3com 3031 Instruccion De Instalación

This chapter covers the following topics:

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Introduction to SNMP

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Currently, the most widely used network management protocol in computer 
network is Simple Network Management Protocol, in short, SNMP, which is an 
applicable industrial standard adopted widely. Its purpose is to ensure the 
transmission of management information between any two points so that the 
network administrator can retrieve the information at any point on the network 
and perform appropriate modification, troubleshooting, fault diagnosis, and 
volume planning and reporting. It adopts a polling mechanism and offers an 
underlying function set, which is appropriate especially in a small environment in 
need of high speed and low cost. It only requires unacknowledged transport 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 
(Network Management Station) is a workstation on which the client program is 
running. Currently, commonly used network management platforms are Sun 
NetManager and IBM NetView while the AGENT is a server-side software running 
on a network device. The NMS can send packets of GetRequest, GetNextRequest, 
Getbulk, or SetRequest to the AGENT. Once the AGENT receives request packets 
from the NMS, it will perform Read or Write operations on variables being 
managed according to the type of the packets and generate a Response packet to 
return to the NMS. On the other hand, if any exception happens to the device, like 
a hot or cold start, the AGENT also can send a Trap packet to the NMS on its own 
initiative, reporting the event happened.

In order to identify a management variable uniquely in the SNMP packets, SNMP 
uses a hierarchical naming convention to distinguish different managed objects 
and the hierarchical structure is like a tree with its nodes representing managed 
objects. Displayed in the diagram below, a managed object can be identified 
uniquely by the path from the root to the node representing it.

In Figure 17, the managed object B can be uniquely determined by a string of 
digits 

{1.2.1.1}, which is the Object Identifier of the managed object. While the 

MIB (Management Information Base) is used to describe the hierarchical structure 
of the tree and is a collection of the definitions of standard variables on monitored 
network devices.