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Configuring an Alarm Entry and Its Attributes

An alarm entry monitors the value of a MIB variable. You can configure how often the value is sampled, the type of sampling to perform, and what event to trigger if a threshold is crossed.

This section discusses the following topics:

Configuring the Alarm Entry

An alarm entry monitors the value of a MIB variable. The rising-event-index, rising-threshold, sample-type, and variable statements are mandatory. All other statements are optional.

To configure the alarm entry, include the alarm statement and specify an index at the [edit snmp rmon] hierarchy level:

[edit snmp rmon]alarm index {description description;falling-event-index index;falling-threshold integer;falling-threshold-interval seconds;interval seconds;rising-event-index index;rising-threshold integer;sample-type (absolute-value | delta-value);startup-alarm (falling-alarm | rising alarm | rising-or-falling-alarm);variable oid-variable;}

index is an integer that identifies an alarm or event entry.

Configuring the Description

The description is a text string that identifies the alarm entry.

To configure the description, include the description statement and a description of the alarm entry at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]description description;

Configuring the Falling Event Index or Rising Event Index

The falling event index identifies the event entry that is triggered when a falling threshold is crossed. The rising event index identifies the event entry that is triggered when a rising threshold is crossed.

To configure the falling event index or rising event index, include the falling-event-index or rising-event-index statement and specify an index at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]falling-event-index index;rising-event-index index;

index can be from 0 through 65,535. The default for both the falling and rising event index is 0.

Configuring the Falling Threshold or Rising Threshold

The falling threshold is the lower threshold for the monitored variable. When the current sampled value is less than or equal to this threshold, and the value at the last sampling interval is greater than this threshold, a single event is generated. A single event is also generated if the first sample after this entry becomes valid is less than or equal to this threshold, and the associated startup alarm is equal to falling-alarm or rising-or-falling-alarm. After a falling event is generated, another falling event cannot be generated until the sampled value rises above this threshold and reaches the rising threshold. You must specify the falling threshold as an integer. Its default is 20 percent less than the rising threshold.

By default, the rising threshold is 0. The rising threshold is the upper threshold for the monitored variable. When the current sampled value is greater than or equal to this threshold, and the value at the last sampling interval is less than this threshold, a single event is generated. A single event is also generated if the first sample after this entry becomes valid is greater than or equal to this threshold, and the associated startup-alarm is equal to rising-alarm or rising-or-falling-alarm. After a rising event is generated, another rising event cannot be generated until the sampled value falls below this threshold and reaches the falling threshold. You must specify the rising threshold as an integer.

To configure the falling threshold or rising threshold, include the falling-threshold or rising-threshold statement at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]falling-threshold integer;rising-threshold integer;

integer can be a value from -2,147,483,647 through 2,147,483,647.

Configuring the Interval

The interval represents the period of time, in seconds, over which the monitored variable is sampled and compared with the rising and falling thresholds.

To configure the interval, include the interval statement and specify the number of seconds at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]interval seconds;

seconds can be a value from 1 through 2,147,483,647. The default is 60 seconds.

Configuring the Falling Threshold Interval

The falling threshold interval represents the interval between samples when the rising threshold is crossed. Once the alarm crosses the falling threshold, the regular sampling interval is used.

Note: You cannot configure the falling threshold interval for alarms that have the request type set to walk-request.

To configure the falling threshold interval, include the falling-threshold interval statement at the [edit snmp rmon alarm index] hierarchy level and specify the number of seconds:

[edit snmp rmon alarm index]falling-threshold-interval seconds;

seconds can be a value from 1 through 2,147,483,647. The default is 60 seconds.

Configuring the Request Type

By default an RMON alarm can monitor only one object instance (as specified in the configuration). You can configure a request-type statement to extend the scope of the RMON alarm to include all object instances belonging to a MIB branch or to include the next object instance after the instance specified in the configuration.

To configure the request type, include the request-type statement at the [edit snmp rmon alarm index] hierarchy level and specify get-next-request, get-request, or walk-request:

[edit snmp rmon alarm index]request-type (get-next-request | get-request | walk-request);

walk extends the RMON alarm configuration to all object instances belonging to a MIB branch. next extends the RMON alarm configuration to include the next object instance after the instance specified in the configuration.

Configuring the Sample Type

The sample type identifies the method of sampling the selected variable and calculating the value to be compared against the thresholds. If the value of this object is absolute-value, the value of the selected variable is compared directly with the thresholds at the end of the sampling interval. If the value of this object is delta-value, the value of the selected variable at the last sample is subtracted from the current value, and the difference is compared with the thresholds.

To configure the sample type, include the sample-type statement and specify the type of sample at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]sample-type (absolute-value | delta-value);
  • absolute-value—Actual value of the selected variable is compared against the thresholds.
  • delta-value—Difference between samples of the selected variable is compared against the thresholds.

Configuring the Startup Alarm

The startup alarm identifies the type of alarm that can be sent when this entry is first activated. You can specify it as falling-alarm, rising-alarm, or rising-or-falling-alarm.

To configure the startup alarm, include the startup-alarm statement and specify the type of alarm at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]startup-alarm (falling-alarm | rising-alarm | rising-or-falling-alarm);
  • falling-alarm—Generated if the first sample after the alarm entry becomes active is less than or equal to the falling threshold.
  • rising-alarm—Generated if the first sample after the alarm entry becomes active is greater than or equal to the rising threshold.
  • rising-or-falling-alarm—Generated if the first sample after the alarm entry becomes active satisfies either of the corresponding thresholds.

The default is rising-or-falling-alarm.

Configuring the System Log Tag

The syslog-subtag statement specifies the tag to be added to the system log message. You can specify a string of not more than 80 uppercase characters as the system log tag.

To configure the system log tag, include the syslog-subtag statement at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]syslog-subtag syslog-subtag;

Configuring the Variable

The variable identifies the MIB object that is being monitored.

To configure the variable, include the variable statement and specify the object identifier or object name at the [edit snmp rmon alarm index] hierarchy level:

[edit snmp rmon alarm index]variable oid-variable;

oid-variable is a dotted decimal (for example, 1.3.6.1.2.1.2.1.2.2.1.10.1) or MIB object name (for example, ifInOctets.1).


Published: 2010-04-27

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