CHAPTER 2 SNMP Overview
Mediant 800 SBC | SNMP Reference Guide
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Table MIB Objects:
Contain multiple pieces of management data. These objects are
distinguished from "Discrete" items (above) by requiring a "." (dot) extension to their
names that uniquely distinguishes the particular value being referenced. The "." (dot)
extension is the "instance" number of an SNMP object. For "Discrete" objects, this
instance number is zero. For "Table" objects, this instance number is the index into the
SNMP table. SNMP tables are special types of SNMP objects, which allow parallel arrays of
information to be supported. Tables are distinguished from scalar objects, such that
tables can grow without bounds. For example, SNMP defines the "ifDescr" object (as a
standard SNMP object) that indicates the text description of each interface supported by a
particular device. Since network devices can be configured with more than one interface,
this object can only be represented as an array.
By convention, SNMP objects are always grouped in an "Entry" directory, within an object with
a "Table" suffix. (The "ifDescr" object described above resides in the "ifEntry" directory
contained in the "ifTable" directory).
SNMP Extensibility Feature
One of the principal components of an SNMP manager is a MIB Compiler, which allows new
MIB objects to be added to the management system. When a MIB is compiled into an SNMP
manager, the manager is made "aware" of new objects that are supported by agents on the
network. The concept is similar to adding a new schema to a database.
Typically, when a MIB is compiled into the system, the manager creates new folders or
directories that correspond to the objects. These folders or directories can typically be viewed
with a "MIB Browser", which is a traditional SNMP management tool incorporated into
virtually all network management systems.
The act of compiling the MIB allows the manager to know about the special objects supported
by the agent and access these objects as part of the standard object set.
Supported MIBs
The device contains an embedded SNMP agent supporting the MIBs listed below. A description
in HTML format for all supported MIBs can be found in the MIBs directory in the release
package.
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Standard MIB (MIB-2):
The various SNMP values in the standard MIB are defined in RFC
1213. The standard MIB includes various objects to measure and monitor IP activity, TCP
activity, UDP activity, IP routes, TCP connections, interfaces, and general system
description.
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The standard icmpStatsTable and icmpMsgStatsTable under MIB-2 support ICMP
statistics for both IPv4 and IPv6.
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The inetCidrRouteTable (from the standard IP-FORWARD-MIB) supports both IPv4 and
IPv6.
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