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   <title>DHCP Performance Guide</title><link rel="stylesheet" type="text/css" href="bind10-guide.css"><meta name="generator" content="DocBook XSL Stylesheets V1.76.1"><meta name="description" content="BIND 10 is a framework that features Domain Name System (DNS) suite and Dynamic Host Configuration Protocol (DHCP) servers with development managed by Internet Systems Consortium (ISC). This document describes various aspects of DHCP performance, measurements and tuning. It covers BIND 10 DHCP (codename Kea), existing ISC DHCP4 software, perfdhcp (a DHCP performance measurement tool) and other related topics."></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book" title="DHCP Performance Guide"><div class="titlepage"><div><div><h1 class="title"><a name="d0e3"></a>DHCP Performance Guide</h1></div><div><div class="author"><h3 class="author"><span class="firstname">Tomasz</span> <span class="surname">Mrugalski</span></h3></div></div><div><div class="author"><h3 class="author"><span class="firstname">Marcin</span> <span class="surname">Siodelski</span></h3></div></div><div><p class="releaseinfo">This is a companion document for BIND 10 version
    20120712.</p></div><div><p class="copyright">Copyright &copy; 2012 Internet Systems Consortium, Inc. ("ISC")</p></div><div><div class="abstract" title="Abstract"><p class="title"><b>Abstract</b></p><p>BIND 10 is a framework that features Domain Name System
      (DNS) suite and Dynamic Host Configuration Protocol (DHCP)
      servers with development managed by Internet Systems Consortium (ISC).
      This document describes various aspects of DHCP performance,
      measurements and tuning. It covers BIND 10 DHCP (codename Kea),
      existing ISC DHCP4 software, perfdhcp (a DHCP performance
      measurement tool) and other related topics.</p></div></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="preface"><a href="#d0e28">Preface</a></span></dt><dd><dl><dt><span class="section"><a href="#acknowledgements">Acknowledgements</a></span></dt></dl></dd><dt><span class="chapter"><a href="#intro">1. Introduction</a></span></dt><dt><span class="chapter"><a href="#dhcp4">2. ISC DHCP 4.x</a></span></dt><dt><span class="chapter"><a href="#kea">3. Kea</a></span></dt><dd><dl><dt><span class="section"><a href="#d0e54">Backend performance evaluation</a></span></dt><dt><span class="section"><a href="#mysql-backend">MySQL backend</a></span></dt><dd><dl><dt><span class="section"><a href="#d0e156">MySQL tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#sqlite-ubench">SQLite-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#sqlite-tweaks">SQLite tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#memfile-ubench">memfile-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#memfile-tweaks">memfile tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#d0e245">Performance measurements</a></span></dt><dt><span class="section"><a href="#d0e521">Possible further optimizations</a></span></dt></dl></dd><dt><span class="chapter"><a href="#perfdhcp">4. perfdhcp</a></span></dt><dd><dl><dt><span class="section"><a href="#d0e533">Purpose</a></span></dt><dt><span class="section"><a href="#d0e538">Key features</a></span></dt><dt><span class="section"><a href="#perfdhcp-command-line">Command line options</a></span></dt><dt><span class="section"><a href="#d0e574">Running a test</a></span></dt></dl></dd></dl></div><div class="list-of-tables"><p><b>List of Tables</b></p><dl><dt>3.1. <a href="#d0e256">Synchronous results</a></dt><dt>3.2. <a href="#d0e332">Asynchronous results</a></dt><dt>3.3. <a href="#tbl-perf-results">Estimated performance</a></dt></dl></div><div class="preface" title="Preface"><div class="titlepage"><div><div><h2 class="title"><a name="d0e28"></a>Preface</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#acknowledgements">Acknowledgements</a></span></dt></dl></div><div class="section" title="Acknowledgements"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="acknowledgements"></a>Acknowledgements</h2></div></div></div><p>ISC would like to acknowledge generous support for
      BIND 10 development of DHCPv4 and DHCPv6 components provided
      by <a class="ulink" href="http://www.comcast.com/" target="_top">Comcast</a>.</p></div></div><div class="chapter" title="Chapter&nbsp;1.&nbsp;Introduction"><div class="titlepage"><div><div><h2 class="title"><a name="intro"></a>Chapter&nbsp;1.&nbsp;Introduction</h2></div></div></div><p>
      This document is in its early stages of development. It is
      expected to grow significantly in a near future. It will
      cover topics like database backend perfomance measurements,
      pros an cons of various optimization techniques and
      tools.
    </p></div><div class="chapter" title="Chapter&nbsp;2.&nbsp;ISC DHCP 4.x"><div class="titlepage"><div><div><h2 class="title"><a name="dhcp4"></a>Chapter&nbsp;2.&nbsp;ISC DHCP 4.x</h2></div></div></div><p>
      TODO: Write something about ISC DHCP4 here.
    </p></div><div class="chapter" title="Chapter&nbsp;3.&nbsp;Kea"><div class="titlepage"><div><div><h2 class="title"><a name="kea"></a>Chapter&nbsp;3.&nbsp;Kea</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#d0e54">Backend performance evaluation</a></span></dt><dt><span class="section"><a href="#mysql-backend">MySQL backend</a></span></dt><dd><dl><dt><span class="section"><a href="#d0e156">MySQL tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#sqlite-ubench">SQLite-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#sqlite-tweaks">SQLite tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#memfile-ubench">memfile-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#memfile-tweaks">memfile tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#d0e245">Performance measurements</a></span></dt><dt><span class="section"><a href="#d0e521">Possible further optimizations</a></span></dt></dl></div><p>

