CFP vs. QSFP28 100G, What's the Difference?

Author Yana

Date 11/15/2024

This article explores the differences between CFP/CFP2/CFP4 and QSFP28 100G optical modules and provides insights into choosing the right 100G modules for your network.

100G optical transceivers are an essential part of 100G network construction, have developed CFP (including CFP/CFP2/CFP4) and QSFP28 form factors are the current 100G network mainstream products. This article will provide an introduction to the 100G CFP optical modules and QSFP28 100G optical modules.

CFP 100G Overview

What is the CFP Form Factor?

CFP (C form-factor pluggable) is a common form factor in modules. The C in CFP represents 100 in Roman numerals. The CFP form factor was first released by the CFP-MSA committee to support early 100G optical modules. To achieve a 100G rate, one solution is to use 10 channels to transmit 10Gbit/s each. The 100G CFP optical module uses this principle to upgrade from 10G to 100G. The following picture shows the size comparison between CFP and SFP+, and it is obvious that the CFP is particularly huge compared to SFP+.

CFP VS SFP+

100G CFP Series Optical Transceiver Types

Because the size of CFP is too large to meet the high-density needs of data centers, the CFP-MSA committee defined two new CFP series optical modules, namely CFP2 optical modules and CFP4 optical modules, so 100G CFP series optical modules are available in three different form factors. This will be introduced in detail below.

CFP VS CFP2 VS CFP4

100G CFP Modules

The 100G CFP optical module is designed based on SFP. It is the largest and supports 100 Gbps data transmission. It supports transmission on single-mode and multi-mode optical fibers with multiple speeds, protocols, and link length requirements. CFP modules include the 100GBASE-SR10 CFP for 150m over multimode fiber, the 100GBASE-LR10 CFP and 100GBASE-LR4 CFP for 10KM over single-mode fiber, and the 100GBASE-ER10 CFP and 100GBASE-ER4 CFP for 40KM over single-mode fiber.

100G CFP2 Modules

Because the size of CFP is too large, as the integration level of optical modules becomes higher and higher, the subsequent development direction is to reduce the size and power consumption, and CFP can evolve to CFP2. The CFP2 module is only half the size of the CFP module and can support ten 10G channels, four 25G channels, eight 25G channels, and eight 50G channels. 100G CFP2 is often used as a 100G Ethernet interconnect link. Its transmission efficiency is higher than that of CFP optical modules, and its smaller size makes it suitable for higher-density wiring.

100G CFP4 Modules

100G CFP4 optical module has the same rate as the CFP/CFP2 optical module, the transmission efficiency has been greatly improved, but the power consumption is reduced, and the cost is also lower than the CFP2, so the CFP4 optical module has irreplaceable advantages, the following to talk about the advantages of CFP4 optical module.

CFP4 modules have several significant advantages over earlier 100G CFP optical modules. Firstly, the CFP4 optical module achieves a 100G transmission rate through four 25G channels, compared with the CFP optical module, which achieves the same rate through ten 10G channels, the transmission efficiency has been significantly improved, and the stability is also stronger. Secondly, the CFP4 optical transceiver is only a quarter of the size of the CFP, which is the smallest among the three CFP series optical modules. In addition, the CFP4 optical module is also more integrated, which is four times that of the CFP, while the CFP2 is twice as integrated as the CFP. Finally, the CFP4 transceiver has a significant increase in transmission efficiency while reducing power consumption, giving the system a cost advantage over the CFP2 optical module.

Applications of CFP Transceiver Modules

100G CFP optical transceivers have a wide range of application scenarios, mainly covering the following aspects:

Transmission applications in networks

100G CFP optical modules can be used for fiber-optic communications and data center connectivity, growth, and expansion. They are suitable for optical networks, data exchange, distributed computing environments, and other advanced applications.

