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Optical fiber transceiver usage and common fault diagnosis guide
Jan 28, 2019

  In the network construction and application, since the maximum transmission distance of the network cable is generally 100 meters, it is necessary to use a relay device such as a fiber transceiver when constructing a long-distance transmission network. Fiber optic transceivers are typically used in real-world network environments where Ethernet cables cannot be covered and fiber must be used to extend the transmission distance.   How to use fiber optic transceivers?   The transmission distance of optical fiber is far. Generally speaking, the transmission distance of single-mode fiber is more than 10 kilometers, and the transmission distance of multi-mode fiber can reach 2 kilometers. When using fiber optics, fiber optic transceivers are often used: the optical signal is input from the optical port, and the electrical signal is output from the electrical port (common RJ45 crystal head interface), and vice versa.   The process is probably: converting an electrical signal into an optical signal, transmitting it through an optical fiber, converting the optical signal into an electrical signal at the other end, and then accessing a device such as a router or a switch .   Fiber optic transceiver applications   Therefore, fiber optic transceivers are generally used in pairs. For example, the optical transceivers (possibly other devices) in the equipment room of the operator (Telecom, Mobile, China Unicom) and your fiber transceiver. If you want to use your fiber transceiver to set up your own LAN, you must use it in pairs.   The fiber optic transceiver, like a normal switch, is powered and plugged in and can be used without any configuration. Optical fiber insertion port, RJ45 crystal head plug. However, pay attention to the transmission and reception of optical fibers, one for each other, if not, change each other.   Learn about fiber optic transceiver lights   Common fiber optic transceivers have six indicators, each with its specific meaning. It is not that all the indicators are on, it means that the fiber transceiver is working normally. Through the working status of the indicator light, some common faults can be initially screened and judged.   Take UPEPO's Gigabit adaptive single-mode single-fiber optical transceiver MC2-GS as an example. The product port is equipped with 6 LEDs to monitor the status of the device. If the device fails, the staff can find it at a glance. The crux of the problem is a very human design.   If the fiber transceiver works normally, the PWR power indicator must be always on;   The FX/ACT fiber link indicator and the TX/ACT network link indicator should be on or blinking.   If the FX/ACT or TX/ACT indicator is off, check whether the link is properly connected.   As for the FDX full/half duplex mode indicator, whether the 1000M and 100M network rate indicators are always on, there is no substantial impact on the fiber transceiver.   Optical transceiver failure judgment   There are many types of optical transceivers, but the method of fault diagnosis is basically the same. To sum up, the faults that occur in optical transceivers are as follows:   1. The PWR light does not illuminate.   electricity failure   2. The light path FX/ACT light does not light up.   The fault may be as follows:   A. Check if the fiber line is open.   B. Check if the fiber line loss is too large and exceed the receiving range of the device.   C. Check whether the fiber interface is connected accurately. The local TX is connected to the remote RX, and the remote TX is connected to the local RX.   D. Check whether the fiber connector is properly inserted into the device interface, whether the jumper type matches the device interface, whether the device type matches the fiber, and whether the device transmission length matches the distance.   3, the circuit TX / ACT light is not bright   The fault may be as follows:   A. Check if the network cable is open.   B. Check whether the connection type matches: devices such as network cards and routers use cross-connection lines, switches, hubs, etc., using straight-through lines.   C. Check if the device transmission rate matches.   4, the network packet loss is serious   Possible faults are as follows:   A. The electrical port of the transceiver is connected to the network device, or the duplex mode of the interface of the two devices does not match.   B. There is a problem with the twisted pair and the RJ-45 head for testing.   C. Fiber connection problem, whether the jumper is aligned with the device interface, whether the pigtail and jumper and coupler type are matched.   5, the fiber transceiver can not communicate after the two ends are connected   A, the fiber is reversed, and the fiber connected to the TX and RX is reversed (there is no such problem in the single fiber device)   B. The RJ45 interface is not properly connected to the external device (focus on straight-through and splicing)   The fiber interface (ceramic ferrule) does not match. This fault is mainly reflected in the 100M transceiver with photoelectric mutual control function. If the pigtail of the APC ferrule is connected to the transceiver of the PC ferrule, it will not be able to communicate normally. The photoelectric intercommunication transceiver has no effect.   6, time pass and break phenomenon   A. It may be that the optical path attenuation is too large. At this time, the optical power of the receiving end can be measured by the optical power meter. If the receiving agility range is around four weeks, the optical path fault can be basically judged within the range of 1-2 dB.   B. The switch connected to the transceiver may be faulty. At this time, the switch is replaced with a PC, that is, the two transceivers are directly connected to the PC, and both ends are connected to PING. If the connection is not broken, the switch may be basically determined to be faulty. .   