    </p><div class="section" title="Backend performance evaluation"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e54"></a>Backend performance evaluation</h2></div></div></div><p>
        Kea will support several different database backends, using
        both popular databases (like MySQL or SQLite) and
        custom-developed solutions (like in-memory database).  BIND 10
        source code features set of performance microbenchmarks.
        These are small tools written in C/C++ that simulate expected
        DHCP server behaviour and evaluate the performance of
        considered databases. As implemented benchmarks are not really
        simulating DHCP operation, but rather use set of primitives
        that can be used by a real server, they are called
        micro-benchmarks.
      </p><p>Although there are many operations and data types that
      server could store in a database, the most frequently used data
      type is lease information. Although lease information for IPv4
      and IPv6 differs slightly, it is expected that the performance
      differences will be minimal between IPv4 and IPv6 lease operations.
      Therefore each test uses lease4 table for performance measurements.
      </p><p>All benchmarks are implemented as single threaded applications
      that take advantage of a single database connection.</p><p>
        Those benchmarks are stored in tests/tools/dhcp-ubench
        directory. This directory contains simplified prototypes for
        various DB back-ends that are planned or considered as a
        backend engine for BIND10 DHCP.  Athough trivial now, they are
        expected to evolve into useful tools that will allow users to
        measure performance in their specific environment.
      </p><p>
      Currently the following benchmarks are implemented:
      </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>in memory+flat file</p></li><li class="listitem"><p>SQLite</p></li><li class="listitem"><p>MySQL</p></li></ul></div><p>
    </p><p>
      As they require additional (sometimes heavy) dependencies, they are not
      built by default. Actually, their build system is completely separated.
      It will be eventually merged with the main BIND10 makefile system, but
      that is a low priority for now.
    </p><p>
      All benchmarks will follow the same pattern:
      </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>prepare operation (connect to a database, create a file etc.)</p></li><li class="listitem"><p>Measure timestamp 0</p></li><li class="listitem"><p>Commit new lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 1</p></li><li class="listitem"><p>Search for random lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 2</p></li><li class="listitem"><p>Update existing lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 3</p></li><li class="listitem"><p>Delete existing lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 4</p></li><li class="listitem"><p>Print out statistics, based on X and measured timestamps.</p></li></ol></div><p>

      Although this approach does not attempt to simulate actual DHCP server
      operation that has mix of all steps intervening, it answers the
      questions about basic database strenghts and weak points. In particular
      it can show what is the impact of specific DB optimizations, like
      changing engine, optimizing for writes/reads etc.
    </p><p>
      The framework attempts to do the same amount of operations for every
      backend thus allowing fair complarison between them.
    </p></div><div class="section" title="MySQL backend"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="mysql-backend"></a>MySQL backend</h2></div></div></div><p>MySQL backend requires MySQL client development libraries. It uses
      mysql_config tool (that works similar to pkg-config) to discover required
      compilation and linking options. To install required packages on Ubuntu,
      use the following command:

