ovn-nb.xml

<?xml version="1.0" encoding="utf-8"?>
<database name="ovn-nb" title="OVN Northbound Database">
  <p>
    This database is the interface between OVN and the cloud management system
    (CMS), such as OpenStack, running above it.  The CMS produces almost all of
    the contents of the database.  The <code>ovn-northd</code> program
    monitors the database contents, transforms it, and stores it into the <ref
    db="OVN_Southbound"/> database.
  </p>

  <p>
    We generally speak of ``the'' CMS, but one can imagine scenarios in
    which multiple CMSes manage different parts of an OVN deployment.
  </p>

  <h2>External IDs</h2>

  <p>
    Each of the tables in this database contains a special column, named
    <code>external_ids</code>.  This column has the same form and purpose each
    place it appears.
  </p>

  <dl>
    <dt><code>external_ids</code>: map of string-string pairs</dt>
    <dd>
      Key-value pairs for use by the CMS.  The CMS might use certain pairs, for
      example, to identify entities in its own configuration that correspond to
      those in this database.
    </dd>
  </dl>

  <table name="NB_Global" title="Northbound configuration">
    <p>
      Northbound configuration for an OVN system.  This table must have exactly
      one row.
    </p>

    <group title="Status">
      These columns allow a client to track the overall configuration state of
      the system.

      <column name="nb_cfg">
        Sequence number for client to increment.  When a client modifies any
        part of the northbound database configuration and wishes to wait for
        <code>ovn-northd</code> and possibly all of the hypervisors to finish
        applying the changes, it may increment this sequence number.
      </column>

      <column name="sb_cfg">
        Sequence number that <code>ovn-northd</code> sets to the value of <ref
        column="nb_cfg"/> after it finishes applying the corresponding
        configuration changes to the <ref db="OVN_Southbound"/> database.
      </column>

      <column name="hv_cfg">
        Sequence number that <code>ovn-northd</code> sets to the smallest
        sequence number of all the chassis in the system, as reported in the
        <code>Chassis</code> table in the southbound database.  Thus, <ref
        column="hv_cfg"/> equals <ref column="nb_cfg"/> if all chassis are
        caught up with the northbound configuration (which may never happen, if
        any chassis is down).  This value can regress, if a chassis was removed
        from the system and rejoins before catching up.
      </column>
    </group>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="Logical_Switch" title="L2 logical switch">
    <p>
      Each row represents one L2 logical switch.
    </p>

    <p>
      There are two kinds of logical switches, that is, ones that fully
      virtualize the network (overlay logical switches) and ones that provide
      simple connectivity to a physical network (bridged logical switches).
      They work in the same way when providing connectivity between logical
      ports on same chasis, but differently when connecting remote logical
      ports.  Overlay logical switches connect remote logical ports by tunnels,
      while bridged logical switches provide connectivity to remote ports by
      bridging the packets to directly connected physical L2 segment with the
      help of <code>localnet</code> ports.  Each bridged logical switch has
      one and only one <code>localnet</code> port, which has only one special
      address <code>unknown</code>.
    </p>

    <column name="name">
      <p>
        A name for the logical switch.  This name has no special meaning or purpose
        other than to provide convenience for human interaction with the ovn-nb
        database.  There is no requirement for the name to be unique.  The
        logical switch's UUID should be used as the unique identifier.
      </p>
    </column>

    <column name="ports">
      <p>
        The logical ports connected to the logical switch.
      </p>

      <p>
        It is an error for multiple logical switches to include the same
        logical port.
      </p>
    </column>

    <column name="load_balancer">
      Load balance a virtual ipv4 address to a set of logical port endpoint
      ipv4 addresses.
    </column>

    <column name="acls">
      Access control rules that apply to packets within the logical switch.
    </column>

    <column name="qos_rules">
      QOS marking rules that apply to packets within the logical switch.
    </column>

    <group title="other_config">
      <p>
        Additional configuration options for the logical switch.
      </p>

      <column name="other_config" key="subnet">
        Set this to an IPv4 subnet, e.g. <code>192.168.0.0/24</code>, to enable
        <code>ovn-northd</code> to automatically assign IP addresses within
        that subnet.  Use the <code>dynamic</code> keyword in the <ref
        table="Logical_Switch_Port"/> table's <ref table="Logical_Switch_Port"
        column="addresses"/> column to request dynamic address assignment for a
        particular port.
      </column>
    </group>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="Logical_Switch_Port" title="L2 logical switch port">
    <p>
      A port within an L2 logical switch.
    </p>

    <group title="Core Features">
      <column name="name">
        <p>
          The logical port name.
        </p>

        <p>
          For entities (VMs or containers) that are spawned in the hypervisor,
          the name used here must match those used in the <ref key="iface-id"
          table="Interface" column="external_ids" db="Open_vSwitch"/> in the
          <ref db="Open_vSwitch"/> database's <ref table="Interface"
          db="Open_vSwitch"/> table, because hypervisors use <ref key="iface-id"
          table="Interface" column="external_ids" db="Open_vSwitch"/> as a lookup
          key to identify the network interface of that entity.
        </p>

        <p>
          For containers that share a VIF within a VM, the name can be any
          unique identifier.  See <code>Containers</code>, below, for more
          information.
        </p>
      </column>

      <column name="type">
        <p>
          Specify a type for this logical port.  Logical ports can be used to
          model other types of connectivity into an OVN logical switch.  The
          following types are defined:
        </p>

        <dl>
          <dt>(empty string)</dt>
          <dd>
            A VM (or VIF) interface.
          </dd>

          <dt><code>router</code></dt>
          <dd>
            A connection to a logical router.
          </dd>

