How Many Types of SFP Transceivers Do You Know?

With the increasing demand for higher bandwidth, multiple types of transceivers are designed for data transmission, including GBIC, SFP, SFP+, QSFP and so on. Among them, SFP transceiver has been used in popularity for over 15 years and it is still available in several different types. This article will give a thorough introduction to the SFP transceiver types.

Figure 1: SFP transceiver types

SFP Transceiver Types

SFP transceiver can be categorized into different versions under Gigabit Ethernet standards and industry-accepted standards, including 1000BASE-T, 1000BASE-TX, 1000BASE-SX, 1000BAS-LX, 1000BASE-LX10, 1000BASE-BX10, 1000BASE-LX/LH, 1000BASE-EX, and 1000BASE-ZX.

SFP Transceivers Over Copper Cabling: 1000BASE-T vs. 1000BASE-TX

1000BASE-T (IEEE 802.3ab) transceiver is 1Gb copper SFP that transmits GE over twisted pairs. They make GE a desktop technology since users can use their existing copper cabling infrastructure. 1000BASE-TX (TIA/EIA-854) is similar to copper SFP but uses only two pairs of wires. Though 1000BASE-TX needs fewer wires for transmission, 1000BASE-T is still more widely used. Because 1000BASE-TX commonly connects with Cat6 cable, which is more expensive than Cat5 that needed by 1000BASE-T.

SFP Transceivers Over Optical Fibre Cabling

SFP transceivers that work over optical fibre consist of standard 1000BASE-SX, 1000BASE-LX and 1000BASE-LX10, and non-standard industry accepted 1000BASE-LX/LH, 1000BASE-LH, 1000BASE-EX and 1000BASE-ZX.

The non-standard SFP transceivers are created by transceivers vendors to meet the Gigabit transmission requirements of different applications. They are all compliant to Multi-Source Agreements (MSA) so as to ensure the SFP is across a range of telecoms vendors’ hardware.

Optical SFP Transceivers of Different Fibre Types

According to fibre types, SFP transceivers that work over optical fibre can also be classified into different types. There are single-mode SFP and multimode SFP, as well as simplex SFP and duplex SFP.

Single-mode SFP vs. Multimode SFP

Based on the types of optical fibres SFP transceivers work with, SFP transceivers are divided into single mode SFP that works with single-mode fibre and multimode SFP that works with multimode fibre. The following figures show the major differences between them.

Figure 2: Color coding and fibre cable for single-mode SFP and multimode SFP

Simplex SFP & Duplex SFP

Apart from the SFP transceivers mentioned above that use dual fibres for duplex transmission, there are SFP transceivers that use only a single fibre for transmission. The latter are called simplex SFPs or bidirectional (BiDi) SFPs, which are equipped with WDM couplers/diplexers. The most frequently used wavelength pairs of BiDi SFPs are 1310nm/1550nm, 1310nm/1490nm and 1510nm/1590nm. And the transmission distances vary from 10 km to 160 km when using different wavelengths. It is very easy to distinguish simplex SFP and duplex SFP from the receptacle.

Figure 3: Duplex SFP with dual fibre port and simplex SFP with single fibre port

WDM SFP Transceivers of Multiple Wavelengths

As an advanced technology that allows to transmit multiple signals simultaneously on a single fibre, wavelength-division multiplexing (WDM) is utilized by telecom systems in long distance transmission, either DWDM (dense WDM) or CWDM (coarse WDM).

CWDM SFPs and DWDM SFPs both connect with LC duplex single-mode fibre cables, but they have more differences than similarities. Generally, when the customer needs a number of channels up to 16, it is more economical to deploy CWDM SFP than DWDM SFP.

Video SFP Transceivers for High-Quality Video Services

3G-SDI (serial digital interface) video SFP transceivers are designed to meet the high standard video transmission needs in the High Definition (HD) environment. The key difference between video SFPs and normal SFPs is that the video transmission is uni-directional. Thus, the video SFP can have either two optical transmitters, two optical receivers, a single transmitter, a single receiver. Similar to normal SFP transceivers, 3G-SDI video SFPs can be multimode, single-mode, BiDi or CWDM transceivers of different wavelengths, and can have different reaches of distances.

PON SFP Transceivers in FTTx Networks

Passive Optical Networking (PON) is the key technology used in fibre-based (FTTx) access networks. PON SFP transceiver is used in the Optical Line Terminal (OLT) at the Central Office and the Optical Network Terminal/Unit (ONT/ONU) at subscriber’s premises. PON SFP differs from other SFP transceivers in that the OLT SFP and ONT SFP are not used in pairs, instead an OLT SFP should communicate with up to 32 or 64 ONT SFPs.

Conclusion

Facing so many types of SFP transceivers, it will be hard to figure out which SFP transceiver is proper in use. FS could help you get away with these problems. It not only provides various SFPs with high quality, but also offers free technical support for you. If you have any needs or questions, welcome to visit FS.COM.