Management information base
Encyclopedia
A management information base (MIB) is a virtual database used for managing the entities in a communications network. Most often associated with the Simple Network Management Protocol
(SNMP), the term is also used more generically in contexts such as in OSI
/ISO Network management model
. While intended to refer to the complete collection of management information available on an entity, it is often used to refer to a particular subset, more correctly referred to as MIB-module.
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 identifier
s. Internet
documentation RFC
s 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".
s for representing, encoding
, transmitting, and decoding data. It provides a set of formal rules for describing the structure of objects that are independent of machine-specific encoding techniques and is a precise, formal notation that removes ambiguities.
ASN.1 is a joint ISO and ITU-T standard, originally defined in 1984 as part of CCITT X.409:1984. ASN.1 moved to its own standard, X.208, in 1988 due to wide applicability. The substantially revised 1995 version is covered by the X.680 series.
An adapted subset of ASN.1, Structure of Management Information
(SMI), is specified in SNMP to define sets of related MIB objects; these sets are termed MIB modules.
s of the OSI reference model, extending into applications
such as database
s, email
, and the Java reference model, as MIBs can be defined for all such area-specific information and operations.
A managed object (sometimes called a MIB object, an object, or a MIB) is one of any number of specific characteristics of a managed device. Managed objects are made up of one or more object instances (identified by their OIDs), which are essentially variables.
Two types of managed objects exist:
An example of a managed object is
object that contains a single object instance, the integer
value that indicates the total number of input AppleTalk
packets on a router interface
.
An object identifier (or object ID or OID) uniquely identifies a managed object in the MIB hierarchy.
(SMIv1) specifies the use of a number of SMI-specific data types, which are divided into two categories:
SMIv2 also specifies information modules, which specify a group of related definitions. Three types of SMI information modules exist: MIB modules, compliance statements, and capability statements.
Simple Network Management Protocol
Simple Network Management Protocol is an "Internet-standard protocol for managing devices on IP networks. Devices that typically support SNMP include routers, switches, servers, workstations, printers, modem racks, and more." It is used mostly in network management systems to monitor...
(SNMP), the term is also used more generically in contexts such as in OSI
Open Systems Interconnection
Open Systems Interconnection is an effort to standardize networking that was started in 1977 by the International Organization for Standardization , along with the ITU-T.-History:...
/ISO Network management model
Network management model
The ISO under the direction of the OSI group has created a network management model as the primary means for understanding the major functions of network management systems....
. While intended to refer to the complete collection of management information available on an entity, it is often used to refer to a particular subset, more correctly referred to as MIB-module.
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 identifier
Object identifier
In computing, an object identifier or OID is an identifier used to name an object . Structurally, an OID consists of a node in a hierarchically-assigned namespace, formally defined using the ITU-T's ASN.1 standard. Successive numbers of the nodes, starting at the root of the tree, identify each...
s. Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
documentation RFC
Request for Comments
In computer network engineering, a Request for Comments is a memorandum published by the Internet Engineering Task Force describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.Through the Internet Society, engineers and...
s 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".
Abstract Syntax Notation One (ASN.1)
In telecommunications and computer networking, Abstract Syntax Notation One (ASN.1) is a standard and flexible notation that describes data structureData structure
In computer science, a data structure is a particular way of storing and organizing data in a computer so that it can be used efficiently.Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks...
s for representing, encoding
Encoder
An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format or code to another, for the purposes of standardization, speed, secrecy, security, or saving space by shrinking size.-Media:...
, transmitting, and decoding data. It provides a set of formal rules for describing the structure of objects that are independent of machine-specific encoding techniques and is a precise, formal notation that removes ambiguities.
ASN.1 is a joint ISO and ITU-T standard, originally defined in 1984 as part of CCITT X.409:1984. ASN.1 moved to its own standard, X.208, in 1988 due to wide applicability. The substantially revised 1995 version is covered by the X.680 series.
An adapted subset of ASN.1, Structure of Management Information
Structure of Management Information
In computing, the Structure of Management Information , an adapted subset of ASN.1, operates in Simple Network Management Protocol to define sets of related managed objects in a Management information base ....
(SMI), is specified in SNMP to define sets of related MIB objects; these sets are termed MIB modules.
