, degraded Tx/Rx levels can cause intermittent flapping, packet loss, or err-disabled states.
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