If the FX lights at both ends are turned off at the same time and there is no optical path, most of the cases are fiber breakage. However, mismatching of wavelengths and reverse TX/RX connection will also cause the same phenomenon. Use the three-step method to first separate the three types of causes: equipment, configuration and wiring, to avoid treating equipment problems as wiring problems.

Step 1: Distinguish the link type and fiber core direction

The dual-fiber link each occupies one fiber core for transmitting and receiving. The two fiber cores can be crossed once at the opposite end for verification; the single-fiber link transmits bidirectionally on one fiber and relies on the 1310 and 1550 wavelengths to distinguish upstream and downstream.100M single mode single fiber one optical one electrical fiber optic transceiver and Gigabit single mode single fiber one optical one electrical fiber optic transceiverThe A and B terminals must be used in pairs. The connection of the same port may appear to be intact but is actually blocked. This pitfall is most likely to be encountered when modifying and replacing the device.

Step 2: Use optical power meter to measure in sections

• Unplug the jumper at the near end and directly measure the device's light emission to determine whether the transceiver itself is good or bad.
• Go to the flange to measure the light coming from the line to determine whether the trunk optical fiber reaches the computer room.
• Step by step along the link, if the section starts to lose light, the fault lies in the previous section.

Step 3: Locate the physical fault point

After confirming the broken fiber, use a red light pen to observe the light leakage point in the dark. Use an OTDR on the long-distance trunk to give the precise mileage. Focus on checking the pipe manhole, the bend of the downpipe and the entrance of the flange box. There is a high probability of rat bites in fields and storage environments, so it is recommended to useSingle mode single core armored patch cord, anti-rat and anti-trampling can significantly reduce recurrence. Welding repair shall be accepted if the single point loss is no higher than 0.1dB, and active jumpers shall be controlled within 0.5dB.

After completing the three steps, you should be able to form a conclusion: the equipment is broken, the configuration is wrong, or the line is broken. Obtain the location and loss data of the fault point before dispatching an order for construction to avoid blind replacement of the whole machine and save a round of useless business trips; if you need assistance in demarcating, please contact EB-LINK technical support.