Appendix C SNMP Management FCD-IPM Installation and Operation Manual
C-2 SNMP Environment
The Management Information Base The management information base (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, types of equipment, etc.
An object's definition includes the range of values (also called “instances”) and the
“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, nor 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. By numbering the branching points from the
top down, 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 Abstract Syntax Notation 1 (ASN.1).
Since the general collection of MIBs can also be organized in a similar structure,
under the supervision of the Internet Activities Board (IAB), any parameter
included in a MIB that is recognized by the IAB is uniquely defined.
MIBs are classified in various classes (branches): the experimental branch, and the
group of private (enterprise-specific) branch. This is to provide the flexibility
necessary in a global structure. 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, which is responsible for their contents.