3Com Router 3000 Ethernet FamilyConfiguration Guide Chapter 9 SNMP Configuration3Com Corporation9-1Chapter 9 SNMP Configuration9.1 Protocol Introduction9.1.1 Brief IntroductionCurrently, the most widely used network management protocol in computer network isSimple Network Management Protocol (SNMP), which is an applicable industrialstandard adopted widely. Its purpose is to ensure the transmission of managementinformation between any two points so that the network administrator can retrieve theinformation at any point on the network and perform appropriate modification,troubleshooting, fault diagnosis, and volume planning and reporting. It adopts a pollingmechanism and offers an underlying function set, which is appropriate especially in asmall environment in need of high speed and low cost. It only requires unacknowledgedtransport layer protocol UDP and is widely supported by a variety of products.Structurally, SNMP can be divided into two parts, NMS and AGENT. The NMS (NetworkManagement Station) is a workstation on which the client program is running. Currently,commonly used network management platforms are Sun NetManager and IBMNetView while the AGENT is a server-side software running on a network device. TheNMS can send packets of GetRequest, GetNextRequest, Getbulk, or SetRequest tothe AGENT. Once the AGENT receives request packets from the NMS, it will performread or write operations on variables being managed according to the type of thepackets and generate a Response packet to return to the NMS. On the other hand, ifany exception happens to the device, like a hot or cold start, the AGENT also can senda Trap packet to the NMS on its own initiative, reporting the event happened.9.1.2 SNMP Versions and MIBIn order to identify a management variable uniquely in the SNMP packets, SNMP usesa hierarchical naming convention to distinguish different managed objects and thehierarchical structure is like a tree with its nodes representing managed objects.Displayed in the diagram below, a managed object can be identified uniquely by thepath from the root to the node representing it.
