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<img alt="Erlang logo" src="../../../../doc/erlang-logo.png"><br><small><a href="users_guide.html">User's Guide</a><br><a href="index.html">Reference Manual</a><br><a href="release_notes.html">Release Notes</a><br><a href="../pdf/snmp-4.22.1.pdf">PDF</a><br><a href="../../../../doc/index.html">Top</a></small><p><strong>Simple Network Management Protocol (SNMP)</strong><br><strong>User's Guide</strong><br><small>Version 4.22.1</small></p>
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<li id="no" title="Running the application" expanded="false">Running the application<ul>
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<li title="Configuring the application"><a href="snmp_config.html#id76778">Configuring the application</a></li>
<li title="Modifying the Configuration Files"><a href="snmp_config.html#id79236">Modifying the Configuration Files</a></li>
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<li title="Debugging the application"><a href="snmp_config.html#id79377">Debugging the application</a></li>
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<li id="no" title="Definition of Agent Configuration Files" expanded="false">Definition of Agent Configuration Files<ul>
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<li title="Agent Information"><a href="snmp_agent_config_files.html#id79867">Agent Information</a></li>
<li title="Contexts"><a href="snmp_agent_config_files.html#id79944">Contexts</a></li>
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<li title="Communities"><a href="snmp_agent_config_files.html#id80066">Communities</a></li>
<li title="MIB Views for VACM"><a href="snmp_agent_config_files.html#id80148">MIB Views for VACM</a></li>
<li title="Security data for USM"><a href="snmp_agent_config_files.html#id80387">Security data for USM</a></li>
<li title="Notify Definitions"><a href="snmp_agent_config_files.html#id80603">Notify Definitions</a></li>
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<li id="no" title="Definition of Manager Configuration Files" expanded="false">Definition of Manager Configuration Files<ul>
<li><a href="snmp_manager_config_files.html">
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<li title="Manager Information"><a href="snmp_manager_config_files.html#id81118">Manager Information</a></li>
<li title="Users"><a href="snmp_manager_config_files.html#id81260">Users</a></li>
<li title="Agents"><a href="snmp_manager_config_files.html#id81361">Agents</a></li>
<li title="Security data for USM"><a href="snmp_manager_config_files.html#id81544">Security data for USM</a></li>
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<li id="no" title="Agent Implementation Example" expanded="false">Agent Implementation Example<ul>
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<li title="MIB"><a href="snmp_impl_example_agent.html#id81793">MIB</a></li>
<li title="Default Implementation"><a href="snmp_impl_example_agent.html#id81833">Default Implementation</a></li>
<li title="Manual Implementation"><a href="snmp_impl_example_agent.html#id81912">Manual Implementation</a></li>
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</li>
<li id="no" title="Manager Implementation Example" expanded="false">Manager Implementation Example<ul>
<li><a href="snmp_impl_example_manager.html">
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<li title="The example manager"><a href="snmp_impl_example_manager.html#id82242">The example manager</a></li>
<li title="A simple standard test"><a href="snmp_impl_example_manager.html#id82333">A simple standard test</a></li>
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<li id="no" title="Instrumentation Functions" expanded="false">Instrumentation Functions<ul>
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<li title="Instrumentation Functions"><a href="snmp_instr_functions.html#id82473">Instrumentation Functions</a></li>
<li title="Using the ExtraArgument"><a href="snmp_instr_functions.html#id83088">Using the ExtraArgument</a></li>
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<li id="no" title="Definition of Instrumentation Functions" expanded="false">Definition of Instrumentation Functions<ul>
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<li title="Variable Instrumentation"><a href="snmp_def_instr_functions.html#id83474">Variable Instrumentation</a></li>
<li title="Table Instrumentation"><a href="snmp_def_instr_functions.html#id83849">Table Instrumentation</a></li>
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<li id="no" title="Definition of Agent Net if" expanded="false">Definition of Agent Net if<ul>
<li><a href="snmp_agent_netif.html">
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<li title="Mandatory Functions"><a href="snmp_agent_netif.html#id84750">Mandatory Functions</a></li>
<li title="Messages"><a href="snmp_agent_netif.html#id84772">Messages</a></li>
</ul>
</li>
<li id="no" title="Definition of Manager Net if" expanded="false">Definition of Manager Net if<ul>
