The function of the indicator light of the optical fiber transceiver and the fault determination method
1. First check whether the indicator light of the fiber optic transceiver or optical module and the indicator light of the twisted pair port are on?
A. If the optical port (FX-LINK/ACT) indicator light of the transceiver is not on, please confirm whether the optical fiber link is a correct cross-link, the optical fiber socket TX-RX; RX-TX.
B. If the optical port (FXFX-LINK/ACT) indicator light of transceiver A is on but the optical port (FXFX-LINK/ACT) indicator light of transceiver B is not on, the fault is at the transceiver end of A: one possibility is: The optical sending port of transceiver A (TX) is broken, because the optical port (RX) of transceiver B cannot receive the optical signal; another possibility is: the optical fiber link of the optical sending port of transceiver A (TX) has Problem (possibly a broken fiber optic cable or patch cord).
C. The twisted pair (TXFX-LINK/ACT) indicator light is not on, please confirm whether the twisted pair connection is wrong or the connection is wrong? Please use a continuity tester to detect (note that the twisted pair indicator of some transceivers It will not light until the optical fiber link is connected).
2. Are the optical cables and jumpers broken?
A. Optical cable on-off detection: Use a laser flashlight or a luminous body to illuminate one end of the optical cable connector or coupler; see if there is visible light at the other end? If there is visible light, it indicates that the optical cable is not broken.
B. On-off detection of optical fiber connection: use a laser flashlight, sunlight, etc. to illuminate one end of the optical fiber jumper; see if there is visible light at the other end? If there is visible light, it indicates that the optical fiber jumper is not broken.
3. Detection with optical power meter
Luminous power of optical fiber transceiver or optical module under normal conditions:
Multi-mode 2Km: between -10db—18db;
Single-mode 20km: between -8db—15db;
Single-mode 60km: between -5db—12db;
If the luminous power of the fiber optic transceiver is between -30db—45db, then it can be judged that there is a problem with the transceiver.
Common faults and solutions
1. Why is the TxLink light off?
A. The network cable is disconnected or damaged
B. Poor contact between the twisted pair crystal head and the equipment
C. The network port of the device is not connected normally
2. What is the reason why the TxLink light does not flash but stays on after the optical fiber is connected normally?
A. The fault is generally caused by the transmission distance being too long;
B. There is no data passing between fiber optic transceivers
3. What is the reason why the Fxlink light is not on?
A. The optical fiber cable is connected incorrectly, the correct connection method is TX-RX, RX-TX or the optical fiber mode is wrong;
B. The transmission distance is too long or the intermediate loss is too large, which exceeds the nominal loss of this product. The solution is: take measures to reduce the intermediate loss or replace it with a transceiver with a longer transmission distance.
C. The problem of the fiber optic transceiver itself.
4. What is the reason why the Fxlink light does not flash but stays on after the optical fiber is connected normally?
Reason: The fault is usually caused by too long transmission distance or too much intermediate loss, which exceeds the nominal loss of this product. The solution is to minimize the intermediate loss or replace it with a transceiver with a longer transmission distance.
5. What should I do if all five lights are on or the indicators are normal but cannot transmit?
Reason: Check whether the front-end network cable is connected normally. Generally, turn off the power and restart it to return to normal.
6. What is the ambient temperature of the transceiver?
Reason: The optical fiber module is greatly affected by the ambient temperature. Although it has a built-in automatic gain circuit, when the temperature exceeds a certain range, the transmitted optical power of the optical module is affected and decreases, thereby weakening the quality of the optical network signal and causing packet loss. rate rises, and even disconnects the optical link; (generally, the working temperature of the optical fiber module can reach 70°C)
7. What is the compatibility with external device protocols?
10/100M fiber optic transceivers, like 10/100M switches, have a certain limit on the frame length, generally no more than 1522B or 1536B, when the switch connected at the central office supports some special protocols (such as: Ciss ISL) The packet overhead increases (the packet overhead of Ciss ISL is 30Bytes), which exceeds the upper limit of the fiber optic transceiver frame length and is discarded by it, reflecting a high packet loss rate or failure. At this time, it is necessary to adjust the MTU (MTU Maximum Transmitting Unit) of the terminal device , the general IP packet overhead is 18 bytes, and the MTU is 1500 bytes. Currently, high-end communication equipment manufacturers have internal network protocols, and generally use separate packets, which will increase the overhead of IP packets. If the data is 1500 bytes, IP After the packet is wrapped, the size of the IP packet will exceed 18 and be discarded), so that the size of the packet transmitted on the line meets the limit of the frame length of the network device. The packet of 1522 bytes is to add VLANtag.
8. After the transceiver chassis has been working normally for a period of time, why do some cards fail to work normally?
The early chassis power supply used the relay method. Insufficient power margin of the power supply and large line loss are the main problems. After the chassis has been working normally for a period of time, some cards cannot work normally. When some cards are pulled out, the rest of the cards work normally. After the chassis has been working for a long time, the connectors are oxidized and cause a large loss of connectors. This kind of power supply drops beyond the specified If the required range is exceeded, it may cause abnormal phenomenon of card insertion in the chassis. Now, high-power Schottky diodes are used for isolation protection for the switching of the power supply of the chassis, and the form of the connector is improved to reduce the power drop caused by the control circuit and the connector. At the same time, the power redundancy of the power supply is increased, which really makes the backup power supply convenient and safe, and makes it more suitable for long-term uninterrupted work requirements.
