Cisco Systems Dial NMS manual About Selecting Dial OIDs, Base MIB and OID Description

Task 3—Using MRTG to Monitor and Graph Traffic Loads

About Selecting Dial OIDs

For each OID referenced in the configuration file, MRTG creates the following graphs:

•Daily graph—5 minute average data points with approximately 33 hours of data presented.

•Weekly graph—30 minute average data points with approximately 8 days of data presented.

•Monthly graph—2 hour average data points with approximately 5 weeks of data presented.

•Yearly graph—1 day average data points with approximately 1 year of data presented.

To quickly create images by using the GD graphics library, go to http://www.boutell.com/gd

About Selecting Dial OIDs

To select which dial OIDs to query when monitoring dial-up activity, see the OIDs listed in the following tables:

•Circuit utilization OIDs (Table 14)

•Modem information OIDs (Table 15)

•User information OIDs (Table 16)

Caution Be cautious when polling network elements. Polling OIDs that retrieve large amounts of data can cause CPU problems on a Cisco IOS device. For example, do not get the ARP table, walk large portions of a MIB tree, poll the wrong OID too frequently, or get statistics that have an entry for every interface. For example, a Cisco 7200 may have 10 interfaces; whereas, a Cisco AS5800 may have 3,000 interfaces.

In this case study, the tools UCD-SNMP and SNMP Commander were used to inspect and understand the MIBs. Based on this research, the network engineers at THEnet identified the OIDs in the following tables to program in to MRTG.

To see the complete structure of the CISCO-POP-MGMT-MIB and CISCO-MODEM-MGMT-MIB, go to the following URLs:

•CISCO-POP-MGMT-MIB http://www.cisco.com/univercd/cc/td/doc/cisintwk/intsolns/dialnms/popmgt.txt

•CISCO-MODEM-MGMT-MIB http://www.cisco.com/univercd/cc/td/doc/cisintwk/intsolns/dialnms/modemmgt.txt

Table 14 Circuit Utilization OIDs

Variable	Base MIB and OID	Description
Analog calls	CISCO-POP-MGMT-MIB	The number of analog calls connected.
	1.3.6.1.4.1.9.10.19.1.1.2
Active DS0s	CISCO-POP-MGMT-MIB	The total number of calls connected.
	1.3.6.1.4.1.9.10.19.1.1.4
Call count	CISCO-POP-MGMT-MIB	The number of calls that have occupied a
	1.3.6.1.4.1.9.10.19.1.1.1.1.7	specific DS0.

Basic Dial NMS Implementation Guide

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