If the link light for the port does not come on, you can consider these possibilities: Connect cable from switch to a known good device. Make sure that both ends of the cable are plugged into the correct ports. Below is a practical mapping used by teams doing transceiver failure troubleshooting in production networks. Laser not emitting: TX power reads near zero; bias current may be normal or abnormal depending on failure mode. The table describes the LED status indicators for Ethernet modules or fixed-configuration switches: Ensure that both sides have a link. A single broken wire or one shutdown port can cause the problem where one side has a link light, but the other side does not. The S3100 series does not have a Power indicator. During the switch's boot process, all panel. Summary: The purpose of this guide is to provide general guidelines for troubleshoot layer 1 connectivity issues when using transceivers in Ethernet switches. Please select a product to check article relevancy This is for Layer 1 connectivity, if the link shows "up/up," but expected traffic is not. Have you ever experienced an unexpected network outage due to the failure of an SFP/SFP+ optical transceiver? Network outages can bring your ability to communicate and work to a halt, and your IT team will likely be frantically looking for a solution. S3100 SERIES SWITCHES TROUBLESHOOTING GUIDE.