      </p><pre class="screen">$ <strong class="userinput"><code>sudo apt-get install mysql-client mysql-server libmysqlclient-dev</code></strong></pre><p>

      Make sure that MySQL server is running. Make sure that you have your setup
      configured so there is a user that is able to modify used database.</p><p>Before running tests, you need to initialize your database. You can
      use mysql.schema script for that purpose. WARNING: It will drop existing
      Kea database. Do not run this on your production server. Assuming your
      MySQL user is kea, you can initialize your test database by:

      </p><pre class="screen">$ <strong class="userinput"><code>mysql -u kea -p &lt; mysql.schema</code></strong></pre><p>
      </p><p>After database is initialized, you are ready to run the test:
      </p><pre class="screen">$ <strong class="userinput"><code>./mysql_ubench</code></strong></pre><p>

      or

      </p><pre class="screen">$ <strong class="userinput"><code>./mysql_ubench &gt; results-&gt;mysql.txt</code></strong></pre><p>

      Redirecting output to a file is important, because for each operation
      there is a single character printed to show progress. If you have a slow
      terminal, this may considerably affect test perfromance. On the other hand,
      printing something after each operation is required, as poor DB setting
      may slow down operations to around 20 per second. Observant user is expected
      to note that initial dots are printed too slowly and abort the test.</p><p>Currently all default parameters are hardcoded. Default values can be
      overwritten using command line switches. Although all benchmarks take
      the same list of parameters, some of them are specific to a given backend
      type. To get a list of supported parameters, run your benchmark with -h option:

      </p><pre class="screen">$ <strong class="userinput"><code>./mysql_ubench -h</code></strong>
This is a benchmark designed to measure expected performance
of several backends. This particular version identifies itself
as following:
MySQL client version is 5.5.24

Possible command-line parameters:
 -h - help (you are reading this)
 -m hostname - specifies MySQL server to connect (MySQL backend only)
 -u username - specifies MySQL user name (MySQL backend only)
 -p password - specifies MySQL passwod (MySQL backend only)
 -f name - database or filename (MySQL, SQLite and memfile)
 -n integer - number of test repetitions (MySQL, SQLite and memfile)
 -s yes|no - synchronous/asynchronous operation (MySQL, SQLite and memfile)
 -v yes|no - verbose mode (MySQL, SQLite and memfile)
 -c yes|no - should compiled statements be used (MySQL only)
</pre><p>

      </p><div class="section" title="MySQL tweaks"><div class="titlepage"><div><div><h3 class="title"><a name="d0e156"></a>MySQL tweaks</h3></div></div></div><p>One parameter that has huge impact on performance is a a backend engine.
        You can get a list of engines of your MySQL implementation by using

        </p><pre class="screen">&gt; <strong class="userinput"><code>show engines;</code></strong></pre><p>

        in your mysql client. Two notable engines are MyISAM and InnoDB. mysql_ubench will
        use MyISAM for synchronous mode and InnoDB for asynchronous.</p></div></div><div class="section" title="SQLite-ubench"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sqlite-ubench"></a>SQLite-ubench</h2></div></div></div><p>SQLite backend requires both sqlite3 development and run-time package. Their
      names may vary from system to system, but on Ubuntu 12.04 they are called
      sqlite3 libsqlite3-dev. To install them, use the following command:

      </p><pre class="screen">&gt; <strong class="userinput"><code>sudo apt-get install sqlite3 libsqlite3-dev</code></strong></pre><p>

      Before running the test the database has to be created. Use the following command for that:
      </p><pre class="screen">&gt; <strong class="userinput"><code>cat sqlite.schema | sqlite3 sqlite.db</code></strong></pre><p>

