What do the six indicators of a fiber optic transceiver represent?

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preface

Hello everyone, cloud intelligence knowledge sharing, our commonly used optical fiber transceivers have 6 indicators, so what does each indicator represent? Do all the indicators be on to indicate that the fiber optic transceiver is working properly?

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PWR: The light is on, which means that the DC5V power supply is working normally;

FDX: The light is on to indicate that the optical fiber transmits data in full-duplex mode;

FX 100: The light is on to indicate that the fiber transmission rate is 100Mbps;

TX 100: If the light is on, the twisted pair transmission rate is 100Mbps, and if the light is not on, the twisted pair transmission rate is 10Mbps.

FX Link/Act: The light is always on, indicating that the fiber link is connected correctly. A flashing light indicates that there is data being transmitted in the fiber;

TX Link/Act: The light is always on, indicating that the twisted pair link is connected. The light is flashing to indicate that there is data in the twisted pair cable in transit 10/100M.

If the optical transceiver is working normally, the PWR power indicator must be solid, the FX-LINK/ACT optical link indicator and TX-LINK/ACT network link indicator must be solid or flashing, if the LINK/ACT indicator is not on, check whether the corresponding link is connected normally; As for whether the FDX operating mode indicator, FX-100 fiber rate indicator, and TX-100 network rate indicator are always on, there is no real impact on the fiber optic transceiver.

1. The function of the indicator light of the optical transceiver and the fault judgment method

1. First of all, check whether the indicator light of the optical transceiver or optical module and the indicator light of the twisted pair port are on?

• A. If the optical port (FX-LINK/ACT) indicator of the transceiver is not lit, please make sure whether the optical fiber link is correctly cross-linked, and the optical fiber socket TX-RX; RX-TX。
• B. If the optical port (FXFX-LINK/ACT) indicator of transceiver A is on and the optical port (FXFX-LINK/ACT) indicator of transceiver B is not on, the fault is on the transceiver side of A: one possibility is that the optical transmitting port of transceiver A (TX) is broken, because the optical port (RX) of transceiver B cannot receive the optical signal; Another possibility is that there is a problem with this fiber link at the optical transmit port of the A transceiver (TX) (the fiber optic cable or fiber patch cord may be broken).
• C. The indicator light of twisted pair (TXFX-LINK/ACT) is not on, please make sure that the twisted pair is connected incorrectly or incorrectly? Please use a turn-off tester (although some transceivers have twisted pair LEDs that do not turn on until the fiber link is connected).
• D. Some transceivers have two RJ45 ports: (To HUB) means that the connection line connecting the switch is a straight line; (To Node) indicates that the connection line connecting the switch is a crossed line.
• E. Some transceivers have MPR switches on the side: it means that the connection line connecting the switch is in pass-through mode; DTE switch: The connecting cable to the switch is crossed.

2. Have the optical cable and optical fiber jumper been broken?

• A. Optical cable on-off detection: use laser pointer, sunlight, and luminaire to illuminate one end of the optical cable connector or coupling; See if there's visible light on the other end? If there is visible light, it means that the fiber optic cable is not broken.
• B. Optical fiber connection on-off detection: use laser flashlight, sunlight, etc. to illuminate one end of the optical fiber jumper; See if there's visible light on the other end? If there is visible light, it means that the fiber optic patch cord is not broken.

3. Is there an error in the half/full-duplex mode?

Some transceivers have FDX switches on the side: full duplex; HDX Switch: Indicates half-duplex.

4. Detect with optical power meter

Luminous power of an optical transceiver or transceiver under normal conditions:

Multi-mode 2Km: -10db-18db;

Single-mode 20 km: -8db-15db;

Single-mode 60 km: between -5db and 12db;

If the luminous power of the optical transceiver is between -30db and 45db, then it can be judged that there is a problem with the transceiver.

2. Common faults and solutions

According to the daily maintenance and the problems of users, it is hoped that it can bring certain help to the maintenance staff, so as to judge the cause according to the fault phenomenon, find the fault point, and "prescribe the right medicine".

1. What kind of connection should be used when the RJ45 port of the transceiver is connected to other devices?

Reason: The RJ45 port of the transceiver is connected to the PC network card (DTE data terminal equipment) using a cross-twisted pair cable, and the HUB or SWITCH (DCE data communication equipment) is connected to a parallel cable.

