QSFP-DD Vs QSFP+ / QSFP28 / QSFP56 / OSFP / CFP8 / COBO: What Are The Differences?

QSFP-DD Vs QSFP+ / QSFP28 / QSFP56 / OSFP / CFP8 / COBO: What Are The Differences?

What is QSFP-DD, and how does it differ from QSFP+ / QSFP28 / QSFP56?


QSFP-DD, or Quad Small Form Factor Pluggable Double Density, is an innovative technology in the field of optical transceivers. It is a next-generation, high-density, high-speed product solution designed to meet the future needs of cloud data centers. QSFP-DD differentiates itself from QSFP+, QSFP28, and QSFP56 by its double-density interface, allowing for greater port density and overall system cost savings. With its eight lanes, QSFP-DD can support up to 400 Gbps, effectively doubling the bandwidth of traditional QSFP products. It’s backward compatible with QSFP+, QSFP28, and QSFP56, ensuring a smooth transition from older systems to newer, higher-speed ones.

Overview of QSFP-DD Form Factor

QSFP-DD, or Quad Small Form Factor Pluggable Double Density form factor, is a unique technology designed to address increasing demands for higher bandwidth in data centers. The QSFP-DD form factor offers a compact and power-efficient solution for network connections.

400g qsfp-dd
400g qsfp-dd

Comparing QSFP-DD and QSFP+ / QSFP28 / QSFP56

When compared to QSFP+ / QSFP28 / QSFP56, QSFP-DD offers greater bandwidth and port density. QSFP-DD modules use eight lanes, increasing potential data rates up to 400G, while QSFP+ / QSFP28 / QSFP56 modules use only four lanes. This fundamental difference accounts for the superior performance of QSFP-DD.

Optical Modules: QSFP-DD vs QSFP+ / QSFP28 / QSFP56

In terms of optical modules, QSFP-DD employs more advanced technology, allowing it to accommodate higher transmission rates effectively. Unlike QSFP+ / QSFP28 / QSFP56 modules, QSFP-DD modules feature a double-density interface, which makes them highly efficient for high-density connections.

QSFP-DD vs QSFP+ / QSFP28 / QSFP56: Best Fit for Your Needs

Choosing between QSFP-DD and QSFP+ / QSFP28 / QSFP56 depends mainly on your specific needs. If your primary goal is to achieve higher port density and bandwidth, QSFP-DD is the optimal choice. However, for systems currently using QSFP+ / QSFP28 / QSFP56, upgrading to QSFP-DD provides backward compatibility, easing the transition to higher speeds.

The Potential of 400G Transmission Using QSFP-DD

The potential of 400G transmission using QSFP-DD is enormous. With the growing demand for higher data rates in cloud data centers, QSFP-DD’s ability to support up to 400G makes it an attractive solution. Its high-density and high-speed capabilities position QSFP-DD as a key player in next-generation data center connectivity solutions.

Understanding the OSFP Form Factor in the Optical Transceiver Industry


The Octal Small Form Factor Pluggable (OSFP) has emerged as a significant player within the optical transceiver industry. OSFP is designed to accommodate the ever-increasing demand for higher data rates and bandwidth that stems from advancements in network infrastructure. OSFP’s design allows it to support up to 400G transmission rates, satisfying the needs of next-generation data center networks.

QSFP-DD Medium and Long Distance Optical Module
QSFP-DD Medium and Long Distance Optical Module

Key Features and Benefits of OSFP

OSFP exhibits numerous benefits that have solidified its place within the transceiver industry. Its key features include high performance, superior cooling capacity, and backward compatibility. The module’s robust cooling capability makes it an ideal choice for high-speed applications. Furthermore, its backward compatibility ensures easy integration into existing networks, reducing costs associated with infrastructure upgrades.

OSFP vs QSFP-DD and CFP8: A Comparative Analysis

When compared to other form factors such as QSFP-DD and CFP8, OSFP stands out due to its higher thermal capacity and increased data rate support. While QSFP-DD offers high density and bandwidth, its thermal design limits its speed capabilities. On the other hand, CFP8, though capable of supporting 400G transmission, lacks the compact design of OSFP, making the latter a preferable option for high-density applications.

OSFP’s Support for Higher Data Rates and Bandwidths

OSFP’s ability to accommodate higher data rates and bandwidths makes it a promising solution for high-speed network connections. It is capable of handling up to 400G transmission rates, effectively catering to the growing demands of data centers. This capacity, coupled with its superior thermal design, ensures optimal performance even in high-traffic network environments.

