QSFP 40G SR BD vs 40GBASE SR4, What’s The Difference

QSFPTEK get 40G transceiver promotion
QSFPTEK get 40G transceiver promotion

QSFP is a hot-pluggable module with fiber optics. The full form of QSFP is Quad Small Form-factor Pluggable. This is the expanded version of the SFP or Small Form-factor Pluggable concept. QSFP uses “Quad” fiber pairs that allow more powerful data transmission.

This transceiver is used for data communication applications. QSFP products support quad small form-factor pluggable with different baud rates, so there is no change in product solution. QSFP is widely used by data centers as it can provide higher bandwidth. There are different types of QSFP  transceivers. SFP 40GBASE-SR BiDi and 40GBASE-SR4 are the most popular among all. You should choose a transceiver according to your network setup. So, today in this article let’s compare QSFP 40G-SR BD and 40GBASE-SR4.

What Is QSFP 40G-SR BD?

QSFP-40G-SR-BD is one of the most well-known QSFP transceivers. QSFP-40G-SR-BD transceiver is a sort of QSFP 40-Gbps bidirectional transceiver. This is a brief distance transceiver that can be utilized a good ways off of 100m and 150m. QSFP-40G-SR-BD transceiver is known as a duplex LC interface. This module is utilized in information correspondence.

There are two 20GB each subsequent sign directs in the QSFP-40G-SR-BD transceiver. Each sign channel is changed over to 2 bidirectional channels of 20Gbps signal channels. These signs are sent over two frequencies.

The QSFP 40 Gbps BiDi transceiver upholds interface lengths of 100 meters and 150 meters, individually, on laser-upgraded OM3 and OM4 multimode fiber.

This sign works on two distinct frequencies, one for sending and one for receiving.



QSFP 40GBASE SR4 is one of the popular short-distance transceivers used widely. To achieve 40G The QSFP 40GBASE- R4 transceiver uses a parallel multimode fiber or MMF link. The lengths of the links are 100m and 150m. This transceiver is commonly used in data centers to interconnect data lanes. These links support OM3 and OM4 fiber. The QSFP 40GBASE SR4 uses Multi-fiber Push-on connectors for optical links support.

The maximum transmission distance of this optical module is 150 meters. It is often used for multimode fiber transmission. It can support signal transduction of about 100 meters of OM3 optical fiber cable and 150 meters of OM4 optical fiber cable. A QSFP 40GBASE SR4 optical module is suitable for short-distance transmission.

The transmission speed of this optical module is 40Gbps. There are four independent transmit and receive optical signal channels, each of which can support 10 Gbps data transmission. Because 40G Ethernet is an important data center technology, 40G optical modules are widely used in fiber-optic networks.

This optical module can arrange multiple lasers in parallel in the direction perpendicular to the substrate, so multiple lasers can be arranged in parallel in the field of parallel optical transmission and parallel optical interconnection. It is very suitable for application and has high-cost performance, so it is used in widely used broadband Ethernet and high-speed data communication networks.

This optical module is mainly used in switches, routers, and host adapter buses. This is especially suitable for high-traffic processing systems. The most common applications for these systems include data centers, network connectivity, and high-performance computing.

40G QSFP transceiver
40G QSFP transceiver


QSFP40G BD vs QSFP 40G SR4, What’s the Difference?

Many people get confused when choosing a 40G transceiver. This is because transceiver standards are typically a combination of letters and numbers. Some standards and models are very similar to each other. Therefore, in this article, I am providing the difference between QSFP 40g sr bd vs QSFP 40gbase sr4.

Working Principle:

In QSFP 40G-SR BD there are two 20G signal channels. Each signal channel is converted to 2 bidirectional channels of 20Gbps signal channels. These signals are transmitted over two wavelengths.

QSFP 40GBASE SR4 has an independent receiver and transmitter.


QSFP 40G-SR BD is a bidirectional module that provides high bandwidth 40G fiber optic link connectivity. It is designed to connect duplex LC interface mode connections by OM3 or OM4 MMF fiber interfaces at 832nm-918nm wavelength.

QSFP 40GBASE SR4 optical module provides high bandwidth 40G fiber optic link connectivity, primarily via a 12-core fiber optic cable with MPO/MTP fiber connectors. You can also connect 4x10G duplex mode connections by connecting 4 fiber branch cable 10G BASE SR optical interfaces.


As a comparison above, you can choose the right QSFP + module for your network. If the link distance is less than 150 meters, the QSFP 40GBASE SR4 transceiver is the best choice. If you need to transmit on duplex multimode fiber, the QSFP 40G SR BD is best because bidirectional connections can be reached via OM3 or OM4 multimode fiber. QSFPTEK offers 40G transceivers, enabling cost-effective, high-density, and low-power 40G Ethernet connectivity solutions for the data centers.


Q. How Many Lengths Does QSFP 40GBASE-SR4 Cover?

A. The QSFP 40GBASE-SR4 Module upholds connect lengths of 100 meters and 150 meters, separately, on laser-streamlined OM3 and OM4 multimode fiber.

It basically empowers high transfer speed 40G optical connections more than 12-fiber equal fiber (MPO) ended with MPO/MTP multifiber female connectors.

Q. How Does QSFP 40 Gbps BiDi Transceiver Work?

A. QSFP 40-Gbps BiDi transceiver consists of two 20 Gbps transmit and receive channels in the 832-918 nanometer wavelength range to support aggregated 40 Gbps links over two-strand multimode fiber connections.



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