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="Logical_Switch" title="L2 logical switch">
    <p>
      Each row represents one L2 logical switch.
    </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="acls">
      Access control rules that apply to packets within the logical switch.
    </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_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 and at most one
            regular logical port.  This is used to model direct connectivity to
            an existing 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>

        <p>
          If a given logical switch has multiple <code>router</code> ports, the
          <ref table="Logical_Router_Port"/> rows that they reference must be
          all on the same <ref table="Logical_Router"/> (for different
          subnets).
        </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>
      </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 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>

    <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_Port"/>.
      </column>

      <column name="tag">
        <p>
          The VLAN tag in the network traffic associated with a container's
          network interface.
        </p>

        <p>
          When <ref column="type"/> is set to <code>localnet</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>
    </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><var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var></code></dt>
          <dd>
            <p>
              An Ethernet address 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>
          </dd>

          <dt><code><var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var> <var>a</var>.<var>b</var>.<var>c</var>.<var>d</var></code></dt>
          <dd>
            <p>
              This form has all the effects of the previous form.  It also
              indicates that the logical port owns the given IPv4 address.
            </p>

            <p>
              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>
          </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>
        </dl>
      </column>

      <column name="port_security">
        <p>
          A set of L2 (Ethernet) addresses from which the logical port is
          allowed to send packets and to which it is allowed to receive
          packets.  If this column is empty, all addresses are permitted.
          Logical ports are always allowed to receive packets addressed to
          multicast and broadcast addresses.
        </p>

        <p>
          Each member of the set is an Ethernet address in the form
          <var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>.
        </p>

        <p>
          This specification will be extended to support L3 port security.
        </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="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>
    </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="default_gw">
      IP address to use as default gateway, if any.
    </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_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_Port"/> or another logical router port in <ref
        table="Logical_Router_Port"/>.
      </p>
    </column>

    <column name="network">
      The IP address of the router and the netmask.  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.
    </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_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_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>
</database>