1. It is necessary to verify that the speed of the optical fiber equipment at both ends is consistent (use the same brand and model of optical fiber modules);

2. It is necessary to verify that the speed of the optical fiber modules at both ends matches the speed of the equipment at both ends (use the same brand and model of optical fiber modules);

3. The optical fiber modules at both ends have the same wavelength and the same speed (use the same brand and model of optical fiber modules);

4. The optical fiber modules used do not match (usually occurs on single-mode single-fiber connection links. The optical fiber modules at both ends use the same model, causing the connection to fail. The parameters of one end are: TX 1550nm RX 1310nm, and the parameters of the opposite end need to be :TX 1310nm RX 1550nm);

5. The sequence of the optical fiber jumper must be correct (generally the connection method for SFP dual-fiber is: A's sending to B's receiving, A's receiving to B's sending);

6. The optical fiber module is compatible with optical fiber equipment (it involves the compatibility of various manufacturers. The best method at present is to inquire and confirm whether it is compatible before purchasing);

7. Check whether the optical module or cable is defective through cross testing (such as moving the normally used optical fiber cable to the doubtful board to confirm).