Cisco WS-X6K-SUP1A-PFC= Software Guide - Page 646

Understanding SNMPv3 Chapter 36 Configuring SNMP Figure 36-1 SNMP Entity for Traditional SNMP Agents UDP IPX Other SNMP Entity Dispatcher Transport Mapping Message Dispatcher PDU Dispatcher Message Processing Subsystem v1MP v2c MP v3MP otherMP Security Subsystem User-based security model Other security model SNMP Engine Access Control Subsystem View-based access control model Other access control model 58568 Proxy foward applications Command responder applications Notification originator applications MIB Instrumentation SNMP Applications Message Processing Subsystem The message processing subsystem accepts outgoing PDUs from the dispatcher and prepares them for transmission by wrapping them in a message header and returning them to the dispatcher. The message processing subsystem also accepts incoming messages from the dispatcher, processes each message header, and returns the enclosed PDU to the dispatcher. An implementation of the message processing subsystem may support a single message format corresponding to a single version of SNMP (SNMPv1, SNMPv2c, SNMPv3), or it may contain a number of modules, each supporting a different version of SNMP. Security Subsystem The security subsystem authenticates and encrypts messages. Each outgoing message is passed to the security subsystem from the message processing subsystem. Depending on the services required, the security subsystem may encrypt the enclosed PDU and some fields in the message header. In addition, the security subsystem may generate an authentication code and insert it into the message header. After encryption, the message is returned to the message processing subsystem. 36-8 Catalyst 6000 Family Software Configuration Guide-Releases 6.3 and 6.4 78-13315-02