How Much Do You Know About SFP+ Transceiver?

In the recent years, the interface technology based on 10G Ethernet has been developed a lot. But the transceiver products of 10G have not been so popular as expectation due to their high cost. Moreover, the low port density caused by power attenuation and cross talk has made them more difficult to marketization. Under this situation, a small form-factor pluggable plus (SFP+) provides a perfect solution with a high port density and low cost.

SFP+ is the advanced version of SFP, which is developed to support 10 Gigabit Ethernet. The data rate of SFP+ can up to 16 Git/s. The SFP+ specification was first published on May 9, 2006, and version 4.1 published on July 6, 2009. SFP+ supports 8 Git/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. The applications have expanded to many others such as, SONET OC-192, SDH STM-64, OTN G.709, CPRI wireless, 16G Fibre Channel, and the emerging 32G Fibre Channel. It is a popular industry format supported by many network component vendors. In the following text, we are going to talk about its types and advantages compared with other types based on 10G.

Types of SFP+ Transceivers

SFP+ modules can be grouped into two types of host interface: linear or limiting. Limiting modules are preferred except when using old fiber infrastructure which requires the use of the linear interface provided by 10GBASE-LRM modules. SFP+ transceivers can further be divided into two groups according to different wavelength. 10GBASE-SR SFP+ is for the short wavelength and short reach. Being quite opposite with 10GBASE-SR SFP+, 10GBASE-LR SFP+, 10GBASE-ER SFP+ and 10GBASE-LRM SFP+ refer to the long wavelength and long transmission distance.

For short wavelength and short distance, the wavelength of 10GBASE-SR SFP+ is 850 nm to support multimode fiber, such as OM3 (300m) and OM4 (400m). With a wavelength of 1310 nm, 10GBASE-LR SFP+ can support a long wavelength and a long distance up to 10 km by using a single-mode fiber. For extra long wavelength and extended reach, 10GBASE-ER SFP+ can reach 40 km with the wavelength of 1550 nm by using a single-mode fiber. 10GBASE-LRM SFP+ is mainly applied to multimode fiber for a long wavelength of 1310 nm and long transmission distance of 220 m.

SFP+ Advantages

Compared to the earlier 10G products, such as X2, XPAK, XFP, SFP+ has many advantages— more compact, low cost, and more efficient (highest density and low power consumption).

• More Compact—The form factor of SFP+ module form factor is 30% smaller based on SFP transceiver. Thus, it uses only a few components and less power, which is much smaller than X2 and XFP.
• Lower Cost—SFP+ optical transceiver is able to offer significantly lower cost than the other modules. The SFP+ module only does optical to electrical conversion; innovation in optics, silicon and module design continue to cut the cost down of optical transceivers. After the not so welcomed products of X2, XPAK, XENPAK, XFP, the developers and researchers designed SFP+ aimed for a transceiver with low cost and lower power. Thus, SFP+ is the most cost-effective product based on 10 Gbit/s Ethernet.
• More efficient—The SFP+ module improved the signal integrity by reducing signals to 20. The fewer signals it have, the higher interface density it has. Supplied by a single power source, SFP+ doesn’t rely too much on power system. In this way, the system energy consumption has been reduced a lot.

The SFP+ form factor significantly optimizes the function of 10G optical module by adding such functions as clock and data recovery (CDR), electronic dispersion compensation (EDC), 10G SERDES as well as the improved signal conditioning. As a result, the low cost SFP+ module has small form factor, less power consumption and higher port density.

Summary

With the advantage of high density, low cost, low power consumption, the small SFP+ has been warmly welcomed in enterprise networks to meet the standard of 10G Ethernet. The most common types of SFP+ transceivers are 10GBASE-SR SFP+, 10GBASE-LR SFP+, 10GBASE-ER SFP+ and 10GBASE-LRM SFP+. For short transmission distance with multimode fiber, you can choose 10GBASE-SR SFP+. If you require longer distance with multimode fiber, and then 10GBASE-LRM SFP+ would be nice. Given that your demand is longest distance with single-mode fiber based on 10G Ethernet, 10GBASE-ER SFP+ is a good choice. You can pick a proper one to meet your demand.