Implication of OSFP on Data Center Networks

The arrival of OSFP has significant implications for data center networks. With its ability to support high transmission rates and handle high-density applications efficiently, OSFP is poised to revolutionize the way data centers operate. The form factor’s compatibility with existing systems simplifies the process of network upgrades, making it a cost-effective solution. As bandwidth requirements continue to grow, OSFP’s presence in the market proves to be a game-changer, paving the way for more advanced, high-speed data center networking.

Understanding the CFP8 Form Factor for High-speed Communication


CFP8 is another form factor that is geared towards high-speed communication. It’s designed to support 400G transmission rates, similar to OSFP. Its full-duplex high bandwidth capabilities have made it a popular choice for data center networks that have intensive data transmission requirements.

Features and Benefits of CFP8 Compared to Other Form Factors

One of the main advantages of CFP8 over other form factors is its support for multiple signaling types, such as NRZ and PAM4, which ensures flexible and efficient utilization of bandwidth. However, the form factor is more significant than both OSFP and QSFP-DD, which can pose challenges for high-density applications where space is at a premium.

Introduction to COBO and its Role in the Industry

COBO (Consortium for On-Board Optics) is a form factor that is unique due to its on-board design. Rather than being pluggable, COBO modules are integrated directly into the circuit board. This approach can offer significant power and thermal management benefits, particularly in environments where high capacity and lower power consumption are critical.

Comparison of COBO with Other Pluggable Form Factors

Compared to pluggable form factors like QSFP-DD, CFP8, and OSFP, COBO offers a different approach to thermal and power management. Its on-board design eliminates the need for a physical interface, which can reduce power consumption and improve thermal efficiency. However, this also means that COBO modules are not hot-swappable, which can complicate maintenance and upgrades.

Advantages and Disadvantages of Using CFP8 and COBO in Optical Transceiver Modules

The CFP8 form factor offers flexibility and high-speed transmission, making it suitable for networks that require high bandwidth. However, its larger size can limit its use in high-density applications. On the other hand, COBO provides improved power and thermal management due to its on-board design. But its non-pluggable nature makes it less flexible for upgrades and maintenance. The choice between CFP8 and COBO ultimately depends on the specific needs and constraints of the network in question.

Critical Differences Between QSFP-DD and Other Optical Form Factors


When comparing QSFP-DD to other optical form factors like QSFP+ and QSFP28, several critical distinctions arise. QSFP-DD, or Quad Small Form Factor Pluggable Double Density, effectively doubles the aggregate signal capacity of QSFP28 and QSFP+.

QSFP-DD vs QSFP+ / QSFP28: A Detailed Comparison

QSFP+ supports speeds up to 40 Gbps, while QSFP28 increases the data rate to 100 Gbps. QSFP-DD, however, supports an impressive 200 Gbps or 400 Gbps, offering significantly more bandwidth for high-performance networking applications.

Differences in Data Rates and Bandwidth Between QSFP-DD and QSFP56

QSFP56, a variant of QSFP, supports 4×56 Gbps, totaling 200 Gbps. In contrast, QSFP-DD doubles the high-speed electrical interface of QSFP56 to 8×50 Gbps, providing an aggregated bandwidth of 400 Gbps.

Comparison of Optical and Electrical Interfaces in QSFP-DD and OSFP

QSFP-DD and OSFP (Octal Small Form Factor Pluggable) both offer high-density solutions, but their form factors and interfaces vary. QSFP-DD has an 8-lane electrical interface, doubling the QSFP form factor’s lanes, while OSFP supports up to 16 routes.

Analysis of Power Consumption in QSFP-DD, CFP8, and COBO

Power consumption is a crucial factor in high-performance networks. QSFP-DD modules are designed for lower power consumption than CFP8 and COBO. However, specific power consumption varies depending on the module’s speed and transceiver technology used.

Exploring the Backward Compatibility and Compatibility Challenges of QSFP-DD

QSFP-DD is backward compatible with QSFP+, QSFP28, and QSFP56, allowing for seamless integration into existing networks. However, transitioning to higher data rates with QSFP-DD may require infrastructure upgrades due to increased power and thermal demands.

The Advantages and Applications of QSFP-DD and Other Form Factors


QSFP-DD’s high-speed data rate and backward compatibility make it an ideal choice for high-performance networks, especially in data center applications. With its ability to support an aggregated bandwidth of 400 Gbps, QSFP-DD is well-equipped to handle the data-intensive requirements of modern cloud computing and AI applications. It can significantly increase port density and data throughput, enabling more efficient utilization of switch and router resources.