          <dt><code>localnet</code></dt>
          <dd>
            A connection to a locally accessible network from each
            <code>ovn-controller</code> instance.  A logical switch can only
            have a single <code>localnet</code> port attached.  This is used
            to model direct connectivity to an existing network.
          </dd>

          <dt><code>l2gateway</code></dt>
          <dd>
            A connection to a physical network.
          </dd>

          <dt><code>vtep</code></dt>
          <dd>
            A port to a logical switch on a VTEP gateway.
          </dd>
        </dl>
      </column>
    </group>

    <group title="Options">
      <column name="options">
        This column provides key/value settings specific to the logical port
        <ref column="type"/>.  The type-specific options are described
        individually below.
      </column>

      <group title="Options for router ports">
        <p>
          These options apply when <ref column="type"/> is <code>router</code>.
        </p>

        <column name="options" key="router-port">
          Required.  The <ref column="name"/> of the <ref
          table="Logical_Router_Port"/> to which this logical switch port is
          connected.
        </column>

        <column name="options" key="nat-addresses">
          MAC address of the <code>router-port</code> followed by a list of
          SNAT and DNAT IP addresses. This is used to send gratuitous ARPs for
          SNAT and DNAT IP addresses via <code>localnet</code> and is valid for
          only L3 gateway ports.  Example: <code>80:fa:5b:06:72:b7 158.36.44.22
          158.36.44.24</code>. This would result in generation of gratuitous
          ARPs for IP addresses 158.36.44.22 and 158.36.44.24 with a MAC
          address of 80:fa:5b:06:72:b7.
        </column>
      </group>

      <group title="Options for localnet ports">
        <p>
          These options apply when <ref column="type"/> is
          <code>localnet</code>.
        </p>

        <column name="options" key="network_name">
          Required.  The name of the network to which the <code>localnet</code>
          port is connected.  Each hypervisor, via <code>ovn-controller</code>,
          uses its local configuration to determine exactly how to connect to
          this locally accessible network.
        </column>
      </group>

      <group title="Options for l2gateway ports">
        <p>
          These options apply when <ref column="type"/> is
          <code>l2gateway</code>.
        </p>

        <column name="options" key="network_name">
          Required.  The name of the network to which the <code>l2gateway</code>
          port is connected.  The L2 gateway, via <code>ovn-controller</code>,
          uses its local configuration to determine exactly how to connect to
          this network.
        </column>

        <column name="options" key="l2gateway-chassis">
          Required. The chassis on which the <code>l2gateway</code> logical
          port should be bound to. <code>ovn-controller</code> running on the
          defined chassis will connect this logical port to the physical network.
        </column>

      </group>

      <group title="Options for vtep ports">
        <p>
          These options apply when <ref column="type"/> is <code>vtep</code>.
        </p>

        <column name="options" key="vtep-physical-switch">
          Required.  The name of the VTEP gateway.
        </column>

        <column name="options" key="vtep-logical-switch">
          Required.  A logical switch name connected by the VTEP gateway.
        </column>
      </group>

      <group title="VMI (or VIF) Options">
        <p>
          These options apply to logical ports with <ref column="type"/> having
          (empty string)
        </p>

        <column name="options" key="qos_max_rate">
          If set, indicates the maximum rate for data sent from this interface,
          in bit/s. The traffic will be shaped according to this limit.
        </column>

        <column name="options" key="qos_burst">
          If set, indicates the maximum burst size for data sent from this
          interface, in bits.
        </column>
      </group>
    </group>

    <group title="Containers">
      <p>
        When a large number of containers are nested within a VM, it may be too
        expensive to dedicate a VIF to each container.  OVN can use VLAN tags
        to support such cases.  Each container is assigned a VLAN ID and each
        packet that passes between the hypervisor and the VM is tagged with the
        appropriate ID for the container.  Such VLAN IDs never appear on a
        physical wire, even inside a tunnel, so they need not be unique except
        relative to a single VM on a hypervisor.
      </p>

      <p>
        These columns are used for VIFs that represent nested containers using
        shared VIFs.  For VMs and for containers that have dedicated VIFs, they
        are empty.
      </p>

      <column name="parent_name">
        The VM interface through which the nested container sends its network
        traffic.  This must match the <ref column="name"/> column for some
        other <ref table="Logical_Switch_Port"/>.
      </column>

      <column name="tag_request">
        <p>
          The VLAN tag in the network traffic associated with a container's
          network interface.  The client can request <code>ovn-northd</code>
          to allocate a tag that is unique within the scope of a specific
          parent (specified in <ref column="parent_name"/>) by setting a value
          of <code>0</code> in this column.  The allocated value is written
          by <code>ovn-northd</code> in the <ref column="tag"/> column.
          (Note that these tags are allocated and managed locally in
          <code>ovn-northd</code>, so they cannot be reconstructed in the event
          that the database is lost.)  The client can also request a specific
          non-zero tag and <code>ovn-northd</code> will honor it and copy that
          value to the <ref column="tag"/> column.
        </p>

        <p>
          When <ref column="type"/> is set to <code>localnet</code> or
          <code>l2gateway</code>, this can
          be set to indicate that the port represents a connection to a
          specific VLAN on a locally accessible network. The VLAN ID is used
          to match incoming traffic and is also added to outgoing traffic.
        </p>
      </column>

      <column name="tag">
        <p>
          The VLAN tag allocated by <code>ovn-northd</code> based on the
          contents of the <ref column="tag_request"/> column.
        </p>
      </column>
    </group>

    <group title="Port State">
      <column name="up">
        This column is populated by <code>ovn-northd</code>, rather than by the
        CMS plugin as is most of this database.  When a logical port is bound
        to a physical location in the OVN Southbound database <ref
        db="OVN_Southbound" table="Binding"/> table, <code>ovn-northd</code>
        sets this column to <code>true</code>; otherwise, or if the port
        becomes unbound later, it sets it to <code>false</code>.  This allows
        the CMS to wait for a VM's (or container's) networking to become active
        before it allows the VM (or container) to start.
      </column>

