Everything you need to know about SFPs

Share post

Brief Introduction:

In an optical networking scenario, multiple devices located at various locations need to be connected through optical fiber cable to attain secure and uninterrupted communication across large distances. Usually, these devices occupy a small physical space; hence, a compact device is preferred for connecting network components.

The SFP module is such a transceiver used widely for connecting network devices, such as Network Interface Card (NIC), media converters and switches, making it important equipment in optical fiber connections. Due to the compact size, these modules have seen a huge demand in recent years. What are SFP modules, and how are they beneficial? Let’s find out:



What are SFPs?

SFP stands for Small Form-factor Pluggable. SFPs are compact, hot-pluggable devices that act as an interface between a networking device and connecting cables. The cables can be either fiber cables or traditional copper cables. The module can perform the conversion between optical signals and electrical signals.

SFPs support several standards, including Ethernet, Fiber Channel, and SONNET. The module allows transmitting gigabit and other Ethernet LAN packets over TDM based WAN. Also, it can be used for the transmission of E1/T1 streams through packet-switched networks. SFPs are an upgrade to Gigabit Interface Converter or GBIC modules and are hence known as mini GBICs because they have the functionality similar to GBIC transceivers but are compact in size. They also allow higher port density compared to GBICs. Port density is the number of transceivers per inch along the motherboard’s edge.


SFPs are available in different specifications, which allow users to customize the networking equipment according to their needs. As the SFP transceiver is hot-pluggable, it also allows users to upgrade or modify the network infrastructure easily. SFPs are available in single mode as well as multimode, and depending on the type of SFP (SFP, SFP+, QSFP, or QSFP+), they can be used for transmitting data from 500m to 80 km, with data transfer rates from 10 Mbps to 40 Gbps.


Functions of SFPs

SFP modules offer multiple functions in optical fiber networking. Here are some functionalities of SFPs:

  • These modules can provide high-speed communication between switches and other network devices, such as routers, media converters, NICs and more.
  • They are widely used with optical fiber and copper cables.
  • The small form factor of the module makes it perfect for difficult-to-access areas.
  •  SFPs are compatible with simplex or duplex single-mode and multimode optical fiber cables.
  • They support wavelengths up to 1550 nanometers for single-mode whilst up to 1310 nanometers for multimode fiber cables.
  • Upgraded versions of the module like SFP+ can offer high data transfer of up to 10 Gbps.



Types of SFPs

SFPs are classified according to their data transfer capabilities. Some of the high data transfer types are 100Base, 1000Base Gigabit and SFP+ or 10 Gigabit. Most SFP modules offer a transmission speed of 1 gigabit, but the advanced versions like SFP+ can provide a data transfer rate of 10 to 25 Gigabits. SFP transceivers have abbreviations like SX, ZX, LX, EX and more. SX indicates the wavelength of 850nm in a multimode fiber, while other abbreviations indicate wavelengths of different capacities with single-mode fiber.


The type of SFPs that work with optical fiber includes standard types like:

  • 1000BASE-LX10
  • 1000BASE-LX
  • 1000BASE-SX


On the other hand, non-standard industry-accepted type SFP modules are:

  • 1000BASE-LH
  • 1000BASE-LH/LX
  • 1000BASE-ZX
  • 1000BASE-EX


Each type of SFP can work with a specific wavelength and for a specific distance. For example, 1000BASE-LX SFPs can work with 1310nm wavelength for a distance of up to 10 kilometers over single-mode fiber, while 1000BASE-ZX SFPs can operate at up to 80 km.


Generally, SFP ports are available in Ethernet switches, NIC cards, routers and firewalls. These modules are used to connect a network device to copper or optical fiber network cables. Moreover, other types of SFP transceivers, such as 3G or 12G video SFP, are commonly used in HD cameras and monitoring systems.


Benefits of SFP ports in a Gigabit Switch

As SFPs are also known as mini GBICs, they are used widely with network equipment, such as Ethernet switches, routers, NIC cards, firewalls and more; they act as an interface between networking cables and network devices or the motherboard of devices. With SFPs, users can configure multiple ports on a single panel. Usually, switches with at least two SFP ports are used for creating network topologies, such as busses, stars, and ring topologies.

How to Choose SFP module?

When choosing the SFP transceiver, one needs to consider the following factors:


  • Check that the module is compatible with the switch port and cable. The abbreviations used in the types of SFPs can also help in determining the right type of module.
  • Check if you need a single-mode or multimode SFP transceiver.
  • The SFP module should be able to meet IEEE standards.
  • Calculate the distance between the two terminals you want to cover. Depending on the distance, you will have to choose long-distance or short-distance transmission.
  • Also, take environmental factors into account. Check the operating temperature around the area and choose accordingly. Along with the operating temperature, consider other factors like protection from electrostatic discharge.


What are MSA standards?

Multi-Source Agreements or MSA Standards allows third-party manufacturers to provide tools compatible with OEM with a 100% guarantee. The MSA standard enables the development of an open market for SFPs. These standards ensure that the manufacturers build SFP modules that are highly compatible. They specify all the mechanical and electrical elements of SFPs. MSA assures users that third-party modules are of the same standard as OEM brands.


Before choosing a third-party SFP module, you need to check how compatible it is with the network devices. Many users think that OEM SPFs are the best with the highest compatibility. OEM SFPs are optional but they have limited variation and are a costly option. This is where thirty-party SFP modules are best suited. These modules provide several compatibility options at a comparatively lower price. Mostly, third-party SFP manufacturers provide a compatibility guarantee with OEM switches. Moreover, some third-party SFPs also exceed the durability and performance of OEM SFP transceivers.


SFPs are an important part of a network. They act as an interface between the connection cables and networking devices. Now that you know everything about SFP transceivers, choose the best SFP module that suits your network requirements.