SNMP Network Management and Monitoring - Key Terms

The following list outlines a set of key terms that are used in context with SNMP, Network Management and Monitoring.

Instance
An instance specifies the row in which an object that is part of a table is located. The instance is appended to the object identifier and has a format that is similar to the latter. For objects that are not part of a table, the instance is zero.

Managed Node
A managed node is a network device that is being monitored actively by an agent. Each managed node is a member of one or more management communities. Each community, in turn, is identified by a community name or community string, which is encapsulated in the SNMP message.

Messages
In an SNMP operation, network information is exchanged through messages or Protocol Data Units (PDUs). Each SNMP operation has its own type of message. Management systems use messages to request that an operation be performed on the managed variable that is maintained by an SNMP agent. SNMPv1 defines three types of request messages: GetRequest, GetNextRequest, and SetRequest. SNMPv2 defines an additional type of request message: GetBulk. The SNMP agent responds to a received request by sending a GetResponse message. If a predefined condition or an extraordinary event occurs, the SNMP agent sends a Trap message to the network management system.

MIB
A Management Information Base (MIB) is a schema or blueprint that contains the hierarchical order of all of the managed objects. Each managed object in an MIB has a unique identifier. The identifier includes the type (such as counter, string, gauge, or address), access level (such as read/write), size restrictions, and range information of the object.

MIB Compiler
An MIB compiler is a program that translates MIB modules that are written in ASN.1 into another data format, such as C (which later is compiled as part of the agent) or a relational database. Most management systems and agents cannot read ASN.1 MIB modules, and they first must compile them into a more readable format.

MIB Module
An MIB module is a readable, ASN.1 description of SNMP MIB objects, data definitions, conventions, subtypes, and events. Because MIB modules usually are compiled into another format before they are used, they can be considered to be the source code of the MIB.

NMS
A Network Management Station (NMS) is a console that monitors and controls network elements by executing management applications. To perform NMS functions, high-performance workstation computers that have fast CPUs and extensive disk space are used. A managed network requires at least one NMS workstation to perform SNMP operations.

Object Identifier
An Object Identifier is the identification value of an object that is defined in a MIB. Object identifiers are arranged in a hierarchical tree structure that is compliant with Internet standard and that consists of roots and branches. An object identifier is written as a sequence of sub-identifiers, starting with the tree root, in dotted decimal notation. For example, the Cisco branch of the MIB naming tree is expressed as 1.3.6.1.4.1.9.

Shooter
FineConnection terminology for "SNMP request definition files" used for MIB querying. A shooter defines which device fields to query, how to process them and how to display the results.

SNMP Agent
An SNMP Agent is an application that performs the operational role of receiving and processing requests, sending responses to the manager, and sending traps when an event occurs.

SNMP Manager
An SNMP Manager or SNMP Service is an application that performs the operational roles of generating requests to modify and retrieve management information, and receiving the requested information and trap-event reports that are generated by the SNMP agent.