A Comparison Helps You Better Choose 10GBASE-SR SFP or 10GBASE-LR SFP?

With the increasing demand for a smaller form factor and high density to meet the speed and standard of 10 Gigabit Ethernet, the 10G small form-factor pluggable (10G SFP) fiber optic transceiver just emerges as the times require around 2009. With a more compact form factor, high density and low cost, the series of 10G SFP became the mainstream on the market over the other packing forms of optic modules. It is used for both telecommunication and data communication. 10G SFP can be divided into many types according to different classification standard, such as 10GBASE-SR SFP, 10GBASE-LR SFP, 10GBASE-ER SFP...In this text, we will mainly introduce the definition and differences between 10GBASE-SR SFP and 10GBASE-LR SFP.

10GBASE-SR SFP

The letters “SR” stand for “short range”, and thus it intends to transfer over short distance. 10GBASE-SR is the original multimode optics specification, and is still by far the most commonly used. As it uses a single, low cost solid state laser assembly operating at 850nm, it is also the least expensive of the optical modules available for a 10G platform. However, 10GBASE-SR is very sensitive to fiber type and very limited by short distance. Because of the distance limits, it is highly recommended that any new multimode fiber deployments use OM3 or higher grade fiber to ensure any 10G deployments do not run into any issues with distance.

10GBASE-LR SFP

Being quite opposite with “SR”, the letters “LR” stand for “long range”, so it designs for data transmission over long distance. 10GBASE-LR can reach 10 km over single-mode fiber. There is no minimum distance for LR, so it is suitable for short connections over single-mode fiber as well.

Differences Between 10GBASE-SR and 10GBASE-LR

Based on the above statement, we analyzed and concluded that the main differences between 10GBASE-SR and 10GBASE-LR lie in the type of fiber mode, transmission distance, wavelength and optical power.

• Type of fiber mode—10GBASE-SR SFP designed for short range, so the media type of it is multimode fiber. It can be connected with a serial multimode fiber such as OM3 and OM4. 10GBASE-LR SFP sets for long distance transmission, and thus single-mode fiber is mainly covered in 10GBASE-LR SFP.
• Transmission distance—By using a multimode fiber, the maximum transmission distance of 10GBASE-SR SFP is 400 m (OM4). The transfer distance of 10GBASE-LR SFP can be up to 10 km with a single-mode fiber. Apparently, 10GBASE-LR SFP is far beyond the 10GBASE-SR SFP on transmission distance.
• Wavelength—10GBASE-SR SFP uses short wavelength to transfer signals, the wavelength of it is 850 nm with a TX range between 840 nm-860 nm and RX range between 840 nm-860 nm. LR uses long wavelength to transfer data, its wavelength is 1310 nm with a TX range between 1260 nm-1355 nm and RX range between 1260 nm-1600 nm.
• Optical power—The optical power of 10GBASE-LR SFP is slightly higher than 10GBASE-SR SFP, the gap between them is around 1.5 dBM. The link budget of SR is 2.6 dB (OM3) while the LR is 6.2 dB. Clearly, 10GBASE-LR SFP uses more power than 10GBASE-SR SFP.

Summary

If you are looking for an optical module to transmit within short distance, 10GBASE-SR SFP would be great choice with low cost and low power. When the distance is much longer, it is highly recommended to use 10GBASE-LR SFP to ensure signals are transferred all the way through. The cost may high, but quality is reserved.