Solaris System Management Agent Developer's Guide

Extending the Agent

The Net-SNMP agent can be extended in the following ways:

The agent can be recompiled to include a static module, which becomes part of the agent infrastructure. Static modules are initialized on agent start up. Examples of static modules include the VACM and USM modules. The System Management Agent was developed by compiling several static modules for MIBs that are not included in the Net-SNMP agent. See Features Added in System Management Agent for a list of the MIBs included in SMA.

You cannot deploy your own modules as static modules with SMA because you cannot recompile the SMA code.
Modules can be loaded into the master agent's process image. A shared object is dynamically loaded into the agent when the agent is running. The shared object registers the OIDs for the MIB that is supported by the shared object. The location of the shared object libraries for the module can be specified through SNMP requests or in the agent configuration file.
Modules can be loaded into secondary SNMP subagents. Subagents are separate executable programs that can dynamically register themselves with the agent that is running on the designated SNMP port. The monitoring agent processes any SNMP request that comes to the SNMP port, and can send a request to a subagent, if needed. In this scenario, the agent on the designated port is called the master agent. The AgentX RFCs 2741 and 2742 define the protocols between the subagent and master agent as well as the MIBs that contain details of the registrations. For more information on master agents and subagents, see Chapter 6, Deploying Modules.
A module can be delivered as an SNMP agent. The master agent can interact with such agents through a proxy mechanism.

Note –

The System Management Agent supports module deployment in the form of dynamically loaded modules or subagents. The agent also provides a proxy mechanism. You cannot recompile the System Management Agent.

See Chapter 6, Deploying Modules for information about how to deploy modules as dynamic modules and in subagents.