      <column name="enabled">
        This column is used to administratively set port state.  If this column
        is empty or is set to <code>true</code>, the port is enabled.  If this
        column is set to <code>false</code>, the port is disabled.  A disabled
        port has all ingress and egress traffic dropped.
      </column>

    </group>

    <group title="Addressing">
      <column name="addresses">
        <p>
          Addresses owned by the logical port.
        </p>

        <p>
          Each element in the set must take one of the following forms:
        </p>

        <dl>
          <dt><code>Ethernet address followed by zero or more IPv4 or IPv6 addresses (or both)</code></dt>
          <dd>
            <p>
              An Ethernet address defined is owned by the logical port.
              Like a physical Ethernet NIC, a logical port ordinarily has
              a single fixed Ethernet address.
            </p>

            <p>
              When a OVN logical switch processes a unicast Ethernet frame
              whose destination MAC address is in a logical port's <ref
              column="addresses"/> column, it delivers it only to that port, as
              if a MAC learning process had learned that MAC address on the
              port.
            </p>

            <p>
              If IPv4 or IPv6 address(es) (or both) are defined, it indicates
              that the logical port owns the given IP addresses.
            </p>

            <p>
              If IPv4 address(es) are defined, the OVN logical switch uses this
              information to synthesize responses to ARP requests without
              traversing the physical network. The OVN logical router connected
              to the logical switch, if any, uses this information to avoid
              issuing ARP requests for logical switch ports.
            </p>

            <p>
              Note that the order here is important. The Ethernet address must
              be listed before the IP address(es) if defined.
            </p>

            <p>
              Examples:
            </p>

            <dl>
              <dt><code>80:fa:5b:06:72:b7</code></dt>
              <dd>
                This indicates that the logical port owns the above mac address.
              </dd>

              <dt><code>80:fa:5b:06:72:b7 10.0.0.4 20.0.0.4</code></dt>
              <dd>
                This indicates that the logical port owns the mac address and two
                IPv4 addresses.
              </dd>

              <dt><code>80:fa:5b:06:72:b7 fdaa:15f2:72cf:0:f816:3eff:fe20:3f41</code></dt>
              <dd>
                This indicates that the logical port owns the mac address and
                1 IPv6 address.
              </dd>

              <dt><code>80:fa:5b:06:72:b7 10.0.0.4 fdaa:15f2:72cf:0:f816:3eff:fe20:3f41</code></dt>
              <dd>
                This indicates that the logical port owns the mac address and
                1 IPv4 address and 1 IPv6 address.
              </dd>
            </dl>
          </dd>

          <dt><code>unknown</code></dt>
          <dd>
            This indicates that the logical port has an unknown set of Ethernet
            addresses.  When an OVN logical switch processes a unicast Ethernet
            frame whose destination MAC address is not in any logical port's
            <ref column="addresses"/> column, it delivers it to the port (or
            ports) whose <ref column="addresses"/> columns include
            <code>unknown</code>.
          </dd>

          <dt><code>dynamic</code></dt>
          <dd>
            Use this keyword to make <code>ovn-northd</code> generate a
            globally unique MAC address and choose an unused IPv4 address with
            the logical port's subnet and store them in the port's <ref
            column="dynamic_addresses"/> column.  <code>ovn-northd</code> will
            use the subnet specified in <ref table="Logical_Switch"
            column="other_config" key="subnet"/> in the port's <ref
            table="Logical_Switch"/>.
          </dd>

          <dt><code>Ethernet address followed by keyword "dynamic"</code></dt>
          <dd>

            <p>
              The keyword <code>dynamic</code> after the MAC address indicates
              that <code>ovn-northd</code> should choose an unused IPv4 address
              from the logical port's subnet and store it with the specified
              MAC in the port's <ref column="dynamic_addresses"/> column.
              <code>ovn-northd</code> will use the subnet specified in <ref
              table="Logical_Switch" column="other_config" key="subnet"/> in
              the port's <ref table="Logical_Switch"/> table.
            </p>

            <p>
              Examples:
            </p>

            <dl>
              <dt><code>80:fa:5b:06:72:b7 dynamic</code></dt>
              <dd>
                This indicates that the logical port owns the specified
                MAC address and <code>ovn-northd</code> should allocate an
                unused IPv4 address for the logical port from the corresponding
                logical switch subnet.
              </dd>
            </dl>
          </dd>

        </dl>
      </column>

      <column name="dynamic_addresses">
        <p>
          Addresses assigned to the logical port by <code>ovn-northd</code>, if
          <code>dynamic</code> is specified in <ref column="addresses"/>.
          Addresses will be of the same format as those that populate the <ref
          column="addresses"/> column.  Note that dynamically assigned
          addresses are constructed and managed locally in ovn-northd, so they
          cannot be reconstructed in the event that the database is lost.
        </p>
      </column>

      <column name="port_security">
        <p>
          This column controls the addresses from which the host attached to the
          logical port (``the host'') is allowed to send packets and to which it
          is allowed to receive packets.  If this column is empty, all addresses
          are permitted.
        </p>

        <p>
          Each element in the set must begin with one Ethernet address.
          This would restrict the host to sending packets from and receiving
          packets to the ethernet addresses defined in the logical port's
          <ref column="port_security"/> column. It also restricts the inner
          source MAC addresses that the host may send in ARP and IPv6
          Neighbor Discovery packets. The host is always allowed to receive packets
          to multicast and broadcast Ethernet addresses.
        </p>

