The target agent consists of several functional units working in tandem. Generally, a packet is sent by a Network Management Station across the UDP layer of a network connection. The packet arrives at the agent via UDP. The agent accepts the packet and decodes it into a buffer, translating the incoming packet in ASN.1 format into a C structure. The structure is processed, and a response is formed. The response is then encoded into a packet in ASN.1 format and sent back across the UDP connection. (For a more detailed discussion, see 4.11 Request Processing.)

MIB extensions may be defined by the programmer and compiled into the target agent using the MIB compiler mibcomp (6.3 Compile-time MIB Extensions). Additionally, a WindNet SNMPv1/v2c view-configuration API (part of snmpdLib; see 4.9 View Tables) allows a Network Management Station user to access selective views of the MIB data tree using view tables (4.9 View Tables). Agent designers have the ability to modify the processing sequence of a set request by defining hooks (4.8 Hooks), to modify the information base itself by dynamically adding parameters (object identifiers) to the MIB (6.4 Dynamic MIB Additions), and to allow the agent to respond to significant events by defining traps (4.7 Traps).

The flow of information among the various routines which make up the agent are shown in 4.12 SNMP Agent Data Flow.