OBJECT-TYPE Macro

The OBJECT-TYPE macro contains mandatory and optional clauses that describe the basic characteristics of a MIB object. The SNMP Provider converts an MIB to the corresponding parts of the OBJECT-TYPE macro.

Components

MIB object

Object that contains most of the data in question.

Object descriptor

Unique name or object descriptor identifying each MIB object. Each MIB object descriptor maps exactly to a CIM property name. For example, ifIndex translates to ifIndex.

SYNTAX Clause

Defines the data and type of an MIB object.

INDEX clause

Defines a key for selecting a unique table row.

AUGMENTS clause

Indicates that the table collection it specifies can be considered an extension of another table collection, and can replace the INDEX clause in SNMPv2. The collections referred to by the AUGMENTS clause can be combined with the other table collection to form one collection. The resulting collection shares the primary key properties specified in the last table collection in the chain.

In this case, the previous mapping rules specified for the INDEX clause are applied to the last table collection in the chain. The collection of objects then maps to one CIM class definition.

OBJECT-IDENTIFIER clause

Contains a unique object identifier for an MIB object. This object identifier maps to the CIM property qualifier object_identifier.

ACCESS and MAX-ACCESS Clauses

Define the access rights to the MIB object.

DESCRIPTION clause

Provides a text description of the object, which maps to the CIM property qualifier Description. This clause may be empty.

Each TABLE and ENTRY object in an SNMP table definition also contains a DESCRIPTION clause, which also may be empty. The TABLE and ENTRY DESCRIPTION clauses are concatenated and the result maps to the CIM class qualifier Description.

STATUS clause

Indicates whether the object must be supported. When the value of the STATUS clause is obsolete, the provider discards the MIB object from the mapping. Otherwise, the STATUS clause maps to the CIM property qualifier Status.

For SNMPv1, the preferred value of Status is either mandatory or optional, but the qualifier can contain some other value. For SNMPv2C, the preferred value of Status is either current or deprecated, but the qualifier can contain some other value.

DEFVAL clause

Assigns a default value to a variable in a logical table row, and maps to the string CIM property qualifier Defval.

REFERENCE clause

Refers to another document that contains more information about the object. This clause maps to the CIM property qualifier Reference, which is of type string.

UNITS clause

Provides a precise definition of what the object represents. This clause maps to the CIM property qualifier Units, which is of type string.

Remarks

The OBJECT-TYPE macro describes the basic characteristics of an individual MIB object. A set of OBJECT-TYPE macros can be considered as a group of related objects. In SNMPv2C, use the OBJECT-GROUP macro to formally group sets of related objects into a collection. However, there is no formal mechanism for creating collections in SNMPv1. For the purposes of the SNMP Provider, the OBJECT-GROUP macro is ignored, but you can invent grouping relationships and fabricate collections.