      A new database called sqlite.db will be created. That is the default name used
      by sqlite_ubench test. If you prefer other name, make sure you update
      sqlite_ubench.cc accordingly.</p><p>Once the database is created, you can run tests:
      </p><pre class="screen">&gt; <strong class="userinput"><code>./sqlite_ubench</code></strong></pre><p>
      or
      </p><pre class="screen">&gt; <strong class="userinput"><code>./sqlite_ubench &gt; results-sqlite.txt</code></strong></pre><p>
      </p><div class="section" title="SQLite tweaks"><div class="titlepage"><div><div><h3 class="title"><a name="sqlite-tweaks"></a>SQLite tweaks</h3></div></div></div><p>To modify default sqlite_ubench parameters, command line
        switches can be used. Currently supported parameters are
        (default values specified in brackets):
        </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>-f filename - name of the database file ("sqlite.db")</p></li><li class="listitem"><p>-n num - number of iterations (100)</p></li><li class="listitem"><p>-s yes|no - should the operations be performend in synchronous (yes)
          or asynchronous (no) manner (yes)</p></li><li class="listitem"><p>-v yes|no - verbose mode. Should the test print out progress? (yes)</p></li><li class="listitem"><p>-c yes|no - compiled statements. Should the SQL statements be precompiled?</p></li></ol></div><p>
        </p><p>SQLite can run in asynchronous or synchronous mode. This
        mode can be controlled by using sync parameter. It is set
        using (PRAGMA synchronous = ON or OFF).</p><p>Another tweakable feature is journal mode. It can be
        turned to several modes of operation. Its value can be
        modified in SQLite_uBenchmark::connect().  See
        http://www.sqlite.org/pragma.html#pragma_journal_mode for
        detailed explanantion.</p></div></div><div class="section" title="memfile-ubench"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="memfile-ubench"></a>memfile-ubench</h2></div></div></div><p>Memfile backend is custom developed prototype backend that
      somewhat mimics operation of ISC DHCP4. It uses in-memory
      storage using standard C++ and boost mechanisms (std::map and
      boost::shared_ptr&lt;&gt;). All database changes are also
      written to a lease file. That file is strictly write-only. This
      approach takes advantage of the fact that simple append is faster
      than edition with potential whole file relocation.</p><div class="section" title="memfile tweaks"><div class="titlepage"><div><div><h3 class="title"><a name="memfile-tweaks"></a>memfile tweaks</h3></div></div></div><p>To modify default memfile_ubench parameters, command line
        switches can be used. Currently supported parameters are
        (default values specified in brackets):
        </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>-f filename - name of the database file ("dhcpd.leases")</p></li><li class="listitem"><p>-n num - number of iterations (100)</p></li><li class="listitem"><p>-s yes|no - should the operations be performend in synchronous (yes)
          or asynchronous (no) manner (yes)</p></li><li class="listitem"><p>-v yes|no - verbose mode. Should the test print out progress? (yes)</p></li></ol></div><p>
        </p><p>memfile can run in asynchronous or synchronous mode. This
        mode can be controlled by using sync parameter. It uses
        fflush() and fsync() in synchronous mode to make sure that
        data is not buffered and physically stored on disk.</p></div></div><div class="section" title="Performance measurements"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e245"></a>Performance measurements</h2></div></div></div><p>This section contains sample results for backend performance measurements,
      taken using microbenchmarks. Tests were conducted on reasonably powerful machine:
      </p><pre class="screen">
CPU: Quad-core Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz (8 logical cores)
HDD: 1,5TB Seagate Barracuda ST31500341AS 7200rpm (used only one of them), ext4 partition
OS: Ubuntu 12.04, running kernel 3.2.0-26-generic SMP x86_64
compiler: g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
MySQL version: 5.5.24
SQLite version: 3.7.9sourceid version is 2011-11-01 00:52:41 c7c6050ef060877ebe77b41d959e9df13f8c9b5e</pre><p>
      </p><p>Benchmarks were run in two series: synchronous and
      asynchronous. As those modes offer radically different
      performances, synchronous mode was conducted for 1000 (one
      thousand) repetitions and asynchronous mode was conducted for
