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Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
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Chapter 36 Configuring SNMP
Understanding SNMPv3
Figure 36-1 SNMP Entity for Traditional SNMP Agents
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.
v1MP
v2c MP
v3MP
UDP
IPX
Other
Message Dispatcher
Proxy
foward
applications
MIB Instrumentation
Command
responder
applications
Notification
originator
applications
Transport Mapping
PDU Dispatcher
SNMP Entity
SNMP Engine
Access Control
Subsystem
Security
Subsystem
Message Processing
Subsystem
Dispatcher
View-based
access control
model
User-based
security
model
Other
security
model
Other
access control
model
SNMP Applications
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otherMP
