Very practical technical knowledge about fiber optic transceivers
ForewordHello, my name is Mr. Lin. Fiber optic transceivers are equipment that we often use. The following points of concern and troubleshooting steps for fiber optic transceivers are provided for you. , Solutions to Common Troubleshooting, and Other Tech Stuff, Must-Haves for Newbies! Veteran drivers also recommend coding for backup. TextWhat is an indicator
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Our widely used fiber optic transceivers have 6 indicators. What does each indicator mean? Does this mean that fiber optic transceiver is working properly if all indicators are lit?
PWR: when LED is on, 5V DC power supply is working properly;
FDX: indicator is on to indicate that optical fiber is transmitting data in full duplex mode.
FX 100: When light is on, fiber data rate is 100 Mbps.
TX 100: When indicator is on, it means twisted-pair transmission rate is 100Mbps, and when indicator is off, it means twisted-pair transmission rate is 10Mbps /s;
FX Link/Act: indicator is always on, indicating that fiber link is properly connected; light is on to indicate that data is being transmitted over fiber;
TX Link/Act: LED is always on, indicating that twisted-pair connection is connected; LED flashes to indicate 10/100M data transmission over twisted pair.
If fiber optic transceiver is working properly, PWR power indicator should always be on, FX-LINK/ACT fiber link indicator, TX-LINK/ACT network link indicator should always be on or blinking. , if LINK/ACT indicator is not lit, check if corresponding channel is connected properly, FDX working mode indicator, FX-100 fiber speed indicator and TX-100 network speed indicator are always on.
Indicator light function and troubleshooting method
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1. First, check if fiber optic transceiver or optical module LED and twisted pair port LED are lit?
A. If optical port indicator (FX-LINK/ACT) of transceiver is off, check that fiber link is correct cross-connect, fiber optic connector TX-RX, RX-TX.
B. If optical port LED (FXFX-LINK/ACT) of transceiver A is on and optical port LED (FXFX-LINK/ACT) of transceiver B is off, fault is transceiver A end: one This could be: The optical transmit port of transceiver A (TX) is faulty because optical port (RX) of transceiver B cannot receive optical signals; another possibility: optical fiber of optical transmitter transceiver port A (TX) Connection problem (possibly broken fiber optic cable or patch cord).
C. Twisted Pair LED (TXFX-LINK/ACT) is off. Please confirm if twisted pair is connected incorrectly or incorrectly? Please use a continuity tester to detect (however, twisted pair LED of some transceivers will not light up until fiber link is connected).
D. Some transceivers have two RJ45 ports: (to hub) indicates that connection line connected to switch is a direct line; (to node) indicates that connection line connected to switch is a crossover line.
E. Some transceivers have an MPR switch: that means connection line connected to switch is a direct method, DTE switch: connection line connected to switch is a crossover line.
2. Are optical cables and jumpers broken?
Use a laser flashlight, sunlight, or a glowing body to illuminate one end of an optical cable connector or connector; is there any visible light at other end? If there is visible light, it means that optical cable is not damaged.
3. Is half/full duplex mode incorrect?
Some transceivers have a side switch FDX: full duplex; HDX switch: half duplex.
4. Detection with an optical power meter
Light Powerperformance of a fiber optic transceiver or optical module under normal conditions:
Multimode 2 km: -10 dB to 18 dB;
Single mode 20 km: -8 dB to 15 dB;
Single mode 60 km: -5 dB to 12 dB;
If light power of fiber optic transceiver is between -30dB and 45dB, it can be assumed that there is a problem with transceiver.
Common mistakes and solutions
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1. When RJ45 port of transceiver is connected to other devices, what type of connection is used?
The RJ45 port of transceiver connects to network card of PC (DTE data terminal equipment) with a crossover twisted pair cable, and connects to HUB or SWITCH (DCE data equipment) with a parallel cable.
