Nortel VoIP Gateway, Руководство по настройке, Страница: 195 / 220

SNMP Extensibility feature 195
Norstar VoIP Gateway Configuration Guide
• 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. In the case of "Discrete" objects, this instance number
is zero. In the case of "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, in 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 could 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 any respectable 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.
VoIP Gateway supported MIBs
The VoIP Gateway contains an embedded SNMP Agent supporting the following MIBs:
• The Standard MIB (MIB-II) - 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.
• RTP MIB - The RTP MIB is supported per the RFC 2959. It contains objects relevant to the
RTP streams generated and terminated by the gateway and to the RTCP information related to
these streams.
• AcBoard MIB - This proprietary MIB contains objects related both to the configuration of the
gateway and channels as well as to run-time information. Through this MIB, the User can set
up the gateway configuration parameters, reset the gateway, and monitor the gateway’s
operational robustness and quality of service during run-time.