Management Information Base
A management information base (MIB) is a system used in a communication network in order to manage the different organizational links. It consists of a hierarchical (tree-structured) database in which each line is called an object identifier (OID).
The prototype for the MIB is a tree with a nameless root, which can be used by different organizations to assign levels corresponding to its branches. Usually, the top tiers of the MIB are designed for different standards organizations, while the lower ones are given by associated organizations.
By adopting this level, management gets involved at all levels of the reference model, applying to databases, email, and area-specific information and operations.
Each MIB has a corresponding object identifier (OID) which is usually a device’s setting or status. The OID uniquely identifies a managed object in the MIB hierarchy. Each managed object is made up of one or more variables called object instances. One of the managed objects is an entry in the MIB with specific characteristics.
There are two types of managed objects:
(1) Scalar objects which correspond to a single object instance;
(2) Tabular objects which define multiple related object instances.
The OIDs are a representation of physical networking components that are SNMP-enabled (such as computers, hubs, routers, switches, and networking software). MIBs contain information about the configuration of these networking components, for example the version of the software running on the component, the IP address or port number, and the amount of available disk space for storage. MIBs work as a kind of directory containing the logical names of the network resources and their configuration parameters that are managed by SNMP.
Because every OID is part of the MIB hierarchy, one can easily identify a MIB for each network component. The name is represented using a standard dotted naming system. The tree-like MIB structure has branches both for public networking standard objects and for proprietary private buyers’ implementations of networking objects. Buyers can reserve certain specific MIB numbers reserved for their products. For example, a MIB manager can have over 90 objects that SNMP management systems can use to obtain information about users who are logged on, sessions, shares etc. One can also use SNMP commands to retrieve the value of a MIB object or, in some cases, to change it. When accessing the MIB, it is not necessary to read every entry, however the manager needs to know how to apply the SNMP commands.