Configuring RMON

This chapter contains the following sections:

Information About RMON

RMON is an Internet Engineering Task Force (IETF) standard monitoring specification that allows various network agents and console systems to exchange network monitoring data. The Cisco NX-OS supports RMON alarms, events, and logs to monitor Cisco Nexus devices.

An RMON alarm monitors a specific management information base (MIB) object for a specified interval, triggers an alarm at a specified threshold value (threshold), and resets the alarm at another threshold value. You can use alarms with RMON events to generate a log entry or an SNMP notification when the RMON alarm triggers.

RMON is disabled by default and no events or alarms are configured in Cisco Nexus devices. You can configure your RMON alarms and events by using the CLI or an SNMP-compatible network management station.

RMON Alarms

You can set an alarm on any MIB object that resolves into an SNMP INTEGER type. The specified object must be an existing SNMP MIB object in standard dot notation (for example, 1.3.6.1.2.1.2.2.1.17 represents ifOutOctets.17).

When you create an alarm, you specify the following parameters:

  • MIB object to monitor

  • Sampling interval—The interval that the Cisco Nexus device uses to collect a sample value of the MIB object.

  • Sample type—Absolute samples take the current snapshot of the MIB object value. Delta samples take two consecutive samples and calculate the difference between them.

  • Rising threshold—The value at which the Cisco Nexus device triggers a rising alarm or resets a falling alarm.

  • Falling threshold—The value at which the Cisco Nexus device triggers a falling alarm or resets a rising alarm.

  • Events—The action that the Cisco Nexus device takes when an alarm (rising or falling) triggers.


Note
Use the hcalarms option to set an alarm on a 64-bit integer MIB object.

For example, you can set a delta type rising alarm on an error counter MIB object. If the error counter delta exceeds this value, you can trigger an event that sends an SNMP notification and logs the rising alarm event. This rising alarm does not occur again until the delta sample for the error counter drops below the falling threshold.


Note
The falling threshold must be less than the rising threshold.

RMON Events

You can associate a particular event to each RMON alarm. RMON supports the following event types:

  • SNMP notification—Sends an SNMP risingAlarm or fallingAlarm notification when the associated alarm triggers.

  • Log—Adds an entry in the RMON log table when the associated alarm triggers.

  • Both—Sends an SNMP notification and adds an entry in the RMON log table when the associated alarm triggers.

You can specify a different even for a falling alarm and a rising alarm.

Configuration Guidelines and Limitations for RMON

RMON has the following configuration guidelines and limitations:

  • You must configure an SNMP user and a notification receiver to use the SNMP notification event type.

  • You can only configure an RMON alarm on a MIB object that resolves to an integer.

Verifying the RMON Configuration

Use the following commands to verify the RMON configuration information:

Command

Purpose

show rmon alarms

Displays information about RMON alarms.

show rmon events

Displays information about RMON events.

show rmon hcalarms

Displays information about RMON hcalarms.

show rmon logs

Displays information about RMON logs.

Default RMON Settings

The following table lists the default settings for RMON parameters.

Table 1. Default RMON Parameters

Parameters

Default

Alarms

None configured.

Events

None configured.

Configuring RMON Alarms

You can configure RMON alarms on any integer-based SNMP MIB object.

You can optionally specify the following parameters:

  • The eventnumber to trigger if the rising or falling threshold exceeds the specified limit.

  • The owner of the alarm.

Ensure you have configured an SNMP user and enabled SNMP notifications.

Before you begin

Ensure you have configured an SNMP user and enabled SNMP notifications.

SUMMARY STEPS

  1. switch# configure terminal
  2. switch(config)# rmon alarm index mib-object sample-interval {absolute | delta} rising-threshold value [event-index] falling-threshold value [event-index] [owner name]
  3. switch(config)# rmon hcalarm index mib-object sample-interval {absolute | delta} rising-threshold-high value rising-threshold-low value [event-index] falling-threshold-high value falling-threshold-low value [event-index] [owner name] [storagetype type]
  4. (Optional) switch# show rmon {alarms | hcalarms}
  5. (Optional) switch# copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# rmon alarm index mib-object sample-interval {absolute | delta} rising-threshold value [event-index] falling-threshold value [event-index] [owner name]

Creates an RMON alarm. The value range is from –2147483647 to 2147483647. The owner name can be any alphanumeric string.

Step 3

switch(config)# rmon hcalarm index mib-object sample-interval {absolute | delta} rising-threshold-high value rising-threshold-low value [event-index] falling-threshold-high value falling-threshold-low value [event-index] [owner name] [storagetype type]

Creates an RMON high-capacity alarm. The value range is from –2147483647 to 2147483647. The owner name can be any alphanumeric string.

The storage type range is from 1 to 5.

Step 4

(Optional) switch# show rmon {alarms | hcalarms}

(Optional)

Displays information about RMON alarms or high-capacity alarms.

Step 5

(Optional) switch# copy running-config startup-config

(Optional)

Saves this configuration change.

Example

The following example shows how to configure RMON alarms: 

switch# configure terminal

switch(config)# rmon alarm 1 1.3.6.1.2.1.2.2.1.17.83886080 5 delta rising-threshold 5 1 falling-threshold 0 owner test

switch(config)# exit

switch# show rmon alarms

Alarm 1 is active, owned by test
 Monitors 1.3.6.1.2.1.2.2.1.17.83886080 every 5 second(s)
 Taking delta samples, last value was 0
 Rising threshold is 5, assigned to event 1
 Falling threshold is 0, assigned to event 0
 On startup enable rising or falling alarm

Configuring RMON Events

You can configure RMON events to associate with RMON alarms. You can reuse the same event with multiple RMON alarms.

Ensure you have configured an SNMP user and enabled SNMP notifications.

Before you begin

Ensure that you have configured an SNMP user and enabled SNMP notifications.

SUMMARY STEPS

  1. switch# configure terminal
  2. switch(config)# rmon event index [description string] [log] [trap] [owner name]
  3. (Optional) switch(config)# show rmon {alarms | hcalarms}
  4. (Optional) switch# copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# rmon event index [description string] [log] [trap] [owner name]

Configures an RMON event. The description string and owner name can be any alphanumeric string.

Step 3

(Optional) switch(config)# show rmon {alarms | hcalarms}

(Optional)

Displays information about RMON alarms or high-capacity alarms.

Step 4

(Optional) switch# copy running-config startup-config

(Optional)

Saves this configuration change.