Fiber Optics

What Are the Differences between SFP, SFP + and XFP

In current optical communication market, there are various kinds of optical transceivers which come in various form factors at speeds from 100Mbps to 100Gbps and are fully compliant with the MSA and IEEE 802.3 standards. Some of the more popular form factors are SFP, SFP +, XFP, GBIC, QSFP, QSFP28 and QSFP-DD. In this post, we will mainly discuss SFP, SFP + and XFP optical transceivers, the main differences among them will be covered in the following parts.

Definition of SFP:

When we discuss what SFP is, SFP stands for Small Form-Factor Pluggable, a compact, hot-pluggable transceiver that can be used in the ports of telecommunications and data communications equipment. SFP modules are designed to support SONET, Gigabit Ethernet, Fiber Channel and other optical communication standards. Due to its small size and improved performance in conjunction with higher speeds, the module has displaced the universally applicable GBIC transceivers and is therefore sometimes referred to as a mini-GBIC.

As an interchangeable fiber connector that can adapt to any existing network, SFP makes network maintenance a lot easier. SFP transceiver modules allow a higher port density (number of transceivers per cm along the edge of a motherboard). These modules are not standardized by a state agency, but specified by a multi-source agreement (MSA), which has been adopted by various manufacturers. Some network component manufacturers have provided protection to the SFPs, deliberately avoiding compatibility with generic “SFPs” by checking firmware or other areas of programming, whereby only the modules approved by the manufacturer can be used. However, some manufacturers have introduced SFPs with empty programmable EEPROMs that can be reprogrammed to match each supplier ID.

Modern SFP transceiver modules also come with standard Digital Diagnostic Monitoring (DDM) functions, which is also known as Digital Optical Monitoring (DOM). This gives end users the ability to monitor in real time SFP parameters such as optical output, optical input power, temperature, laser current, supply voltage, etc. This functionality can be used to monitor routers, switches, and other optical devices, which can be reprogrammed to match any supplier ID.

Definition of SFP +:

SFP + stands for Small Form-Factor Pluggable Plus. SFP + transceivers are an enhanced version of the SFP that can support data rates up to 16Gbps. The SFP + specification were first published on May 9, 2006 and the first version 4.2 was released on July 6, 2009. As one of the most popular industry standards in optical communication industry, SFP + transceivers are supported by many network component providers. SFP + offers standard 8 Gbps Fiber Channel, 10 Gigabit Ethernet and the Optical Transport Network Standard OTU2.

SFP + transceiver modules have the same dimensions as the SFP. The big difference between the SFP and SFP + modules is the coding method. These modules have more circuitry on the host board than the internal module. SFP + modules can also be used in older devices with XENPAK or X2 ports through the use of an active electronic adapter. SFP + modules come in two types linear and limited. Linear SFP + modules are best for 10GBase-LRM, otherwise limited modules are preferred. These contain a signal amplifier to redesign the degraded (received) signal, whereas linear modules do not.

Definition of XFP:

XFP stands for 10 Gigabit Small Form Factor Pluggable, a hot-swappable and protocol independent module. It enables a fast transmission of data in the computer network. XFP was devised by the XFP Multi-source Agreement Group and first emerged in the year 2002 along with XFI, one of its electrical components.

XFP transceiver modules are protocol-independent and fully compliant to various standards, including: 10G Ethernet, 10G Fibre Channel, SONET OC-192, SDH STM-64 and OTN G.709. It supports bit rate from 9.95G through 11.3G, along with its interface to other electrical components which is called XFI. The 10-Gigabit XFP transceiver module is a hot-swappable I/O device that plugs into 10-Gigabit ports.XFP transceiver modules connects the electrical circuitry of the system with the optical network.

SFP package — hot-plug small- package module, the highest rate is up to 4G , usually LC interface connect.
SFP + package — standard package, the working speed can be 10G, the application of 10G Ethernet.
XFP — standardized package of serial 10G optical transceiver modules.

The Difference between SFP and SFP +:

1. The look and the size of the SFP and SFP + are the same;
2. The highest rate of SFP is up to 4G is the rate of SFP + 10G;
3. The protocol specification of the SFP: SFP: IEEE802.3, SFF-8472;
4. SFP + supports DDM .

The Difference between SFP + and XFP:

1. SFP + and XFP both are 10G optical module , and can be connected with other types of 10G modules;
2. The look and the size of the SFP + is less than XFP;
3. Because of the smaller size, SFP + moves the signal modulation function, serial / deserialization program, MAC, clock and data recovery ( CDR ) and electronic distribution compensation ( EDC ) function to the motherboard card from modules;
4. Compliance agreement of XFP: MSA XFP agreement;
5. Compliance Agreement of SFP +: IEEE 802.3ae, SFF-8431, SFF-8432;
6. SFP + is a mainstream design;
7. The Protocol Specification of SFP +: IEEE 802.3ae, SFF-8431, and SFF-8432.

10G optical module underwent the development of 300Pin, XENPAK, X2, XFP, which finally realize that the transmission of 10G signal with the same size as SFP, this is SFP +. SFP + met the requirements of the high-density optical module, gradually replacing XFP and become the mainstream of the 10G market. People around the world learn the difference between SFP, SFP + and XFP, and avoid unnecessary hassles to the customer, so we provide some information for them.

In the above, we mainly discussed what is SFP, SFP + and XFP as well as the main difference between them. After learning the difference between SFP, SFP + and XFP, people are able to avoid unnecessary hassles to the customer. This is why we are dedicated to bring important information about optical transceivers to all of you.


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