Based on application feedback and accumulated experience, Guangte has collected and organized some common problems encountered by customers during the use of fiber optic transceivers, and attached possible causes and troubleshooting.
1. The power light is not on
Power Failure
2. Link light is not on
1) Check if the fiber optic line is broken
2) Check if the fiber optic line has excessive losses beyond the device's receiving range
3) Check if the fiber optic interface is connected correctly, connect the local TX to the remote RX, and connect the remote TX to the local RX.
4) Check if the fiber optic connector is properly inserted into the device interface, if the jumper type matches the device interface, if the device type matches the fiber optic cable, and if the device transmission length matches the distance.
3. The circuit link light is not on
1) Check if the network cable is open circuited
2) Check if the connection type matches: network cards and routers use cross cables, while switches, hubs, and other devices use straight cables.
3) Check if the device transmission rate matches
4. Severe network packet loss
1) The electrical port of the transceiver does not match the duplex mode of the network device interface or the interfaces of both devices.
2) There is an issue with the twisted pair cable and RJ-45 connector, please conduct a test
3) Fiber optic connection issues, whether the jumper is aligned with the device interface, whether the tail fiber matches the jumper and coupler types, etc.
5. After connecting the fiber optic transceiver, the two ends cannot communicate
1) Fiber optic connection reversed, TX and RX fiber optic connections swapped
2) The RJ45 interface is not connected correctly to external devices (pay attention to direct and twisted connections)
3) The fiber optic interface (ceramic plug) does not match, and this fault is mainly reflected in the 100M transceiver with optoelectronic mutual control function. For example, if the tail fiber of the APC plug is connected to the transceiver of the PC plug, it will not communicate normally, but connecting to a non optoelectronic mutual control transceiver will not affect it.
6. Time on and time off phenomenon
1) It may be due to excessive attenuation of the optical path. In this case, an optical power meter can be used to measure the optical power at the receiving end. If it is near the receiving sensitivity range, it can be basically judged as an optical path fault within the range of 1-2dB
2) It may be a fault in the switch connected to the transceiver. In this case, replace the switch with a PC, that is, connect the two transceivers directly to the PC with PING on both ends. If there is no on-off phenomenon, it can be basically judged as a switch fault
3) It may be a problem with the transceiver. In this case, connect both ends of the transceiver to a PC (not through a switch). After both ends have no problem with PING, transfer a large file (100M or more) from one end to the other and observe its speed. If the speed is very slow (files below 200M can be transferred for more than 15 minutes), it can be basically judged as a transceiver failure
7. After a period of communication, the system crashes, meaning it cannot communicate. After restarting, it returns to normal
This phenomenon is generally caused by switches, which perform CRC error detection and length verification on all received data. Any packets found to have errors will be discarded, and the correct packets will be forwarded. However, during this process, some packets with errors cannot be detected in CRC error detection and length check. Such packets will not be sent or discarded during forwarding, and will accumulate in the dynamic buffer, which will never be sent. When the buffer is full, it will cause the switch to crash. Because restarting the transceiver or switch at this time can restore normal communication, users usually assume that it is a problem with the transceiver.
Transceiver testing method
If a problem is found with the transceiver connection, please test it according to the following method to identify the cause of the malfunction
a) Near end testing:
If both ends of the computer can ping, it proves that there is no problem with the fiber optic transceiver. If communication cannot be achieved through near end testing, it can be determined as a fiber optic transceiver failure.
b) Remote testing:
If the PING is not working on both ends of the computer, it is necessary to check whether the optical path connection is normal and whether the transmission and reception power of the fiber optic transceiver is within the allowable range. If the PING rule can prove that the optical path connection is normal. It can be determined that the fault lies in the switch.
c) Remote testing to determine the fault point:
First, connect one end to the switch and pair both ends with PING. If there is no fault, it can be determined that the other switch is faulty.