Over recent two decades, the SFP connector module as the mainstream optical transceiver type has undergone migration to diverse forms - SFP connector, SFP+ connector, SFP28 connector, QSFP connector, QSFP+ connector, QSFP28 connector, QSFP56 connector, SFP-DD connector, QSFP-DD connector, and OSFP connector. What are SFP connectors? what are SFP connector types? And what are the types of SFP interfaces? Read this post for reference.

What is SFP Connector?

SFP connector or SFP plug is another name of SFP as SFP (small form-factor pluggable) is a compact and hot-pluggable interface connector. The SFP connector module functions as the intercommunication media between the network devices and cables to achieve photoelectric and electro-to-optical conversion. SFP interface is commonly used in SFP port network equipment such as Ethernet switches, firewalls, routers, network interface cards (NICs) for both data communication and telecommunication applications.

Figure 1: direct connection for 1000BASE-SX SFP connector modules with Ethernet switches and fiber optic patch cables. The SX connector SFP  with a duplex SFP LC connector is for connecting multimode fiber for short-range application.

 

Why SFP Connector is the Most Commonly Used Transceiver Module?

The transceiver module is developing towards miniaturization, hot-swap, low cost, low power consumption, high speed, and long-distance. At the end of the 20th century, the pressure of high-density data racks applications begged for deploying more ports in a network switch unit. SFP connector modules with smaller sizes were introduced in 2001. Since which, SFP has replaced the bigger gigabit interface converter (GBIC) and become the most commonly used module type in data communication areas. 

 

Over the recent two decades, the ever-increasing massive data traffic and cutting-edge technologies such as cloud computing, 5G, WiFi-6 request for more bandwidth and higher data rates, which have driven the SFP plug module to evolve into diverse siblings.  

Figure 2: The evolution history of the SFP connector optical transceiver.

 

What are the Form Factors of SFP Connector?

In the following part, we will introduce SFP connector types one by one over time. As the QSFP connector is another version of the SFP module, here we regard it as an individual part.

 

SFP Connector Types

An SFP connector module has 100Mbit/s SFP, 1 Gbit/s SFP, and 4 Gbit/s SFP available divided by data rates. The typical is 1 Gbit/s SFP for Ethernet standard SFP modules and up to 4 Gbit/s for fiber channel SFP applications.

 

The first iteration is the SFP+ connector (SFP Plus) module, brought up in 2006 to raise data rate up to 10Gbit/s. Then comes the SFP28 connector for speed up to 25 Gbit/s. cSFP connector (compact small form-factor pluggable) came out to provide higher port density and save fibers. cSFP connector module can be regarded as two BiDi SFPs in one unit. It has two BiDirectional ports with each port supporting a bidirectional connection over a single cable. Therefore the cSFP connector supports double capacity with halved fiber. SFP-DD connector (small form-factor pluggable double density) enables 100Gbit/s over two transmission lanes. 

 

QSFP Connector Types

The next bro born after the SFP module is the QSFP connector module (Quad Small Form-factor Pluggable), which can be regarded as another module variant for it first introduced four channels to the SFP module family. The original QSFP supports  4Gbit/s by four channels carrying 1Gbit/s simultaneously. Here are other derivative forms of the QSFP connectors. 

 

QSFP+ connector speeds up to 40Gbit/s by each of the four-channel carrying 10Gbit/s data rates. Going further, the QSFP28 connector (quad small form-factor pluggable 28) brought up to 25 Gbit/s data rates to four channels to achieve a total of 100Gbit/s speed. QSFP56 connector (Quad Small Form-factor Pluggable double density) was published to double the data rate to 200Gbit/s. 

 

QSFP-DD connector (Quad Small Form-factor Pluggable Double Density) MSA was preliminarily published on September 19, 2016. It allows a total of 400 Gbit/s via eight lanes. On May 24, 2021, the latest QSFP-DD800 was released by QSFP-DD MSA to run at up to 800G performance over 8 lanes of 100 Gb/s.

 

OSFP Connector

According to osfpms, the OSFP connector (Octal Small Format Pluggable) was initially designed in 2016 to provide 8 channels x 50Gbit/s to achieve 400 Gbps. In 2021, the latest OSFP 4.0 was released for speeding up to 800 Gbit/s via breakout 2x 400G FR4 for future needs.

 

What is the Optical Interface of SFP Connector?

An SFP connector has an interface at both ends. One end with Goldfinger is inserted into the network device SFP slot. And the other end protected by a dust cap is known as an optical interface, which is used to connect fiber optic cables or Ethernet copper cables. The optical SFP socket built in the SFP transceiver module varies from the SFP type form factor and cables required to use together with the SFP optics.

Figure 3: the optical interface of the 1000BASE-SX SFP connector module is located at the side of the dust cap. Once unplug the cap, will you see the optical interface.

 

According to transmission media, there are SFP copper connectors and SFP fiber connectors. Copper SFP uses an RJ45 SFP connector interface, whereas fiber SFP uses SFP lc connector, SFP sc connector, and SFP MTP/MPO connector interface as typical ones. According to the SFP forms, different SFP form factors often utilize corresponding SFP connectors.

 

The table below shows the SFP connector interface types for different SFP types.

 

What Type of Connector is Used with an SFP Port?

SFP ports are frequently found in Ethernet network switches. These switches with 1G SFP ports as the major functional switch ports are called gigabit SFP switches.

 

SFP port on SFP switch supports both SFP copper connector and SFP fiber connector while RJ45 port can only take copper SFP module RJ45 connector. SFP connector types that 1G SFP port can take are RJ45 SFP connector, SFP lc connector, SFP sc connector.

 

Summary

Today we talked about SFP plug definition and SFP connector types. According to form factor, there are SFP, cSFP, SFP+, SFP28, QSFP, QSFP+, SFP-DD, QSFP28, and the higher speed 200G QSFP58, 400G QSFP-DD, and 400G/800G OSFP. Divided by the optical interface, there are RJ45 connectors for the SFP copper module, and SFP connector LC, SFP SC connector, and MTP/MPO SFP connector for the SFP fiber connector module. No matter which SFP connector type you’re searching for, please feel free to contact us via [email protected] to get a quote.