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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-69B46D92-8D07-5B42-B603-3F725977AA4A" xml:lang="en"><title>DHCP</title><shortdesc>The Dynamic Host Configuration Protocol (DHCP) is an Internet standard
defined in RFC2131 (IPv4) and RFC3315 (IPv6). </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The DHCP client implementation in Symbian platform enables the client applications
to configure a network connection with a DHCP server. </p>
<p>For more details on the DHCP standards, see RFC2131<xref href="http://www.ietf.org/rfc/rfc2131.txt" scope="external">RFC2131</xref> for IPv4, and RFC3315<xref href="http://www.ietf.org/rfc/rfc3315.txt" scope="external">RFC3315</xref> for IPv6.</p>
<p>This document explains the following concepts: </p>
<ul>
<li id="GUID-77B3171B-FCF4-5744-B288-AFCC81B93488"><p>DHCP States </p> </li>
<li id="GUID-460F04A8-5FF1-578F-B129-3C61264044D4"><p>DHCP Options </p> </li>
</ul>
<section id="GUID-D83FB908-53EC-4019-A8E4-8B633FEC7F0B"><title>DHCP States </title> <p>The
following are the states of the DHCP daemon in Symbian platform: </p> <ul>
<li id="GUID-ACD085A9-E25C-58A8-859E-1E42BC467089"><p>DHCP Discover </p> </li>
<li id="GUID-18AAC18A-9A29-5B5D-AEC1-E64B8A81A149"><p>Bind </p> </li>
<li id="GUID-04DF8A2D-4CCD-59A3-8346-CF7D5E1F176C"><p>Renew lease </p> </li>
<li id="GUID-56E8EDB9-EBF7-5A66-B85B-E0685BED0C6C"><p>Release lease </p> </li>
</ul> <p><b>DHCP Discover </b> </p> <p>This stage gets the IP address from
the server by the DHCP clients. The DHCP client sends a DISCOVER message to
the DHCP server and waits for the responses from the various DHCP servers. </p> <p><b>Bind </b> </p> <p>The
DHCP server acknowledges the BIND request with an IP address. The client selects
one of the IP addresses and responds back with a BIND message. If the DHCP
server acknowledges the BIND request, the client can use the IP address. If
the server responds with a negative acknowledgement, the DHCP client begins
the DHCP DISCOVER state. </p> <p><b>Renew lease </b> </p> <p>The DHCP server
issues an IP address, called a lease, during the bind state. When the lease
is about to expire the client requests the server to renew the lease. If the
client is connected to the same network the lease gets renewed. If the client
has moved to a domain with a different DHCP server the client requests a new
IP address using DISCOVER message. </p> <p><b>Release lease </b> </p> <p>When
the DHCP client does not require a connection it releases the lease, so that
it can be configured to any other client requesting a connection. </p> </section>
<section id="GUID-C5F11CA2-8880-4FDB-8065-149C5EAA7A44"><title>DHCP Options</title> <p>To
obtain the network parameters from the DHCP server, the client uses the DHCP
options. The Internet standard <xref href="http://www.ietf.org/rfc/rfc2132.txt" scope="external">RFC 2132</xref> specifies the various DHCP options. The client
uses the <xref href="GUID-95F9FA1F-5AA5-3C2F-ADE0-34668B499C50.dita"><apiname>aOptionLevel</apiname></xref> and <xref href="GUID-DA7EBA40-EF88-3C95-9361-E3A199783CE2.dita"><apiname>aOptionName</apiname></xref> arguments
while calling <xref href="GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD.dita#GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD/GUID-9F820CF9-1D4F-3452-983B-E0C694D6783A"><apiname>RConnection::Ioctl()</apiname></xref> function. </p> </section>
</conbody><related-links>
<link href="GUID-45E1953A-DEFB-5E48-AC96-443A3234F913.dita"><linktext>Retrieving
an IP Network  Parameters</linktext></link>
</related-links></concept>