SNMP Alarms

Clearwater nodes report errors over the SNMP interface when they are in an abnormal state, and clear them when they return to normal. They only report errors relating to that node - not errors relating to the whole deployment, which is the role of an external monitoring service.

Error indications come in two forms:

  • For clearly-defined errors not based on thresholds, the Clearwater node sets an ITU Alarm MIB from RFC 3877 and sends an SNMP notification to a configured external SNMP manager.
  • For errors based on a threshold set on a statistic (such as latency targets or number of failed connections), the Clearwater node exposes that statistic over SNMP. A downstream statistics aggregator from the Management and Orchestration (MANO) layer monitors these statistics, compares them to its configured thresholds, and raises alarms on that basis.

EMS

To integrate with an EMS, the EMS must support the following capabilities of RFC 3877 to obtain the brief description, detailed description, and severity for the alarm:

  • The EMS must be configured to catch the SNMP INFORM messages used to report alarms from Clearwater. It is also recommended that the EMS must display the alarm information provided by the following MIBs.
  • Upon receiving a SNMP INFORM message from Clearwater the EMS can obtain the alarm data by the following:
    • The EMS must retrieve the AlarmModelEntry MIB table data associated with the current SNMP INFORM message from Clearwater. This MIB provides the active/clear state, alarm description, and a table index for the ituAlarmEntry MIB.
    • The EMS must the retrieve the ituAlarmEntry MIB table data associated with the current alarm from Clearwater. This MIB provides the alarm severity and the additional detailed alarm description.

Alarm Models

The alarm models used by Clearwater are defined in alarmdefinition.h.