SNMP Agent Hierarchy and Objects
The SNMP agent configuration consists of:
Figure 1 shows a sample set of system management objects that make up the SNMP agent.
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System Management Configurations
A system management configuration consists of components and traps. The SRC software comes with a default system management configuration that has an ou=components object and an ou=traps object. The components and traps in the default system management configuration are called global components and global traps.
You can add components to, delete components from, or modify components in the global components object. You can modify the trap configurations in the global traps object, but you cannot add or delete traps in the global traps object.
You can create additional system management configurations with their own components and traps. System management configurations are a convenient way to specify a configuration for multiple SNMP agents installed on multiple hosts that all run the same set of components.
For instance, if you have a host in a point of presence (POP) that runs an SAE and shadow directory, you could set up a POPHost system management configuration for the POP host. You could also have a host in a back office that runs a master directory, a NIC host, and a RADIUS server. For this setup, you could create a BackOfficeHost system management configuration. Typical deployments have a small number of roles for hosts, and the system management configuration can be shared across a potentially large number of hosts with the same role.
For a given system management configuration, both the local and global components and traps are considered part of the configuration. Traps in parent system management configurations or subordinate system management configurations are not considered. If a component or trap occurs in both the global and local folder, then the local version overrides the global one.
Subfolders
SDX Admin lets you create subfolders to organize your system management configurations.
Components
Components are SRC and other network components that you can monitor with the SNMP agent; for example, the SAE, NIC hosts, RADIUS servers, directory servers, and SRC license servers.
The SNMP agent automatically creates local components for each SRC package that is installed on the host where it runs. In this case, most attributes of the component are automatically configured, including the type, start, and stop commands, and the installation date and version.
A global component is a component that is defined for all system management configurations. The global component saves you from defining the local component for each individual system management configuration when the local component definitions would all be the same. If you define a global component and a particular system management configuration requires a different definition, you can define a local component that would override the global component definition.
You can also create a container component and put subcomponents into it. Generally, container components are for monitoring components that require multiple processes, such as DirX. The SNMP agent considers the operational status of a container component as up only when all subcomponents are up, and it considers the container down if any of the subcomponents is down.
The container component start and stop commands are ignored when SNMP is used to set the administrative state of the container component. The start and stop commands of the container component are used to start and stop the whole component and are assumed to manage the starting and stopping of the processes corresponding to the contained components.
Traps
Traps are individual events that the SNMP agent can monitor, such as the number of timeouts or errors that have occurred or connections that have opened or closed. There are two types of traps:
- Performance traps—Traps that poll MIB variables associated with the trap to determine whether a variable has crossed configured thresholds. If the variable crosses a threshold, an alarm is triggered and a trap is sent to the list of receivers configured in the master agent.
A global performance trap provides thresholds and polling intervals that are used by default wherever the trap is enabled. To enable a trap for a particular system management configuration, you must create a local version of the trap. Any local definitions of thresholds or polling intervals will override the global definitions.
- Event traps—Traps that are sent when an event occurs; for example, when a connection is established or closed.
Global event traps do not have any effect on the system management configuration. To enable an event trap for a particular system management configuration, you must create a local version of the trap. To define trap receivers, you must configure the trap receivers in the master agent configuration.
For a list and description of all traps, see Chapter 11, Understanding Traps.
SNMP Traps and Informs
SNMP notifications can be sent as traps or inform requests. SNMP traps are unconfirmed notifications. SNMP informs are confirmed notifications.
SNMP traps are defined in either standard or enterprise-specific MIBs. The standard and enterprise-specific traps are compiled into the network management software. For more information on SRC traps, see Chapter 11, Understanding Traps. For information on system logging severity levels for SNMP traps, see Chapter 2, Configuring Logging for SRC Components.
With traps, the receiver does not send any acknowledgment when it receives a trap and the sender cannot determine if the trap was received. To increase reliability, SNMP informs are supported in SNMPv3. With an inform, the receiver acknowledges the message with a response. For information about configuring SNMP notification handling, see the master agent documentation.