Appendix C SNMP Management LRS-24 Installation and Operation Manual
C-2 SNMP Environment
GetNextRequest Command for retrieving sequentially specific management information
from the managed entity. The managed entity responds with a
getResponse message.
SetRequest Command for manipulating specific management information within the
managed entity. The managed entity responds with a setResponse
message.
Trap Management message carrying unsolicited information on extraordinary
events, e.g., alarms, reported by the managed entity.
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.
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 and the “access” rights:
Read-only Object value can be read, but cannot be set
Read-write Object value can be read or set
Write-only Object value can be set, but cannot be read
Not accessible Object value can be neither read nor set
MIB Structure
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. A unique path
reaches each leaf in the MIB. Therefore, by numbering the branching points from
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 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.
To provide the flexibility necessary in a global structure, MIBs are classified in
various classes (branches), one of them being the experimental branch, and
another the group of private (enterprise-specific) branches. 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.
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