MIB hierarchy
The MIB hierarchy can be depicted as a tree with a nameless root, the levels of which are assigned by different organizations. The top-level MIB OIDs belong to different standards organizations, while lower-level object IDs are allocated by associated organizations. This model permits management across all layerAbstraction layer
An abstraction layer is a way of hiding the implementation details of a particular set of functionality...
s of the OSI reference model, extending into applications
Application software
Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...
such as database
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
s, email
Email
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
, and the Java reference model, as MIBs can be defined for all such area-specific information and operations.
A managed object (sometimes called a MIB object, an object, or a MIB) is one of any number of specific characteristics of a managed device. Managed objects are made up of one or more object instances (identified by their OIDs), which are essentially variables.
Two types of managed objects exist:
- Scalar objects define a single object instance.
- Tabular objects define multiple related object instances that are grouped in MIB tables.
An example of a managed object is
atInput, which is a scalarScalar (computing)
In computing, a scalar variable or field is one that can hold only one value at a time; as opposed to composite variables like array, list, hash, record, etc. In some contexts, a scalar value may be understood to be numeric. A scalar data type is the type of a scalar variable...
object that contains a single object instance, the integer
Integer
The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...
value that indicates the total number of input AppleTalk
AppleTalk
AppleTalk is a proprietary suite of protocols developed by Apple Inc. for networking computers. It was included in the original Macintosh released in 1984, but is now unsupported as of the release of Mac OS X v10.6 in 2009 in favor of TCP/IP networking...
packets on a router interface
Network interface
Network interface may refer to:* Network interface controller, the device a computer uses to connect to a computer network* Network interface device, a demarcation point for a telephone network...
.
An object identifier (or object ID or OID) uniquely identifies a managed object in the MIB hierarchy.
SNMPv1 and SMI-specific data types
The first version of the SMIStructure of Management Information
In computing, the Structure of Management Information , an adapted subset of ASN.1, operates in Simple Network Management Protocol to define sets of related managed objects in a Management information base ....
(SMIv1) specifies the use of a number of SMI-specific data types, which are divided into two categories:
- Simple data types
- Application-wide data types
Simple data types
Three simple data types are defined in the SNMPv1 SMI:- The integer data type is a signed integer in the range of −231 to 231−1.
- Octet strings are ordered sequences of 0 to 65,535 octets.
- Object IDs come from the set of all object identifiers allocated according to the rules specified in ASN.1.
Application-wide data types
The following application-wide data types exist in the SNMPv1 SMI:- Network addresses represent addresses from a particular protocol family. SMIv1 supports only 32-bit (IPv4) addresses (SMIv2 uses Octet Strings to represent addresses generically, and thus are usable in SMIv1 too. SMIv1 had an explicit IPv4 address datatype.)
- Counters are non-negative integers that increase until they reach a maximum value and then roll over to zero. SNMPv1 specifies a counter size of 32 bits.
- Gauges are non-negative integers that can increase or decrease between specified minimum and maximum values. Whenever the system property represented by the gauge is outside of that range, the value of the gauge itself will vary no further than the respective maximum or minimum, as specified in RFC 2578.
- Time ticks represent time since some event, measured in hundredths of a second.
- Opaques represent an arbitrary encoding that is used to pass arbitrary information strings that do not conform to the strict data typing used by the SMI.
- Integers represent signed integer-valued information. This data type redefines the integer data type, which has arbitrary precision in ASN.1 but bounded precision in the SMI.
- Unsigned integers represent unsigned integer-valued information, which is useful when values are always non-negative. This data type redefines the integer data type, which has arbitrary precision in ASN.1 but bounded precision in the SMI.
SNMPv1 MIB tables
The SNMPv1 SMI defines highly structured tables that are used to group the instances of a tabular object (that is, an object that contains multiple variables). Tables are composed of zero or more rows, which are indexed in a way that allows SNMP to retrieve or alter an entire row with a singleGet, GetNext, or Set command.SMIv2 and structure of management information
The second version of the SMI (SMIv2) is described in RFC 2578 and RFC 2579. It enhances and adds to the SMIv1-specific data types, such as including bit strings, network addresses, and counters. Bit strings are defined only in SMIv2 and comprise zero or more named bits that specify a value. Network addresses represent an address from a particular protocol family. Counters are non-negative integers that increase until they reach a maximum value and then return to zero. In SMIv1, a 32-bit counter size is specified. In SMIv2, 32-bit and 64-bit counters are defined.SMIv2 also specifies information modules, which specify a group of related definitions. Three types of SMI information modules exist: MIB modules, compliance statements, and capability statements.
