What does Small Form-Factor Pluggable Transceiver (SFP) mean?

A small form-factor pluggable (SFP) transceiver is a compact, hot-swappable, input/output transceiver used in data communication and telecommunications networks. SFP interfaces between communication devices like switches, routers and fiber optic cables, and performs conversions between optical and electrical signals. SFP transceivers support communications standards including synchronous optical networking (SONET)/synchronous digital hierarchy (SDH), gigabit ethernet and fiber channel. They also allow the transport of fast Ethernet and gigabit Ethernet LAN packets over time-division-multiplexing-based WANs, as well as the transmission of E1/T1 streams over packet-switched networks.

Picture from: https://commons.wikimedia.org/wiki/File:SFP_board_2.jpg

SFP connects the mainboard and optical fiber or UTP cable of network equipment such as switches and routers. SFP is an industrial specification supported by some fiber optic device providers.

The SFP transceiver supports SONET, Gigabit Ethernet, Fibre Channel (Fibre Channel) and some other communication standards. This standard extends to SFP+ and can support 10.0 Gbit/s transmission rate, including 8 gigabit Fibre Channel and 10GbE. Introduced the SFP+ module version of the optical fiber and copper core version. Compared with the Xenpak, X2 or XFP version of the module, the SFP+ module leaves part of the circuit to be implemented on the motherboard, not the module.

SFP Types

SFP transceivers have many different types of transmission and reception, and users can select the appropriate transceiver for each link to provide “optical performance” based on the available fiber types (such as multimode fiber or single mode fiber). SFP optical modules can be generally divided into the following categories:

  • SX: 850 nm wavelength, transmission distance 550 meters, using multimode fiber MMF
  • LX: 1310 nm wavelength, 10 km transmission distance, using single-mode fiber SMF
  • EX: 1310 nm wavelength, 40 km transmission distance, using single-mode fiber SMF
  • ZX: 1550 nm wavelength, 80 km transmission distance, using single-mode fiber SMF
  • TX: the electrical port module, using RJ-45 copper cable interface
  • CWDM: sparse wavelength division multiplexing SFP optical module
  • DWDM: Dense wavelength division multiplexing SFP optical module

Commercial SFP transceivers can provide speeds up to 4.25 G bps. Several packages of 10 Gbps transceivers are XFP, and the new variant “SFP+” which is basically the same as the SFP package.

Learn more with SFP Types

SFP Standardization

SFP transceivers are regulated by a multilateral agreement (MSA) between competing vendors. SFP is designed according to the GBIC interface, allowing a greater port density (number of transceivers per inch on the edge of the motherboard) than GBIC, so SFP is also called “mini-GBIC”. The related small package transceiver (SFF transceiver) is smaller in size than SFP, but SFF is inserted vertically as a pin (as a pin through-hole device) on the motherboard (not hot swappable), and It is not inserted parallel to the side card slot like SFP (supports hot swap).

Digital diagnostics monitoring

Modern optical SFP transceivers support standard digital diagnostics monitoring (DDM) functions. This feature is also known as digital optical monitoring (DOM). This capability allows monitoring of the SFP operating parameters in real time. Paramters include optical output power, optical input power, temperature, laser bias current, and transceiver supply voltage. In network equipment, this information is typically made available via Simple Network Management Protocol (SNMP). A DDM interface allows end users to display diagnostics data and alarms for optical fiber transceivers and can be used to diagnose why a transceiver is not working.


  1. Small form-factor pluggable transceiver – Wikipedia
  2. Small Form-Factor Pluggable Transceiver (SFP) – techopedia