Optical fiber transceivers are very common in weak current engineering. How to choose fiber optic transceivers? The fiber optic transceiver fails, how to maintain? These problems are difficult for novices. Today, ZR Cable will share the knowledge of fiber optic transceivers.
ZR Cable Optical Transceiver
1. What is a fiber optic transceiver?
Optical fiber transceivers, also known as photoelectric converters, are Ethernet transmission media conversion units that exchange short-distance twisted-pair electrical signals and long-distance optical signals. Different observation angles make people have different understandings of fiber optic transceivers, such as single 10M, 100M fiber optic transceivers, 10/100M adaptive fiber optic transceivers and 1000M fiber optic transceivers according to the transmission rate;
According to the working mode, it can be divided into optical fiber transceivers working at the physical layer and optical fiber transceivers working at the data link layer; The different access fibers are called multi-mode fiber transceivers and single-mode fiber transceivers.
In addition, there are single-fiber fiber optic transceivers and dual-fiber fiber optic transceivers, built-in power fiber optic transceivers and external power supply fiber optic transceivers, as well as managed fiber optic transceivers and unmanaged fiber optic transceivers. Optical fiber transceivers break the 100-meter limitation of Ethernet cables in data transmission. Relying on high-performance switching chips and large-capacity caches, they can achieve non-blocking transmission and switching performance, and also provide balanced traffic, isolation and conflict. Error detection and other functions ensure high security and stability during data transmission.
Second, the application of fiber optic transceivers
In essence, the optical fiber transceiver only completes the data conversion between different media, and can realize the connection between two switches or computers within 0--100Km, but the practical application has more expansion.
1. Realize the interconnection between switches.
2. Realize the interconnection between switches and computers.
3. Realize the interconnection between computers.
4. Transmission relay: When the actual transmission distance exceeds the nominal transmission distance of the transceiver, especially when the actual transmission distance exceeds 100Km, if the site conditions permit, using 2 transceivers for back-to-back relay is a kind of Very cost-effective solution.
5. Single-multi-mode conversion: When single-multi-mode fiber connection is required between networks, a multi-mode transceiver and a single-mode transceiver can be used for back-to-back connection, which solves the problem of single-multi-mode fiber conversion.
6. Wavelength division multiplexing transmission: When the long-distance optical cable resources are insufficient, in order to improve the utilization rate of the optical cable and reduce the cost, the transceiver and the wavelength division multiplexer can be used together, so that the two channels of information can be transmitted on the same pair of optical fibers.
3. Precautions for the use of fiber optic transceivers
From the introduction, we know that there are many different classifications of fiber optic transceivers, but in actual use, most of the attention is paid to the categories distinguished by different fiber optic connectors: SC connector fiber optic transceivers and ST connector fiber optic transceivers.
When using fiber optic transceivers to connect different devices, you must pay attention to the different ports used.
1. Connection of fiber optic transceivers to 100BASE-TX devices (switches, hubs):
Confirm that the length of the twisted pair does not exceed 100 meters;
Connect one end of the twisted pair to the RJ-45 port (Uplink port) of the optical transceiver, and the other end to the RJ-45 port (common port) of the 100BASE-TX device (switch, hub).
2. The connection of the optical transceiver to the 100BASE-TX device (network card):
Confirm that the length of the twisted pair does not exceed 100 meters;
Connect one end of the twisted pair to the RJ-45 port (100BASE-TX port) of the optical transceiver, and the other end to the RJ-45 port of the network card.
3. Connection of optical transceiver to 100BASE-FX:
Confirm that the fiber length does not exceed the distance range that the device can provide;
One end of the optical fiber is connected to the SC/ST connector of the fiber optic transceiver, and the other end is connected to the SC/ST connector of the 100BASE-FX device.
In addition, it is necessary to add that many users think when using optical fiber transceivers: as long as the length of the optical fiber is within the maximum distance supported by single-mode optical fiber or multi-mode optical fiber, it can be used normally. In fact, this is a wrong understanding. This understanding is correct only when the connected devices are full-duplex devices. When there are half-duplex devices, the transmission distance of the optical fiber is limited to a certain extent.
Fourth, the purchase principle
As an area network connector device, the main task of the optical fiber transceiver is how to seamlessly connect the data between the two parties. Therefore, it is necessary to consider its compatibility with the surrounding environment, as well as the stability and reliability of its own products. On the contrary, no matter how low the price is, it cannot be selected!
1. Does it support full duplex and half duplex?
Some chips on the market can only use the full-duplex environment at present, and cannot support half-duplex. Serious collisions and packet loss.
2. Has the connection test been done with other fiber optic transceivers?
At present, there are more and more fiber optic transceivers on the market. If the compatibility of different brands of transceivers has not been tested beforehand, there will also be packet loss, long transmission time, and sometimes fast and slow.
