[3210] Docs updated.

doc/guide/bind10-guide.xml

@@ -4414,6 +4414,26 @@ Dhcp4/subnet4	[]	list	(default)
 
     </section>
 
+    <section id="dhcp4-echo-client-id">
+      <title>Echoing client-id (RFC6842)</title>
+      <para>Original DHCPv4 spec (RFC2131) states that the DHCPv4 server must not
+      send back client-id options when responding to clients. However, in some cases
+      that confused clients that did not have MAC address or client-id. See RFC6842
+      for details. That behavior has changed with the publication of RFC6842 which
+      updated RFC2131. That update now states that the server must send client-id.
+      That is the default behaviour that Kea offers. However, in some cases older
+      devices that do not support RFC6842 may refuse to accept responses that include
+      client-id options. To enable backward compatibility, an optional flag has been
+      introduced. To configure it, use the following commands:</para>
+
+<screen>
+&gt; <userinput>config add Dhcp4/echo-client-id</userinput>
+&gt; <userinput>config set Dhcp4/echo-client-id True"</userinput>
+&gt; <userinput>config commit</userinput>
+</screen>
+
+    </section>
+
     <section id="dhcp4-std">
       <title>Supported Standards</title>
       <para>The following standards and draft standards are currently
@@ -4424,11 +4444,18 @@ Dhcp4/subnet4	[]	list	(default)
             REQUEST, RELEASE, ACK, and NAK.</simpara>
           </listitem>
           <listitem>
-            <simpara><ulink url="http://tools.ietf.org/html/rfc2132">RFC 2132</ulink>: Supported options are: PAD (0),
+            <simpara><ulink url="http://tools.ietf.org/html/rfc2132">RFC 2132</ulink>:
+            Supported options are: PAD (0),
             END(255), Message Type(53), DHCP Server Identifier (54),
             Domain Name (15), DNS Servers (6), IP Address Lease Time
             (51), Subnet mask (1), and Routers (3).</simpara>
           </listitem>
+          <listitem>
+            <simpara><ulink url="http://tools.ietf.org/html/rfc6842">RFC 6842</ulink>:
+            Server by default sends back client-id option. That capability may be
+            disabled. See <xref linkend="dhcp4-echo-client-id"/> for details.
+            </simpara>
+          </listitem>
       </itemizedlist>
     </section>
 
@@ -4451,21 +4478,6 @@ Dhcp4/renew-timer	1000	integer	(default)
 &gt; <userinput>config commit</userinput></screen>
           </para>
         </listitem>
-          <listitem>
-            <simpara>During the initial IPv4 node configuration, the
-            server is expected to send packets to a node that does not
-            have IPv4 address assigned yet. The server requires
-            certain tricks (or hacks) to transmit such packets. This
-            is not implemented yet, therefore DHCPv4 server supports
-            relayed traffic only (that is, normal point to point
-            communication).</simpara>
-          </listitem>
-
-          <listitem>
-            <simpara>Upon start, the server will open sockets on all
-            interfaces that are not loopback, are up and running and
-            have IPv4 address.</simpara>
-          </listitem>
 
           <listitem>
             <simpara>The DHCPv4 server does not support