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Optical modules are widely used in optical communication networks. Optical modules with digital diagnostics (DDM) are also called intelligent optical modules, which provide a real-time parameter monitoring means to predict laser degradation.

What is Digital Diagnostics?

DDM stands for Digital Diagnostic Monitoring. is a technology used in optical modules so that users can monitor real-time parameters of optical modules. These parameters include operating temperature, operating voltage, operating current, transmitting and receiving optical power, etc., and can also display the module's factory information, prompt alarm/warning.

The DDM function in the module provides a means for system performance monitoring to help system management predict module life, isolate system failures, and verify module compatibility during field installation.

How do I make a digital diagnosis?

Confirm that the optical module under test is placed into the switch port and record the port number.

Open the Super Terminal and enter the following command (Huawei equipment is an example):

Light Module Digital Diagnostic Information Read Command:

display transceiver diagnosis interface XGigabitEthernet 0/0/1

What is the implementation of digital diagnostic functions? 1, predict the life of the optical module

Optical module digital diagnostics provide a means of monitoring parameters in real time to predict laser degradation. The process of controlling the output power to maintain a stable level is realized by the optical power feedback control unit inside the optical module by increasing the bias current of the laser (Tx_Bias). As the laser gradually ages, the quantum efficiency of the laser will decrease. Therefore, we can predict the lifetime of the laser by monitoring the bias current of the laser.

2. Locating the fault position of the optical module

In optical link, locating fault location of optical module is very important for normal operation of network. Through comprehensive analysis of detected temperature, supply voltage, transmitting and receiving optical power and warning and alarm status of laser bias current, fault isolation characteristics can quickly locate fault location whether in module or on line; whether in local module or remote module.

Real-time monitoring of the operating voltage and temperature inside the transceiver module allows system administrators to identify potential problems:

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

2) The receiving power is too high, which will damage the receiving module.

3) The operating temperature is too high, which will accelerate the aging of the device. In addition, by monitoring the received optical power, the performance of the line and remote transmitter can be monitored.

3. Verification

Another function of digital diagnostics is module compatibility verification. Compatibility verification is whether the operating environment of the analytical module conforms to the datasheet or is compatible with relevant standards. The performance of the module can only be guaranteed in this compatible operating environment. In some cases, because environmental parameters exceed the data manual or relevant standards, module performance will be degraded, resulting in transmission errors. The working environment is incompatible with the module:

1) Voltage exceeds the specified range;

2) received optical power overload or lower than receiver sensitivity;

3) The temperature exceeds the working temperature range.

Original address: https://www.linuxprobe.com/ddm.html

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