With the rapid development of data centers, low-rate optical communication products cannot meet the everyday data transmission demand. High-speed 100G QSFP28 transceivers are greatly used by communication service providers today. The article next will introduce you to the four most popular types of QSFP28 modules and show you a QSFP28 price investigation, helping your 100G Ethernet connectivity deployment.

What is QSFP28?

QSFP stands for Quad Small Form-factor Pluggable, and ‘28’ indicates that each lane has a maximum transmission rate of 28Gbps, resulting in a total of approximately 100G data rate with all 4 lanes. QSFP28 evolved from CFP, CFP2, and CFP4. CFP is the first generation of 100G optical transceiver, which features a large size. Subsequently, CFP4 launched, which is a quarter of CFP. And now comes the QSFP28, the latest generation of 100G transceiver modules solution, the form factor of which is smaller than CFP4. QSFP28 has become the most mainstream transceiver solution in 100GbE Ethernet with the significant advantage of high-density.

Four of the Most Popular Types of QSFP28

These are four of the most popular types of QSFP28, QSFP-100G-SR4, QSFP-100G-LR4, QSFP-100G-CWDM4, and QSFP-100G-PSM4. Next, this blog will give an extensive introduction about these four QSFP28 100G transceivers.

QSFP-100G-SR4 Introduction

100GBASE-SR4 QSFP28 transceiver supports a transmission distance of 100m over OM4 and 70m over OM3 with an MTP/MPO-12 connector. The 100GBASE SR4 transceiver carries 100G Ethernet signals with 12 fibers MTP-12 multimode trunk cable. 100GBASE SR4 provides 4 independent full-duplex transmit and receive lanes, each of which supports a 25 Gbit/s data rate, resulting in a total data rate of 100Gbps. In the transmitter of QSFP28 SR4, electric signals are converted into optical signals through a 4 laser array. Subsequently, optical signals are transmitted in parallel over the multi-mode fiber to the receiver. The parallel optical signals revert to parallel electric signals through the 4 PIN array on the receiver side. The working principle of 100GBASE QSFP28 SR4 is shown in figure 1.

QSFP-100G-LR4 Introduction

100GBASE-LR4 QSFP28 transceiver supports transmission distance up to 10km over single-mode fiber with duplex LC connectors. The 100GBASE LR4 transceiver enables high-bandwidth 100G optical links over duplex single-mode fiber. Different from 100GBASE SR4, QSFP28 LR4 converts 4 lanes of 25Gbps electric signals into 4 lanes LAN WDM optical signals, then multiplexing them as a single lane with MUX to realize 100Gbps data rate transmission. On the receiver side, instead, the 100G optical signals are demultiplexed as four lanes LAN WDM optical signals with DEMUX and output as four lanes electric signals. The working principle of 100GBASE QSFP28 LR4 is shown in figure 2.

QSFP-100G-CWDM4 Introduction

100GBASE-CWDM4 QSFP28 transceiver supports a transmission distance up to 2km over duplex single-mode fiber (SMF) with duplex LC connectors. Based on CWDM technology, QSFP28 CWDM multiplexes four wavelengths of 1270nm、1290nm、1310nm, and 1330nm to a single single-mode fiber to transmit 100Gps data. On the receiver side, instead, the module optically demultiplexes the 100Gbps dates as 4 lanes signals and converts them to 4 lanes of electrical signals. The working principle of 100GBASE QSFP28 CWDM4 is shown in figure 3.

QSFP-100G-PSM4 Introduction

The QSFP-100G-PSM4-S Module supports link lengths of up to 500 meters over SMF with MPO connectors. The 100 Gigabit Ethernet signal is carried over 12-fiber parallel fiber terminated with MPO connectors. The 100GBASE PSM4 transceiver enables four independent full-duplex lanes, each of which transmits data rate up to 25Gbps at the wavelength of 1310nm. It is generally applied in 40G Ethernet and 100G Ethernet. The working principle of 100GBASE QSFP28 PSM4 is shown in figure 4.

Price Investigation of the 4 Types of QSFP28 100G in 2021

To intuitively understand the cost and market information of the 4 types of QSFP28 100G transceivers, I made a price investigation based on three third-party suppliers in Nov. 2021, as shown in table 1.

Conclusion 

The mentioned above introduced the specification, matching fiber cable, working principle, and the current market price of the four most popular types of QSFP28 100G modules, including QSFP-100G-SR4, QSFP-100G-LR4, QSFP-100G-CWDM4, and QSFP-100G-PSM4. Among the suppliers investigated, QSFPTEK provides the lowest price of all these 4 types of QSFP28. If you’re interested, you are welcome to visit qsfptek.com.

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