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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <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

    13 defined in RFC2131 (IPv4) and RFC3315 (IPv6). </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>The DHCP client implementation in Symbian platform enables the client applications

    15 to configure a network connection with a DHCP server. </p>

    16 <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>

    17 <p>This document explains the following concepts: </p>

    18 <ul>

    19 <li id="GUID-77B3171B-FCF4-5744-B288-AFCC81B93488"><p>DHCP States </p> </li>

    20 <li id="GUID-460F04A8-5FF1-578F-B129-3C61264044D4"><p>DHCP Options </p> </li>

    21 </ul>

    22 <section id="GUID-D83FB908-53EC-4019-A8E4-8B633FEC7F0B"><title>DHCP States </title> <p>The

    23 following are the states of the DHCP daemon in Symbian platform: </p> <ul>

    24 <li id="GUID-ACD085A9-E25C-58A8-859E-1E42BC467089"><p>DHCP Discover </p> </li>

    25 <li id="GUID-18AAC18A-9A29-5B5D-AEC1-E64B8A81A149"><p>Bind </p> </li>

    26 <li id="GUID-04DF8A2D-4CCD-59A3-8346-CF7D5E1F176C"><p>Renew lease </p> </li>

    27 <li id="GUID-56E8EDB9-EBF7-5A66-B85B-E0685BED0C6C"><p>Release lease </p> </li>

    28 </ul> <p><b>DHCP Discover </b> </p> <p>This stage gets the IP address from

    29 the server by the DHCP clients. The DHCP client sends a DISCOVER message to

    30 the DHCP server and waits for the responses from the various DHCP servers. </p> <p><b>Bind </b> </p> <p>The

    31 DHCP server acknowledges the BIND request with an IP address. The client selects

    32 one of the IP addresses and responds back with a BIND message. If the DHCP

    33 server acknowledges the BIND request, the client can use the IP address. If

    34 the server responds with a negative acknowledgement, the DHCP client begins

    35 the DHCP DISCOVER state. </p> <p><b>Renew lease </b> </p> <p>The DHCP server

    36 issues an IP address, called a lease, during the bind state. When the lease

    37 is about to expire the client requests the server to renew the lease. If the

    38 client is connected to the same network the lease gets renewed. If the client

    39 has moved to a domain with a different DHCP server the client requests a new

    40 IP address using DISCOVER message. </p> <p><b>Release lease </b> </p> <p>When

    41 the DHCP client does not require a connection it releases the lease, so that

    42 it can be configured to any other client requesting a connection. </p> </section>

    43 <section id="GUID-C5F11CA2-8880-4FDB-8065-149C5EAA7A44"><title>DHCP Options</title> <p>To

    44 obtain the network parameters from the DHCP server, the client uses the DHCP

    45 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

    46 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

    47 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>

    48 </conbody><related-links>

    49 <link href="GUID-45E1953A-DEFB-5E48-AC96-443A3234F913.dita"><linktext>Retrieving

    50 an IP Network  Parameters</linktext></link>

    51 </related-links></concept>