2. What is the reason why the TxLink light does not light up?

Answer:

• 1. Connect the wrong twisted pair
• 2. Poor contact between the twisted pair crystal head and the equipment, or the quality of the twisted pair itself
• 3. The device is not connected normally

3. What is the reason why the TxLink light does not flash but stays on after the optical fiber is connected normally?

Cause:

• 1. The fault is generally caused by the transmission distance being too long;
• 2. Compatibility with network card (connection with PC)

4. What is the reason why the Fxlink light does not light up?

Cause:

• 1. The optical fiber line is connected incorrectly, and the correct connection method is TX-RX, RX-TX or the optical fiber mode is wrong;
• 2. If the transmission distance is too long or the intermediate loss is too large, exceeding the nominal loss of this product, the solution is: take a way to reduce the intermediate loss or replace it with a longer transmission distance.
• 3. The working temperature of the optical fiber transceiver is too high.

5. What is the reason why the Fxlink light does not flash but stays on after the fiber is connected normally?

Reason: The fault is generally caused by too long transmission distance or too large intermediate loss, exceeding the nominal loss of this product, and the solution is to minimize the intermediate loss or replace it with a transceiver with a longer transmission distance.

6. What should I do if the five lights are fully on or the indicator is normal but cannot be transmitted?

Reason: Generally, the power is turned off and restarted to return to normal.

7. 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, but after 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, increasing the packet loss rate, and even disconnecting the optical link. (Generally, the working temperature of optical fiber module can reach 70°C)

8. What is the compatibility with external device protocols?

Cause:

10/100M fiber optic transceiver and 10/100M switch are the same, there are certain limits on the frame length, generally not more than 1522B or 1536B, when the switch connected at the central office supports some more special protocols (such as: ISL of Ciss) and the packet overhead increases (the packet overhead of ISL of Ciss is 30Bytes), so that the upper limit of the frame length of the optical transceiver is exceeded and is dropped by it, reflecting that the packet loss rate is high or not passable, At this time, need to adjust the MTU of the terminal equipment (MTU maximum sending unit, the overhead of the general IP packet is 18 bytes, the MTU is 1500 bytes, the existing internal network protocol of the high-end communication equipment manufacturer now, generally adopt the mode of another packet, will aggravate the overhead of the IP packet, if the data is 1500 bytes, the size of the IP packet will exceed 18 and be discarded after the IP packet), the size of the packet transmitted on the line is satisfied with the limit of the frame length of the network equipment.

9. After the chassis has been working normally for a period of time, why do some cards fail to work normally?

Cause:

In the early days, the chassis power supply was relayed. The lack of power margin and large line losses are the main problems. After the chassis works normally for a period of time, some cards can not work normally, when pulling out part of the card, the remaining cards work normally, the chassis works for a long time, the joint oxidation causes a large joint loss, this power drop exceeds the specified requirements range, may cause the chassis card to be abnormal. Now the high-power Schottky diode is used for isolation protection for the power switching 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, and the backup power supply is truly convenient and safe, and it is more suitable for the requirements of long-term uninterrupted work.

10. What is the function of providing link alarm on the transceiver?

Reason: The transceiver has a link alarm function (linkloss), which will automatically feed back to the electrical port when a fiber is disconnected (that is, the indicator light on the electrical port will also be extinguished), and if the switch has a network manager, it will be immediately reflected to the network management software of the switch.

3. Matters that should be paid attention to in optical fiber transceivers

1. Does the optical transceiver itself support full-duplex and half-duplex?

Some chips on the market can only use a full-duplex environment at present, and cannot support half-duplex, if it is connected to another brand of adapter (SWITCH) or hub (HUB), and it uses half-duplex mode, it will definitely cause serious conflicts and packet loss.

2. Have you done connection tests with other fiber optic transceivers?

At present, there are more and more optical fiber transceivers on the market, and if the compatibility of different brands of transceivers has not been tested in advance, it will also produce packet loss, excessive transmission time, fast and slow and other phenomena.

3. Is there a safety device to prevent packet loss?

In order to reduce costs, some manufacturers use the register data transmission mode when manufacturing optical fiber transceivers, the biggest disadvantage of this method is that the transmission is unstable and packet loss, and the best is to use the buffer line design, which can safely avoid data packet loss.

4. Temperature adaptability?

When the fiber optic transceiver itself is used, it will generate high heat, and when the temperature is too high (not greater than 50 °C), whether the fiber optic transceiver is working properly is a factor worth considering when purchasing!