SNR S2989G-48TX-DC — основы управления и конфигурации сети: Руководство по MIB [40/553]

S2989G-24TX Operation Manual

Chapter

Basic

Management

Configuration

1-25

VACM is used to classify the users’ access permission. It puts the users with the

same access permission in the same group. Users can’t conduct the operation which is

not authorized.

1.2.4.2 Introduction to MIB

The network management information accessed by NMS is well defined and

organized in a Management Information Base (MIB). MIB is pre-defined information which

can be accessed by network management protocols. It is in layered and structured form.

The pre-defined management information can be obtained from monitored network

devices. ISO ASN.1 defines a tree structure for MID. Each MIB organizes all the available

information with this tree structure. And each node on this tree contains an OID (Object

Identifier) and a brief description about the node. OID is a set of integers divided by

periods. It identifies the node and can be used to locate the node in a MID tree structure,

shown in the figure below:

Figure 1-13 ASN.1 Tree Instance

In this figure, the OID of the object A is 1.2.1.1. NMS can locate this object through

this unique OID and gets the standard variables of the object. MIB defines a set of

standard variables for monitored network devices by following this structure.

If the variable information of Agent MIB needs to be browsed, the MIB browse

software needs to be run on the NMS. MIB in the Agent usually consists of public MIB and

private MIB. The public MIB contains public network management information that can be

accessed by all NMS; private MIB contains specific information which can be viewed and

controlled by the support of the manufacturers.

MIB-I [RFC1156] is the first implemented public MIB of SNMP, and is replaced by

MIB-II [RFC1213]. MIB-II expands MIB-I and keeps the OID of MIB tree in MIB-I. MIB-II

contains sub-trees which are called groups. Objects in those groups cover all the