3. Is there a safety device to prevent packet loss?
When manufacturing fiber optic transceivers, some manufacturers adopt the register data transmission mode in order to reduce the cost. The biggest disadvantage of this method is that the transmission is unstable and packet loss, and the best is to use the buffer circuit design. Data packet loss can be safely avoided.
4. Temperature adaptability?
When the optical fiber transceiver itself is used, it will generate high heat. When the temperature is too high (generally not higher than 85°C), does the optical fiber transceiver work normally? What is the maximum allowable operating temperature? For a device that needs to run for a long time, this is very important. Worth our attention!
5. Does it comply with the IEEE802.3u standard?
If the fiber optic transceiver conforms to the IEEE802.3 standard, that is, the delay time is controlled at 46bit. If it exceeds 46bit, it means that the distance transmitted by the fiber optic transceiver will be shortened!!!
6. After-sales service
In order to make the after-sales service respond in a timely and early manner, it is recommended that customers choose a professional company with strong strength, superb technical force and good reputation in the local area.
Five, common fault solutions
1. The Power light is off
electricity failure
2. The Link light is off
The fault may be as follows:
(a) Check whether the optical fiber line is broken
(b) Check whether the loss of the optical fiber line is too large and exceeds the receiving range of the equipment
(c) Check whether the optical fiber interface is connected correctly, the local TX is connected to the remote RX, and the remote TX is connected to the local RX. (d) Check whether the optical fiber connector is well inserted into the device interface, whether the jumper type matches the device interface, whether the device type matches the optical fiber, and whether the device transmission length matches the distance.
3. The circuit Link light does not light up
The fault may be as follows:
(a) Check whether the network cable is broken
(b) Check whether the connection type matches: the network card and routers and other devices use crossover cables, and switches, hubs and other devices use straight-through cables.
(c) Check whether the device transmission rate matches
4. Serious network packet loss
Possible failures are as follows:
(1) The electrical port of the transceiver does not match the interface of the network device, or the duplex mode of the device interface at both ends.
(2) There is a problem with the twisted pair cable and the RJ-45 head, check it
(3) Optical fiber connection problems, whether the jumper is aligned with the device interface, whether the pigtail matches the jumper and the coupler type, etc.
(4) Whether the loss of the optical fiber line exceeds the acceptance sensitivity of the equipment.
5. After the optical transceiver is connected, the two ends cannot communicate
(1). The optical fibers are reversed, and the optical fibers connected to TX and RX are reversed
(2). The connection between the RJ45 interface and the external device is incorrect (pay attention to the straight-through and splicing) The optical fiber interface (ceramic ferrule) does not match. This fault is mainly reflected in the 100M transceiver with optoelectronic mutual control function, such as the APC ferrule. If the pigtail is connected to the transceiver of the PC ferrule, it will not be able to communicate normally, but it will not affect the connection of the non-optical-electrical mutual control transceiver.
6. On and off phenomenon:
(1) It may be that the attenuation of the optical path is too large. At this time, an optical power meter can be used to measure the optical power of the receiving end. If it is near the receiving sensitivity range, it can be basically judged as an optical path failure within the range of 1~2dB.
(2). It may be the failure of the switch connected to the transceiver. At this time, replace the switch with a PC, that is, the two transceivers are directly connected to the PC, and the two ends are pinged. Fault
(3). The transceiver may be faulty. At this time, you can connect both ends of the transceiver to the PC (not through the switch). After the two ends have no problem with PING, transfer a large file (100M) from one end to the other. Observe Its speed, such as the speed is very slow (the file below 200M is transmitted for more than 15 minutes), it can be basically judged as a transceiver failure.
7. The machine crashes after a period of communication, that is, it cannot communicate, and it returns to normal after restarting
This phenomenon is generally caused by the switch. The switch will perform CRC error detection and length check on all the received data. The packets with errors will be discarded, and the correct packets will be forwarded. However, some erroneous packets in this process cannot be detected in CRC error detection and length verification. Such packets will not be sent or discarded during the forwarding process, and they will accumulate in the dynamic buffer. (buffer), it can never be sent out. When the buffer is full, it will cause the switch to crash. Because restarting the transceiver or restarting the switch can make the communication return to normal at this time, users usually think that the problem is the transceiver.
8. Transceiver test method
If you find a problem with the transceiver connection, please test it as follows to find out the cause of the failure.
a) Near-end test: PING the computers at both ends, if PING is possible, it proves 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: PING the computers at both ends. If the PING fails, you must check whether the optical path connection is normal and whether the transmit and receive power of the fiber optic transceiver is within the allowable range. If you can PING, it proves that the optical path connection is normal. It can be judged that the fault lies in the switch.
C)Remote test to determine the fault point: First connect one end to the switch, and both ends to PING, if there is no fault, it can be judged as the fault of the other switch.