C. It may be a transceiver failure. At this time, connect the transceiver to the PC at both ends (do not pass the switch). After both sides have no problem with PING, transfer a large file (100M) from one end to the other end, observe it. Speed, such as slow speed (file transfer of less than 200M for more than 15 minutes), can be basically judged as a transceiver failure.   7, after a period of communication, crash, that is, can not communicate, return to normal after restart   This phenomenon is generally caused by the switch. The switch performs CRC error detection and length check on all received data. It checks that the packet with the error will be discarded and the correct packet will be forwarded.   However, some packets with errors in this process are not detected in the CRC error detection and length check. Such packets will not be sent during the forwarding process and will not be discarded. They will accumulate in the dynamic cache ( Buffer), can never be sent out, wait until the buffer is full, it will cause the switch to crash. Because restarting the transceiver or restarting the switch at this time can restore the communication to normal, the user is usually considered to be a problem with the optical transceiver.   8, optical transceiver test method   If you find a problem with the fiber optic transceiver connection, test it as follows to find out the cause of the problem.   A, near-end test   If the computer at both ends is PING, if it can be PING通, it is confirmed that there is no problem with the optical transceiver. If the near-end test cannot communicate, it can be judged that the optical transceiver is faulty.   B, remote test   If the computer at both ends is not connected to PING, if the PING is unreachable, it must check whether the optical path connection is normal and whether the transmitting and receiving power of the optical transceiver is within the agreed range. If PING is passed, it proves that the optical path is connected properly. You can determine the fault problem on the switch.   C, remote test to determine the point of failure   First connect one end to the switch, and both ends to PING. If there is no end fault, it can be judged as failure of another switch.   Optical transceiver use precautions   1. The connection of the fiber interface must pay attention to single mode and multimode matching.   Single mode transceivers can operate with single mode fiber and multimode fiber, but multimode fiber transceivers cannot operate with single mode fiber. Taking the MC2-FS and MC2-GS fiber transceivers as an example, the technicians say that single-mode devices can be used with multimode fibers when the fiber transmission distance is short, but the technicians suggest that it is better to switch to the corresponding fiber transceiver. The device is used together, so that the device works more stably and reliably, and there is no packet loss.   2, distinguish between single fiber and dual fiber equipment   The transmitting port (TX) of the transceiver at one end of the dual-fiber device is connected to the receiving port (RX) of the transceiver at the other end.   Compared with dual-fiber devices, single-fiber devices can avoid the problem of the insertion port (TX) and the receiving port (RX) being inserted incorrectly during use. Because it is a single-fiber transceiver, only one optical port is both TX and RX, and the fiber of the SC interface can be inserted, which is simpler to use. Moreover, the single fiber device can save fiber usage and effectively reduce the overall cost of the monitoring solution .   Utech's 100M/Gigabit fiber optic transceivers MC2-FS and MC2-GS are single-mode single-fiber devices that support fiber transmission distances up to 25KM.   3. Focus on the reliability of fiber optic transceiver equipment   Ambient temperature   The fiber optic transceiver itself generates high heat when used, and the fiber transceiver will not work properly when the temperature is too high. For example, the UTP optical transceivers MC2-FS and MC2-GS are used as examples. The maximum operating temperature range allowed by the device is -20°C~+60°C. The wide operating temperature range undoubtedly reduces the possibility of unexpected failures for equipment that requires long-term operation, resulting in higher product reliability.   Lightning protection performance   Most of the front-end cameras of the surveillance system are installed in outdoor open-air environments, and the risk of damage to the equipment or cables subjected to direct lightning strikes is relatively high. In addition, it is also very sensitive to electromagnetic interference such as lightning overvoltage, power system operation overvoltage, electrostatic discharge, etc., which may cause equipment damage, which may cause the entire monitoring system to collapse. Most fiber optic transceivers on the market are inexpensive, but they do not have lightning protection capabilities.   The UTP optical fiber transceiver MC2-FS/MC2-GS product protection circuit adopts TSS discharge tube, which can reach 6KV lightning protection, effectively reducing the maintenance cost caused by lightning damage.   4. Do you support full-duplex and half-duplex?   Some fiber optic transceivers on the market can only use full-duplex environment and cannot support half-duplex. If you connect to other brands of switches (SWITCH) or hub (HUB), and it uses half-duplex mode, it will definitely cause serious Conflicts and packet loss.   Utech's 100M and Gigabit fiber optic transceivers MC2-FS and MC2-GS are designed with imported chips to support full-duplex half-duplex mode for automatic switching, stable and reliable without packet loss. 

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