Compatible Module's Price Is So Cheap, What About the Quality?
Home Data Center Compatible Module’s Price Is So Cheap, What About the Quality?

Compatible Module’s Price Is So Cheap, What About the Quality?

Posted on by FS.COM

Fiber optic communication has become a major part in today’s telecommunication network. Photoelectric conversion is a necessary part in fiber optic network. And it is fiber optic transceiver that has the function of photoelectric conversion. As a must in fiber network architectures, we cannot have a complete data transfer link without it. Though a single fiber optic transceiver may not be expensive, the total quantities of transceiver modules needed for a data center will cost a large sum of money. Fortunately, the transceiver market provides customers compatible modules at low cost from third-party manufacturers. However, people may wonder why the compatible modules are so cheap, and may have doubts about their quality or compatibility. This article will introduce some tips of judging the quality of several most commonly used compatible transceiver modules: GBIC, SFP and SFP+.

FS.COM SFP Transceivers

How Do I Know the Optical Module Have a Problem?

To judge the quality and compatibility of the GBIC, SFP or SFP+ optical module we bought, we can refer to the latest SFF-8472 specification. SFF-8472 defines digital diagnostic monitoring interface (DDMI) for optical transceivers which allows real time access to device operating parameters. It was published by the SFF Committee (Small Form Factor Committee), an industry group established to define the shape of the new disk drive for portable computers initially. And now the newest revision is SFF-8472 Rev.11.0, released on September 14, 2010. We can refer to SFF-8472 to judge our optical modules because it sets a reference framework for transceiver vendors and networking equipment manufacturers to ensure interoperability between different platforms. And a common set of OAM (operation and maintenance) parameters, a common language, also can be shared by the whole industry.

DDMI Specified in SFF-8472

DDM is a technology used in SFP and SFP+ transceivers as well as GBIC transceivers. So that users are able to monitor real-time parameters of transceivers. According to SFF-8472, there are five parameters for transceivers (shown in the following table). The interface allows real time access to device operating parameters, and it includes a system of alarm and warning flags which alerts the host system when particular operating parameters are outside of a factory set normal operating range. Whenever the monitored parameter exceeds the threshold value stated in the memory map of the device, the bit are set at once. And the platform supervision system can quickly check if the interface is working correctly by polling the status registers.

Parameter Range Accuracy
Supply voltage 0~6.55V +/-3% nominal value
Temperature -128~128℃ +/-3℃
Rx power -40~8.2 dBm +/-3dBm
Tx power -40~8.2 dBm +/-3dBm
Laser bias 0~131 mA +/-10% nominal value
Fault location

In optical link, locate the fault occurred in the fast loading of business is essential. Quickly locating the fault can reduce the time of restoring the system. Fault location comprises a comprehensive analysis of Tx power, Rx power, temperature, Vcc (virtual channel connection), Tx Bias warning and alarm status. DDM makes it easy in optical module. The DDM function can be used to isolate the particular location of fault in the fiber optic link. Fault isolation characteristics allow system administrators to quickly locate the position of a link failure. This feature can locate the fault in module on the line; local modules or modules in the remote.

Compatibility verification

Another feature of DDM is module compatibility verification. Compatibility verification is the analysis of whether the work environment of the module meets the data sheet or related standards. The performance of the module can be guaranteed only in this compatible work environment.

In some cases, when the working environment is not suitable, it will cause the degradation in performance, and thereby transmission error. Situations when work environment and the module is not compatible may include:
1) voltage outside the specified range;
2) received optical power saturation or lower than the receiver sensitivity;
3) the temperature out of the operating temperature range.

FS.COM Test Assured Compatible Transceiver Modules

FS.COM is a professional optical transceiver manufacturer. The main advantages of FS.COM are competitive prices, large inventory and excellent quality. Every FS.COM compatible module is individually tested on a wide range of the same brand devices to ensure transceivers’ quality and compatibility. Our test center is visible anytime. FS.COM provides a full selection of major brands’ compatible modules and generic modules, not limited to GBIC, SFP, SFP+, QSFP+, CFP and other transceivers of Cisco, Arista, Juniper, Huawei, Dell, HPE, etc.

FS.COM test center


Good quality fiber optic transceivers are vital to the success of a fiber optic link. Apart from the budget for the infrastructure, it is also important to choose a reliable transceiver manufacturer or vendor that provides compatible modules with guaranteed quality. FS.COM is a company that has confidence in our products and in offering solutions and services that can satisfy your specific needs.

Copyright © 2002-2017. All Rights Reserved.