SNR S2940-8G-v2 Switch Configuration Guide
DDM Configuration
Chapter 12
DDM Configuration
12.1 Introduction to DDM
12.1.1 Brief Introduction to DDM
DDM (Digital Diagnostic Monitor) makes the detailed digital diagnostic function standard in SFF-
8472 MSA. It set that the parameter signal is monitored and make it to digitize on the circuit board
of the inner module. After that, providing the demarcated result or the digitize measure result and
the demarcate parameter which are saved in the standard memory framework, so as to expediently
read by serial interface with double cables.
Normally, intelligent fiber modules support Digital Diagnostic function. Network management
units is able to monitor the parameters (temperature, voltage, bias current, tx power and rx power)
of the fiber module to obtain theirs thresholds and the real-time state of the current fiber module
by the inner MCU of the fiber module. That is able to help the network management units to locate
the fault in the fiber link, reduce the maintenance workload and enhance the system reliability.
DDM applications are shown in the following:
1. Module lifetime forecast
Monitoring the bias current is able to forecast the laser lifetime. Administrator is able to find
some potential problems by monitoring voltage and temperature of the module.
1. High Vcc voltage will result in the breakdown CMOS, low Vcc voltage will result in the ab-
normity work.
2. High rx power will damage the receiving module, low rx power will result that the receiving
module cannot work normally.
3. High temperature will result in the fast aging of the hardware.
4. Monitoring the received fiber power to monitor the capability of the link and the remote switch.
2. Fault location
In fiber link, locating the fault is important to the fast overload of the service, fault isolation is
able to help administrator to fast locate the location of the link fault within the module (local module
or remote module) or on the link, it also reduce the time for restoring the fault of the system.
Analyzing warning and alarm status of real-time parameters (temperature, voltage, bias cur-
rent, tx power and rx power) can fast locate the fault through Digital Diagnostic function. Besides,
the state of Tx Fault and Rx LOS is important for analyzing the fault.
86
To Next Page
Loading...
General