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<li title="Mandatory Functions"><a href="snmp_manager_netif.html#id85574">Mandatory Functions</a></li>
<li title="Messages"><a href="snmp_manager_netif.html#id85591">Messages</a></li>
</ul>
</li>
<li id="no" title="Audit Trail Log" expanded="false">Audit Trail Log<ul>
<li><a href="snmp_audit_trail_log.html">
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<li title="Agent Logging"><a href="snmp_audit_trail_log.html#id85997">Agent Logging</a></li>
<li title="Manager Logging"><a href="snmp_audit_trail_log.html#id86040">Manager Logging</a></li>
</ul>
</li>
<li id="no" title="Advanced Agent Topics" expanded="false">Advanced Agent Topics<ul>
<li><a href="snmp_advanced_agent.html">
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<li title="When to use a Sub-agent"><a href="snmp_advanced_agent.html#id86186">When to use a Sub-agent</a></li>
<li title="Agent Semantics"><a href="snmp_advanced_agent.html#id86296">Agent Semantics</a></li>
<li title="Sub-agents and Dependencies "><a href="snmp_advanced_agent.html#id86360">Sub-agents and Dependencies </a></li>
<li title="Distributed Tables"><a href="snmp_advanced_agent.html#id86378">Distributed Tables</a></li>
<li title="Fault Tolerance"><a href="snmp_advanced_agent.html#id86434">Fault Tolerance</a></li>
<li title="Using Mnesia Tables as SNMP Tables"><a href="snmp_advanced_agent.html#id86508">Using Mnesia Tables as SNMP Tables</a></li>
<li title="Deviations from the Standard"><a href="snmp_advanced_agent.html#id86786">Deviations from the Standard</a></li>
</ul>
</li>
<li id="no" title="SNMP Appendix A" expanded="false">SNMP Appendix A<ul>
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<li title="Appendix A"><a href="snmp_app_a.html#id86932">Appendix A</a></li>
</ul>
</li>
<li id="no" title="SNMP Appendix B" expanded="false">SNMP Appendix B<ul>
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<li title="Appendix B"><a href="snmp_app_b.html#id87320">Appendix B</a></li>
</ul>
</li>
</ul>
</div></div>
<div id="content">
<div class="innertube">
<h1>1 SNMP Introduction</h1>
<p>The SNMP development toolkit contains the following parts:
</p>
<ul>
<li>An Extensible multi-lingual SNMP agent, which understands SNMPv1
(RFC1157), SNMPv2c (RFC1901, 1905, 1906 and 1907), SNMPv3
(RFC2271, 2272, 2273, 2274 and 2275), or any combination of
these protocols.
</li>
<li>A multi-lingual SNMP manager.
</li>
<li>A MIB compiler, which understands SMIv1 (RFC1155, 1212, and
1215) and SMIv2 (RFC1902, 1903, and 1904).
</li>
</ul>
<p>The SNMP development tool provides an environment for
rapid agent/manager prototyping and construction. With the
following information provided, this tool is used to set up a
running multi-lingual SNMP agent/manager:
</p>
<ul>
<li>a description of a Management Information Base (MIB) in
Abstract Syntax Notation One (ASN.1)
</li>
<li>instrumentation functions for the managed objects in the MIB,
written in Erlang.
</li>
</ul>
<p>The advantage of using an extensible (agent/manager) toolkit is to
remove details such as type-checking, access rights, Protocol Data Unit
(PDU), encoding, decoding, and trap distribution from the
programmer, who only has to write the instrumentation functions,
which implement the MIBs. The <span class="code">get-next</span> function only
has to be implemented for tables, and not for every variable in
the global naming tree. This information can be deduced from the
ASN.1 file.
</p>
<h3><a name="id73205">1.1
Scope and Purpose</a></h3>
<p>This manual describes the SNMP development tool,
as a component of the Erlang/Open Telecom Platform development
environment. It is assumed that the reader is familiar with the
Erlang Development Environment, which is described in a separate
User's Guide.</p>
<h3><a name="id63280">1.2
Prerequisites</a></h3>
<p>The following prerequisites
is required for understanding the material in the SNMP
User's Guide:
</p>
<ul>
<li>the basics of the Simple Network Management Protocol
version 1 (SNMPv1)
</li>
<li>the basics of the community-based Simple Network
Management Protocol version 2 (SNMPv2c)
</li>
<li>the basics of the Simple Network Management Protocol
version 3 (SNMPv3)
</li>
<li>the knowledge of defining MIBs using SMIv1 and SMIv2
</li>
<li>familiarity with the Erlang system and Erlang programming
</li>
</ul>
<p>The tool requires Erlang release 4.7 or later.
</p>
<h3><a name="id61217">1.3
Definitions</a></h3>
<p>The following definitions are used in the SNMP User's Guide.
</p>
<dl>
<dt><strong>MIB</strong></dt>
<dd>The conceptual repository for management information is
called the Management Information Base (MIB). It does not
hold any data, merely a definition of what
data can be accessed. A definition of an MIB is a
description of a collection of managed objects.
</dd>
<dt><strong>SMI</strong></dt>
<dd>The MIB is specified in an adapted subset of the Abstract
Syntax Notation One (ASN.1) language. This adapted subset is
called the Structure of Management Information (SMI).