        <p>
          Each element in the set may additionally contain one or more IPv4 or
          IPv6 addresses (or both), with optional masks.  If a mask is given, it
          must be a CIDR mask.  In addition to the restrictions described for
          Ethernet addresses above, such an element restricts the IPv4 or IPv6
          addresses from which the host may send and to which it may receive
          packets to the specified addresses.  A masked address, if the host part
          is zero, indicates that the host is allowed to use any address in the
          subnet; if the host part is nonzero, the mask simply indicates the size
          of the subnet. In addition:
        </p>

        <ul>
          <li>
            <p>
              If any IPv4 address is given, the host is also allowed to receive
              packets to the IPv4 local broadcast address 255.255.255.255 and to
              IPv4 multicast addresses (224.0.0.0/4).  If an IPv4 address with a
              mask is given, the host is also allowed to receive packets to the
              broadcast address in that specified subnet.
            </p>

            <p>
              If any IPv4 address is given, the host is additionally restricted
              to sending ARP packets with the specified source IPv4 address.
              (RARP is not restricted.)
            </p>
          </li>

          <li>
            <p>
              If any IPv6 address is given, the host is also allowed to receive
              packets to IPv6 multicast addresses (ff00::/8).
            </p>

            <p>
              If any IPv6 address is given, the host is additionally restricted
              to sending IPv6 Neighbor Discovery Solicitation or Advertisement
              packets with the specified source address or, for solicitations,
              the unspecified address.
            </p>
          </li>
        </ul>

        <p>
          If an element includes an IPv4 address, but no IPv6 addresses, then
          IPv6 traffic is not allowed.  If an element includes an IPv6 address,
          but no IPv4 address, then IPv4 and ARP traffic is not allowed.
        </p>

        <p>
          This column uses the same lexical syntax as the <ref column="match"
          table="Pipeline" db="OVN_Southbound"/> column in the OVN Southbound
          database's <ref table="Pipeline" db="OVN_Southbound"/> table.  Multiple
          addresses within an element may be space or comma separated.
        </p>

        <p>
          This column is provided as a convenience to cloud management systems,
          but all of the features that it implements can be implemented as ACLs
          using the <ref table="ACL"/> table.
        </p>

        <p>
          Examples:
        </p>

        <dl>
          <dt><code>80:fa:5b:06:72:b7</code></dt>
          <dd>
            The host may send traffic from and receive traffic to the specified
            MAC address, and to receive traffic to Ethernet multicast and
            broadcast addresses, but not otherwise.  The host may not send ARP or
            IPv6 Neighbor Discovery packets with inner source Ethernet addresses
            other than the one specified.
          </dd>

          <dt><code>80:fa:5b:06:72:b7 192.168.1.10/24</code></dt>
          <dd>
            This adds further restrictions to the first example.  The host may
            send IPv4 packets from or receive IPv4 packets to only 192.168.1.10,
            except that it may also receive IPv4 packets to 192.168.1.255 (based
            on the subnet mask), 255.255.255.255, and any address in 224.0.0.0/4.
            The host may not send ARPs with a source Ethernet address other than
            80:fa:5b:06:72:b7 or source IPv4 address other than 192.168.1.10.
            The host may not send or receive any IPv6 (including IPv6 Neighbor
            Discovery) traffic.
          </dd>

          <dt><code>"80:fa:5b:12:42:ba", "80:fa:5b:06:72:b7 192.168.1.10/24"</code></dt>
          <dd>
            The host may send traffic from and receive traffic to the
            specified MAC addresses, and
            to receive traffic to Ethernet multicast and broadcast addresses,
            but not otherwise.   With MAC 80:fa:5b:12:42:ba, the host may
            send traffic from and receive traffic to any L3 address.
            With MAC 80:fa:5b:06:72:b7, the host may send IPv4 packets from or
            receive IPv4 packets to only 192.168.1.10, except that it may also
            receive IPv4 packets to 192.168.1.255 (based on the subnet mask),
            255.255.255.255, and any address in 224.0.0.0/4.  The host may not
            send or receive any IPv6 (including IPv6 Neighbor Discovery) traffic.
          </dd>
        </dl>
      </column>
    </group>

    <group title="Common Columns">
      <column name="dhcpv4_options">
        This column defines the DHCPv4 Options to be included by the
        <code>ovn-controller</code> when it replies to the DHCPv4 requests.
        Please see the <ref table="DHCP_Options"/> table.
      </column>

      <column name="dhcpv6_options">
        This column defines the DHCPv6 Options to be included by the
        <code>ovn-controller</code> when it replies to the DHCPv6 requests.
        Please see the <ref table="DHCP_Options"/> table.
      </column>

      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="Address_Set" title="Address Sets">
    <p>
      Each row in this table represents a named set of addresses.
      An address set may contain Ethernet, IPv4, or IPv6 addresses
      with optional bitwise or CIDR masks.
      Address set may ultimately be used in ACLs to compare against
      fields such as <code>ip4.src</code> or <code>ip6.src</code>.
      A single address set must contain addresses of the
      same type. As an example, the following would create an address set
      with three IP addresses:
    </p>

    <pre>
      ovn-nbctl create Address_Set name=set1 addresses='10.0.0.1 10.0.0.2 10.0.0.3'
    </pre>

    <p>
      Address sets may be used in the <ref column="match" table="ACL"/> column
      of the <ref table="ACL"/> table.  For syntax information, see the details
      of the expression language used for the <ref column="match"
      table="Logical_Flow" db="OVN_Southbound"/> column in the <ref
      table="Logical_Flow" db="OVN_Southbound"/> table of the <ref
      db="OVN_Southbound"/> database.
    </p>

    <column name="name">
      A name for the address set.  Names are ASCII and must match
      <code>[a-zA-Z_.][a-zA-Z_.0-9]*</code>.
    </column>

