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QSFP28 Transceiver Application Guide

Apr. 12, 2022

The 100G QSFP28 optical module is suitable for 100G Ethernet, EDR InfiniBand, and 32G Fibre Channel, and usually has exactly the same volume and panel density as 40G QSFP+. 40G QSFP+ uses 4* 10Gbps channels, and the 100G QSFP28 module is similar to it, using 4 high-speed differential signal channels with data rate。


 In addition, the QSFP28 has an upgraded electrical interface capable of supporting signals up to 28 Gbps. QSFP28 SR4, QSFP28 LR4, QSFP28 PSM4, QSFP28 CWDM4, QSFP28 ER4, compare with other package types of 100G optical modules (CFP/CFP2/CFP4), 100G QSFP28 offers higher density, lower power consumption, and significant price advantages.

100G QSFP28 ER4 Optical Module

 100G QSFP28 ER4 Optical Module 


Standard of 100G QSFP28 optical module

The standards for 100G QSFP28 optical modules are mainly defined by two major organizations, IEEE and MSA, among which IEEE has defined the standards for QSFP28 SR4, QSFP28 LR4, and QSFP28 ER4.


"QSFP" indicates the package of an optical module;

"28" indicates the maximum transmission rate of 28Gbps per channel;

"SR" indicates a short distance (up to 100m),

"LR" indicates long-distance (up to 10km),

"ER" means extended distance (up to 40km);

"4" means the module has 4 channels.


For example, QSFP28 LR4 means that the 100G long-range module can transmit 100G signals using four wavelengths up to 10km.

100GBASE-QSFP28-PSM4-500m/2km Optical Transceiver Module

 100GBASE-QSFP28-PSM4-500m/2km Optical Transceiver Module     


QSFP28 Transceiver Application Guide

Nowadays, 100G optical QSFP28 transceivers account for a significant portion of networking construction. Due to their compact size, low power consumption, and high performance, 100G QSFP28 optics are mainly used for the following situations.


However, due to the different properties and functions of various types, their exact application is based on the actual needs in the real environment. QSFP28 100G SR4 is mainly applicable in a 100G data center with a demand for a short transmission distance between 5m and 100m.


QSFP28 100G PSM4 and QSFP28 100G CWDM4 can are specially designed for network applications with a transmission distance of 500m and 2km. While QSFP28 100G CWDM4 is relatively more costly, it requires only two single-mode fibers for transceiving and transmitting in both directions, which is much less than the eight single-mode fibers of PSM4, making it a high-quality choice for Enterprise networking and 100G Ethernet.

100GBASE-QSFP28-LR4-10km Optical Transceiver Module

 100GBASE-QSFP28-LR4-10km Optical Transceiver Module

QSFP28 100G LR4, generally used together with LC single-mode fiber cables, can reach a maximum transmission distance of 10km. It converts 4X25Gbps electrical signals into 4 LAN WDM optical signals and then multiplexes them into a single channel to realize 100G optical transmission.


QSFP28 100G ER4 supports the 100G data connection by using WDM multiplexing wavelength division technology. It can reach a maximum transmission distance of up to 40KM, making it a perfect choice for optical communication and applications compliant with the Ethernet 100GBASE-ER4 Lite standard.


How to Select the Best QSFP28 Optics?

Now that we know we have to choose the best 100G optics based on our actual demand, how? How can we choose the right one? Here is a selection guide for you. For transmission distances between 5m and 100m, you can choose the QSFP28 SR4 optical transceiver module. It can transmit 70m using OM3 fibers or 100m using OM4 fibers.

Find out How to Solve It


For transmission distances between 100m to 2km, QSFP 100G PSM4 or QSFP28 CWDM4 modules would be better. The cost of QSFP28 CWDM4 is much higher than the QSFP28 PSM4. However, the QSFP28 CWDM4 requires only two single-mode fibers in two-way transmission which is much less than the eight single-mode fibers of QSFP28 PSM4, the total cost of the QSFP 100G PSM4 raises very quickly. In practical applications, it is necessary to decide whether to use QSFP28 PSM4 or QSFP28 CWDM4 depending on the interconnection distance.


For transmission distances between 10km to 40km, you can consider QSFP 100G LR4 which has a maximum transmission distance of up to 10 km, or QSFP28 ER4 transceivers which can reach up to a maximum transmission distance of even further—40km.

Guanglian is dedicated to the research, development, manufacture, and market of high-speed and high-performance optical transceiver modules and optical components for various ICT applications, such as Data centers, Telecom Networks, and Security Monitoring.  Our 100G QSFP28 can solve all compatibility problems for you, contact us!

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