</section>
+ <section id="dhcp4-stats">
+ <title>Statistics in DHCPv4 server</title>
+ <note>
+ <para>This section describes DHCPv4-specific statistics. For a general
+ overview and usage of statistics, see <xref linkend="stats" />.</para>
+ </note>
+
+ <para>
+ The DHCPv4 server supports the following statistics:
+ </para>
+ <para>
+ <itemizedlist>
+ <listitem>
+ <simpara><emphasis>pkt4-received</emphasis> (integer) - this
+ statistic shows the the number of received packets. That includes
+ all packets: valid, bogus, corrupted, rejected etc. This statistic
+ is expected to grow rapidly.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-discover-received</emphasis> (integer) -
+ specifies the number of received DHCPDISCOVER packets. This statistic
+ is expected to grow. Its increase means that clients that just booted
+ started their configuration process and their initial packets reached
+ your server.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-offer-received</emphasis> (integer) -
+ specifies the number of received DHCPOFFER packets. This statistic
+ is expected to remain zero at all times, as DHCPOFFER packets are sent
+ by the server and the server is never expected to receive them. Non-zero
+ value indicates an error. One likely cause would be a misbehaving relay
+ agent that incorrectly forwards DHCPOFFER messages towards the server,
+ rather back to the clients.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-request-received</emphasis> (integer) -
+ specifies the number of received DHCPREQUEST packets. This statistic
+ is expected to grow. Its increase means that clients that just booted
+ received server's response (DHCPOFFER), accepted it and now requesting
+ an address (DHCPREQUEST).</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-ack-received</emphasis> (integer) -
+ specifies the number of received DHCPACK packets. This statistic
+ is expected to remain zero at all times, as DHCPACK packets are sent
+ by the server and the server is never expected to receive them. Non-zero
+ value indicates an error. One likely cause would be a misbehaving relay
+ agent that incorrectly forwards DHCPACK messages towards the server,
+ rather back to the clients.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-nak-received</emphasis> (integer) -
+ specifies the number of received DHCPNAK packets. This statistic
+ is expected to remain zero at all times, as DHCPNAK packets are sent
+ by the server and the server is never expected to receive them. Non-zero
+ value indicates an error. One likely cause would be a misbehaving relay
+ agent that incorrectly forwards DHCPNAK messages towards the server,
+ rather back to the clients.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-release-received</emphasis> (integer) -
+ specifies the number of received DHCPRELEASE packets. This statistic
+ is expected to grow. Its increase means that clients that had an address
+ are shutting down or stop using their addresses.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-decline-received</emphasis> (integer) -
+ specifies the number of received DHCPDECLINE packets. This statistic
+ is expected to remain close to zero. Its increase means that clients
+ that leased an address, but discovered that the address is currently
+ used by an unknown device in your network.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-decline-received</emphasis> (integer) -
+ specifies the number of received DHCPDECLINE packets. This statistic
+ is expected to remain close to zero. Its increase means that a client
+ that leased an address, but discovered that the address is currently
+ used by an unknown device in your network.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-inform-received</emphasis> (integer) -
+ specifies the number of received DHCPINFORM packets. This statistic
+ is expected to grow. Its increase means that there are clients that
+ either do not need an address or already have an address and are
+ interested only in getting additional configuration parameters.
+ </simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-unknown-received</emphasis> (integer) -
+ specifies the number of received packets of uknown type. Non-zero
+ value of this statistic indicates that the server received a packet
+ that it wasn't able to recognize: either with unsupported type
+ or possibly malformed (without message type option).</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-sent</emphasis> (integer) - specifies the
+ number of sent DHCPv4 packets. This statistic is expected to grow
+ every time the server transmits a packet. In general, it should
+ roughly match pkt4-received, as most incoming packets cause
+ server to respond. There are exceptions (e.g. DHCPRELEASE), so
+ do not worry, if it is lesser than pkt4-received.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-sent</emphasis> (integer) - specifies the
+ number of sent DHCPv4 packets. This statistic is expected to grow
+ every time the server transmits a packet. In general, it should
+ roughly match pkt4-received, as most incoming packets cause
+ server to respond. There are exceptions (e.g. DHCPRELEASE), so
+ do not worry, if it is lesser than pkt4-received.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-offer-sent</emphasis> (integer) - specifies
+ the number of sent DHCPOFFER packets. This statistic is expected to
+ grow in most cases after a DHCPDISCOVER is processed. There are
+ certain uncommon, but valid cases where incoming DHCPDISCOVER is
+ dropped, but in general this statistic is expected to be close to
+ pkt4-discover-received.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-ack-sent</emphasis> (integer) - specifies
+ the number of sent DHCPACK packets. This statistic is expected to
+ grow in most cases after a DHCPREQUEST is processed. There are
+ certain cases where DHCPNAK is sent instead. In general, the sum of
+ pkt4-ack-sent and pkt4-nak-sent should be close to
+ pkt4-request-received.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-nak-sent</emphasis> (integer) - specifies
+ the number of sent DHCPNAK packets. This statistic is expected to
+ grow when the server choses to not honor the address requested by a
+ client. In general, the sum of pkt4-ack-sent and pkt4-nak-sent
+ should be close to pkt4-request-received.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-parse-failed</emphasis> (integer) - this
+ statistic denote the number of packets that were received, but the
+ Kea server was unable to parse it. Non-zero value of this statistic
+ indicates that the server received malformed or truncated packet.
+ This may indicate problems in your network, faulty clients or server
+ code bug.</simpara>
+ </listitem>
+ <listitem>
+ <simpara><emphasis>pkt4-receive-drop</emphasis> (integer) - this
+ statistic indicate number of incoming packets that were dropped.
+ Exact reason for dropping packets is logged, but the most common
+ reasons may be not accepted packet type, direct responses are
+ forbidden or the server-id the client had sent doesn't match the
+ server's.</simpara>
+ </listitem>
+ </itemizedlist>
+ </para>
+ </section>
<section id="dhcp4-std">
<title>Supported DHCP Standards</title>