      100000 (hundred thousand) repetitions.</p><div class="table"><a name="d0e256"></a><p class="title"><b>Table&nbsp;3.1.&nbsp;Synchronous results</b></p><div class="table-contents"><table summary="Synchronous results" border="1"><colgroup><col align="center" class="Backend"><col align="center" class="Num"><col align="center" class="Create"><col align="center" class="Search"><col align="center" class="Update"><col align="center" class="Delete"></colgroup><thead><tr><th align="center">Backend</th><th align="center">Operations</th><th align="center">Create</th><th align="center">Search</th><th align="center">Update</th><th align="center">Delete</th><th align="center">Average</th></tr></thead><tbody><tr><td align="center">MySQL</td><td align="center">1000</td><td align="center">31.603978s</td><td align="center"> 0.116612s</td><td align="center">27.964191s</td><td align="center">27.695209s</td><td align="center">21.844998s</td></tr><tr><td align="center">SQLite</td><td align="center">1000</td><td align="center">61.421356s</td><td align="center"> 0.033283s</td><td align="center">59.476638s</td><td align="center">56.034150s</td><td align="center">44.241357s</td></tr><tr><td align="center">memfile</td><td align="center">1000</td><td align="center">41.711886s</td><td align="center"> 0.000724s</td><td align="center">42.267578s</td><td align="center">42.169679s</td><td align="center">31.537467s</td></tr></tbody></table></div></div><br class="table-break"><p>Following parameters were measured for asynchronous mode.
      MySQL and SQLite were run with 100 thousand repetitions. Memfile
      was run for 1 million repetitions due to much larger performance.</p><div class="table"><a name="d0e332"></a><p class="title"><b>Table&nbsp;3.2.&nbsp;Asynchronous results</b></p><div class="table-contents"><table summary="Asynchronous results" border="1"><colgroup><col align="center" class="Backend"><col align="center" class="Num"><col align="center" class="Create"><col align="center" class="Search"><col align="center" class="Update"><col align="center" class="Delete"></colgroup><thead><tr><th align="center">Backend</th><th align="center">Operations</th><th align="center">Create [s]</th><th align="center">Search [s]</th><th align="center">Update [s]</th><th align="center">Delete [s]</th><th align="center">Average [s]</th></tr></thead><tbody><tr><td align="center">MySQL</td><td align="center">100000</td><td align="center">10.584842s</td><td align="center">10.386402s</td><td align="center">10.062384s</td><td align="center"> 8.890197s</td><td align="center"> 9.980956s</td></tr><tr><td align="center">SQLite</td><td align="center">100000</td><td align="center"> 3.710356s</td><td align="center"> 3.159129s</td><td align="center"> 2.865354s</td><td align="center"> 2.439406s</td><td align="center"> 3.043561s</td></tr><tr><td align="center">memfile</td><td align="center">1000000 (sic!)</td><td align="center"> 6.084131s</td><td align="center"> 0.862667s</td><td align="center"> 6.018585s</td><td align="center"> 5.146704s</td><td align="center"> 4.528022s</td></tr></tbody></table></div></div><br class="table-break"><p>Presented performance results can be computed into operations per second metrics.
      It should be noted that due to large differences between various operations (sometime
      over 3 orders of magnitude), it is difficult to create a simple, readable chart with
      that data.</p><div class="table"><a name="tbl-perf-results"></a><p class="title"><b>Table&nbsp;3.3.&nbsp;Estimated performance</b></p><div class="table-contents"><table summary="Estimated performance" border="1"><colgroup><col align="center" class="Backend"><col align="center" class="Create"><col align="center" class="Search"><col align="center" class="Update"><col align="center" class="Delete"><col align="center" class="Average"></colgroup><thead><tr><th align="center">Backend</th><th align="center">Create [oper/s]</th><th align="center">Search [oper/s]</th><th align="center">Update [oper/s]</th><th align="center">Delete [oper/s]</th><th align="center">Average [oper/s]</th></tr></thead><tbody><tr><td align="center">MySQL (async)</td><td align="center">9447.47</td><td align="center">9627.97</td><td align="center">9938.00</td><td align="center">11248.34</td><td align="center">10065.45</td></tr><tr><td align="center">SQLite (async)</td><td align="center">26951.59</td><td align="center">31654.29</td><td align="center">34899.70</td><td align="center">40993.59</td><td align="center">33624.79</td></tr><tr><td align="center">memfile (async)</td><td align="center">164362.01</td><td align="center">1159195.84</td><td align="center">166152.01</td><td align="center">194299.11</td><td align="center">421002.24</td></tr><tr><td align="center">MySQL (sync)</td><td align="center">31.64</td><td align="center">8575.45</td><td align="center">35.76</td><td align="center">36.11</td><td align="center">2169.74</td></tr><tr><td align="center">SQLite (sync)</td><td align="center">16.28</td><td align="center">20045.37</td><td align="center">16.81</td><td align="center">17.85</td><td align="center">7524.08</td></tr><tr><td align="center">memfile (sync)</td><td align="center">23.97</td><td align="center">1381215.47</td><td align="center">23.66</td><td align="center">23.71</td><td align="center">345321.70</td></tr></tbody></table></div></div><br class="table-break"><div class="mediaobject"><img src="performance-results-graph1.png" alt="Performance measurements"><div class="caption"><p>Graphical representation of the performance results
          presented in table <a class="xref" href="#tbl-perf-results" title="Table&nbsp;3.3.&nbsp;Estimated performance">Table&nbsp;3.3, &#8220;Estimated performance&#8221;</a>.</p></div></div></div><div class="section" title="Possible further optimizations"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e521"></a>Possible further optimizations</h2></div></div></div><p>
        For debugging purposes the code was compiled with -g -O0
        flags. While majority of the time was spent in backend
