Move the cable to a known good port to troubleshoot a suspect port or module. The show module command can indicate faulty, which can indicate a hardware problem. Sometimes, we will encounter the compatible problem that the TP-link smart/managed switches cannot link up with other brands switch when they connected by SFP port. For example, as shown in the picture, the two switches are connected by the fiber, and the LED lights are lighting on, but there is no. This document describes how to determine why a port or interface experiences problems. This document applies to Catalyst switches that run on Cisco IOS® System Software. The information in this document was created from the devices in a specific. TL-SG3109/TL-SL3428/TL-SL3452 Gigabit Managed Switch Family CLI Reference Guide show fiber-ports optical-transceiver The show fiber-ports optical-transceiver Privileged EXEC command displays the optical transceiver diagnostics. We connect Moduletek SFP-25G-SR transceiver to Cisco. 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.
