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Views: 399 Author: Addams Publish Time: 2025-08-05 Origin: Site
1. GBIC (Gigabit Bit Rate Interface Converter)
2. SFP (Small Form-factor Pluggable)
3. SFP+ (Small Form-factor Pluggable)
5. QSFP+ (Quad Small Form-factor Pluggable)
7. QSFP-DD (Quad Small Form-factor Pluggable - Double Density)
With the invention of optical fiber, the use of optical signals for data transmission and the emergence of optical modules—components for transmitting and receiving optical signals. As optical signal speeds continue to increase, optical module packaging has also evolved, generally following the path of high speed, long distance, low power consumption, low cost, miniaturization, and hot-swappability. Currently, the most commonly used form factor in optical communications is the SFP family, found in virtually all network communication scenarios. Over the past 25 years, the SFP family has charted a course in the evolution of speed and density. This article will provide an overview of its history and future evolution.
The GBIC form factor was introduced around 1995 and became the most popular and widely used form factor for optical modules by 2000. Hot-swappable and supporting speeds up to 1G, GBIC typically utilizes SC or LC optical connectors, offering significant advantages in the early days of the optical communications industry. However, its drawbacks were significant: high power consumption, bulk, and low supported data rates, which gradually led to its demise in favor of the more advantageous SFP form factor.
In 2001, the industry launched the SFP form factor protocol standard, SFF-8472, marking the official entry of SFP into the optical communications industry. SFP is an upgraded version of GBIC, offering improved power consumption, a maximum data rate of 4G, and a significantly smaller size, only 50% of the GBIC. It also supports hot swapping. However, its low data rate was a significant drawback, increasingly failing to keep pace with the rapid development and iteration of data rates. Consequently, the enhanced SFP+ form factor emerged.
Because the SFP form factor was so popular, when it failed to meet speed requirements, the cost of replacing it was prohibitive. Consequently, the industry had to improve upon the SFP form factor. The SFP+ form factor, which is identical in size to the SFP form factor, differs in appearance from the SFP form factor, but features an upgraded PHY chip, increasing its supported speed to 11.3G. The SFP+ form factor combines the advantages of small size, low power consumption, long reach, and hot pluggability. However, its speed was a minor improvement over the SFP form factor and fell far short of meeting the ever-increasing speed requirements.
Introduced in 2016, SFP28 is an upgraded version of SFP+, supporting speeds up to 25G, 2.5 times that of SFP+, while maintaining the same small form factor. What enables this exponentially improved transmission performance within the same form factor? The answer lies in the FEC function, which ensures signal quality during transmission in the SFP28 module, enabling it to achieve a high transmission rate of 25G in a compact form factor. However, this wasn't fast enough, and the small size of the SFP package also limited further speed increases. Therefore, the SFP path was temporarily abandoned, and QSFP took over.
QSFP+, a quad-channel small form-factor pluggable optical module, features four independent full-duplex transmit and receive channels. Its original design was to replace single-channel SFPs with high-density optical modules, achieving higher transmission rates at higher densities. While only 30% larger than standard SFP modules, QSFP+ modules offer four times the speed, initially meeting the needs of high-speed applications. However, their cost-performance ratio is not ideal. QSFP28, while maintaining the same size as QSFP+, boasts a 100G speed, making it a popular choice for networking.
QSFP28 is an upgraded version of QSFP+. Its four channels support 25G speeds, which together support 100G speeds. QSFP28 was launched in 2014. Yes, it predates SFP28. As their names suggest, SFP28 and QSFP28 are closely related. SFP28 is a form factor developed by splitting QSFP28 into different applications. Therefore, QSFP28 also requires FEC for transmission. Due to its small size, high speed, high density, low power consumption, and hot-swappability, QSFP28 is currently the predominant form factor in 100G networks.
The 100G bandwidth of QSFP28 can meet most data center needs, but with the advent of AI, 100G bandwidth is no longer sufficient. Data centers urgently need higher-speed modules, but the electrical port speed of the QSFP28 form factor has reached its limit, leaving little room for improvement. Furthermore, the QSFP28 form factor has been so successful that the cost of abandoning it is too high. A solution quickly emerged: since the single-layer gold finger has reached its limit, a double-layer gold finger was developed. Thus, the industry introduced the QSFP-DD form factor in 2016. Using a double-layer electrical interface, it increased transmission bandwidth to 800G, meeting the initial requirements of data centers. It also offers strong compatibility, including backward compatibility with QSFP28 and QSFP+ form factors, making it an ideal choice for data center network deployment.
This article introduces the evolution of the SFP form factor and the members of the SFP form factor family. We hope this article will be helpful. The SFP family's development continues unabated. In the future, smaller, faster, and more energy-efficient forms factors will continue to emerge as market demand demands, ensuring stable network connectivity. YXFiber, a professional optical module supplier, provides high-quality, highly compatible optical modules for your network.
