h Algorithm 1) and the privacy protocol suggested for encryption and decryption is DES (Data Encryption Standard). Other authentication and privacy protocols can also be used. 6. RFC 3415: View-Based Access Control Model (VACM): VACM details admin- istrative capabilities involving access to objects in the MIB. The community string that was discussed in SNMPv1 and SNMPv2 is also used in SNMPv3. Here the community string is used to identify the data requester and its location, and to determine access control and MIB view information. This is achieved in SNMPv3 using a mode dynamic access control model that is easy to administer. The Architecture of SNMPv3 is explained using an SNMP entity which is an implementation feature. In SNMPv3, the protocol entities and application entities involved in an SNMP interaction are clearly marked under SNMP engine and SNMP application, respectively. SNMP manager and SNMP agent are two SNMP entities. The architecture of SNMPv3 is shown in Figure 14.5. The protocol engine performs actions like message processing, dispatch of pro- cessed message, and security handling. It does not deal with application specific interactions, which are done by "SNMP Applications." SNMP entity SNMP engine Message processing Security Access control Dispatcher subsystem subsystem subsystem SNMP applications Command Command Notification Notification Proxy generator originator receiver forwarder Other responder Figure 14.5 SNMPv3 architecture. Fundamentals of EMS, NMS and OSS/BSS The components in the SNMP engine are: Dispatcher: This module handles sending and receiving of messages. This module does the transport mapping, interacts with the message processing module to get messages and dispatches the PDUs to command and notifica- tion handlers. Message processing subsystem: The message process subsystem supports one or more message processing models. This subsystem has one or more modules corresponding to the versions of SNMP supported. The dispatcher module identifies the version of the SNMP message and 