Introduction to SNMP

The Simple Network Management Protocol (SNMP) is an industry-standard management protocol, originally designed for managing TCP/IP networks. SNMP is described by a series of Request for Comments (RFCs) that specifies and structures the information that is exchanged between managing and managed systems. Although SNMP is used predominately in TCP/IP networks, its popularity has caused its use to be extended to managing additional software and hardware products.

An SNMP agent is a process that runs on a system being managed and maintains the MIB database for the system. An SNMP manager is an application that generates requests for MIB information and processes the responses. The manager and agent communicate using the Simple Network Management Protocol.

SNMP agents (like the SNMPD daemon snmpd that ships with the AIX Base Operating System) typically have predefined MIB objects that they can access. An SNMP subagent is used to extend the number and type of MIB objects that an SNMP agent can support.

An SNMP manager can issue requests to an agent either to retrieve information from the agent's MIB (an SNMP Get request), or to change information in the agent's MIB (an SNMP Set request). An SNMP agent can also send unsolicited messages to the SNMP manager (SNMP traps).

The interaction between SNMP components in a system is shown in Figure 1.

The SNMP agent talks to both subagents and managers. The SNMP manager (which resides on one node in the network) sends requests to the agent (which resides on another). The agent sends responses and traps to the manager. For CS/AIX, the APPN MIB is implemented by the CS/AIX SNMP subagent.