Configuring RMON

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Prerequisites for RMON

  • You must configure SNMP on the switch to access RMON MIB objects.
  • We recommend that you use a generic RMON console application on the network management station (NMS) to take advantage of the RMON network management capabilities.

Restrictions for RMON

  • 64-bit counters are not supported for RMON alarms.

Information About RMON

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. You can use the RMON feature with the Simple Network Management Protocol (SNMP) agent in the switch to monitor all the traffic flowing among switches on all connected LAN segments as shown in Figure 34-1.

Figure 34-1 Remote Monitoring Example

 

The switch supports these RMON groups (defined in RFC 1757):

  • Statistics (RMON group 1)—Collects Ethernet statistics (including Fast Ethernet and Gigabit Ethernet statistics, depending on the switch type and supported interfaces) on an interface.
  • History (RMON group 2)—Collects a history group of statistics on Ethernet ports (including Fast Ethernet and Gigabit Ethernet statistics, depending on the switch type and supported interfaces) for a specified polling interval.
  • Alarm (RMON group 3)—Monitors a specific management information base (MIB) object for a specified interval, triggers an alarm at a specified value (rising threshold), and resets the alarm at another value (falling threshold). Alarms can be used with events; the alarm triggers an event, which can generate a log entry or an SNMP trap.
  • Event (RMON group 9)—Specifies the action to take when an event is triggered by an alarm. The action can be to generate a log entry or an SNMP trap.

Because switches supported by this software release use hardware counters for RMON data processing, the monitoring is more efficient, and little processing power is required.

Note 64-bit counters are not supported for RMON alarms.

RMON is disabled by default; no alarms or events are configured.

How to Configure RMON

Configuring RMON Alarms and Events

You can configure your switch for RMON by using the command-line interface (CLI) or an SNMP-compatible network management station.

 

Command
Purpose

Step 1

configure terminal

Enters global configuration mode.

Step 2

rmon alarm number variable interval { absolute | delta } rising-threshold value [ event-number ]
falling-threshold value [ event-number ]
[ owner string ]

Sets an alarm on a MIB object.

  • number —Specifies the alarm number. The range is 1 to 65535.
  • variable —Specifies the MIB object to monitor.
  • interval —Specifies the time in seconds the alarm monitors the MIB variable. The range is 1 to 4294967295 seconds.
  • Specifies the absolute keyword to test each MIB variable directly. Specifies the delta keyword to test the change between samples of a MIB variable.
  • value —Specifies a number at which the alarm is triggered and one for when the alarm is reset. The range for the rising threshold and falling threshold values is -2147483648 to 2147483647.
  • (Optional) event-number —Specifies the event number to trigger when the rising or falling threshold exceeds its limit.
  • (Optional) owner string —Specifies the owner of the alarm.

Step 3

rmon event number [ description string ] [ log ] [ owner string ] [ trap community ]

Adds an event in the RMON event table that is associated with an RMON event number.

  • number —Assigns an event number. The range is 1 to 65535.
  • (Optional) description string —Specifies a description of the event.
  • (Optional) log —Generates an RMON log entry when the event is triggered.
  • (Optional) owner string —Specifies the owner of this event.
  • (Optional) trap community —Enters the SNMP community string used for this trap.

Step 4

end

Returns to privileged EXEC mode.

Collecting Group History Statistics on an Interface

You must first configure RMON alarms and events to display collection information.

 

Command
Purpose

Step 1

configure terminal

Enters global configuration mode.

Step 2

interface interface-id

Specifies the interface on which to collect history, and enters interface configuration mode.

Step 3

rmon collection history index
 [ buckets bucket-number ] [ interval seconds ] [ owner ownername ]

Enables history collection for the specified number of buckets and time period.

  • index —Identifies the RMON group of statistics. The range is 1 to 65535.
  • (Optional) buckets bucket-number —Specifies the maximum number of buckets desired for the RMON collection history group of statistics. The range is 1 to 65535. The default is 50 buckets.
  • (Optional) interval seconds —Specifies the number of seconds in each polling cycle. The range is 1 to 3600. The default is 1800 seconds.
  • (Optional) owner ownername —Enters the name of the owner of the RMON group of statistics.

Step 4

end

Returns to privileged EXEC mode.

Collecting Group Ethernet Statistics on an Interface

 

Command
Purpose

Step 1

configure terminal

Enters global configuration mode.

Step 2

interface interface-id

Specifies the interface on which to collect statistics, and enters interface configuration mode.

Step 3

rmon collection stats index [ owner ownername ]

Enables RMON statistic collection on the interface.

  • index —Specifies the RMON group of statistics. The range is from 1 to 65535.
  • (Optional) owner ownername —Enters the name of the owner of the RMON group of statistics.

Step 4

end

Returns to privileged EXEC mode.

Monitoring and Maintaining RMON

 

Table 34-1 Commands for Displaying RMON Status

Command
Purpose

show rmon

Displays general RMON statistics.

show rmon alarms

Displays the RMON alarm table.

show rmon events

Displays the RMON event table.

show rmon history

Displays the RMON history table.

show rmon statistics

Displays the RMON statistics table.

Configuration Examples for RMON

Configuring an RMON Alarm Number: Example

The following example shows how to configure an RMON alarm number:

Switch(config)# rmon alarm 10 ifEntry.20.1 20 delta rising-threshold 15 1 falling-threshold 0 owner jjohnson
 

The alarm monitors the MIB variable ifEntry.20.1 once every 20 seconds until the alarm is disabled and checks the change in the variable’s rise or fall. If the ifEntry.20.1 value shows a MIB counter increase of 15 or more, such as from 100000 to 100015, the alarm is triggered. The alarm in turn triggers event number 1, which is configured with the rmon event command. Possible events can include a log entry or an SNMP trap. If the ifEntry.20.1 value changes by 0, the alarm is reset and can be triggered again.

 

Creating an RMON Event Number: Example

The following example creates RMON event number 1:

Switch(config)# rmon event 1 log trap eventtrap description "High ifOutErrors" owner jjones
 

The event is defined as High ifOutErrors and generates a log entry when the event is triggered by the alarm. The user jjones owns the row that is created in the event table by this command. This example also generates an SNMP trap when the event is triggered.

Configuring RMON Statistics: Example

This example shows how to collect RMON statistics for the owner root :

Switch(config)# interface gigabitethernet1/1
Switch(config-if)# rmon collection stats 2 owner root
 

Additional References

The following sections provide references related to switch administration:

Related Documents

Related Topic
Document Title

Cisco IE 2000 commands

Cisco IE 2000 Switch Command Reference, Release 15.0(1)EY

Cisco IOS basic commands
Cisco IOS system management commands

Cisco IOS Configuration Fundamentals Command Reference

SNMP configuration

Chapter 36, “Configuring SNMP”

Alarm and event interaction

RFC 1757

Standards

Standards
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

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MIBs

MIBs
MIBs Link

—

To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

RFCs

RFCs
Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

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Technical Assistance

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