9
SNMP and the Management Information Base
A Simple Network Management Protocol (SNMP) Management Information Base (MIB) is a hierarchically organized collection of information. MIB’s
consists of managed objects that are identified by object identifiers (OIDs). Some attributes in the MIB are fixed while others are dynamic values calculated
by the agent software running on the device.
Ethernet SNMP agent operates together with optical transmitter and provides remote diagnostics and control of the transmitter via Ethernet type network
using SNMP protocol.
The agent of transmitter can receive SNMP requests from a number of SNMP managers and can send traps to dedicated trap receiver.
The SNMP agent generates all alarms and events as SNMP traps (notifications) if parameters of the transmitter exceed limits and/or abnormal situations
occur. These traps will be sent to trap manager, identified by host IP address. The SNMP agent generates traps containing an object ID (OID) that uniquely
identifies the alarm. The traps also contain a date/time stamp that shows the date and time of the alarm.
The a network management system (NMS) can be implemented to enable a more sophisticated alarm management with alarm filtering, alarm
acknowledgement and automatic messaging through Emails or SMS etc.
The table 2 shows the notification type and the MIB object for each event notification.
Table 2
. Notification type and the MIB object
OID
Notification type
MIB object
Description
30631.1.2.3.1
notifyBusVoltage
alarmBusVoltage
Supply bus voltage out of range
30631.1.2.3.2
notifyTecOverCurrent
alarmTecOverCurrent
TEC current out of range
30631.1.2.3.3
notifyLaserFail
alarmLaserFail
Laser diode failure
30631.1.2.3.4
notifyLaserDegrade
alarmLaserDegrade
Laser diode degradation threshold level reached
30631.1.2.3.5
notifyLaserOverCurrent
alarmLaserOverCurrent
Laser diode current reached dangerous level
30631.1.2.3.6
notifyLaserShutdown
alarmLaserShutdown
Laser diode auto switched off
30631.1.2.3.7
notifyTemprUnlock
alarmTemprUnlock
TEC regulation loop unlocked
30631.1.2.3.8
notifyOverTemperature
alarmOverTemperature
Device temperature reaches dangerous level
30631.1.2.3.9
notifyLowRf
alarmLowRf
Low RF level
30631.1.2.3.10
notifyHighRf
alarmHighRf
High RF level
30631.1.2.3.11
notifyAgcRange
alarmAgcRange
AGC out of range
30631.1.2.3.12
notifyExtSupply1
alarmExtSupply1
External supply 1 - attention required
30631.1.2.3.13
notifyExtSupply2
alarmExtSupply2
External supply 2 - attention required
It is possible to get transmitter diagnostic data and indications of parameters exceeding operating limits – alarms (Table 3).
Table 3
. Alarm OID’s
OID
alarm
Description
30631.1.2.2.1
alarmBusVoltage
Supply bus voltage out of range
30631.1.2.2.2
alarmTecOverCurrent
TEC current out of range
30631.1.2.2.3
alarmLaserFail
Laser diode failure
30631.1.2.2.4
alarmLaserDegrade
Laser diode degradation threshold level reached
30631.1.2.2.5
alarmLaserOverCurrent
Laser diode current reached dangerous level
30631.1.2.2.6
alarmLaserShutdown
Laser diode auto switched off
30631.1.2.2.7
alarmTemprUnlock
TEC regulation loop unlocked
30631.1.2.2.8
alarmOverTemperature
Device temperature reaches dangerous level
30631.1.2.2.9
alarmLowRf
Low RF level
30631.1.2.2.10
alarmHighRf
High RF level
30631.1.2.2.11
alarmAgcRange
AGC out of range
30631.1.2.2.12
alarmExtSupply1
External supply 1 - attention required
30631.1.2.2.13
alarmExtSupply2
External supply 2 - attention required
By means of SNMP protocol it is possible to get status parameters values of the transmitter (RF level, laser current, supply voltages, temperature inside
module) and parameters of the external power suppliers (Table 4).