</dd>
<dt><strong>ASN.1</strong></dt>
<dd>ASN.1 is used in two different ways in SNMP. The SMI is
based on ASN.1, and the messages in the protocol are defined by
using ASN.1.
</dd>
<dt><strong>Managed object</strong></dt>
<dd>
<p>A resource to be managed is represented by a managed
object, which resides in the MIB. In an SNMP MIB, the managed
objects are either:</p>
<ul>
<li>
<strong>scalar variables</strong>, which have only one instance
per context. They have single values, not multiple values like
vectors or structures.
</li>
<li>
<strong>tables</strong>, which can grow dynamically.
</li>
<li>a <strong>table element</strong>, which is a special type of
scalar variable.</li>
</ul>
</dd>
<dt><strong>Operations</strong></dt>
<dd>SNMP relies on the three basic operations: get (object),
set (object, value) and get-next (object).
</dd>
<dt><strong>Instrumentation function</strong></dt>
<dd>An instrumentation function is associated with each
managed object. This is the function, which actually implements
the operations and will be called by the agent when it receives
a request from the management station.</dd>
<dt><strong>Manager</strong></dt>
<dd>A manager generates commands and receives notifications
from agents. There usually are only a few managers in a system.</dd>
<dt><strong>Agent</strong></dt>
<dd>An agent responds to commands from the manager, and sends
notification to the manager. There are potentially many agents
in a system.</dd>
</dl>
<h3><a name="id66265">1.4
About This Manual</a></h3>
<p>In addition to this introductory chapter, the SNMP User's Guide
contains the following chapters:
</p>
<ul>
<li>Chapter 2: "Functional Description" describes the features
and operation of the SNMP development toolkit. It includes
topics on Sub-agents and MIB loading, Internal MIBs, and Traps.
</li>
<li>Chapter 3: "The MIB Compiler" describes the features and the
operation of the MIB compiler.
</li>
<li>Chapter 4: "Running the application" describes how to start and
configure the application. Topics on how to debug the application
are also included.
</li>
<li>Chapter 5: "Definition of Agent Configuration Files" is a
reference chapter, which contains more detailed information about
the agent configuration files.
</li>
<li>Chapter 6: "Definition of Manager Configuration Files" is a
reference chapter, which contains more detailed information about
the manager configuration files.
</li>
<li>Chapter 7: "Agent Implementation Example" describes how an MIB
can be implemented with the SNMP Development Toolkit.
Implementation examples are included.
</li>
<li>Chapter 8: "Instrumentation Functions" describes how
instrumentation functions should be defined in Erlang for the
different operations.
</li>
<li>Chapter 9: "Definition of Instrumentation Functions" is a
reference chapter which contains more detailed information
about the instrumentation functions.
</li>
<li>Chapter 10: "Definition of Agent Net if" is a reference chapter,
which describes the Agent Net if function in detail.
</li>
<li>Chapter 11: "Definition of Manager Net if" is a reference chapter,
which describes the Manager Net if function in detail.
</li>
<li>Chapter 12: "Advanced Agent Topics" describes sub-agents, agent
semantics, audit trail logging, and the consideration of
distributed tables.
</li>
<li>Appendix A describes the conversion of SNMPv2 to SNMPv1
error messages.
</li>
<li>Appendix B contains the RFC1903 text on <span class="code">RowStatus</span>.
</li>
</ul>
<h3><a name="id65242">1.5
Where to Find More Information</a></h3>
<p>Refer to the following documentation for more information about
SNMP and about the Erlang/OTP development system:
</p>
<ul>
<li>Marshall T. Rose (1991), "The Simple Book - An
Introduction to Internet Management", Prentice-Hall
</li>
<li>Evan McGinnis and David Perkins (1997), "Understanding SNMP
MIBs", Prentice-Hall
</li>
<li>RFC1155, 1157, 1212 and 1215 (SNMPv1)
</li>
<li>RFC1901-1907 (SNMPv2c)
</li>
<li>RFC1908, 2089 (coexistence between SNMPv1 and SNMPv2)
</li>
<li>RFC2271, RFC2273 (SNMP std MIBs)
</li>
<li>the Mnesia User's Guide
</li>
<li>the Erlang 4.4 Extensions User's Guide
</li>
<li>the Reference Manual
</li>
<li>the Erlang Embedded Systems User's Guide
</li>
<li>the System Architecture Support Libraries (SASL) User's
Guide
</li>
<li>the Installation Guide
</li>
<li>the Asn1 User's Guide
</li>
<li>Concurrent Programming in Erlang, 2nd Edition (1996),
Prentice-Hall, ISBN 0-13-508301-X.
</li>
</ul>
</div>
<div class="footer">
<hr>
<p>Copyright © 1997-2012 Ericsson AB. All Rights Reserved.</p>
</div>
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