What is Management Information Database?

MIB - Management Information Database

SNMP systems have OIDs that define each thing for the SNMP agents and manager.

OIDs point to network monitoring objects stored in a database called the Management Information Base (MIB). A MIB holds the structure of the network alarms being monitored (like a map of the "city"), and it uses the OIDs to keep track of the individual components (like the address to a house or other location).

an SNMP OID is like the address the fire truck would drive to if the fire alarm sounded. What if a fire broke out at your house, and you called the fire department with GPS coordinates (representing the Object ID or OID)? The fire department would have to look that up in its MIB to determine the correct street address.


In telecom, SNMP OIDs describe specific locations in the managed network. The OID allows the MIB to translate the location of the event into a status description for your network administrators.

What Does an SNMP OID Look Like Again?

1.3.6.1.4.1.2681.1.2.102

Dot Format notation

While it may look daunting, the OID follows a simple structure, with each "dot" segment identifying a part of a network element. Going back to the home address example, the beginning of the Object Identifier tells us the hemisphere of the world, the country, state, city, zip code, street address and eventually leads us to our driveway. In the above OID, the specific "driveway" is 102. With this structure, very specific elements can be identified and located even in very complex networks.

MIB and SNMP Manager

When the SNMP Manager, requests the value ("state") of any object it is monitoring, it sends a message with that object's OID to its Management Information Base. The MIB will decode the address and attach a text description to it. This allows the SNMP Manager to present the value of the alarm condition with the identifying description of the labeled alarm.


So for example, let's say the SNMP Manager wants to know if there is a car in the driveway of your house (a "yes or no" question, often referred to as a discrete alarm in the alarm monitoring world). The SNMP Manager would look up the corresponding reference in the MIB in order to "poll" (ask) if there is a car in the driveway at 123 Main St. The MIB references 123 Main St. and translates it into the OID of your driveway.


In our example OID above, it would be 123 Main St = 1.3.6.1.4.1.2681.1.2.102. The driveway (or alarm point we want to monitor) would be represented by the "102" portion of the address. The "value" reported is the current state of the driveway 102 : occupied by a car or not.


If an SNMP managed object does not have an OID listed within a MIB, the SNMP Manager cannot identify it. Even if that object has a sensor and can transmit data, the SNMP Manager is blind without the MIB. For a condition or device to be monitored, it must have a corresponding MIB definition.

Vendors and Their Unique MIBs

The first several pieces of each OID are almost always the same. These upper location levels are defined by a series of standard reference within the MIB. These series are called RFCs, or Requests for Comments.

The RFCs that define SNMP OIDs are part of a larger group of RFC documents that define the Internet as a whole. Individual vendors create their own SNMP enterprise MIBs that only include the OIDs for their devices.