    <column name="addresses">
      The set of addresses in string form.
    </column>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="Load_Balancer" title="load balancer">
    <p>
      Each row represents one load balancer.
    </p>

    <column name="name">
      A name for the load balancer.  This name has no special meaning or
      purpose other than to provide convenience for human interaction with
      the ovn-nb database.
    </column>

    <column name="vips">
      <p>
        A map of virtual IPv4 addresses (and an optional port number with
        <code>:</code> as a separator) associated with this load balancer and
        their corresponding endpoint IPv4 addresses (and optional port numbers
        with <code>:</code> as separators) separated by commas.  If
        the destination IP address (and port number) of a packet leaving a
        container or a VM matches the virtual IPv4 address (and port number)
        provided here as a key, then OVN will statefully replace the
        destination IP address by one of the provided IPv4 address (and port
        number) in this map as a value.  Examples for keys are "192.168.1.4"
        and "172.16.1.8:80".  Examples for value are "10.0.0.1, 10.0.0.2" and
        "20.0.0.10:8800, 20.0.0.11:8800".
      </p>
    </column>

    <column name="protocol">
      <p>
        Valid protocols are <code>tcp</code> or <code>udp</code>.  This column
        is useful when a port number is provided as part of the
        <code>vips</code> column.  If this column is empty and a port number
        is provided as part of <code>vips</code> column, OVN assumes the
        protocol to be <code>tcp</code>.
      </p>
    </column>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="ACL" title="Access Control List (ACL) rule">
    <p>
      Each row in this table represents one ACL rule for a logical switch
      that points to it through its <ref column="acls"/> column.  The <ref
      column="action"/> column for the highest-<ref column="priority"/>
      matching row in this table determines a packet's treatment.  If no row
      matches, packets are allowed by default.  (Default-deny treatment is
      possible: add a rule with <ref column="priority"/> 0, <code>0</code> as
      <ref column="match"/>, and <code>deny</code> as <ref column="action"/>.)
    </p>

    <column name="priority">
      <p>
        The ACL rule's priority.  Rules with numerically higher priority
        take precedence over those with lower.  If two ACL rules with
        the same priority both match, then the one actually applied to a
        packet is undefined.
      </p>

      <p>
        Return traffic from an <code>allow-related</code> flow is always
        allowed and cannot be changed through an ACL.
      </p>
    </column>

    <column name="direction">
      <p>Direction of the traffic to which this rule should apply:</p>
      <ul>
        <li>
          <code>from-lport</code>: Used to implement filters on traffic
          arriving from a logical port.  These rules are applied to the
          logical switch's ingress pipeline.
        </li>
        <li>
          <code>to-lport</code>: Used to implement filters on traffic
          forwarded to a logical port.  These rules are applied to the
          logical switch's egress pipeline.
        </li>
      </ul>
    </column>

    <column name="match">
      <p>
        The packets that the ACL should match, in the same expression
        language used for the <ref column="match" table="Logical_Flow"
        db="OVN_Southbound"/> column in the OVN Southbound database's
        <ref table="Logical_Flow" db="OVN_Southbound"/> table.  The
        <code>outport</code> logical port is only available in the
        <code>to-lport</code> direction (the <code>inport</code> is
        available in both directions).
      </p>

      <p>
        By default all traffic is allowed.  When writing a more
        restrictive policy, it is important to remember to allow flows
        such as ARP and IPv6 neighbor discovery packets.
      </p>

      <p>
        Note that you can not create an ACL matching on a port with
        type=router.
      </p>

      <p>
        Note that when <code>localnet</code> port exists in a lswitch, for
        <code>to-lport</code> direction, the <code>inport</code> works only if
        the <code>to-lport</code> is located on the same chassis as the
        <code>inport</code>.
      </p>
    </column>

    <column name="action">
      <p>The action to take when the ACL rule matches:</p>
      <ul>
        <li>
          <code>allow</code>: Forward the packet.
        </li>

        <li>
          <code>allow-related</code>: Forward the packet and related traffic
          (e.g. inbound replies to an outbound connection).
        </li>

        <li>
          <code>drop</code>: Silently drop the packet.
        </li>

        <li>
          <code>reject</code>: Drop the packet, replying with a RST for TCP or
          ICMP unreachable message for other IP-based protocols.
          <code>Not implemented--currently treated as drop</code>
        </li>
      </ul>
    </column>

    <column name="log">
      <p>
        If set to <code>true</code>, packets that match the ACL will trigger a
        log message on the transport node or nodes that perform ACL processing.
        Logging may be combined with any <ref column="action"/>.
      </p>

      <p>
        Logging is not yet implemented.
      </p>
    </column>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="Logical_Router" title="L3 logical router">
    <p>
      Each row represents one L3 logical router.
    </p>

    <column name="name">
      <p>
        A name for the logical router.  This name has no special meaning or purpose
        other than to provide convenience for human interaction with the ovn-nb
        database.  There is no requirement for the name to be unique.  The
        logical router's UUID should be used as the unique identifier.
      </p>
    </column>

    <column name="ports">
      The router's ports.
    </column>

    <column name="static_routes">
      One or more static routes for the router.
    </column>

    <column name="enabled">
      This column is used to administratively set router state.  If this column
      is empty or is set to <code>true</code>, the router is enabled.  If this
      column is set to <code>false</code>, the router is disabled.  A disabled
      router has all ingress and egress traffic dropped.
    </column>

    <column name="nat">
      One or more NAT rules for the router. NAT rules only work on the
      Gateway routers.
    </column>

    <column name="load_balancer">
      Load balance a virtual ipv4 address to a set of logical port ipv4
      addresses.  Load balancer rules only work on the Gateway routers.
    </column>

    <group title="Options">
      <p>
        Additional options for the logical router.
      </p>