        functions (that was probably compiled with -O2 flags), the
        benchmark code could perform faster, when compiled with -O2,
        rather than -O0. That is expected to affect memfile benchmark.
      </p><p>
        Currently all operations were conducted on one by one
        basis. Each operation was treated as a separate
        transaction. Grouping X operations together will potentially
        bring almost X fold increase in synchronous operations.
        Extension for this benchmark in this regard should be considered.
        That affects only write operations (insert, update and delete). Read
        operations (search) are expected to be barely affected.
      </p><p>
        Multi-threaded or multi-process benchmark may be considered in
        the future. It may be somewhat difficult as only some backends
        support concurrent access.
      </p></div></div><div class="chapter" title="Chapter&nbsp;4.&nbsp;perfdhcp"><div class="titlepage"><div><div><h2 class="title"><a name="perfdhcp"></a>Chapter&nbsp;4.&nbsp;perfdhcp</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#d0e533">Purpose</a></span></dt><dt><span class="section"><a href="#d0e538">Key features</a></span></dt><dt><span class="section"><a href="#perfdhcp-command-line">Command line options</a></span></dt><dt><span class="section"><a href="#d0e574">Running a test</a></span></dt></dl></div><div class="section" title="Purpose"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e533"></a>Purpose</h2></div></div></div><p>
        There is a growing need to evaluate performance of DHCP servers in
        different traffic conditions to understand their bottle necks.
        This helps to elimante bugs in existing DHCP software as well
        as make informed decisions regarding new DHCP software designs
        to significantly improve its performance. The perfdhcp tool has
        been created to fill the gap in performance measurement capabilities
        mostly. However, the number of implemented features and parameters
        exposed to the user make this tool useful for functional testing as
        well.
      </p></div><div class="section" title="Key features"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e538"></a>Key features</h2></div></div></div><p>
        The perfdhcp exposes the number of command line parameters to
        control DHCP message exchanges. Currently they fall back to
        the following categories:
        </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>
              Rate control - control how many DHCP exchanges
              are initiated within a period of time. Tool can also simulate
              best effort conditions where it attempts to start as many
              exchanges as possible.
            </p></li><li class="listitem"><p>
              Test exit specifiers - control the conditions when test
              completes including number of initiated exchanges, test period or
              maximum number of dropped packets.
            </p></li><li class="listitem"><p>
              Packet templates - specify files containing packet templates that
              are used by perfdhcp to create custom DHCP messages instead of
              default. Tool also allows to specify number of values indicating
              offsets of variable values within a packet that are modified in
              flight by the tool.
            </p></li><li class="listitem"><p>
              Reporting - for each test produce the set of performance data
              including achieved packet exchange rate (server performance).
              There is also a number of diagnostic selectors available that
              enable periodic (intermediate) reporting, packet timestamps
              printing and detailed information about perfdhcp internal
              states (for debugging).
            </p></li><li class="listitem"><p>
              Different mode of operations - specify DHCP version used
              (v4 or v6), 2-way or 4-way exchanges, use Rapid Commit option
              for DHCPv6.
            </p></li><li class="listitem"><p>
              IP layer options - specify local/remote address, local interface
              and local port to be used for communication with DHCP server.
            </p></li></ol></div><p>
      </p></div><div class="section" title="Command line options"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="perfdhcp-command-line"></a>Command line options</h2></div></div></div><p>
        The following command line options may be used with perfdhcp tool.
        This summary also presents its possible exit codes as well as
        error counters printed along when test is complete:
        </p><pre class="screen">$ <strong class="userinput"><code>./perfdhcp -h</code></strong>
perfdhcp [-hv] [-4|-6] [-r&lt;rate&gt;] [-t&lt;report&gt;] [-R&lt;range&gt;] [-b&lt;base&gt;]
    [-n&lt;num-request&gt;] [-p&lt;test-period&gt;] [-d&lt;drop-time&gt;] [-D&lt;max-drop&gt;]
    [-l&lt;local-addr|interface&gt;] [-P&lt;preload&gt;] [-a&lt;aggressivity&gt;]
    [-L&lt;local-port&gt;] [-s&lt;seed&gt;] [-i] [-B] [-c] [-1]
    [-T&lt;template-file&gt;] [-X&lt;xid-offset&gt;] [-O&lt;random-offset]
    [-E&lt;time-offset&gt;] [-S&lt;srvid-offset&gt;] [-I&lt;ip-offset&gt;]
    [-x&lt;diagnostic-selector&gt;] [-w&lt;wrapped&gt;] [server]

