of variables without issuing repeated requests (i.e., GetBulkRequest). This feature should cut down the level of packet activity dedicated to network management and yet improve network management efficiency. Another advantage of SNMPv.2 over its predecessor is manager-to-manager commu- nications, which allows a station to act as either manager or agent. This allows SNMPv.2 systems to offer hierarchical management using mid-level managers to offload tasks from the central network management console. SNMPv.2 does not have to rely on TCP/IP. It can run over a variety of protocol stacks including OSI and Internet packet exchange (IPX). It also has notably enhanced security features over its predecessor. Figure 21.11 shows a generic SNMPv.2-managed configuration. 21.7.5 SNMP Version 3 (SNMPv.3) SNMP Version 3, as described in RFC 3410 (Ref. 13), points up deficiencies in Version 2 of SNMP. These were unmet design goals of Version 2 and included provision of security and administration delivering so-called "commercial grade" security with: Authentication: origin identification, message integrity, and some aspects of replay protection Privacy: confidentiality Authorization and access control Suitable remote configuration and administration capabilities for these features SNMPv.3 can be thought of as SNMPv.2 with additional security and administration capabilities. The documents that specify the SNMPv.3 management framework follow 21.7 NETWORK MANAGEMENT SYSTEMS IN ENTERPRISE NETWORKS Manager Server Management applications SNMPv2 Manager Element manager SNMPv2 SNMPv2 manager/agent manager/agent Agent SNMPv2 agent SNMPv2 agent SNMPv2 agent = SNMPv2 party Figure 21.11 A generic SNMPv.2-managed configuration. (From Ref. 2, Chapter 3.) the same architecture as previous versions and for expository purposes are organized into four main categories as follows: The data definition language Management information base (MIB) modules Protocol operations Security and administration The first three categories are covered in SNMPv.2. T