Configuring RMON Support

First Published: July 27, 1999
Last Updated: February 17, 2011

This module describes the Remote Monitoring (RMON) MIB agent specification and its usage in conjunction with Simple Network Management Protocol (SNMP) to monitor traffic using alarms and events.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Configuring RMON Support" section.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Prerequisites for Configuring RMON Support

•Restrictions for Configuring RMON Support

•Information About Configuring RMON Support

•How to Configure RMON Support

•Configuration Examples for RMON Support

•Additional References

•Feature Information for Configuring RMON Support

Prerequisites for Configuring RMON Support

•RMON requires SNMP to be configured (you must be running a version of SNMP on the server that contains the RMON MIB).

•RMON can be very data and processor intensive. You must measure usage effects to ensure that router performance is not degraded by RMON and to minimize excessive management traffic overhead. Native mode in RMON is less intensive than promiscuous mode.

Restrictions for Configuring RMON Support

•Full RMON packet analysis (as described in RFC 1757) is supported only on an Ethernet interface of Cisco 2500 series routers and Cisco AS5200 series universal access servers.

•A generic RMON console application is recommended in order to take advantage of the RMON network management capabilities.

Information About Configuring RMON Support

To configure RMON, you need to understand the following concepts:

•RMON Overview

•RMON Groups

•RMON Event and Alarm Notifications

•RMON MIB

•HC Alarm MIB

RMON Overview

RMON is a standard monitoring specification that enables various network monitors and console systems to exchange network-monitoring data. RMON provides network administrators with more flexibility in selecting network-monitoring probes and consoles with features that meet their particular networking needs.

The RMON specification defines a set of statistics and functions that can be exchanged between RMON-compliant console managers and network probes. RMON provides network administrators with comprehensive network-fault diagnosis, planning, and performance-tuning information.

The RMON feature identifies activity on individual nodes and allows you to monitor all nodes and their interaction on a LAN segment. Used in conjunction with the SNMP agent in a router, RMON allows you to view both traffic that flows through the router and segment traffic that is not necessarily destined for the router. Combining RMON alarms and events (classes of messages that indicate traffic violations and various unusual occurrences over a network) with existing MIBs allows you to choose where proactive monitoring will occur.

RMON Groups

RMON delivers information in RMON groups of monitoring elements, each providing specific sets of data to meet common network-monitoring requirements. Each group is optional so that you do not need to support all the groups within the Management Information Base (MIB). Some RMON groups require support of other RMON groups to function properly.

Table 1 summarizes the nine monitoring groups specified in the RFC 1757 Ethernet RMON MIB. For more information on gathering RMON statistics for these data types, refer to "Configuring RMON Groups" section.

Note All Cisco IOS software images ordered without the explicit RMON option include limited RMON support (RMON alarms and event groups only). Images ordered with the RMON option include support for all nine management groups (statistics, history, alarms, hosts, hostTopN, matrix, filter, capture, and event). As a security precaution, support for the capture group allows capture of packet header information only; data payloads are not captured.

Table 1 RMON Monitoring Groups

RMON Group
Function
Elements

Statistics

Contains statistics measured by the probe for each monitored interface on this device.

Packets dropped, packets sent, bytes sent (octets), broadcast packets, multicast packets, CRC errors, runts, giants, fragments, jabbers, collisions, and counters for packets ranging from 64 to 128, 128 to 256, 256 to 512, 512 to 1024, and 1024 to 1518 bytes.

History

Records periodic statistical samples from a network and stores them for later retrieval.

Sample period, number of samples, items sampled.

Alarm

Periodically takes statistical samples from variables in the probe and compares them with previously configured thresholds. If the monitored variable crosses a threshold, an event is generated.

Includes the alarm table and requires the implementation of the event group. Alarm type, interval, starting threshold, stop threshold.

Host

Contains statistics associated with each host discovered on the network.

Host address, packets, and bytes received and transmitted, as well as broadcast, multicast, and error packets.

HostTopN

Prepares tables that describe the hosts that top a list ordered by one of their base statistics over an interval specified by the management station. Thus, these statistics are rate-based.