The [server] argument is the name/address of the DHCP server to
contact.  For DHCPv4 operation, exchanges are initiated by
transmitting a DHCP DISCOVER to this address.

For DHCPv6 operation, exchanges are initiated by transmitting a DHCP
SOLICIT to this address.  In the DHCPv6 case, the special name 'all'
can be used to refer to All_DHCP_Relay_Agents_and_Servers (the
multicast address FF02::1:2), or the special name 'servers' to refer
to All_DHCP_Servers (the multicast address FF05::1:3).  The [server]
argument is optional only in the case that -l is used to specify an
interface, in which case [server] defaults to 'all'.

The default is to perform a single 4-way exchange, effectively pinging
the server.
The -r option is used to set up a performance test, without
it exchanges are initiated as fast as possible.

Options:
-1: Take the server-ID option from the first received message.
-4: DHCPv4 operation (default). This is incompatible with the -6 option.
-6: DHCPv6 operation. This is incompatible with the -4 option.
-a&lt;aggressivity&gt;: When the target sending rate is not yet reached,
    control how many exchanges are initiated before the next pause.
-b&lt;base&gt;: The base mac, duid, IP, etc, used to simulate different
    clients.  This can be specified multiple times, each instance is
    in the &lt;type&gt;=&lt;value&gt; form, for instance:
    (and default) mac=00:0c:01:02:03:04.
-d&lt;drop-time&gt;: Specify the time after which a request is treated as
    having been lost.  The value is given in seconds and may contain a
    fractional component.  The default is 1 second.
-E&lt;time-offset&gt;: Offset of the (DHCPv4) secs field / (DHCPv6)
    elapsed-time option in the (second/request) template.
    The value 0 disables it.
-h: Print this help.
-i: Do only the initial part of an exchange: DO or SA, depending on
    whether -6 is given.
-I&lt;ip-offset&gt;: Offset of the (DHCPv4) IP address in the requested-IP
    option / (DHCPv6) IA_NA option in the (second/request) template.
-l&lt;local-addr|interface&gt;: For DHCPv4 operation, specify the local
    hostname/address to use when communicating with the server.  By
    default, the interface address through which traffic would
    normally be routed to the server is used.
    For DHCPv6 operation, specify the name of the network interface
    via which exchanges are initiated.
-L&lt;local-port&gt;: Specify the local port to use
    (the value 0 means to use the default).
-O&lt;random-offset&gt;: Offset of the last octet to randomize in the template.
-P&lt;preload&gt;: Initiate first &lt;preload&gt; exchanges back to back at startup.
-r&lt;rate&gt;: Initiate &lt;rate&gt; DORA/SARR (or if -i is given, DO/SA)
    exchanges per second.  A periodic report is generated showing the
    number of exchanges which were not completed, as well as the
    average response latency.  The program continues until
    interrupted, at which point a final report is generated.
-R&lt;range&gt;: Specify how many different clients are used. With 1
    (the default), all requests seem to come from the same client.
-s&lt;seed&gt;: Specify the seed for randomization, making it repeatable.
-S&lt;srvid-offset&gt;: Offset of the server-ID option in the
    (second/request) template.
-T&lt;template-file&gt;: The name of a file containing the template to use
    as a stream of hexadecimal digits.
-v: Report the version number of this program.
-w&lt;wrapped&gt;: Command to call with start/stop at the beginning/end of
    the program.
-x&lt;diagnostic-selector&gt;: Include extended diagnostics in the output.
    &lt;diagnostic-selector&gt; is a string of single-keywords specifying
    the operations for which verbose output is desired.  The selector
    keyletters are:
   * 'a': print the decoded command line arguments
   * 'e': print the exit reason
   * 'i': print rate processing details
   * 'r': print randomization details
   * 's': print first server-id
   * 't': when finished, print timers of all successful exchanges
   * 'T': when finished, print templates
-X&lt;xid-offset&gt;: Transaction ID (aka. xid) offset in the template.

