At present, all kinds of networks need to receive and receive one of the more and more types of modules, the requirements are getting higher and higher. In order to meet the growing needs of the system, optical modules are constantly moving towards standardization, miniaturization, intelligent development. Intelligent SFP module, which uses digital diagnostic function SFP optical module, is the manufacturers of technology upgrading of the iconic products.
For example: Huawei, H3C devices represented by ESFP Gigac as the representative of the optical module manufacturers with DDM function module. With the intelligent optical module, the network management unit can monitor the temperature, supply voltage, laser bias current and transmit and receive optical power of the transceiver module in real time. The measurement of these parameters can help the management unit to identify the location of the fiber link failure, simplify maintenance work, improve system reliability. This article will introduce Gigac's optical module how to digitally diagnose a system fault that locates an optical module.
Digital diagnostic function In the SFF MSA, the digital diagnostic function and the details of the SFF are specified. The specification specifies that the signal is detected and digitized on the circuit board inside the module. Then, the calibrated results are provided or the digitized measurement results and calibration parameters are provided. This information is stored in a standard memory structure for reading through a dual cable serial interface. SFF retains the original SFP / GBIC address mapping at address A0h and adds a 256-byte memory location at address A2h. In addition to providing parameter detection information, this memory cell defines alarm flags or alarm conditions, status mirroring for each pin, limited digital control capability, and user-writable memory locations.
The following are some of the information that Gigac has saved in the address space of the DDM-enabled optical module:
1) Real-time measurement parameters - Emission optical power Tx_power, received optical power Rx_power, temperature temp, operating voltage, laser bias Laser Bias;
2) alarm or alarm - Tx_faul, LOS measurement parameters of the alarm and alarm flag;
3) Control flag - Tx_disable, Rate_select.
Application of digital diagnostic function
The fault diagnosis function in the fiber transceiver module provides a performance monitoring means for the system to help the system manage the life of the transceiver module, isolate the system faults and verify the module compatibility in the field installation. Gigac's optical module successfully resolved the compatibility of intelligent SFP and H3C devices in 2008, and was fully compatible. Is now in the major telecommunications network operators CISCO, H3C, Huawei, ZTE and other mature applications.
1. Module life prediction This fault prediction allows network managers to find potential link failures before system performance is affected. With the fault notice, the system administrator can switch the service to the backup link or replace the suspicious device, so that in the case of uninterrupted business repair system.
Intelligent SFP provides a real-time parameter monitoring tool for predicting laser degradation. The optical power feedback control unit inside the optical module will control the output power at 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 bias current of the laser (Tx_Bias). Therefore, we can monitor the laser's bias current to predict the life of the laser. This method can roughly estimate whether the life of the laser is nearing its end. Since the bias current of the laser is related to the operating temperature and operating voltage of the module, it is necessary to consider the effect of Temp when setting the bias current limit.
Real-time monitoring of the operating voltage and temperature inside the transceiver module allows the system administrator to identify potential problems: 1) The voltage is too high to cause breakdown of the CMOS device; the voltage is too low and the laser does not work properly.
2) Received power is too high to damage the receiving module.
3) the working temperature is too high, will accelerate the aging of the device. In addition, the performance of lines and remote transmitters can be monitored by monitoring the received optical power.
Fault Location In the optical link, locate the location of the fault is critical to the rapid loading of the service. The fault isolation feature allows the system administrator to quickly locate the location of the link failure. This feature can locate whether the fault is in the module or on the line; whether it is in the local module or in the remote module. Through the rapid positioning failure, reducing the system fault repair time. Fault location, the need for comprehensive analysis of status bits, pins and measurement parameters.
In short, through the digital diagnostic function, you can locate the fault. In the fault location, you need to Tx_power, Rx_power, TempTx_Bias warning and alarm status of a comprehensive analysis. The state variables Tx Fault and Rx LOS in the memory mirrors all play an important role in the analysis of faults.
Compatibility Verification Another function of digital diagnostics is module compatibility verification. Compatibility verification is to analyze whether the module's work environment conforms to the data sheet or is compatible with the relevant standards. The performance of the module can only be guaranteed in this compatible working environment. In some cases, due to environmental parameters beyond the data manual or related standards, will cause the module performance degradation, resulting in transmission error.
The working environment is not compatible with the module:
1) the voltage exceeds the specified range;
2) receive optical power overload or below receiver sensitivity;
3) The temperature is outside the operating temperature range. Gigac's intelligent SFPs are compatible with CISCO, H3C, Huawei, ZTE, and other branded device models and other SFP-compliant switches
Address:No.66#-46,Jiaoyu Rd.,Paojiang Industrial Zone,Shaoxing City,Zhejiang Prov.China 312071