Statistics, host(s), sample start and stop periods, rate base, duration.

Matrix

Stores statistics for conversations between sets of two addresses. As the device detects a new conversation, it creates a new entry in its table.

Source and destination address pairs and packets, bytes, and errors for each pair.

Filters

Enables packets to be matched by a filter equation. These matched packets form a data stream that might be captured or that might generate events.

Bit-filter type (mask or not mask), filter expression (bit level), conditional expression (and, or not) to other filters.

Packet Capture

Enables packets to be captured after they flow through a channel.

Size of buffer for captured packets, full status (alarm), number of captured packets.

Events

Controls the generation and notification of events from this device.

Event type, description, last time event sent.


RMON Event and Alarm Notifications

Thresholds allow you to minimize the number of notifications sent on the network. The RMON MIB defines two traps, the risingAlarm trap which is the rising-threshold value and fallingAlarm trap which is the falling-threshold value. Alarms are triggered when a problem exceeds a set rising-threshold value. No alarm notifications are sent until the agent recovers, as defined by the falling-threshold value. This means that notifications are not sent each time a minor failure or recovery occurs.

You can set an RMON alarm on any MIB object in the access server. You cannot disable all the alarms you configure at once. The delta value tests the change between MIB variables, which affects the alarmSampleType in the alarmTable of the RMON MIB. The absolute value tests each MIB variable directly, which affects the alarmSampleType in the alarmTable of the RMON MIB.

Refer to RFC 1757 to learn more about alarms and events and how they interact with each other.

RMON MIB

RMON MIB supports for polling of 64 bit counters and includes the following features:

•usrHistory group. This MIB group is similar to the RMON etherHistory group except that the group enables you to specify the MIB objects that are collected at each interval.

•partial probeConfig group. This MIB group is a subset of the probeConfig group implemented in read-only mode. These objects implement the simple scalars from this group. Table 2 details new partial probeConfig group objects.

Table 2 partial probeConfig Group Objects 

Object
Description

probeCapabilities

The RMON software groups implemented.

probeSoftwareRev

The current version of Cisco IOS software running on the device.

probeHardwareRev

The current version of the Cisco device.

probeDateTime

The current date and time.

probeResetControl

Initiates a reset.

probeDownloadFile

The source of the image running on the device.

probeDownloadTFTPServer

The address of the server that contains the Trivial File Transfer Protocol (TFTP) file that is used by the device to download new versions of Cisco IOS software.

probeDownloadAction

Specifies the action of the commands that cause the device to reboot.

probeDownloadStatus

The state of a reboot.

netDefaultGateway

The router mapped to the device as the default gateway.

hcRMONCapabilities

Specifies the features mapped to this version of RMON.


In Cisco IOS Release 12.1, the RMON agent was rewritten to improve performance and add some new features. Table 3 highlights some of the improvements implemented.

Table 3 RMON MIB Updates

Prior to the RMON MIB Update in Cisco IOS Release 12.1
New Functionality in Cisco IOS Release 12.1

RMON configurations do not persist across reboots. Information is lost after a new session on the RMON server.

RMON configurations persist across reboots. Information is preserved after a new session on the RMON server.

Packet analysis applies only on the MAC header of the packet.

Complete packet capture is performed with analysis applied to all frames in packet.

Only RMON I MIB objects are used for network monitoring.

RMON I and selected RMON II objects are used for network monitoring.


HC Alarm MIB

The high-capacity (HC) Alarm MIB, which is an extension of RMON Alarm group table objects, supports polling of RMON variables up to 64 bit values. The HC-ALARM-MIB defines two traps, the hcRisingAlarm which provides the rising-threshold value and hcFallingAlarm which provides the falling-threshold value.

Refer to RFC 3434 to learn more about HC alarms.

