SFP Types

By | April 14, 2022
  • The small form-factor pluggable (SFP) is a compact, hot-pluggable network interface module used for both telecommunication and data communications applications.
  • The form factor and electrical interface are specified by a multi-source agreement (MSA) under the auspices of the Small Form Factor Committee.
  • It is a popular industry format jointly developed and supported by many network component vendors. The advantage of using SFPs instead of fixed interfaces (e.g. modular connectors in Ethernet switches) is that the interface port can be equipped with any suitable type of transceiver as needed.

An SFP interface on networking hardware is a modular (plug-and-play) slot for a media-specific transceiver in order to connect a fiber optic cable or sometimes a copper cable.
There are two types of sfp , Single-mode & Multimode SFP.

Single Mode & Multime SFP.

As we know, a common SFP transceiver is generally with two ports, one is TX port which is used to transmit the signal, and the other one is the RX port which is used to receive signals. Unlike common SFP transceivers, the BiDi SFP transceiver is only one port that uses an integral WDM coupler to transmit and receive signals over a single strand fiber. 

1-Uni-Directional SFP

In All Unidirectional SFP, We must be used in pairs. For common SFPs, we should connect the two SFPs which have the same wavelength together. For example, we use an 850nm SFP at one end, then we must use an 850nm SFP on the other end .

2-BIDI (Bidrectional )SFP in Single Mode.

  • As you can see from the below diagram, the paired BiDi transceivers are being used to connect two devices.
  • BIDI SFP are called as WDM SFP, it means a single port will transmit and receive the optical power at the same at a different wavelength,
  • Device A is used to get upstream data, and Device B is used to get downstream data. Tx means to transmit and Rx means to receive.
  • The duplexer in one transceiver (Device A) should have a transmitting wavelength of 1310 nm and a receiving wavelength of 1550 nm.
  • The diplexer in the other transceiver (Device B) should have a transmitting wavelength of 1550 nm and a receiving wavelength of 1310 nm.


SFP+ is the upgraded model of XFp. XFP is old and both function at 10G . These SFP’s are also available in BIDI and Unidirectional as well. you can choose whatever you want.

4-QSFP+/QSFP28 Optical Module.

The enhanced quad small form-factor pluggable (QSFP+) optical module uses the LC/MPO optical connector and supports data rates up to 40 Gbit/s. It features low power consumption, small size, and high rates, and is mainly used in data center networks, campus networks, and metro networks. Currently, the main port types are SR4, LR4, ER4, and IR4.

QSFP28 (28G QSFP) is a 100G pluggable optical module that uses the LC/MPO connector. It is a next-generation optical module that features a small size, high port density, and low power consumption. Mainly used in 40G and 100G Ethernet applications, it uses four transmission channels of different rates to transmit data. Currently, the main port types are 100GBASE-SR4/LR4/SW4.

5-CFP Transceiver Module

The CFP MSA (Multi-Source Agreement) defines hot-pluggable optical transceiver form factors to enable 40/100G and the looming 400G applications. It includes pluggable CFP, CFP2, and CFP4 transceivers to support the high bandwidth requirements of data communication networks. Compared with the CFP form factor, the latter CFP2 and CFP4 modules are of smaller size and will double and quadruple front panel port density, respectively. CFP 2 and CFP4 modules support existing and future duplex single-mode fiber (SMF) and multimode fiber (MMF) interfaces. The figure below shows drawings of the CFP, CFP2, and CFP4 form factors.


The QSFP-DD modules can support 400Gbps while QSFP+/QSFP28/QSFP56 can only reach 40Gbps/100Gbps/200Gbps respectively. Therefore, QSFP-DD connectors are used in 400G optical modules, DACs and AOCs, and applied for the 400G data center interconnections. And QSFP+/QSFP28/QSFP56 modules and DAC/AOC are used for 40G/100G/200G networks. interconnection.