
1000BASE-SX VS 1000BASE-LX SFP Transceivers
Updated at Dec 31st 20241 min read
SFP module is a small pluggable optical module for supporting optical fiber communication with a 1G rate, which has many different types. The two most commonly used LC SFP transceiver modules in the market are 1000BASE-SX and 1000BASE-LX SFP. In this article, we will provide a brief introduction to these two types of LC SFP transceivers.
What is 1000BASE-SX SFP?
1000BASE-SX is a gigabit Ethernet standard over fiber optic. It is used for operating on wavelengths of 850 or 1310 nanometers. In other words, 1000BASE-SX can operate over both single-mode fiber and multimode fiber. It has a working distance of up to 2km over single-mode fiber and a maximum length of 550 meters on multimode fiber. This standard is widely used in large office buildings, co-location facilities, and carrier-neutral Internet exchanges. The “SX” stands for short distances between 220m and 550m reach over multimode fiber. Taking FS 850nm 1000BASE-SX SFP module (SFP1G-SX-85) as an example, transmission reaches 275 meters by 62.5μm/125µm OM1 fibers, and up to 550 meters if 50μm/125µm OM2/OM3/OM4 fibers are deployed.

What is 1000BASE-LX SFP?
IEEE 802.3 Clause 38 specifies 1000BASE-LX as a standard for implementing Gigabit Ethernet networks. The “LX” in 1000BASE-LX stands for long wavelength, indicating that this version of Gigabit Ethernet is intended for use with long-wavelength transmissions (1270–1355nm) over long cable runs of fiber optic cabling. 1000BASE-LX LC SFP transceiver is mainly intended for connecting high-speed hubs, Ethernet switches, and routers in different wiring closets or buildings using long cable runs. Due to the low cost and extended reach that meets most enterprise networks, 1000BASE-LX has become one of the most popular standards. Such as SFP1G-LX-31, is an LX single-mode transceiver that operates over a wavelength of 1310nm for up to 20km.

1000BASE-SX VS 1000BASE-LX SFP Transceivers
The 1000BASE-SX and 1000BASE-LX LC SFP transceivers are used for Gigabit Ethernet over fiber optic cabling, following the IEEE 802.3z standard. There are nuances shown in fiber types, transmission distance, dispersion, and application scenarios.
Types of Optical Fibers
Regarding the types of optical fibers, the 1000BASE-SX LC SFP transceiver continues to work with single-mode or multimode fiber, the latter has a thicker core and allows for higher speeds but at shorter distances. On the other hand, the 1000BASE-LX LC SFP transceiver works with single-mode fiber for both data transmission and reception.
Transmission Distance
In terms of transmission distance, the 1000BASE-SX LC SFP transceivers are suitable for short distances, typically within small areas or buildings, reaching up to 2km. In contrast, the 1000BASE-LX LC SFP transceivers are primarily used for long-distance transmission, supporting distances of up to 20km.
Dispersion
Dispersion characteristics differ between the two types of optics. The 1000BASE-SX SFP modules are affected by modal dispersion, as light rays follow different paths through the fiber, resulting in varied arrival times at the receiving end. This mode of dispersion limits the distance achievable. In contrast, the 1000BASE-LX SFP modules are affected by waveguide dispersion, caused by the light's width being larger than the core of the fiber. While this allows for better control of photon paths, it is more susceptible to microbeads, twists, and stress on the fiber.
Application Scenarios
The application environment for the 1000BASE-SX SFP module is commonly found in short-range applications within local area networks (LANs), data centers, and campus networks. On the other hand, the 1000BASE-LX SFP module is suitable for long-range applications, including wide area networks (WANs), metropolitan area networks (MANs), and long-haul connections between different locations.
The following table lists the main differences between them.
Features | 1000BASE-SX SFP | 1000BASE-LX SFP |
Data Rate | 1.25Gbps | 1.25Gbps |
Interface | Duplex LC | Duplex LC |
Fiber Type | Single-Mode or Multi-Mode | Single-Mode |
Transmission Distance | Short distance, max. 2km | Long distance, max. 20km |
Dispersion | Mode dispersion Different light paths lead to varied arrival times at the receiving end | Waveguide dispersion Light width exceeds core diameter, significantly affected by micro-beads, twists, and stress |
Application Scenarios | Local Area Networks (LANs) Data Centers Campus Networks Small Areas or Buildings | Wide Area Networks (WANs) Metropolitan Area Networks (MANs) Long-distance Connections |
Conclusion
1000BASE SFP transceivers are essential components for Gigabit Ethernet applications, and FS offers a wide range of highly compatible 1000BASE SFP transceivers that work seamlessly with leading brands such as Cisco, Juniper, Dell, Finisar, Brocade, and Netgear. Our modules not only ensure extensive applicability across various platforms but also come at low maintenance costs. With internationally recognized original product quality, FS has demonstrated its strong commitment and expertise in providing reliable and efficient networking solutions. In addition, FS can also provide switches, jumpers, network cables and other products to meet the needs of systematized solution products. If you have any specific product requirements, please feel free to send us your request.