About the SNMP Management Information Base (MIB)

The MIB contains the essential objects that make up the management information for the device. The Internet TCP/IP MIB, commonly referred to as MIB-II, defines the network objects to be managed for a TCP/IP network and provides a standard format for each object.

The MIB is structured as a hierarchical object tree divided into logically related groups of objects. For example, MIB-II contains the following groups of objects:

• System. Contains general information about the device, for example: sysDescr (description), sysContact (person responsible), and sysName (device name).
• Interfaces. Contains information about network interfaces, such as Ethernet adapters, or point-to-point links; for example: ifDescr (name), ifOperStatus (status), ifPhysAddress (physical address), ifInOctets, and ifOutOctets (number of octets received and sent by the interface).
• IP. Contains information about the processing of IP packets, such as routing table information: ipRouteDest (the destination), and ipRouteNextHop (the next hop of the route entry).
  • Other groups provide information about the operation of a specific protocol, for example, tcp ,udp, icmp, snmp, and egp.
  • The enterprise group contains vendor-provided objects that are extensions to the MIB.

Each object of the MIB is identified by a numeric object identifier (OID) and each OID can be referred to by its text label. For example, the system group contains an object named sysDescr, which provides a description of the device. The sysDescr object has the following object identifier:

iso.org.dod.Internet.mgmt.mib.system.sysDescr

1.3.6.1.2.1.1.1

This object identifier would be 1.3.6.1.2.1.1.1 to which is appended an instance sub-identifier of 0. That is, 1.3.6.1.2.1.1.1.0 identifies the one and only instance of sysDescr.

All of the MIB-II objects (for TCP/IP networks) are under the "mib" sub tree (so all these objects will have an identifier that starts with 1.3.6.1.2.1).

For a detailed description of the MIB, see RFC 1213.