ovn-northd: Add logical flows to support native DHCPv4

[cascardo/ovs.git] / ovn / northd / ovn-northd.8.xml

diff --git a/ovn/northd/ovn-northd.8.xml b/ovn/northd/ovn-northd.8.xml
index ced2839..b95caef 100644 (file)
--- a/ovn/northd/ovn-northd.8.xml
+++ b/ovn/northd/ovn-northd.8.xml
@@ -457,7 +457,90 @@ output;
       </li>
     </ul>
 
-    <h3>Ingress Table 10: Destination Lookup</h3>
+    <h3>Ingress Table 10: DHCP option processing</h3>
+
+    <p>
+      This table adds the DHCPv4 options to a DHCPv4 packet from the
+      logical ports configured with IPv4 address(es) and DHCPv4 options.
+    </p>
+
+    <ul>
+      <li>
+        <p>
+          A priority-100 logical flow is added for these logical ports
+          which matches the IPv4 packet with <code>udp.src</code> = 68 and
+          <code>udp.dst</code> = 67 and applies the action
+          <code>put_dhcp_opts</code> and advances the packet to the next table.
+        </p>
+
+        <pre>
+reg0[3] = put_dhcp_opts(offer_ip = <var>O</var>, <i>options</i>...);
+next;
+        </pre>
+
+        <p>
+          For DHCPDISCOVER and DHCPREQUEST, this transforms the packet into a
+          DHCP reply, adds the DHCP offer IP <var>O</var> and options to the
+          packet, and stores 1 into reg0[3].  For other kinds of packets, it
+          just stores 0 into reg0[3].  Either way, it continues to the next
+          table.
+        </p>
+
+      </li>
+
+      <li>
+        A priority-0 flow that matches all packets to advances to table 11.
+      </li>
+    </ul>
+
+    <h3>Ingress Table 11: DHCP responses</h3>
+
+    <p>
+      This table implements DHCP responder for the DHCP replies generated by
+      the previous table.
+    </p>
+
+    <ul>
+      <li>
+        <p>
+          A priority 100 logical flow is added for the logical ports configured
+          with DHCPv4 options which matches IPv4 packets with <code>udp.src == 68
+          &amp;&amp; udp.dst == 67 &amp;&amp; reg0[3] == 1</code> and
+          responds back to the <code>inport</code> after applying these
+          actions.  If <code>reg0[3]</code> is set to 1, it means that the
+          action <code>put_dhcp_opts</code> was successful.
+        </p>
+
+        <pre>
+eth.dst = eth.src;
+eth.src = <var>E</var>;
+ip4.dst = <var>O</var>;
+ip4.src = <var>S</var>;
+udp.src = 67;
+udp.dst = 68;
+outport = <var>P</var>;
+inport = ""; /* Allow sending out inport. */
+output;
+        </pre>
+
+        <p>
+          where <var>E</var> is the server MAC address and <var>S</var> is the
+          server IPv4 address defined in the DHCPv4 options and <var>O</var> is
+          the IPv4 address defined in the logical port's addresses column.
+        </p>
+
+        <p>
+          (This terminates ingress packet processing; the packet does not go
+           to the next ingress table.)
+        </p>
+      </li>
+
+      <li>
+        A priority-0 flow that matches all packets to advances to table 12.
+      </li>
+    </ul>
+
+    <h3>Ingress Table 12: Destination Lookup</h3>
 
     <p>
       This table implements switching behavior.  It contains these logical
@@ -531,6 +614,12 @@ output;
       there are no rules added for load balancing new connections.
     </p>
 
+    <p>
+      Also a priority 34000 logical flow is added for each logical port which
+      has DHCPv4 options defined to allow the DHCPv4 reply packet from the
+      <code>Ingress Table 11: DHCP responses</code>.
+    </p>
+
     <h3>Egress Table 6: Egress Port Security - IP</h3>
 
     <p>