Digital diagnostic monitoring (DDM) function of Optical module

With the application of Optical module in optical communication becoming more and more extensive, its speed, packaging, power consumption and functions are developing towards the direction of high speed, small size, low power consumption and multi-function. The Optical module provided in the market basically support the DDM function.

Definition of DDM

DDM (Digital Diagnostic Monitoring) is developed by the SFF Committee, an industry organization. It works in accordance with the standard parameters defined by the SFF-8472 multi-source protocol. It standardizes the standard values or ranges to be followed by the software and hardware of the Optical module and network equipment, and ensures that the interoperability of products provided by network equipment suppliers and Optical module suppliers is different. DDM is a real-time parameter monitoring technology for Optical module, including operating voltage, operating temperature, received optical power, transmitted optical power and laser bias current.

Functions of DDM

DDM not only monitors parameters, but also has functions such as alarm, fault prediction, and fault location.

1. Alarm function: when the environmental parameters of the Optical module exceed the specified standard range, an alarm will be sent to the system. When the display module is in a bad state, the transmitter will stop sending data, and the receiver will also refuse to receive data.

2. Fault prediction: It can predict the deterioration of the laser by monitoring the bias current of the laser, so as to ensure that the service is switched to the standby link or replace the Optical module that may fail before the fault occurs. Therefore, it plays a role in predicting the life of the Optical module.

3. Fault location: through comprehensive analysis of alarm signs or alarm conditions, monitoring parameter information and Optical module pins, quickly locate the link fault location, thus reducing the system fault repair time.

There are two main ways to view the DDM information of the Optical module: SNMP and commands.

1. SNMP, also known as the Simple Network Management Protocol, is a standard protocol specifically used for managing network nodes in IP networks. The DDM information of the Optical module can read the received optical power and transmitted optical power of the Optical module through SNMP.

2. Due to differences in the MIB (Management Information Base) and OID (Object Identifiers) of SNMP among different device suppliers, some devices can directly obtain DDM information through simple commands.