Applications in Data Centres

The 100G CFP optical transceiver can also be used in data centers to connect high-bandwidth servers, network switches, and storage systems to support quasi-real-time applications in cloud computing environments. It also enables high-density port expansion and high-speed interconnections (Infiniband, Ethernet). In the field of networking and data centers, 100G CFP optical transceivers, as high-quality, high-reliability products, can ensure transmission performance and reduce optical transmission losses. The development prospects are also very broad.

In addition, DWDM technology with coherent CFP modules is widely used in 100G MANs to meet their high capacity and long-distance requirements. This 100G coherent CFP module ensures transmission performance while reducing optical transmission loss, making it an effective solution for 100G MANs.

QSFP28 100G Overview

What is QSFP28?

The 100G QSFP28 optical module was first launched in 2013. After years of development, it has been derived into multiple categories. Currently, the common ones are the QSFP28 SR4 transceiver module, QSFP28 LR4 transceiver module, QSFP28 PSM4 transceiver module, and QSFP28 ER4 optical modules. They have different standards and transmission distances and are suitable for different transmission applications.

The 100G QSFP28 optical module is the same size as the QSFP+ optical module. Its working principle is similar to that of the 40G QSFP+ optical module. It also has four parallel data channels, but the transmission rate of each channel is increased from 10Gbit/s to 25Gbit/s, thus achieving a transmission rate of 100Gbps.

100G QSFP28 Transceiver Module Applications

Data Center

As data centers continue to expand, high-bandwidth, high-speed communications are rapidly gaining popularity. 100G QSFP28 optical module can accelerate the connection speed of Ethernet networks and improve data transmission efficiency. In addition, it also supports the connection of Ethernet switches and routers, enabling higher-end data centre applications.

Telecom Networks

100G QSFP28 optical module is also one of the essential communication devices in telecommunication networks. When telecom data transmission requires higher rates and high traffic transmission, 100G QSFP28 optical modules can better achieve data transmission efficiency. According to the analysis of industry data, the application of 100G QSFP28 optical modules in telecom networks is growing gradually, showing a broad market demand.

CFP vs QSFP28 100G, What's the Difference?

The following table shows the differences between these two 100G transceivers:

Feature	100G CFP	100G QSFP28
Power Consumption	100G CFP modules consume more power	QSFP28 transceiver’s power consumption is much lower than CFP.
Port Density	Larger size reduces port density; CFP4 is 66% larger than QSFP28 despite size reduction	QSFP28 transceiver features a more compact design than the CFP4, enabling it to achieve higher port density on network switches.
Cost	Higher, due to greater power consumption and lower port density, leading to increased operational expenses.	Lower, with cost savings from better power efficiency and higher port density, and lower initial purchase price
Application	Mainly applied in metro networks and long-distance WDM transmission	Typically used in data centers for 100G connectivity in core switches, core routers

QSFP28 or CFP 100G Optical Modules, How to Choose?

When choosing 100G optical modules, the choice between CFP and QSFP28 depends on two main factors: the port type of the hardware device and the application scenario. CFP modules are larger, while QSFP28 is more compact and suitable for different needs.100G QSFP28 has become the mainstream choice and is widely used for short distances between switches (0-10km) and sometimes can also be used for longer distances (up to 40/80 km), especially when using QSFP28 ER4/ZR4 modules. In contrast, 100G CFPs, while also capable of being used for short distances, are more commonly used in metropolitan area network (MAN) and long-distance wavelength-division multiplexing (WDM) transmission scenarios and are suitable for applications that require higher bandwidth and longer transmission distances.

Therefore, which module to choose depends on your network equipment and specific application requirements. If your network mainly involves short-distance high-speed connectivity, QSFP28 may be a better choice, while CFP may be more suitable if you need to cover longer distances, especially in MAN or long-distance WDM transmission.

Conclusion

Although CFP modules appeared earlier than QSFP28, QSFP28 modules show more advantages in terms of power consumption, cost and port density. However, CFP series optical transceivers still have irreplaceable advantages in large bandwidth and long-distance WDM transmission. With the development of 100G technology, QSFP28 optical transceivers have become the mainstream solution in 100G applications due to their efficient power consumption management and higher port density.