Tremendous progress has been made over the past few decades with advent and development of Ethernet network. During this period, a variety of optical fiber transceivers have been designed and manufactured by several optical fiber manufacturers for meeting the requirements of Ethernet network, such as, Cisco gigabit SFP, NETGEAR GBIC. As one of the most pivotal component among these optical fiber transceivers, SFP modules play an important role in Ethernet network that largely made the GBIC modules obsolete and greatly accelerated the development of optical fiber transceivers. To better understand SFP modules, this article will make a brief introduction of SFP transceiver and study three kinds of SFP modules, SFP, BiDi SFP and compact SFP.
SFP Transceiver Overview
SFP transceiver is one of the variation of the GBIC transceiver, which can also be called small form-factor pluggable transceiver or mini-GBIC. Its function is the same as GBIC transceiver, but it has a smaller form factor and higher performance than GBIC transceiver. Due to its smaller size and higher speed, it is largely used in the field of telecommunication and data communication, instead of GBIC transceiver.
SFP transceiver is consisted of a transmitter on one end and a receiver on the other end which are designed to work separately. In data transmission process, the transmitter will convert the electrical signal into light signal and transmit the light signal to the receiver. Once the receiver receives the light signal, it will convert the light signal into electrical signal again to finish the data transmission.
Comparative Analysis of SFP, BiDi SFP and Compact SFP
As technologies drive to maturity stage, SFP transceivers become diversified, designed for different aims with various feature. Meanwhile, the functions of these SFP transceivers are improved greatly to meet increasing demands of network. The following will make a comparative analysis of three commonly used SFP transceivers, SFP, BiDi SFP and compact SFP, which may help you make a decision when selecting proper SFP transceiver for your network.
Structural Differences
It is well known that a common SFP transceiver is usually with two ports, TX port and RX port. The TX port is to transmit the signal, while the latter one receives the signal. Clearly different from the common SFP transceiver, BiDi SFP transceiver has only one port, working with an integral WDM coupler to transmit and receive signals. Its transmission is also done through a single strand fiber. As for the compact SFP, it is much more complicated than the previous ones. In fact, it is designed as a 2-channel BiDi SFP that integrates two BiDi SFP in one SFP module. That’s to say, there are two ports in a compact SFP to transmit and receive signals, which is the same as the common SFP. To better know about the structural differences among the three kinds of SFP modules, you can take the following figure as reference.
Connection Method Differences
In general, all SFP transceivers must be used in pairs. However, since the structure of these three kinds of SFP modules are different, they should be connected to fiber equipment in different methods.
As for the common SFPs, when connecting two SFPs for data transmission, you should ensure that they works with the same wavelength together. For example, if you use a 850nm SFP at one end, a 850nm SFP on the other end is also required for the whole transmission. For the detailed connection of common SFPs, it is presented in the following figure for your reference.
As for BiDi SFP, it has the ability to transmit and receive signals with different wavelengths, but you should connect two BiDi SFPs with opposite wavelengths together. Hence, the transmission can be processed correctly. As shown in the following figure, if you use a 1310nm-TX/1490nm-RX BiDi SFP at one end, a 1490nm-TX/1310nm-RX BiDi SFP should be used on the other end.
As for the compact SFP, it usually transmit signals with 1490nm wavelength and receive signals with 1310nm wavelength. That is, if you choose the compact SFP for your network, two 1310nm-TX/1490nm-RX BiDi SFPs should be connected through single-mode fibers as shown in the figure below.
Conclusion
As one of the most basic modules, SFP transceivers is of epoch-making significance in the history of optical fiber transceivers. And the three types of SFP transceivers mentioned in this article with various features are suitable for different application, which should be connected with specific methods. Hope the information in this article can guide you to select the proper SFP modules for your network.
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