- MIB modules contain definitions of interrelated managed objects.
- Compliance statements provide a systematic way to describe a group of managed objects that must be implemented for conformance to a standard.
- Capability statements are used to indicate the precise level of support that an agent claims with respect to a MIB group. A NMS can adjust its behavior toward agents according to the capabilities statements associated with each agent.
Updating MIBs
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)".MIBs index
There are a large number of MIBs defined by both standards organizations like the IETF, private enterprises and other entities.IETF maintained
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:- SNMP - SMI:RFC 1155 — Defines the Structure of Management Information (SMI)
- MIB-I: RFC 1156 — Historically used with CMOTCommon management information protocolThe Common Management Information Protocol is the OSI specified network management protocol.Defined in . It provides an implementation for the services defined by the Common Management Information Service specified in , allowing communication between network management applications and...
, not to be used with SNMPSimple Network Management ProtocolSimple Network Management Protocol is an "Internet-standard protocol for managing devices on IP networks. Devices that typically support SNMP include routers, switches, servers, workstations, printers, modem racks, and more." It is used mostly in network management systems to monitor... - SNMPv2-SMI: RFC 2578 — Structure of Management Information Version 2 (SMIStructure of Management InformationIn computing, the Structure of Management Information , an adapted subset of ASN.1, operates in Simple Network Management Protocol to define sets of related managed objects in a Management information base ....
v2) - MIB-II: RFC 1213 — Management Information Base for Network Management of TCP/IP-based internets
- SNMPv2-MIB: RFC 3418 — Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)
- TCP-MIB: RFC 4022 — Management Information Base for the Transmission Control Protocol (TCP)
- UDP-MIB: RFC 4113 — Management Information Base for the User Datagram Protocol (UDP)
- IP-MIB: RFC 4293 — Management Information Base for the Internet Protocol (IP)
- IF-MIB: RFC 2863 — The Interfaces Group MIB
- ENTITY-MIB: RFC 4133 — Entity MIB (Version 3)
- ENTITY-STATE-MIB: RFC 4268 — Entity State MIB
- ALARM-MIB: RFC 3877 — Alarm Management Information Base (MIB)
- Fibre ChannelFibre ChannelFibre Channel, or FC, is a gigabit-speed network technology primarily used for storage networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards , an American National Standards Institute –accredited standards...
- FC-MGMT-MIB: RFC 4044 Fibre ChannelFibre ChannelFibre Channel, or FC, is a gigabit-speed network technology primarily used for storage networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards , an American National Standards Institute –accredited standards...
Management MIB - FIBRE-CHANNEL-FE-MIB: RFC 2837 Definitions of Managed Objects for the Fabric Element in Fibre Channel Standard
- FC-MGMT-MIB: RFC 4044 Fibre Channel
- HPR-IP-MIB: RFC 2584 — Definitions of Managed Objects for APPN/HPR in IP Networks
IEEE maintained
The IETF and IEEE have agreed to move MIBs relating to IEEE work (for example Ethernet and bridging) to their respective IEEE workgroup. This is in process and a few items are complete.- Network bridge
- IEEE 802.1ap-2008 consolidated the IEEE and IETF RFCs related to bridging networks into eight related MIBs.
External links
- ByteSphere's MIB Database, a free online MIB repository for thousands of SNMP MIBs.
- MIBSearch, a free search engine for SNMP MIB files.
- SimpleWeb MIBs..
- ipMonitor's SNMP Center
- MIB Depot — extensive list of MIBs
- PEN (Private Enterprise Number) registry
- PEN request authority
MIB Browsers
- SnmpB: A graphical open source MIB browser for Windows, MacOSX and Linux.
- mbrowse: A graphical SNMP MIB browser for Linux, based upon GTK+ and Net-SNMP.
- BlackOwl MIB Browser: A graphical MIB browser for Windows and Linux which can extract MIBs from RFCs and display graphs.
- SMI-Mib Browser: A graphical MIB browser — as of 2010-05-18, this project is no longer under active development.
- MBJ: A graphical MIB browser, written in Java
- JMibBrowser: A graphical MIB browser, written in Java. It can send SNMP requests and dynamically load MIB data.