Nowadays, there are various kinds of optical modules in the market, which are often dazzling. So how do we choose the most suitable optical module for many different speed, different packaging and different functions of optical modules?
Common optical module type
Before we begin to discuss how to choose the optical module, it is necessary to have a basic understanding of the common encapsulated optical modules. This section will introduce the optical modules encapsulated by XFP, SFP, SFP+ and QSFP, respectively.
XFP optical module
The XFP optical module is a standardized package for the serial 10G optical transceiver module. It meets the following standards: 10G Ethernet, 10G fiber channel, SONET/OC-192 and SDH/STM-64.
SFP optical module
SFP optical module is a mini version of the GBIC optical module, the two functions are roughly the same, SFP optical module volume than GBIC optical module is much smaller, generally used in the SONET/SDH network, fast / Gigabit Ethernet and other high-speed transmission applications.
SFP+ optical module
The SFP+ optical module is an upgraded version of the SFP optical module, which has the same physical encapsulation, but the SFP+ optical module can support the transmission rate of the 10Gbps. Compared with other 10G optical modules, such as Xenpak and XFP optical modules, SFP+ optical module has the smallest volume and the most suitable for high-density port applications. Now it has become a popular 10G optical module in the market.
QSFP optical module
The QSFP optical module conforms to Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards, and uses four 4Gbit/s transmission channels to transmit data.
Factors to be considered when choosing a light module
In the purchase of optical modules, the following four points are the key factors to be considered.
The transmission distance supported by different optical modules is different. Generally speaking, the transmission distance of multimode optical modules is much shorter than that of single-mode optical modules, and the price is also cheaper. For example, the transmission distance of a 10GBASE-SR SFP+ optical module can only reach 400m at the farthest distance, and the transmission distance of a 10GBASE-LR SFP+ optical module can reach 10km. Therefore, it is very important to find out the transmission distance you want to reach. Besides, we should also consider the attenuation and dispersion of optical signal during transmission. It is recommended that you use the optical module which supports transmission distance slightly larger than the actual demand. For short distance connections between equipment in the rack, it is recommended that you use a high - speed cable product that is cheaper than the light module.
The optical module mainly has three kind of data transmission: simplex, half duplex and full duplex data transmission, simplex transmission support only one direction; half duplex transmission allows data transmission in two directions, one direction of data transmission is only allowed but in a moment; full duplex transmission allows two the direction of data transmission at the same time. It is best to choose the optical module that supports full duplex transmission.
Copper and fibre is currently using two kinds of transmission medium, so the most widely, some light module is the electrical design, some light is light module design. In general, light optical module commonly used in 10G, 40G Ethernet transmission application, and the electric light module is used in fast and Gigabit Ethernet Applications, and the transmission distance of optical optical module is generally higher than the electric light module far.
The temperature of the working environment of the optical module should not be too high. If it exceeds the temperature that the optical module can bear, the link failure is likely to occur. Therefore, the light module with good heat resistance should be selected.
The above points are only the factors to be taken into consideration when purchasing the optical module. In addition, the work wavelength and the working rate should be considered.