How to Configure RMON Support

The tasks in the following sections explain how to configure RMON support:

•Configuring RMON (required)

•Configuring RMON Event and Alarm Notifications (required)

•Configuring RMON Groups (optional)

Configuring RMON

This task explains how to configure RMON and RMON queue size. In native mode, RMON monitors only those packets that are received by the interface. In promiscuous mode, RMON monitors all packets on the LAN segment.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface type number

4. rmon {native | promiscuous}

5. exit

6. rmon queuesize size

7. exit

8. show rmon

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

interface type number

Example:

Router(config)# interface FastEthernet 1/0

Specifies an interface type and number, and places the router in interface configuration mode.

Step 4 

rmon {native | promiscuous}

Example:

Router(config-if)# rmon native

Configures RMON on Ethernet interfaces in native or promiscuous mode.

•In the example, RMON is configured in the native mode.

Step 5 

exit

Example:

Router(config-if)# exit

Exits the interface configuration mode and places the router in global configuration mode.

Step 6 

rmon queuesize size

Example:

Router(config)# rmon queuesize 128

(Optional) Configures the size of the queue that holds packets for analysis by the RMON process.

Step 7 

exit

Example:

Router(config)# exit

Exits global configuration mode and enters privileged EXEC mode.

Step 8  

show rmon
Example:

Router# show rmon

Displays general RMON statistics.

Configuring RMON Event and Alarm Notifications

The following tasks describe how to configure RMON event and alarm notifications.

SUMMARY STEPS

1. enable

2. configure terminal

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

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

5. rmon hc-alarms number variable interval {delta | absolute} rising-threshold value [event-number] falling-threshold value [event-number] [owner string]

6. exit

7. show rmon alarms

8. show rmon hc-alarms

9. show rmon events

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

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

Example:

Router(config)# rmon event number

Adds or removes an event (in the RMON event table) that is associated with an RMON event number.

Step 4 

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

Example:

Router(config)# rmon alarm 10 ifEntry.20.1 20 delta rising-threshold 15 1 falling-threshold 0 owner owner1

Configures an alarm on any MIB object.

Step 5 

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

Example:

Router(config)# rmon hc-alarms 2 ifInOctets.2 20 delta rising-threshold 2000 2 falling-threshold 1000 1 owner own

(Optional) Configures an HC alarm on any MIB object.

Step 6 

exit

Example:

Router(config)# exit

Exits the global configuration mode and enters the privileged EXEC mode.

Step 7 

show rmon alarms

Example:

Router# show rmon alarm

Displays the RMON alarm table.

Step 8 

show rmon hc-alarms

Example:

Router# show rmon hc-alarms

Displays the RMON HC alarm table.

Step 9 

show rmon events

Example:

Router# show rmon events

Displays the RMON event table.

Configuring RMON Groups

The following tasks explain how to configure RMON groups by gathering RMON statistics for data types.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface type number

4. rmon collection history controlEntry integer [owner ownername] [buckets bucket-number] [interval seconds]

5. rmon collection host controlEntry integer [owner ownername]

6. rmon collection matrix controlEntry integer [owner ownername]

7. rmon collection rmon1 controlEntry integer [owner ownername]

8. exit

9. rmon capture-userdata

10. exit

11. show rmon history

12. show rmon hosts

13. show rmon matrix

14. show rmon statistics

15. show rmon capture

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

interface type number

Example:

Router(config)# interface FastEthernet 1/0

Specifies an interface type and number, and places the router in interface configuration mode.

Step 4 

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

Example:

Router(config-if)# rmon collection history controlEntry 20 owner john

(Optional) Enables RMON history gathering on an interface.

Step 5 

rmon collection host controlEntry integer [owner ownername]

Example:

Router(config-if)# rmon collection host controlEntry 40 owner own1

(Optional) Enables RMON MIB host collection group of statistics on an interface.

Step 6 

rmon collection matrix controlEntry integer [owner ownername]

Example:

Router(config-if)# rmon collection matrix controlEntry 25 owner john

(Optional) Enables RMON MIB matrix group of statistics on an interface.

Step 7 

rmon collection rmon1 controlEntry integer [owner ownername]

Example:

Router(config-if)# rmon collection rmon1 controlEntry 30 owner john

(Optional) Enables all possible autoconfigurable RMON MIB statistic collections on an interface.

