Small Form-factor Pluggable

Small Form-factor Pluggable connected to a pair of fiber-optic cables

Small Form-factor Pluggable (SFP) is a compact, hot-pluggable network interface module format used for both telecommunication and data communications applications. An SFP interface on networking hardware is a modular slot for a media-specific transceiver, such as for a fiber-optic cable or a copper cable.[1] The advantage of using SFPs compared to fixed interfaces (e.g. modular connectors in Ethernet switches) is that individual ports can be equipped with different types of transceivers as required, with the majority including optical line terminals, network cards, switches and routers.

The form factor and electrical interface are specified by a multi-source agreement (MSA) under the auspices of the Small Form Factor Committee.[2] The SFP replaced the larger gigabit interface converter (GBIC) in most applications, and has been referred to as a Mini-GBIC by some vendors.[3]

SFP transceivers exist supporting synchronous optical networking (SONET), Gigabit Ethernet, Fibre Channel, PON, and other communications standards. At introduction, typical speeds were 1 Gbit/s for Ethernet SFPs and up to 4 Gbit/s for Fibre Channel SFP modules.[4] In 2006, SFP+ specification brought speeds up to 10 Gbit/s and the later SFP28 iteration, introduced in 2014,[5] is designed for speeds of 25 Gbit/s.[6]

A slightly larger sibling is the four-lane Quad Small Form-factor Pluggable (QSFP). The additional lanes allow for speeds 4 times their corresponding SFP. In 2014, the QSFP28 variant was published allowing speeds up to 100 Gbit/s.[7] In 2019, the closely related QSFP56 was standardized[8] doubling the top speeds to 200 Gbit/s with products already selling from major vendors.[9] There are inexpensive adapters allowing SFP transceivers to be placed in a QSFP port.

Both a SFP-DD,[10] which allows for 100 Gbit/s over two lanes, as well as a QSFP-DD[11] specifications, which allows for 400 Gbit/s over eight lanes, have been published.[12] These use a form factor which is directly backward compatible to their respective predecessors.[13]

An even larger sibling, the OSFP (Octal Small Format Pluggable) has products being released in 2022[14] capable of 800 Gbit/s links between network equipment. It is a slightly larger version than the QSFP form factor allowing for larger power outputs. The OSFP standard was initially announced in 2016[15] with the 4.0 version released in 2021 allowing for 800 Gbit/s via 8×100 Gbit/s electrical data lanes.[16] Its proponents say a low-cost adapter will allow for backwards compatibility with QSFP modules.[17]

  1. ^ Cite error: The named reference pcmag was invoked but never defined (see the help page).
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  3. ^ Cite error: The named reference Cisco MGBSX1 was invoked but never defined (see the help page).
  4. ^ "4G Fibre Channel SFP". Flexoptix GmbH. Retrieved October 5, 2019.
  5. ^ "DRAFT SFF-8402 CB". SNIA Members. Storage Networking Industry Association (SNIA). December 2, 2022. Retrieved September 24, 2024.
  6. ^ Cite error: The named reference snia was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference sff-8665 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference sff-8636r2.9.2draft was invoked but never defined (see the help page).
  9. ^ "Mellanox Quantum 8700 40 port QSFP56 Product Brief" (PDF).
  10. ^ Cite error: The named reference SFP-DD MSA was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference QSFP-DD MSA was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Lightwave was invoked but never defined (see the help page).
  13. ^ "Backward Compatibility: QSFP-DD/QSFP28/QSFP+/SFP+". Derek. Retrieved July 21, 2022.
  14. ^ "Introduction - NVIDIA QM97X0 NDR SWITCH SYSTEMS USER MANUAL - NVIDIA Networking Docs". docs.nvidia.com. Retrieved January 18, 2022.
  15. ^ Cite error: The named reference OSFP MSA was invoked but never defined (see the help page).
  16. ^ "OSFP MSA Announces Release of OSFP 4.0 Specification for 800G Modules". www.osfpmsa.org (Press release). Retrieved January 18, 2022. With the 800G spec completed, group is developing specification for 1600G modules
  17. ^ "OSFP to QSFP Adapter" (PDF). Retrieved November 2, 2021.