SFP optical module with DDM / DOM Data diagnostic functions applications

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At present, the optical transceiver module in a variety of network types is more and more, increasingly high requirements. In order to meet the growing needs of the system, optical module is constantly moving towards standardization, miniaturization, intelligence development. Intelligent SFP modules, digital diagnostic functions SFP optical module is a symbol of technological upgrading of various manufacturers products.





Using of intelligent optical modules, network management unit can real-time monitor transceiver module temperature, supply voltage, laser bias current, as well as transmit and receive optical power. The measurement of these parameters can help manage the unit to identify the location of the fiber link failure, simplify maintenance, improve system reliability. This article will describe how the light module in Gigac Lee digital diagnostic functions of positioning optical module system failure.

Digital diagnostic functions


SFF-8472 MSA specification digital diagnostic functions and SFF-8472 details. The specification states that the circuit board inside the module detection and digital parameter signal. Then, after calibration or digital measurement results and calibration parameters. This information is stored in the memory structure of the standard, in order to read through the dual-cable serial interface. The SFF-8472 to retain the original SFP / GBIC address A0h at the address mapping and address A2h added a 256-byte storage unit. Storage unit in addition to the parameter detection information, and also defines the alarm flag or alarm conditions, the state of each pin image, the limited number of control capabilities and user-writable storage unit.The following are some of the information stored in the address space of the light module Gigac with DDM function:

1) Real-time measurement of parameters – transmit optical power Tx_power received optical power Rx_power temperature the temp, the operating voltage Vcc, laser bias Laser the Bias;

2) the alarm or alarm – Tx_faul, the LOS measure the parameters of the alarm and the alarm flag;3) control flag – Tx_disable, Rate_select.The application of digital diagnostic functionsTroubleshooting features in the optical transceiver system provides a means of performance monitoring, system management can help to predict the life of the transceiver module, the failure of the isolation system and to verify the compatibility of the module in the on-site installation. Luma Optics the light module in 2008 to solve the intelligent SFP with H3C equipment compatibility issues, do fully compatible. Now available at major telecommunications network operators, CISCO, H3C, Huawei, ZTE and other mature applications.1 module life predictionThis failure to predict that allows network managers to find potential link failure in the system performance affected. Failure notice, the system administrator can business to switch to the backup link or replace a suspicious device, which in the case of non-stop services to repair the system.Smart SFP provides a predictive laser deterioration of real-time parameter monitoring instruments. The optical module within the optical power feedback control unit will control the output power in a stable level, but with the aging of the laser, the quantum efficiency of the laser will be reduced. The power control is achieved by increasing the laser bias current (Tx_Bias). Therefore, we can predict the life of the laser through the monitoring of the laser bias current. This method can be a rough estimate of the life of the laser near the end. Have a relationship because of the laser bias current and module temperature and the working voltage, so the need to consider when setting the bias current limit Temp and Vcc.By real-time monitoring of transceiver module within the operating voltage and temperature, allowing the system administrator to find some potential problems:

1) the Vcc voltage is too high, will bring the breakdown of the CMOS device; the Vcc voltage is too low, the laser does not work properly.

2) power consumption is too high will damage the receiver module.

3) The operating temperature is too high, will accelerate the aging of the device. In addition, through the monitoring of the received optical power lines and the performance of the remote transmitter can be monitored.Fault locationIn the optical link, locate the fault location is critical to business fast loading. The fault isolation feature allows system administrators to quickly locate the position of a link failure. This feature can locate the fault line in the module; local modules or remote modules. By quickly locate the fault, reducing the repair time of system failure. Fault location, a comprehensive analysis of the status bits, pins and measurement parameters.In short, digital diagnostic functions, you can locate the fault. Fault location on Tx_power Rx_power, Temp, and Vcc, Tx_Bias, warning and alarm status of a comprehensive analysis. Memory mirroring the state variables of the Tx to the Fault and Rx LOS (loss of signal) failure analysis plays an important role.Verified for compatibilityAnother feature of digital diagnostic module compatibility verification. Compatibility verification is the analysis module of the working environment in line with the Data Sheet and the relevant standard compatible. Module performance can be guaranteed only in the work environment that is compatible. In some cases, due to environmental parameters beyond the data sheet or the relevant standards, will cause the module performance degradation, and thus transmission error. Working environment and the modules are not compatible:

1) the voltage beyond the specified scope;

2) received optical power overload or below the receiver sensitivity;

3) the temperature exceeds the operating temperature range.

This artical introduced digital diagnostic functions of the optical module (DDM), and describes its application in the system management: forecasting transceiver module life, isolating system failures and site installation to verify the compatibility of the module. Luma Optics intelligent SFP module can be compatible with CISCO, H3C, Huawei, ZTE,HP,Jumper and other brands of equipment, models and other SFP specification switch.

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