      <column name="options" key="chassis">
        <p>
          If set, indicates that the logical router in question is a Gateway
          router (which is centralized) and resides in the set chassis.  The
          same value is also used by <code>ovn-controller</code> to
          uniquely identify the chassis in the OVN deployment and
          comes from <code>external_ids:system-id</code> in the
          <code>Open_vSwitch</code> table of Open_vSwitch database.
        </p>

        <p>
          The Gateway router can only be connected to a distributed router
          via a switch if SNAT and DNAT are to be configured in the Gateway
          router.
        </p>
      </column>
      <column name="options" key="dnat_force_snat_ip">
        <p>
          If set, indicates the IP address to use to force SNAT a packet
          that has already been DNATed in the gateway router.  When multiple
          gateway routers are configured, a packet can potentially enter any
          of the gateway router, get DNATted and eventually reach the logical
          switch port.  For the return traffic to go back to the same gateway
          router (for unDNATing), the packet needs a SNAT in the first place.
          This can be achieved by setting the above option with a gateway
          specific IP address.
        </p>
      </column>
      <column name="options" key="lb_force_snat_ip">
        <p>
          If set, indicates the IP address to use to force SNAT a packet
          that has already been load-balanced in the gateway router.  When
          multiple gateway routers are configured, a packet can potentially
          enter any of the gateway router, get DNATted as part of the load-
          balancing and eventually reach the logical switch port.
          For the return traffic to go back to the same gateway router (for
          unDNATing), the packet needs a SNAT in the first place.  This can be
          achieved by setting the above option with a gateway specific IP
          address.
        </p>
      </column>
    </group>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="QoS" title="QOS table">
    <p>
      Each row in this table represents one QOS rule for a logical switch
      that points to it through its <ref column="qos_rules"/> column.  The <ref
      column="action"/> column for the highest-<ref column="priority"/>
      matching row in this table determines a packet's qos marking.  If no row
      matches, packets will not have any qos marking.
    </p>

    <column name="priority">
      <p>
        The QOS rule's priority.  Rules with numerically higher priority
        take precedence over those with lower.  If two QOS rules with
        the same priority both match, then the one actually applied to a
        packet is undefined.
      </p>
    </column>

    <column name="direction">
      <p>
        The value of this field is similar to <ref colun="direction"
        table="ACL" db="OVN_Northbound"/> column in the OVN Northbound
        database's <ref table="ACL" db="OVN_Northbound"/> table.
      </p>
    </column>

    <column name="match">
      <p>
        The packets that the QOS rules should match, in the same expression
        language used for the <ref column="match" table="Logical_Flow"
        db="OVN_Southbound"/> column in the OVN Southbound database's
        <ref table="Logical_Flow" db="OVN_Southbound"/> table.  The
        <code>outport</code> logical port is only available in the
        <code>to-lport</code> direction (the <code>inport</code> is
        available in both directions).
      </p>
    </column>

    <column name="action">
      <p>The action to be performed on the matched packet</p>
      <ul>
        <li>
          <code>dscp</code>: The value of this action should be in the
          range of 0 to 63 (inclusive).
        </li>
      </ul>
    </column>

    <column name="external_ids">
      See <em>External IDs</em> at the beginning of this document.
    </column>
  </table>

  <table name="Logical_Router_Port" title="L3 logical router port">
    <p>
      A port within an L3 logical router.
    </p>

    <p>
      Exactly one <ref table="Logical_Router"/> row must reference a given
      logical router port.
    </p>

    <column name="name">
      <p>
        A name for the logical router port.
      </p>

      <p>
        In addition to provide convenience for human interaction with the
        ovn-nb database, this column is used as reference by its patch port in
        <ref table="Logical_Switch_Port"/> or another logical router port in
        <ref table="Logical_Router_Port"/>.
      </p>
    </column>

    <column name="networks">
      <p>
        The IP addresses and netmasks of the router.  For example,
        <code>192.168.0.1/24</code> indicates that the router's IP
        address is 192.168.0.1 and that packets destined to
        192.168.0.<var>x</var> should be routed to this port.
      </p>

      <p>
        A logical router port always adds a link-local IPv6 address
        (fe80::/64) automatically generated from the interface's MAC
        address using the modified EUI-64 format.
      </p>
    </column>

    <column name="mac">
      The Ethernet address that belongs to this router port.
    </column>

    <column name="enabled">
      This column is used to administratively set port state.  If this column
      is empty or is set to <code>true</code>, the port is enabled.  If this
      column is set to <code>false</code>, the port is disabled.  A disabled
      port has all ingress and egress traffic dropped.
    </column>

    <group title="Attachment">
      <p>
        A given router port serves one of two purposes:
      </p>

      <ul>
        <li>
          To attach a logical switch to a logical router.  A logical router
          port of this type is referenced by exactly one <ref
          table="Logical_Switch_Port"/> of type <code>router</code>.
          The value of <ref column="name"/> is set as
          <code>router-port</code> in column <ref column="options"/> of
          <ref table="Logical_Switch_Port"/>.  In this case <ref
          column="peer"/> column is empty.
        </li>

        <li>
          To connect one logical router to another.  This requires a pair of
          logical router ports, each connected to a different router.  Each
          router port in the pair specifies the other in its <ref
          column="peer"/> column.  No <ref table="Logical_Switch"/> refers to
          the router port.
        </li>
      </ul>

      <column name="peer">
        <p>
          For a router port used to connect two logical routers, this
          identifies the other router port in the pair by <ref column="name"/>.
        </p>

        <p>
          For a router port attached to a logical switch, this column is empty.
        </p>
      </column>
    </group>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>

  <table name="Logical_Router_Static_Route" title="Logical router static routes">
    <p>
      Each record represents a static route.
    </p>

