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SNMP Alerts

This section describes how to configure and use the Simple Network Management Protocol (SNMP) package to monitor your IMS AAA Server.

About SNMP

SNMP is an IETF standard protocol that lets an administrator set configuration parameters and monitor operating statistics and status for a managed device, such as a server or router, from a remote location.

About the SNMP Package

The IMS AAA Server is shipped with an SNMP agent (daemon) which must be installed on the server host machine if you want the IMS AAA Server to generate alerts to your SNMP network management station.


The IMS AAA Server must be started with the SNMP agent (daemon) enabled in order for the server to send SNMP alerts to the SNMP network management station. The server can be started automatically with SNMP enabled, or it can be started manually.

During the server installation procedure, if you answered "Yes" when asked:

Do you want to configure a3s to be automatically launched during boot time and stopped during shutdown time [y,n]: y

the server will automatically re-start each time the host machine is booted. The server installation procedure also includes a number of questions related to SNMP operation. See Example Output of pkgadd Command for IMS AAA Server Package-New Installation.

However, if you answered "No" to the above question, you will need to manually start the server and the SNMP agent (daemon) whenever the host machine is booted. See Starting and Stopping the IMS AAA Server.

The first time you start the IMS AAA Server, SNMP alerts are not generated until you configure the SNMP alerts in the server. You then need to re-start the SNMP agent (daemon) using the # ./S89snmpd start command.

SNMP Network Management Architecture

The SNMP network management architecture consists of managed devices, SNMP agents, and network management stations (NMS).

An SNMP subagent may be responsible for gathering information about network activity relating to a particular service running on the managed device.

Figure 113 illustrates the SNMP management architecture.

Figure 113: SNMP Architecture

SNMP Versions

The IMS AAA Server supports SNMP version 1 (SNMPv1), SNMP version 2c and SNMP version 3 (SNMPv3).


A management information base (MIB) is a hierarchical collection of information that resides on a managed device. A MIB defines the types of information (objects) that can be controlled and collected by an NMS and includes thresholds, counters, tables, lists, and values. Managed objects consist of one or more object instances.

MIB objects can be read-only or read-write:

For convenience, all MIBs are stored in the /usr/local/a3s_visited/current/snmp/mib directory. The IMS AAA Server supports the MIBs listed in Table 38 for server authentication and accounting statistics.

Table 38: MIBs Supported by IMS AAA Server  



Maintains authentication client statistics.


Maintains authentication server statistics.


Maintains accounting client statistics.


Maintains accounting server statistics.

Diameter MIBs


Describes Diameter Base Protocol statistics. This MIB is based on draft: DIAMETER-BASE-PROTOCOL-MIB-koehler-03.txt and DIAMETER-BASE-PROTOCOL-MIB-zorn-00-diameterBaseTraps.txt


Describes Diameter NAS application statistics. This MIB is based on draft: DIAMETER-NASREQ-APPLICATION-MIBkoehler-01.txt

SNMP Messages

SNMP uses different types of messages to send and retrieve information.

There are three types of traps or alerts:

Figure 114: SNMP Messages


Alert event dilution means you can configure IMS AAA Server so that a particular alert is sent to the NMS once for every n occurrences of the condition that generated the alert. This allows for a fine degree of control with respect to alert generation for certain warning and error conditions.

SNMP Communities

An SNMP community defines an administrative relationship between a managed device and one or more management stations on your network. Each community has a name called the community string. The community string provides access control for SNMP objects. When an NMS sends a Get or Set message to a managed device that belongs to an SNMP community, it must include the appropriate community string in the request. If the community string in the request is correct, the managed device sends back the requested information. If the community string is incorrect, the managed device discards the request without responding.

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