Optical module digital diagnostic monitoring (DDM) function

With the more and more extensive application of optical module in optical communication, its speed, package, power consumption and function are developing towards the direction of high speed, small size, low power consumption and multi-function. The optical modules provided in the market basically support the DDM function. In this issue, etu-link will talk about the function of digital diagnostic monitoring (DDM).



Definition of DDM



DDM (digital diagnostic monitoring) is developed by the industry organization SFF Committee and works in accordance with the standard parameters defined by the sff-8472 multi-source protocol. It specifies the standard values or ranges to be followed by the software and hardware of optical modules and network equipment, and ensures the interoperability of products provided by network equipment suppliers and optical module suppliers. DDM is a real-time parameter monitoring technology of optical module, including working voltage, working temperature, received optical power, transmitted optical power and laser bias current.



Functions of DDM



In addition to monitoring parameters, DDM 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 transmitting end will stop sending data, and the receiving end will refuse to receive data.



2. Fault prediction: by monitoring the bias current of the laser, the degradation of the laser is predicted, 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, thus playing the role of 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, the location of link fault can be quickly located, so as to reduce the system fault repair time.



How to view DDM information



There are two methods to view the optical module DDM information: SNMP and command.



1. SNMP, that is, simple network management protocol, is a standard protocol specially used for IP network management network nodes. The optical module DDM information can read the received optical power and transmitted optical power of the optical module through SNMP.



2. Due to different brands of equipment suppliers, the MIB (management information base) and oid (object identifiers) of SNMP are different. Some equipment can directly obtain DDM information through simple commands. For example, the Huawei switch can input the display command.
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