SFP transceiver: purpose, types, features

The improvement of data transmission technologies led to the appearance of an optical fiber network, where special equipment is needed to connect devices - the SFP transceiver. The SFP modules replaced the more cumbersome GBIC equipment and are used in telecommunication lines with a streaming rate of data above 100 Mbps.

Purpose

SFP-transceivers are used as transceiver equipment. In other words, they act as intermediaries between an optical fiber cable or an unshielded twisted pair and a network device card-switch, modem or router. The main advantage of the module is a very small connector. Due to this, a SFP-transceiver with a width of only 20 centimeters can accommodate up to 20 slots.

The equipment is used for high-speed data transmission (more than 10 Mbps) using the following technologies: SDH and Fiber Channel. In addition, there is equipment that can operate with three types of signal transmission.

Types of SFP transceivers

Depending on the tasks assigned, such as fiber-optic cable, as well as the equipment used, all SFP modules are divided according to several criteria:

1. Data transmission speed. An ordinary SFP transceiver retransmits the signal at a rate of 100 Mb / s and 1 Gb / s, the SFP + and XFP standards - up to 10 Gb / s.
2. Type of connector used. SC-slot is used to connect a single-fiber cable, where the reception and transmission of information occurs over a single fiber, and the LC-connector for two-fiber, where the reception and transmission of signals is carried out through its own channels.
3. Type of fiber. For connection to a single-mode wire, an SM-transceiver is used, and for multimode wires - MM-modules.
4. The highest power of the transmitted signal. This characteristic varies in the range of 1310 nm and 1550 nm for singlemode connection, and within 850 nm and 1310 nm for multimode cables.

Each SFP transceiver has a certain optical budget, or the range of signal reception and transmission. As the light travels through the cable, the signal is damped. The difference between the maximum distance that a signal module can send and the power of the received light flux is called the optical budget. These data are indicated in the transceiver's data sheet in dB.

Features of working with modules

During the transfer of the SFP data, the module emits a light signal in an invisible spectrum (there is a special laser inside the equipment). Therefore, it is strictly forbidden to look into the "eye" of the device to avoid damage to the retina.

When connecting the SFP transceiver, it is necessary to wear an antistatic wrist strap, after connecting it to the case. Otherwise, the discharge of electrostatic current can disable the device.

In addition, the "eye" of the laser is sensitive to dust, so do not remove the protective plugs before turning on the device. To extend the life of the module, try not to remove the cable from the connector without needing it.

Rules for selecting SFP modules

Select the SFP transceiver according to the characteristics of your fiber optic cable. At the same time, it is necessary to focus attention on several issues. First, we need to determine the optical budget accurately. For this purpose, special devices are recommended. When there are none, you can find out this value "by eye", it is enough to know the distance between the point of reception and transmission to within a kilometer.

Secondly, determine the type of latch on the board of your network device. Optical SFP transceiver must be selected with exactly the same lock. Otherwise, you simply can not use the module. Currently, there are three types of latches on the market: Button, Mylar Tab, Bale-Clasp. You can determine the type visually.