FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
This article describes how to troubleshoot malfunctioning or flapping optical modules.
Scope
Any FortiGates using optical fiber module.
Solution
In case of a flapping interface or low level of power for optical fiber modules like SFP or qSFP, those verification steps should be considered to improve the situation:
Remove the SFP module from the slot.
Clean any dust.
Clean any dust on the fiber.
Clean any dust on the fiber patch or patch panel.
Use a power meter and light source to test the fiber link's attenuation (loss), it can identify fiber or SFP issue
Plug the SFP back in and assess.
Use 'get sys interface transceiver' to check signal level and alarms if any
