RMON Alarm Threshold Triggers Events | Generated by AI
Question: When an alarm event is generated at the console, it is caused by network performance metrics in the network device exceeding the __ defined by the RMON alarm group.
Answer:
Correct Option: C
Detailed Explanation:
1. Overview of RMON (Remote Monitoring) RMON is a standard monitoring specification that enables various network agents and console systems to exchange network monitoring data. It is defined by the IETF, primarily in RFC 2819 (which obsoletes RFC 1757). The RMON MIB (Management Information Base) contains several groups, one of which is the Alarm Group.
2. Function of the RMON Alarm Group The Alarm Group is designed to periodically take statistical samples from variables in the MIB and compare them against previously configured values. Its primary purpose is to detect when network performance metrics deviate from acceptable norms.
3. Mechanism of Alarm Triggering
- Sampling: The network device samples specific performance variables (such as bandwidth utilization, packet errors, etc.) at regular intervals.
- Threshold Comparison: These sampled values are compared against configured thresholds. There are typically two types of thresholds:
- Rising Threshold: Triggers an alarm if the value goes above this limit.
- Falling Threshold: Triggers an alarm if the value goes below this limit.
- Event Generation: When a sampled value crosses (exceeds or falls below) these thresholds, an alarm event is generated and sent to the management console.
4. Analysis of Options
- A (Minimum) & B (Maximum): While thresholds can represent minimum or maximum acceptable limits, the technical term for the boundary that triggers an alarm in the RMON specification is a “threshold.”
- C (Threshold): This is the correct terminology. The RMON Alarm Group specifically defines “alarm thresholds” that, when crossed, generate events.
- D (Default): Alarms are generated based on configured limits specific to the network’s requirements, not merely based on factory default values.
Conclusion: An alarm event is generated at the console when network performance metrics exceed the threshold (门限值) defined by the RMON alarm group.
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