    <p>
      When multiple routes match a packet, the longest-prefix match is chosen.
      For a given prefix length, a <code>dst-ip</code> route is preferred over
      a <code>src-ip</code> route.
    </p>

    <column name="ip_prefix">
      <p>
        IP prefix of this route (e.g. 192.168.100.0/24).
      </p>
    </column>

    <column name="policy">
      <p>
        If it is specified, this setting describes the policy used to make
        routing decisions.  This setting must be one of the following strings:
      </p>
      <ul>
        <li>
          <code>src-ip</code>: This policy sends the packet to the
          <ref column="nexthop"/> when the packet's source IP address matches
          <ref column="ip_prefix"/>.
       </li>
        <li>
          <code>dst-ip</code>: This policy sends the packet to the
          <ref column="nexthop"/> when the packet's destination IP address
          matches <ref column="ip_prefix"/>.
        </li>
      </ul>
      <p>
        If not specified, the default is <code>dst-ip</code>.
     </p>
    </column>

    <column name="nexthop">
      <p>
        Nexthop IP address for this route.  Nexthop IP address should be the IP
        address of a connected router port or the IP address of a logical port.
      </p>
    </column>

    <column name="output_port">
      <p>
        The name of the <ref table="Logical_Router_Port"/> via which the packet
        needs to be sent out.  This is optional and when not specified,
        OVN will automatically figure this out based on the
        <ref column="nexthop"/>.
      </p>
    </column>
  </table>

  <table name="NAT" title="NAT rules for a Gateway router.">
    <p>
      Each record represents a NAT rule in a Gateway router.
    </p>

    <column name="type">
      <p>Type of the NAT rule.</p>
      <ul>
        <li>
          When <ref column="type"/> is <code>dnat</code>, the externally
          visible IP address <ref column="external_ip"/> is DNATted to the IP
          address <ref column="logical_ip"/> in the logical space.
        </li>
        <li>
          When <ref column="type"/> is <code>snat</code>, IP packets
          with their source IP address that either matches the IP address
          in <ref column="logical_ip"/> or is in the network provided by
          <ref column="logical_ip"/> is SNATed into the IP address in
          <ref column="external_ip"/>.
        </li>
        <li>
          When <ref column="type"/> is <code>dnat_and_snat</code>, the
          externally visible IP address <ref column="external_ip"/> is
          DNATted to the IP address <ref column="logical_ip"/> in the
          logical space. In addition, IP packets with the source IP
          address that matches <ref column="logical_ip"/> is SNATed into
          the IP address in <ref column="external_ip"/>.
        </li>
      </ul>
    </column>

    <column name="external_ip">
      An IPv4 address.
    </column>

    <column name="logical_ip">
      An IPv4 network (e.g 192.168.1.0/24) or an IPv4 address.
    </column>
  </table>

  <table name="DHCP_Options" title="DHCP options">
    <p>
      OVN implements native DHCPv4 support which caters to the common
      use case of providing an IPv4 address to a booting instance by
      providing stateless replies to DHCPv4 requests based on statically
      configured address mappings. To do this it allows a short list of
      DHCPv4 options to be configured and applied at each compute host
      running <code>ovn-controller</code>.
    </p>

    <p>
      OVN also implements native DHCPv6 support which provides stateless
      replies to DHCPv6 requests.
    </p>

    <column name="cidr">
      <p>
        The DHCPv4/DHCPv6 options will be included if the logical port has its
        IP address in this <ref column="cidr"/>.
      </p>
    </column>

    <group title="DHCPv4 options">
      <p>
        The CMS should define the set of DHCPv4 options as key/value pairs
        in the <ref column="options"/> column of this table. For
        <code>ovn-controller</code> to include these DHCPv4 options, the
        <ref column="dhcpv4_options"/> of <ref table="Logical_Switch_Port"/>
        should refer to an entry in this table.
      </p>

      <group title="Mandatory DHCPv4 options">
        <p>
          The following options must be defined.
        </p>

        <column name="options" key="server_id">
          The IP address for the DHCP server to use.  This should be in the
          subnet of the offered IP.  This is also included in the DHCP offer as
          option 54, ``server identifier.''
        </column>

        <column name="options" key="server_mac">
          The Ethernet address for the DHCP server to use.
        </column>

        <column name="options" key="router">
          <p>
            The IP address of a gateway for the client to use.  This should be
            in the subnet of the offered IP.  The DHCPv4 option code for this
            option is 3.
          </p>
        </column>

        <column name="options" key="lease_time"
                type='{"type": "integer", "minInteger": 0, "maxInteger": 4294967295}'>
          <p>
            The offered lease time in seconds, 
          </p>

          <p>
            The DHCPv4 option code for this option is 51.
          </p>
        </column>
      </group>

      <group title="IPv4 DHCP Options">
        <p>
          Below are the supported DHCPv4 options whose values are an IPv4
          address, e.g. <code>192.168.1.1</code>.  Some options accept multiple
          IPv4 addresses enclosed within curly braces, e.g. <code>{192.168.1.2,
          192.168.1.3}</code>. Please refer to RFC 2132 for more details on
          DHCPv4 options and their codes.
        </p>

        <column name="options" key="netmask">
          <p>
            The DHCPv4 option code for this option is 1.
          </p>
        </column>

        <column name="options" key="dns_server">
          <p>
            The DHCPv4 option code for this option is 6.
          </p>
        </column>

        <column name="options" key="log_server">
          <p>
            The DHCPv4 option code for this option is 7.
          </p>
        </column>

        <column name="options" key="lpr_server">
          <p>
            The DHCPv4 option code for this option is 9.
          </p>
        </column>

        <column name="options" key="swap_server">
          <p>
            The DHCPv4 option code for this option is 16.
          </p>
        </column>

