Appendix C SNMP Management Installation and Operation Manual
C-2 SNMP Environment IPmux-11 Ver. 2.00
Management Information Base (MIB) The MIB includes a collection of managed objects. A managed object is defined as
a parameter that can be managed, such as a performance statistics value. The MIB
includes the definitions of relevant managed objects. Various MIBs can be defined
for various management purposes or types of equipment.
An object definition includes the range of values (also called instances) and the
following access rights:
• Read-only: Instances of that object can be read, but cannot be set.
• Read-write: Instances of that object can be read or set.
• Write-only: Instances of that object can be set, but cannot be read.
• Not accessible: Instances of that object cannot be read, or set.
MIB Structure The MIB has an inverted tree-like structure, with each definition of a managed
object forming one leaf, located at the end of a branch of that tree.
Each leaf in the MIB is reached by a unique path. Thus, by numbering the
branching points starting with the top, each leaf can be uniquely defined by a
sequence of numbers.
The formal description of the managed objects and the MIB structure is provided
in a special standardized format, called ASN.1 (Abstract Syntax Notation 1). Since
the general collection of MIBs can also be organized in a similar structure, under
IAB (Internet Activities Board) supervision, any parameter included in a MIB that is
recognized by the IAB is uniquely defined.
To provide the flexibility necessary in a global structure, MIBs are classified in
various classes (branches). One is the experimental branch and another the group
of private (enterprise-specific) branch.
Under the private enterprise-specific branch of MIBs, each enterprise
(manufacturer) can be assigned a number, which is its enterprise number. The
assigned number designates the top of an enterprise-specific sub-tree of non-
standard MIBs. Within this context, RAD has been assigned the enterprise number
164. Therefore, enterprise MIBs published by RAD can be found under
1.3.6.1.4.1.164.
MIBs of general interest are published by the IAB in the form of a Request for
Comment (RFC) document. In addition, MIBs are also often assigned informal
names that reflect their primary purpose. Enterprise-specific MIBs are published
and distributed by their originator, who is responsible for their contents.