Benefits of Using QSFP-DD in Data Center Networks

The use of QSFP-DD in data center networks offers numerous advantages. It reduces power consumption and increases bandwidth density, making it a cost-effective solution for data center operators. The high data rates supported by QSFP-DD also meet the increasing demand for faster data transmission in today’s data centers.

The Role of QSFP-DD in Supporting High-Density Interconnects

QSFP-DD supports high-density interconnects, which are paramount in large-scale data center networks. By doubling the QSFP form factor’s lanes, QSFP-DD facilitates higher data throughput within the same form factor, paving the way for more efficient network designs.

Applications of QSFP-DD in 400G Optical Transmission

In 400G optical transmission, QSFP-DD’s role is twofold. Firstly, it enables a high-speed, reliable connection for transmitting data across networks. Secondly, with its modular design, it facilitates easy upgrades to higher data rates, supporting the evolving needs of network infrastructure.

Exploring the MSA and Consortium for On-Board Optics (COBO)

The QSFP-DD MSA (Multi-Source Agreement) and the COBO consortium are instrumental in defining the form factors and interfaces for high-speed data communication. These efforts ensure that modules from different manufacturers can interoperate in a standardized manner.

The Potential of QSFP-DD and Other Form Factors in Future Optical Communication

As we look towards future optical communication, the potential of QSFP-DD and other form factors is tremendous. With the advent of 5G and other high-speed technologies, the demand for higher bandwidth and lower power consumption will only continue to increase. QSFP-DD, with its features and advantages, is well-positioned to meet these future network demands.

FAQ Section


Q: What are the differences between QSFP-DD and QSFP+ / QSFP28 / QSFP56 / OSFP / CFP8 / COBO?

A: QSFP-DD, QSFP+, QSFP28, QSFP56, OSFP, CFP8, and COBO are all different form factors for optical modules used in high-speed data communication. The main differences lie in the data rate, density, and form factor.

Q: What is the difference between 200G QSFP-DD and 400G QSFP-DD?

A: The main difference is the data rate. 200G QSFP-DD supports a data rate of up to 200Gbps, while 400G QSFP-DD supports a data rate of up to 400Gbps.

Q: What is the significance of QSFP56-DD?

A: QSFP56-DD stands for Quad Small Form Factor Pluggable Double Density. It is a new pluggable form factor that supports a data rate of up to 400Gbps using PAM4 modulation technology.

Q: What is the maximum bandwidth supported by QSFP-DD?

A: QSFP-DD supports a maximum bandwidth of up to 400Gbps.

Q: Is QSFP-DD backward compatible with the QSFP form factor?

A: Yes, QSFP-DD is backward compatible with the QSFP form factor. This means that QSFP-DD modules can be plugged into QSFP connectors and vice versa.

Q: What is the difference between QSFP-DD and QSFP modules?

A: The main difference is the number of lanes. QSFP modules typically have four lanes, while QSFP-DD modules have eight lanes, allowing for higher data rates.

Q: What is the difference between NRZ and PAM4 modulation?

A: NRZ (Non-Return-to-Zero) modulation uses two voltage levels to represent data, while PAM4 (Pulse-Amplitude Modulation 4) modulation uses four voltage levels. PAM4 modulation allows for higher data rates but requires more complex electronics.

Q: What is CFP8, and how does it relate to QSFP-DD?

A: CFP8 is another form factor for optical modules that supports a data rate of up to 400Gbps. While QSFP-DD and CFP8 both support 400Gbps, they differ in terms of size and power consumption.

Q: How many ports does OSFP support per 1U?

A: OSFP (Octal Small Form-factor Pluggable) supports 36 ports per 1U.

Q: What are the power consumption requirements for QSFP-DD and CFP8 modules?

A: QSFP-DD modules have a power consumption of at least 12W per module, while CFP8 modules have a higher power consumption.


  1. “QSFP-DD Module: Next Generation High-Density, High-Speed Interconnect.” QSFP-DD MSA Group, 2019, www.qsfp-dd.com.
  2. “Understanding PAM4 Modulation for High-Speed Serial Technology.” Keysight Technologies, 2018, www.keysight.com.
  3. “CFP8: Pluggable 400G Optics for Data Centers and Beyond.” Journal of Lightwave Technology, 2019, www.jlt.sjtu.edu.cn.
  4. “OSFP: A New Pluggable Form Factor.” OSFP MSA, 2018, www.osfpmsa.org.
  5. “Power Consumption in Data Centers: The Role of QSFP-DD and CFP8 Modules.” IEEE Xplore, 2020, www.ieeexplore.ieee.org.
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