Step 8 

exit

Example:

Router(config-if)# exit

Exits the interface configuration mode and places the router in global configuration mode.

Step 9 

rmon capture-userdata

Example:

Router(config)# rmon capture-userdata

Disables the packet zeroing feature that initializes the user payload portion of each RMON MIB packet.

Step 10 

exit

Example:

Router(config)# exit

Exits global configuration mode and enters privileged EXEC mode.

Step 11 

show rmon history

Example:

Router# show rmon history

Displays the RMON history table.

Step 12 

show rmon hosts

Example:

Router# show rmon hosts

Displays the RMON hosts table.

Step 13 

show rmon matrix

Example:

Router# show rmon matrix

Displays the RMON matrix table and values associated with RMON variables.

Step 14 

show rmon statistics

Example:

Router# show rmon statistics

Displays the RMON statistics table.

Step 15 

show rmon capture

Example:

Router# show rmon capture

Displays the contents of the router's RMON capture table.

Configuration Examples for RMON Support

This section provides the following examples:

•Configuring RMON: Example

•Configuring RMON Event and Alarm Notifications: Example

•Configuring RMON Tables: Example

Configuring RMON: Example

The following example shows how to configure RMON with a queuesize of 100 packets in promiscuous mode: 

Router> enable

Router# configure terminal

Router(config)# interface fastethernet 0/0

Router(config-if)# rmon promiscuous

Router(config-if)# exit

Router(config)# rmon queuesize 100

The following is a sample output from the show rmon command. All counters are from the time the router was initialized: 

Router# show rmon


145678 packets input (34562 promiscuous), 0 drops

145678 packets processed, 0 on queue, queue utilization 15/100

Configuring RMON Event and Alarm Notifications: Example

The following example shows how to enable the rmon event global configuration command: 

Router> enable

Router# configure terminal

Router(config)# rmon event 1 log trap eventtrap description "High ifOutErrors" owner 
ownerA

This example creates RMON event number 1, which is defined as High ifOutErrors, and generates a log entry when the event is triggered by an alarm. The user ownerA 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.

The following is a sample output from the show rmon events command: 

Router# show rmon events


Event 1 is active, owned by ownerA

 Description is High ifOutErrors

 Event firing causes log and trap to community rmonTrap, last fired 00:00:00

The following example shows how to configure an RMON alarm using the rmon alarm global configuration command: 

Router> enable

Router# configure terminal

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

This example configures RMON alarm number 10. The alarm monitors the MIB variable ifEntry.20.1 once every 20 seconds until the alarm is disabled, and checks the change in the rise or fall of the variable. 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 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.

The following is sample output from the show rmon alarms command 

Router# show rmon alarms


Alarm 2 is active, owned by owner_a

 Monitors ifEntry.20.1.20 every 20 seconds

 Taking delta samples, last value was 0

 Rising threshold is 15, assigned to event 12

 Falling threshold is 0, assigned to event 0

 On startup enable rising or falling alarm

The following example shows how to configure an RMON HC alarm using the rmon hc-alarms global configuration command: 

Router> enable

Router# configure terminal

Router(config)# rmon hc-alarms 2 ifInOctets.2 20 delta rising-threshold 2000 2 
falling-threshold 1000 1 owner own

This example configures RMON HC alarm number 2. The alarm monitors the MIB variable ifInOctets.2 once every 20 seconds until the alarm is disabled, and checks the change in the rise or fall of the variable. If the ifInOctets.2 value shows a MIB counter increase of 2000 or more, such as from 100000 to 103000, the alarm is triggered. The alarm in turn triggers event number 2, which is configured with the rmon event command. Possible events include a log entry or a Simple Network Management Protocol (SNMP) trap. If the ifInOctets.2 value changes by 1000 (falling threshold is 1000), the alarm is reset and can be triggered again.


