If possible, remove and reinstall the optical modules to check whether the fault is rectified. I noticed something odd with a fiber SFP module. When it's plugged in, there's no light visible from the transmitter. To compare, I checked another working SFP — the TX light is visible immediately, and the RX/TX power levels look. One switch shows light when I plug in the fiber, but the other side doesn't. Details: one switch is a Fortinet 424e with 24 ports RJ45 and 4 ports. This article describes steps to perform when SFP/SFP+ fiber link is not coming up. Scope FortiSwitch and FortiGate. Download the file 'Compatible Transceivers' from the link below, or. Even after unplugging the network cable, the port LED continues to flash even though no cable is plugged in and no data is being transmitted. However, a "show interface transceiver" looked great. I can't even get a connection to come up between the 3560 and the 5k (taking the 3650 completely out of the equation).
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