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<title>DHCP Manager Help: About Macros and Options</title>
<meta NAME="AUTHOR" CONTENT="smorgan">
<meta NAME="KEYWORDS" CONTENT="DHCP">
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<P>&nbsp;</P>
<A HREF="dhcp_main_top.html"><STRONG>Overview</STRONG></A><BR>
&nbsp;&nbsp;<A HREF="dhcp_solaris_about.html">Solaris DHCP</A><BR>
<IMG SRC="art/tip2.gif" WIDTH=12 HEIGHT=10 BORDER=0 ALT="">About Macros<BR>
&nbsp;&nbsp;<A HREF="dhcp_main_hlp.html">Getting Help</A><P>
<A HREF="dhcp_relay_ref.html"><STRONG>Servers and Relays</STRONG></A><P>
<A HREF="dhcp_net_ref.html"><STRONG>Networks</STRONG></A><P>
<A HREF="dhcp_addr_ref.html"><STRONG>Addresses</STRONG></A><P>
<A HREF="dhcp_macro_ref.html"><STRONG>Macros</STRONG></A><P>
<A HREF="dhcp_option_ref.html"><STRONG>Options</STRONG></A><P>
<A HREF="dhcp_main_how.html"><STRONG>How To..</STRONG></A><P>
<A HREF="dhcp_main_idx.html"><STRONG>Index</STRONG></A>
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<P>&nbsp;</P>
<h1>About Macros and Options</H1>
In a DHCP environment, <em>macros</em> are containers for <em>option values</em> that are
passed as configuration parameters from the DHCP server to the DHCP client. For example,
you might define a macro that contains options specifying a DNS server and print server
to be used by all clients using IP addresses owned by a particular DHCP server.<p>
<em>Options</em> specify the format in which option values are
defined in the DHCP server's <tt>dhcptab</tt> (in which all DHCP
options and macros are stored). For example, option category, data type, vendor, and granularity all determine the <em>shape</em> of the options
contained in your macros. Creating and modifying options is described
further in the help pages for <a href="dhcp_option_create.html">Create Option</a> and
<a href="dhcp_option_mod.html">Modify Option</a>.<p>
<h1>
Macro Processing
</h1>
<p>
Remember the following points when naming DHCP macros and adding
options to macros:
</p>
<ol>
<li>
<strong>Automatic processing</strong> occurs for Client Class,
Network, and Client ID category macros when the macro category
matches the client's class, network address, or client
identifier.
<br>
</li>
<li>
<strong>Macro categories</strong> determine the order in which
macros are processed automatically.
<br>
</li>
<li>
<strong>Macro names</strong> determine macro categories, with the
exception of IP address macros, which are categorized by their
assignment to an IP address.<br>
<p>
For most macros, make your macro names <strong>match the names
of the resources or devices</strong> to which you want the
macros to apply. For example:
</p>
<br>
<table cellpadding="4" cellspacing="4" border="1">
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<p>
For Clients...
</p>
</td>
<td bgcolor="#CCCFFF" valign="middle" align="left">
<p>
Name Your Macro
</p>
</td>
</tr>
<tr>
<td valign="top">
<p>
Of a particular client class
</p>
</td>
<td valign="top">
<p>
Same name as the DHCP client's client class. The
client class is determined by the client vendor. For
example, the client class name for a Sun Blade <sup><font
size="-2"> TM</font></sup> 150 client is SUNW,Sun-Blade-100 so
you must name your macro <tt> SUNW.Sun-Blade-100</tt> . On
Solaris DHCP client systems, you
can determine the client class by typing the command
<tt> uname -i</tt> on the client machine. Note that
macro names cannot contain commas; if a comma appears
in the client class, replace it with a period in the
macro name.
</p>
</td>
</tr>
<tr>
<td valign="top">
<p>
On a particular network
</p>
</td>
<td valign="top">
<p>
Same as the IP address of the network through which the
client is connecting; for example, name your macro <tt>
10.0.0.0</tt>.
</p>
</td>
</tr>
<tr>
<td valign="top">
<p>
Using a particular IP Address
</p>
</td>
<td valign="top">
<p>
Any name, but using the DHCP server's hostname or IP
address is recommended; for example, name your macro
<tt> shiva</tt> or <tt> 125.53.224.45</tt> . This kind
of macro is valuable for use as a configuration macro
for all clients obtaining configuration information
from this DHCP server.
</p>
</td>
</tr>
<tr>
<td valign="top">
<p>
Identified by a particular client ID
</p>
</td>
<td valign="top">
<p>
Same as the unique client identifier; for example,
name your macro <tt> 010800201112B7</tt> .
</p>
</td>
</tr>
</table>
<br>
</li>
<li>
<strong>Order is important.</strong> The order in which macros are
processed is significant. If an option is contained in more than
one macro, the option value passed to the client is the value
assigned in the macro processed last. Macros are processed in the
order shown in the illustration.<br>
<br>
<p>
<img src="art/macroflow.gif" alt="order of macro processing" vspace="0" hspace="0" border="0"
height="225" width="400">
</p>
<p>
As shown in the illustration, macro processing progresses from
the general to the specific.
</p>
<ul type="disc">
<li>
<p>
Client Class macros are processed first.<br>
</p>
</li>
<li>
<p>
Network macros are processed second, superseding any
competing settings in Client Class macros.<br>
</p>
</li>
<li>
<p>
IP Address macros are processed third, superseding any
competing settings in previous macros.<br>
</p>
</li>
<li>
<p>
Client ID macros are processed last, superseding any
competing settings in all previous macros.<br>
</p>
</li>
</ul>
</li>
<li>
<p>
<strong>Macros can include other macros.</strong> Regardless of a
macro's category, it can include other macros so that, for example,
a client class macro could be called from an IP Address macro.<br>
<br>
</li>
</ol>
<p>
�
</p>
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