anaged objects or variables that can be managed. Each data element, such as a node table, is modeled as an object and given a unique name and identifier for management purposes. The complete definition of a managed object includes its naming, syntax, definitions, access method (such as read-only or read-write) that can be used to protect sensitive data and status. By allowing a status of "required" or "optional," the SNMP formulating committee allowed for the possibility that some vendors may not wish to support optional variables. Products are obligated support required objects if they wish to be compliant with the SNMP standard. Figure 21.5 also shows an agent. One can imagine an agent in every data equipment to be managed as shown in Figure 21.6. Here it shows that the (Network) Management Console manages "agents." SNMP utilizes an architecture that depends heavily upon communication between one or a small number of managers and a large number of remote agents scattered throughout the network. Agents use the MIB to provide a view of the local data that is available for manipulation by the Network Management Station. In order for a variable, such as the CPU utilization of a remote Sun workstation, to be monitored by the Network Management Station, it must be represented as an MIB object. The management station sends get and set requests to remote agents. These agents initiate traps to the management station when an unexpected event occurs. In such a con- figuration, most of the burden for retrieving and analyzing data rests on the management application. Unless data are requested in a proactive way, little information will be shown Management Console GetRequest GetResponse Agent Agent Agent MIB View MIB View MIB View HP3000 Clsco Router Sun Workstation Figure 21.6 The network management console manages agents. NETWORK MANAGEMENT at the management station. This poll-based approach increases network traffic, especially on the backbone where some users report a 5% to 10% increase in traffic due to SNMP network man