2 introduction to mib – Amer Networks SS2R48G4i V2 User Manual
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5.4.2 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
Fig 5-1 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 functional domains in network management. NMS
obtains the network management information by visiting the MIB of SNMP Agent.
The switch can operate as a SNMP Agent, and supports both SNMP v1/v2c and SNMP v3. The
switch supports basic MIB-II, RMON public MIB and other public MID such as BRIDGE MIB. Besides,
the switch supports self-defined private MIB.