DHCPv4 only options:
-B: Force broadcast handling.

DHCPv6 only options:
-c: Add a rapid commit option (exchanges will be SA).

The remaining options are used only in conjunction with -r:

-D&lt;max-drop&gt;: Abort the test if more than &lt;max-drop&gt; requests have
    been dropped.  Use -D0 to abort if even a single request has been
    dropped.  If &lt;max-drop&gt; includes the suffix '%', it specifies a
    maximum percentage of requests that may be dropped before abort.
    In this case, testing of the threshold begins after 10 requests
    have been expected to be received.
-n&lt;num-request&gt;: Initiate &lt;num-request&gt; transactions.  No report is
    generated until all transactions have been initiated/waited-for,
    after which a report is generated and the program terminates.
-p&lt;test-period&gt;: Send requests for the given test period, which is
    specified in the same manner as -d.  This can be used as an
    alternative to -n, or both options can be given, in which case the
    testing is completed when either limit is reached.
-t&lt;report&gt;: Delay in seconds between two periodic reports.

Errors:
- tooshort: received a too short message
- orphans: received a message which doesn't match an exchange
   (duplicate, late or not related)
- locallimit: reached to local system limits when sending a message.

Exit status:
The exit status is:
0 on complete success.
1 for a general error.
2 if an error is found in the command line arguments.
3 if there are no general failures in operation, but one or more
  exchanges are not successfully completed.

        </pre><p>
      </p></div><div class="section" title="Running a test"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e574"></a>Running a test</h2></div></div></div><p>
        In order to run performance test at least two separate systems
        have to be installed: client and server. The first one has to have
        perfdhcp tool installed, the latter has to have DHCP server
        running (v4 or v6). If only single system is available the client
        and server can be run on virtual machines (running on the same
        phisical system) but in this case performance data may be heavily
        impacted by the performance of VMs.
      </p><p>
        The DHCP operates on low port numbers (67 for DHCPv4 relays and
        547 for DHCPv6) running perfdhcp with non-root priviliges will
        usually result in the error message similar to this:
        </p><pre class="screen"><strong class="userinput"><code>$./perfdhcp -4 -l eth3 -r 100 all</code></strong>
Error running perfdhcp: Failed to bind socket 3 to 172.16.1.2/port=67
        </pre><p>
        perfdhcp exposes '-L' command line option that
        imposes use of custom local port and the following command line will
        work:
        </p><pre class="screen"><strong class="userinput"><code>$./perfdhcp -4 -l eth3 -r 100 -L 10067 all</code></strong></pre><p>
        but in the standard configuration no responses will be received
        from the ISC DHCP server because server responds to default relay
        port 67.
      </p><p>
        Alternative way to overcome the issue with lack of privileges
        to use default DHCP port number is to run perfdhcp as root.
      </p><p>
        In this section the perfdhcp command line options examples
        are presented as a quick start guide for new users. For the
        detailed list of command line options refer to
        <a class="xref" href="#perfdhcp-command-line" title="Command line options">the section called &#8220;Command line options&#8221;</a>.
      </p><p>
        </p><pre class="screen">
          <strong class="userinput"><code></code></strong>
        </pre><p>
      </p></div></div></div></body></html>