68 SNMP C ONFIGURATIONSNMP Overview By far, the simple network management protocol (SNMP) has gained the mostextensive application in the computer networks. SNMP has been put into use andwidely accepted as an industry standard in practice. It is used for ensuring thetransmission of the management information between any two nodes. In this way,network administrators can easily search and modify the information on any nodeon the network. In the meantime, they can locate faults promptly and implementthe fault diagnosis, capacity planning and report generating.SNMP adopts the polling mechanism and provides the most basic function set. It ismost applicable to the small-sized, fast-speed and low-cost environment. It onlyrequires the connectionless transport layer protocol UDP; and is thus widelysupported by many products.SNMP OperationMechanismSNMP can be divided into two parts, namely, Network Management Station andAgent:Network management station (NMS) is the workstation for running the clientprogram. At present, the commonly used NM platforms include 3Com’s NetworkManagement Products, Sun NetManager and IBM NetView.Agent is the server software operated on network devices.The NMS can send GetRequest, GetNextRequest and SetRequest messages to theAgent. Upon receiving the requests from the NMS, Agent will perform Read orWrite operation according to the message types, generate and return theResponse message to the NMS.Agent will send Trap message on its own initiative to the NMS to report the eventswhenever the device status changes or the device encounters any abnormalitiessuch as restarting the device.SNMP Versions Currently SNMP Agent of the device supports SNMP V3, and is compatible withSNMP V1 and SNMP V2C.SNMP V3 adopts user name and password authentication.SNMP V1 and SNMP V2C adopt community name authentication. The SNMPpackets failing to pass community name authentication are discarded. Thecommunity name is used to define the relation between SNMP NMS and SNMPAgent. The community name can limit access to SNMP Agent from SNMP NMS,functioning as a password. You can define the following features related to thecommunity name.
