28 SNMP CONFIGURATIONSNMP ConfigurationIntroductionThe Simple Network Management Protocol (SNMP) has gained the most extensiveapplication in the computer networks. SNMP has been put into use and widelyaccepted as an industry standard in practice. It is used for ensuring the transmissionof the management information between any two nodes. In this way, networkadministrators can easily search and modify the information on any node on thenetwork. In the meantime, they can locate faults promptly and implement the faultdiagnosis, capacity planning and report generating. SNMP adopts the pollingmechanism and provides the most basic function set. It is most applicable to thesmall-sized, fast-speed and low-cost environment. It only requires the unverifiedtransport layer protocol UDP; and is thus widely supported by many other products.In terms of structure, SNMP can be divided into two parts, namely, NetworkManagement Station and Agent. Network Management Station is the workstationfor running the client program. At present, the commonly used NM platforms includeSun NetManager and IBM NetView. Agent is the server software operated onnetwork devices. Network Management Station can send GetRequest,GetNextRequest and SetRequest messages to the Agent. Upon receiving the requestsfrom the Network Management Station, Agent will perform Read or Write operationaccording to the message types, generate and return the Response message toNetwork Management Station. On the other hand, Agent will send Trap message onits own initiative to the Network Management Station to report the events wheneverthe device encounters any abnormalities such as new device found and restart.SNMP Versions andSupported MIBTo uniquely identify the management variables of a device in SNMP messages, SNMPadopts the hierarchical naming scheme to identify the managed objects. It is like atree. A tree node represents a managed object, as shown in the Figure 165. Thus theobject can be identified with the unique path starting from the root.Figure 165 Architecture of the MIB TreeThe MIB (Management Information Base) is used to describe the hierarchicalarchitecture of the tree and it is the set defined by the standard variables of themonitored network device. In Figure 166, the managed object B can be uniquelyspecified by a string of numbers {1.2.1.1}. The number string is the Object Identifier ofthe managed object.A261521121B
