Objects in the MIB are defined using a subset of Abstract Syntax Notation One (ASN.1) called "Structure of Management Information Version 2 (SMIv2)" RFC 2578.The software that performs the parsing is a MIB compiler.
The database is hierarchical (tree-structured) and entries are addressed through object identifiers. Internet documentation RFCs discuss MIBs, notably RFC 1155, "Structure and Identification of Management Information for TCP/IP based internets", and its two companions, RFC 1213, "Management Information Base for Network Management of TCP/IP-based internets", and RFC 1157, "A Simple Network Management Protocol".
SNMP, a communication protocol between management stations, such as consoles, and managed objects (MIB objects), such as routers, gateways, and switches, makes use of MIBs. Components controlled by the management console need a so-called SNMP agent — a software module that can communicate with the SNMP manager.
SNMP uses a specified set of commands and queries. A MIB should contain information on these commands and on the target objects (controllable entities or potential sources of status information) with a view to tuning the network transport to the current needs.
Examples of MIB objects include:
RFC 1213 defines these as mandatory: if an environment does not use the atTable (as in the case of DDN-X.25 units) then the atTable simply remains empty. The table object includes, of course, definitions of table entries, atEntry and information about interfaces (if) for each atEntry, etc.
MIBs are periodically updated to add new functionality, remove ambiguities and to fix defects. These changes are made in conformance to section 10 of RFC 2578. An example of an MIB that has been updated many times is the important set of objects that was originally defined in RFC 1213 "MIB-II". This MIB has since been split up and can be found in MIBs such as RFC 4293 "Management Information Base for the Internet Protocol (IP)", RFC 4022 "Management Information Base for the Transmission Control Protocol (TCP)", RFC 4113 "Management Information Base for the User Datagram Protocol (UDP)", RFC 2863 "The Interfaces Group MIB" and RFC 3418 "Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)".
There are a large number of MIBs defined by both standards organizations like the IETF, private enterprises and other entities. There are 318 RFCs in the first 5000 RFCs from the IETF that contain MIBs. This list is merely a fraction of the MIBs that have been written: