1.2 Enterprise Agent Components

The SNMP based component of the SEA product consists of various components.

Figure 1-1 illustrates the architecture of the SEA.

Figure 1-1 Architecture of the SEA

The following is a description of each of the components associated with the SEA product.

1.2.1 SNMP Master Agent

The Master Agent is an entity or process on a managed node that exchanges SNMP protocol messages with the Managers (for example, Domain Manager, Enterprise Manager, and HP Openview).

The Master Agent listens on port 161.

1.2.2 Subagents

Subagents are zero or more processes that have access to the management information and provide manageability to various applications/components within a system. These subagents interact with the Master Agent using SNMP. These subagents do not interact with the managers directly.

1.2.3 Agent/Subagent Software Development Toolkit

The Software Development Toolkit has multiple components. It includes agent/subagent libraries, a MIB compiler, and example subagents. The MIB compiler parses a MIB and creates stub files. The stub files consist of functions that you modify and enhance appropriately to provide manageability of the respective component or application.

1.2.4 Legacy SNMP Agents

Legacy SNMP Agents are SNMP-based and work as monolithic entities in a system. The Enterprise Agent allows the integration of legacy SNMP agents. The legacy agents are those agents already in released products from Sun or other companies.

1.2.5 Mapper

The Enterprise Agent technology also allows you to integrate DMI 2.0 functionality. This is accomplished through the mapper, that acts as a subagent. The mapper receives requests from the Master Agent and converts them into appropriate DMI requests, that are then sent to the DMI Service Provider. When the mapper receives the response back from the DMI Service Provider, it converts this response into the SNMP response and forwards it to the Manager through the Master Agent.

1.2.6 Terminology

Following are additional terms you need to be familiar with when using the SEA product.

Registration occurs when the Master Agent receives information from a subagent and then provides the subagent with management of a MIB subtree.

A subtree is indicated by a single oid. The Master Agent has no understanding of what this subtree is without any MIB specification. The subtree may actually be an entire MIB (e.g., 'host'), a full instance (e.g., hrDeviceDescr.42), or may not even be a subtree named in any MIB specification.

An oid range is the range of oids implied by a subtree. For instance, the subtree 1.2.3 carries an implied range of 1.2.3 up to but not including 1.2.4.

A duplicate registration is an attempt by one subagent to register a subtree that exactly matches a subtree already registered by another subagent.

An overlapping registration is an attempt by one subagent to register a subtree that is contained within, or contains, a subtree already registered by another subagent.

Dispatching is the communication of a management request from the Master Agent to one or more subagents. Dispatching is performed according to the Master Agent's current view of registered subtrees, and an explicitly stated algorithm.

Additional terms are described in this guide's glossary.