March 6, 2018

What is DDM or DOM for Optical Transceivers

What Is DDM (Digital Diagnostic Monitoring)?
DDM is short for Digital Diagnostic Monitoring, according to the industry standard MSA (Multi-Source Agreement) SFF-8472 and is also known as DOM (Digital Optical Monitoring). When choosing the fiber optic transceivers for your equipment, you can choose transceiver modules with or without DDM/DOM function. Most of fiber optic transceivers now are support DDM/DOM function. This technology allows the operator to monitor the parameters of the fiber optic transceivers  like optical input/output power, temperature, laser bias current, and transceiver supply voltage, and so on in realtime.

What Can DDM Do?
DDM can provide component monitoring on transceiver applications in details. The SFF-8472 added DDM interface and outlined that DDM interface is an extension of the serial ID interface defined in GBIC specification, as well as the SFP MSA. DDM interface includes a system of alarm and warning flags which alert the host system when particular operating parameters are outside of a factory set normal operating. Thus, DDM interface can also enable the end user with the capabilities of fault isolation and failure prediction. This part will explain what can be done with DDM.

What Is DOM?
DOM, short for Digital Optical Monitoring, is used to monitor some parameters of the transceiver in real-time, helping to identify the location of the fiber link failure, simplify maintenance, and improve system reliability. DOM allows you to monitor the TX (transmit) and RX (receive) power of the module, temperature, and transceiver supply voltage. You can configure your device to monitor optical transceivers in the system, either globally or by specified port. When this feature is enabled, the system monitors the temperature and signal power levels for the optical transceivers in the specified ports. Console messages and syslog messages are sent when optical operating conditions fall below or rise above the SFP manufacturer’s recommended thresholds. With DOM, network administrators can check and ensure that the module is functioning correctly in an easy and convenient way. This is why most of modern optical SFP transceivers support DOM functions.