2. Why is TxLink LED not on?
1. Connect wrong twisted pair cable.
2. Poor contact between crystal head of twisted pair and equipment, or a quality problem of twisted pair cable itself.
3. The device is not connected correctly.
3. Why does TxLink LED not flash but stay on after a normal fiber connection?
1. The error usually occurs because transmission distance is too large.
2. Compatible with network card (connected to PC)
4. Why is Fxlink indicator off?
1. The fiber optic cable is not connected correctly. Correct connection method: TX-RX, RX-TX or wrong fiber mode.
2.The transmission distance is too long or intermediate loss is too large, exceeding rated loss of this product. Solution: take measures to reduce intermediate loss or replace it with a transceiver with a longer transmission distance< /li>
3. The operating temperature of fiber optic transceiver is too high.
5. Why does Fxlink LED not flash but stay on after a normal fiber connection?
The error is usually caused by too long a transmission distance or too much intermediate loss that exceeds rated loss of this product. The solution is to minimize intermediate losses or replace it with a transceiver with a longer transmission distance.
6. What should I do if all five indicators are on, or indicators are normal, but transmission is not possible?
Usually turn off power and reboot it to return to normal operation.
7. What is ambient temperature of transceiver?
The fiber optic module is highly dependent on ambient temperature. Although it has a built-in automatic amplification circuit, when temperature exceeds a certain range, transmitted optical powerThe optical module will be affected and fall down, which will degrade signal quality of optical network and cause loss. The packet rate increases and even optical link is disabled (typically, operating temperature of fiber optic module can reach 70 °C).
8. What is compatibility with external device protocols?
A 10/100M fiber optic transceiver, like a 10/100M switch, has a certain frame length limit, usually no more than 1522 or 1536 bytes. When switch connected to central office supports some special protocols (such as: Ciss ISL) increments packet overhead (Ciss ISL packet overhead is 30 bytes) that exceeds and is discarded by fiber optic transceiver's upper frame length limit, reflecting a high rate of packet loss or failures. you need to configure MTU of terminal device (MTU. The largest sending unit, total overhead of an IP packet is 18 bytes, and MTU is 1500 bytes. At present, high-performance communication equipment manufacturers have internal network protocols and usually use separate packets, which will increase overhead IP packets. If data is a 1500 word section, IP packet size will exceed 18 after IP packet is dropped) so that packet size transmitted over line is within frame length limit of network device.
9. Why did some cards stop working properly after chassis worked fine for a while?
Early chassis power supplies used relays. The main problems are insufficient power reserve of power supply and high losses in line. After chassis has been working normally for a while, some cards cannot work normally. When some cards are pulled out, rest of cards work normally. After chassis has been working for a long time, connectors will oxidize and lead to a large loss of connectors. This type of source power out of specified range If required range is exceeded, it may cause an abnormal phenomenon when card is inserted into chassis. Powerful Schottky diodes can be used to protect insulation of chassis power key, and shape of connector can be improved to reduce power drop caused by control circuit and connector. At same time, power supply redundancy of power supply is increased, which really makes backup power supply convenient and safe, and also makes it more suitable for requirement of long-term uninterrupted operation.
10. The communication report is provided on transceiver What functions does police perform?
The transceiver has a link signaling (link loss) function. When a certain fiber is disconnected, it will automatically return to electrical port (i.e. LED on electrical port will also turn off).T). If switch has a network management system, this will be immediately reflected in switch's network management software.
Notes on fiber optic transceiver
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1. Does optical transceiver itself support full duplex and half duplex modes?
Some chips on market currently can only use full duplex media and cannot support half duplex. If they are connected to a switch (SWITCH) or hub (HUB) of another brand and use half-duplex mode, this is sure to cause serious collisions and packet loss.
2. Have you tested connection with other fiber optic transceivers?
There are more and more fiber optic transceivers on market at present. If compatibility of different brands of transceivers has not been tested in advance, there will be packet loss, long transmission time, and sudden fast and slow transmission.
3. Is there a guard to prevent packet loss?
When some manufacturers produce fiber optic transceivers, they use Register mode to reduce cost. The biggest disadvantage of this method is unstable transmission and packet loss, and it is best to use buffer line design, which can safely avoid data packet loss.
4. Temperature adaptation
The fiber optic transceiver itself becomes very hot when used. If temperature is too high (not higher than 50 ° C), when purchasing, it is worth considering whether fiber optic transceiver can work normally!
5. Buy equipment from professional manufacturers
The manufacturer's professional equipment can guarantee product quality and have excellent after-sales service capabilities, so that engineering projects can be more reliable and worry-free.