        <column name="options" key="policy_filter">
          <p>
            The DHCPv4 option code for this option is 21.
          </p>
        </column>

        <column name="options" key="router_solicitation">
          <p>
            The DHCPv4 option code for this option is 32.
          </p>
        </column>

        <column name="options" key="nis_server">
          <p>
            The DHCPv4 option code for this option is 41.
          </p>
        </column>

        <column name="options" key="ntp_server">
          <p>
            The DHCPv4 option code for this option is 42.
          </p>
        </column>

        <column name="options" key="tftp_server">
          <p>
            The DHCPv4 option code for this option is 66.
          </p>
        </column>

        <column name="options" key="classless_static_route">
          <p>
            The DHCPv4 option code for this option is 121.
          </p>

          <p>
             This option can contain one or more static routes, each of which
             consists of a destination descriptor and the IP address of the
             router that should be used to reach that destination. Please see
             RFC 3442 for more details.
          </p>

          <p>
            Example: <code>{30.0.0.0/24,10.0.0.10, 0.0.0.0/0,10.0.0.1}</code>
          </p>
        </column>

        <column name="options" key="ms_classless_static_route">
          <p>
            The DHCPv4 option code for this option is 249. This option is
            similar to <code>classless_static_route</code> supported by
            Microsoft Windows DHCPv4 clients.
          </p>
        </column>
      </group>

      <group title="Boolean DHCP Options">
        <p>
          These options accept a Boolean value, expressed as <code>0</code> for
          false or <code>1</code> for true.
        </p>

        <column name="options" key="ip_forward_enable"
                type='{"type": "string", "enum": ["set", ["0", "1"]]}'>
          <p>
            The DHCPv4 option code for this option is 19.
          </p>
        </column>

        <column name="options" key="router_discovery"
                type='{"type": "string", "enum": ["set", ["0", "1"]]}'>
          <p>
            The DHCPv4 option code for this option is 31.
          </p>
        </column>

        <column name="options" key="ethernet_encap"
                type='{"type": "string", "enum": ["set", ["0", "1"]]}'>
          <p>
            The DHCPv4 option code for this option is 36.
          </p>
        </column>
      </group>

      <group title="Integer DHCP Options">
        <p>
          These options accept a nonnegative integer value.
        </p>

        <column name="options" key="default_ttl"
                type='{"type": "integer", "minInteger": 0, "maxInteger": 255}'>
          The DHCPv4 option code for this option is 23.
        </column>

        <column name="options" key="tcp_ttl"
                type='{"type": "integer", "minInteger": 0, "maxInteger": 255}'>
          The DHCPv4 option code for this option is 37.
        </column>

        <column name="options" key="mtu"
                type='{"type": "integer", "minInteger": 68, "maxInteger": 65535}'>
          The DHCPv4 option code for this option is 26.
        </column>

        <column name="options" key="T1"
                type='{"type": "integer", "minInteger": 68, "maxInteger": 4294967295}'>
          This specifies the time interval from address assignment until the
          client begins trying to renew its address.  The DHCPv4 option code
          for this option is 58.
        </column>

        <column name="options" key="T2"
                type='{"type": "integer", "minInteger": 68, "maxInteger": 4294967295}'>
          This specifies the time interval from address assignment until the
          client begins trying to rebind its address.  The DHCPv4 option code
          for this option is 59.
        </column>
      </group>
    </group>

    <group title="DHCPv6 options">
      <p>
        OVN also implements native DHCPv6 support. The CMS should define
        the set of DHCPv6 options as key/value pairs. The define DHCPv6
        options will be included in the DHCPv6 response to the DHCPv6
        Solicit/Request/Confirm packet from the logical ports having the
        IPv6 addresses in the <ref column="cidr"/>.
      </p>

      <group title="Mandatory DHCPv6 options">
        <p>
          The following options must be defined.
        </p>

        <column name="options" key="server_id">
          <p>
            The Ethernet address for the DHCP server to use. This is also
            included in the DHCPv6 reply as option 2, ``Server Identifier''
            to carry a DUID identifying a server between a client and a server.
            <code>ovn-controller</code> defines DUID based on
            Link-layer Address [DUID-LL].
          </p>
        </column>
      </group>

      <group title="IPv6 DHCPv6 options">
        <p>
          Below are the supported DHCPv6 options whose values are an IPv6
          address, e.g. <code>aef0::4</code>.  Some options accept multiple
          IPv6 addresses enclosed within curly braces, e.g. <code>{aef0::4,
          aef0::5}</code>. Please refer to RFC 3315 for more details on
          DHCPv6 options and their codes.
        </p>

        <column name="options" key="dns_server">
          <p>
            The DHCPv6 option code for this option is 23. This option specifies
            the DNS servers that the VM should use.
          </p>
        </column>
      </group>

      <group title="String DHCPv6 options">
        <p>
          These options accept string values.
        </p>

        <column name="options" key="domain_search">
          <p>
            The DHCPv6 option code for this option is 24. This option specifies
            the domain search list the client should use to resolve hostnames
            with DNS.
          </p>

          <p>
            Example: <code>"ovn.org"</code>.
          </p>
        </column>

        <column name="options" key="dhcpv6_stateless">
          <p>
            This option specifies the OVN native DHCPv6 will work in stateless
            mode, which means OVN native DHCPv6 will not offer IPv6 addresses
            for VM/VIF ports, but only reply other configurations, such as
            DNS and domain search list. When setting this option with string
            value "true", VM/VIF will configure IPv6 addresses by stateless
            way. Default value for this option is false.
          </p>
        </column>
      </group>
    </group>

    <group title="Common Columns">
      <column name="external_ids">
        See <em>External IDs</em> at the beginning of this document.
      </column>
    </group>
  </table>
</database>