The optical transceiver is an Ethernet transmission medium conversion unit that exchanges short-distance twisted pair electrical signals and long-distance optical signals. In many places, it is also called a Fiber Converter. Products are generally used in actual network environments where Ethernet cables cannot be covered and must use optical fibers to extend the transmission distance, and are usually located in access layer applications of broadband metropolitan area networks; for example, high-definition video image transmission for monitoring security engineering; It also played a huge role in connecting the last mile of the fiber to the metro and the outer network.
Fiber Transceiver Classification
Nature classification
Single mode fiber optic transceiver: transmission distance 20 km to 120 km
Multimode fiber optic transceiver: transmission distance 2 km to 5 km
For example, the transmission power of a 5 km fiber optic transceiver is generally between -20 and -14 db, the receiving sensitivity is -30 db, and the wavelength of 1310 nm is used; and the transmitting power of a 120 km optical transceiver is between -5 and 0 dB, and the receiving sensitivity is For -38dB, use a wavelength of 1550nm.
Required classification
Single fiber optical transceiver: Receive and transmit data transmitted on one fiber
Dual fiber optic transceiver: receiving and transmitting data transmitted on a pair of optical fibers
As the name implies, single-fiber devices can save half of the fiber, that is, to receive and transmit data on one fiber, which is very suitable in places where fiber resources are tight. These products use wavelength division multiplexing technology, using wavelengths of 1310nm and 1550nm. However, since there is no unified international standard for single-fiber transceiver products, there may be incompatibilities in the interconnection of different vendors' products.
In addition, due to the use of wavelength division multiplexing, single-fiber transceiver products are generally characterized by large signal loss.
Working level/rate
100M Ethernet Optical Transceiver: Working at the Physical Layer
10/100M Adaptive Ethernet Optical Transceiver: Working at the Data Link Layer
According to the working level/rate, it can be divided into single 10M, 100M optical transceiver, 10/100M adaptive optical transceiver and 1000M optical transceiver and 10/100/1000 adaptive transceiver. Among them, single 10M and 100M transceiver products work in the physical layer, and the transceiver products working at this layer are used to forward data in bits. The forwarding mode has the advantages of fast forwarding speed, high transparency, low delay, etc., and is suitable for being applied to a fixed-speed link. At the same time, since such devices do not have an auto-negotiation process before normal communication, they are compatible. Doing better in terms of sex and stability.
Structural classification
Desktop (standalone) fiber optic transceiver: stand-alone client device
Rackmount (Modular) Fiber Transceiver: Mounted in a 16-slot chassis with centralized power supply
According to the structure, it can be divided into desktop (stand-alone) fiber transceivers and rack-mount fiber transceivers. The desktop fiber optic transceiver is suitable for single users, such as meeting the uplink of a single switch in the corridor. Rack-mount (modular) fiber optic transceivers are suitable for multi-user aggregation. At present, domestic racks are mostly 16-slot products, that is, up to 16 modular fiber-optic transceivers can be inserted into one rack.
Management type classification
Unmanaged Ethernet fiber transceiver: plug and play, set the electrical port working mode through the hardware DIP switch
Managed Ethernet Optical Transceiver: Supports Carrier-Grade Network Management
Network management
Can be divided into non-managed optical transceivers and managed optical transceivers. Most operators hope that all devices in their network can achieve remote network management. Fiber transceiver products are gradually moving in this direction as switches and routers. For the network management of the optical transceiver, it can be subdivided into the central office network management system and the user end network management system. The optical transceivers of the central office network management are mainly rack-mounted products. Most of them adopt the master-slave management structure. The main network management module needs to poll the network management information on its own rack on the one hand, and collect all the secondary subracks on the other hand. The information on it is then summarized and submitted to the network management server. For example, the OL200 series managed optical transceiver products provided by Wuhan Fenghuo Network support 1 (main) + 9 (slave) network management structure, and can manage up to 150 optical transceivers at one time.
The client network management can be divided into three main ways:
The first one is to run a specific protocol between the central office and the client device. The protocol is responsible for sending the status information of the client to the central office, and processing the status information through the CPU of the central office device, and submitting the status information to the network management server;
The second type is that the optical transceiver on the optical end can detect the optical power on the optical port. Therefore, when there is a problem on the optical path, it can be judged whether the optical fiber is faulty or the fault of the user equipment according to the optical power;
The third is to install the main control CPU on the fiber transceiver of the user end, so that the network management system can monitor the working state of the user equipment on the one hand, and remote configuration and remote restart.
Among the three types of client network management methods, the first two are strictly remote monitoring of the client device, and the third is the real remote network management. However, since the third method adds a CPU to the user side, which also increases the cost of the client device, the first two methods are more advantageous in terms of price. As operators demand more and more equipment network management, it is believed that the network management of optical transceivers will become more practical and intelligent.
Power classification
Built-in power fiber transceiver: built-in switching power supply for carrier-grade power supply;
External power fiber optic transceiver: External transformer power supply is used in civilian equipment.
Working style classification
Full duplex means that when data is transmitted and received and shunted by two different transmission lines, both sides of the communication can transmit and receive at the same time. This transmission mode is full-duplex. ,As shown in Figure 1. In the full-duplex mode, the transmitter and the receiver are provided at each end of the communication system, so that data can be controlled to be transmitted in both directions simultaneously. The full-duplex mode eliminates the need to switch direction, so there is no time delay caused by the switching operation.
Half duplex refers to the use of the same transmission line for both reception and transmission. Although the data can be transmitted in both directions, the communication cannot simultaneously transmit and receive data. This transmission method is half-duplex. In the half-duplex mode, the transmitter and receiver at each end of the communication system are switched to the communication line through the receive/transmit switch, and the direction is switched. Therefore, a time delay occurs.
The difference between the optical transceiver ab end
First, the fiber transceivers are classified into two types according to the number of fiber cores, one is a single mode dual fiber optical transceiver, and the other is a single mode single fiber optical transceiver. The A and B ports we talked about can only be used with single-mode single-fiber transceivers. Because a single-mode single-fiber transceiver transmits through a single-core fiber, both transmitted and received light are transmitted simultaneously through a single fiber core. In this case, to achieve normal communication, it is necessary to distinguish between two wavelengths of light. Therefore, the optical module of the single-mode single-fiber transceiver emits two wavelengths, generally 1310nm/1550nm, and the long-distance is 1490nm/1550nm. There is a difference between the two ends of a pair of transceivers, one end transceiver The emission is 1310nm and the reception is 1550nm. The other end is 1550nm and 1310nm. It is convenient for users to distinguish, and it is usually replaced by letters. The A end (1310 nm / 1550 nm) and the B end (1550 nm / 1310 nm) appeared. User use must be paired with AB. Cannot be connected to AA or BB.
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