About RMON
RMON is a Simple Network Management Protocol (SNMP) Internet Engineering Task Force (IETF) standard monitoring specification that allows various network agents and console systems to exchange network monitoring data. Cisco NX-OS supports RMON alarms, events, and logs to monitor Cisco NX-OS 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 enabled by default, but no alarms are configured in Cisco NX-OS. You can configure RMON alarms 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, 1.3.6.1.2.1.2.2.1.14 represents ifInOctets.14).
When you create an alarm, you specify the following parameters:
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MIB object to monitor.
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Sampling interval—The interval that the device uses to collect a sample value of the MIB object.
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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.
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Rising threshold—The value at which the device triggers a rising alarm or resets a falling alarm.
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Falling threshold—The value at which the device triggers a falling alarm or resets a rising alarm.
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Events—The action that the 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 will 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:
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SNMP notification—Sends an SNMP risingAlarm or fallingAlarm notification when the associated alarm triggers.
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Log—Adds an entry in the RMON log table when the associated alarm triggers.
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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.
Note |
You may choose to use the default RMON events template configuration or you can delete these entries and create new RMON events. Until you create RMON alarm configurations, no alarms will be triggered by these configurations. |
High Availability for RMON
Cisco NX-OS supports stateless restarts for RMON. After a reboot or supervisor switchover, Cisco NX-OS applies the running configuration.
Virtualization Support for RMON
Cisco NX-OS supports one instance of RMON.
RMON is virtual routing and forwarding (VRF) aware. You can configure RMON to use a particular VRF to reach the RMON SMTP server.