To display the contents of the RMON HC alarm table of the router, use the show rmon hc-alarms command in privileged EXEC mode. The following is sample output: 

Router# show rmon hc-alarms


Router#show rmon hc-alarms 

 Monitors ifInOctets.1 every 20 second(s)

 Taking absolute samples, last value was 0

 Rising threshold Low is 4096, Rising threshold Hi is 0, 

               assigned to event 0

 Falling threshold Low is 1280, Falling threshold Hi is 0,

               assigned to event 0

 On startup enable rising or falling alarm

Configuring RMON Tables: Example

The following example shows how to enable the RMON collection matrix group of statistics with an ID number of 25 and specifies john as the owner: 

Router> enable

Router# configure terminal

Router(config)# interface fastethernet 0/0

Router(config-if)# rmon collection matrix controlEntry 25 owner john

To view values associated with RMON variables, enter the show rmon matrix privileged EXEC command (Cisco 2500 series routers and Cisco AS5200 access servers only). The following is a sample output: 

Router# show rmon matrix


Matrix 1 is active and owned by john

Monitors controlEntry

Table size is 25, last time an entry was deleted was at 11:18:09

Source addr is 0000.0c47.007b, dest addr is ffff.ffff.ffff

Transmitted 2 pkts, 128 octets, 0 errors

Source addr is 0000.92a8.319e, dest addr is 0060.5c86.5b82

Transmitted 2 pkts, 384 octets, 1 error

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

CNS commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS Network Management Command Reference 3.0


Standards

Standard
Title

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

—


MIBs

MIB
MIBs Link

•RMON MIB

•HC-Alarm MIB

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

RFC 1757

Remote Network Monitoring Management Information Base

RFC 2021

Remote Network Monitoring Management Information Base Version 2 using SMIv2

RFC 3434

Remote Monitoring MIB Extensions for High Capacity Alarms


Technical Assistance

Description
Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html


Feature Information for Configuring RMON Support

Table 4 lists the release history for this feature and provides links to specific configuration information.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 4 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Table 4 Feature Information for Configuring RMON Support 

Feature Name
Releases
Feature Information

HC Alarm MIB

12.2(33)SXI
12.2(33)SRE

The HC Alarm MIB feature provides an extension to the RMON-1 Alarm group table objects which was used to support counter 32 objects for threshold capabilities. The HC Alarm MIB adds support to threshold capabilities for counter 64 objects.

The following sections provide information about this feature:

•HC Alarm MIB

•Configuration Examples for RMON Support

The following commands were introduced: rmon hc-alarms, show rmon hc-alarms.

Remote Monitoring MIB Update

12.0(5)T

The RMON Rewrite feature updated the Remote Monitoring MIB to improve performance and available features.

The following sections provide information about this feature:

•RMON MIB

•Configuring RMON Groups

•Configuration Examples for RMON Support

The following commands were introduced: rmon capture-userdata, rmon collection history, rmon collection host, rmon collection matrix, rmon collection rmon1, show rmon capture, show rmon filter, show rmon hosts, show rmon matrix.

RMON Events and Alarms

11.2
Cisco IOS XE Release 2.1

The RMON Events and Alarms feature introduces the ability to combine RMON alarms and events (classes of messages that indicate traffic violations and various unusual occurrences over a network) with existing MIBs allows you to choose where proactive monitoring will occur.

In Cisco IOS XE Release 2.1, this feature was introduced on Cisco ASR 1000 series routers.

The following sections provide information about this feature:

•RMON Event and Alarm Notifications

•Configuration Examples for RMON Support

The following commands were introduced: rmon alarm, rmon event, rmon queuesize.

RMON Full

11.2

The RMON Full feature identifies activity on individual nodes and helps monitor all nodes and their interaction on a LAN segment. Used in conjunction with the SNMP agent in a router, RMON can be used to view both traffic that flows through the router and segment traffic not necessarily destined for the router.

The following sections provide information about this feature:

•Information About Configuring RMON Support

•Configuration Examples for RMON Support

RMON MIB enhancement to support 64 bit counters

12.2(33)SXI
12.2(33)SRE

RMON MIB enhancement to support 64 bit counters features provides support for the ability to poll 64 bit counters.

The following section provides information about this feature:

•RMON MIB


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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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