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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html>
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<html xmlns="http://www.w3.org/1999/xhtml">
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  <body>
    <h1>Network XML format</h1>

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    <ul id="toc">
    </ul>

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    <p>
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      This page provides an introduction to the network XML format. For
      background information on the concepts referred to here, consult the
      <a href="https://wiki.libvirt.org/page/Networking">relevant wiki page</a>.
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    </p>

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    <h2><a id="elements">Element and attribute overview</a></h2>
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    <p>
      The root element required for all virtual networks is
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      named <code>network</code> and has no configurable attributes
      (although <span class="since">since 0.10.0</span> there is one
      optional read-only attribute - when examining the live
      configuration of a network, the
      attribute <code>connections</code>, if present, specifies the
      number of guest interfaces currently connected via this
      network).  The network XML format is
      available <span class="since">since 0.3.0</span>
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    </p>

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    <h3><a id="elementsMetadata">General metadata</a></h3>
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    <p>
      The first elements provide basic metadata about the virtual
      network.
    </p>

    <pre>
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&lt;network ipv6='yes' trustGuestRxFilters='no'&gt;
  &lt;name&gt;default&lt;/name&gt;
  &lt;uuid&gt;3e3fce45-4f53-4fa7-bb32-11f34168b82b&lt;/uuid&gt;
  &lt;metadata&gt;
    &lt;app1:foo xmlns:app1="http://app1.org/app1/"&gt;..&lt;/app1:foo&gt;
    &lt;app2:bar xmlns:app2="http://app1.org/app2/"&gt;..&lt;/app2:bar&gt;
  &lt;/metadata&gt;
  ...</pre>
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    <dl>
      <dt><code>name</code></dt>
      <dd>The content of the <code>name</code> element provides
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        a short name for the virtual network. This name should
        consist only of alpha-numeric characters and is required
        to be unique within the scope of a single host. It is
        used to form the filename for storing the persistent
        configuration file. <span class="since">Since 0.3.0</span></dd>
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      <dt><code>uuid</code></dt>
      <dd>The content of the <code>uuid</code> element provides
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        a globally unique identifier for the virtual network.
        The format must be RFC 4122 compliant, eg <code>3e3fce45-4f53-4fa7-bb32-11f34168b82b</code>.
        If omitted when defining/creating a new network, a random
        UUID is generated. <span class="since">Since 0.3.0</span></dd>
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      <dd>The <code>metadata</code> node can be used by applications to
        store custom metadata in the form of XML nodes/trees. Applications
        must use custom namespaces on their XML nodes/trees, with only
        one top-level element per namespace (if the application needs
        structure, they should have sub-elements to their namespace
        element). <span class="since">Since 2.1.0</span></dd>
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      <dt><code>ipv6</code></dt>
      <dd>When set to <code>yes</code>, the optional parameter
        <code>ipv6</code> enables
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        a network definition with no IPv6 gateway addresses specified
        to have guest-to-guest communications.  For further information,
        see the example below for the example with no gateway addresses.
        <span class="since">Since 1.0.1</span></dd>
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      <dt><code>trustGuestRxFilters</code></dt>
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      <dd>The optional parameter <code>trustGuestRxFilters</code> can
        be used to set that attribute of the same name for each domain
        interface connected to this network (<span class="since">since
        1.2.10</span>). See
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        the <a href="formatdomain.html#elementsNICS">Network
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        interfaces</a> section of the domain XML documentation for
        more details. Note that an explicit setting of this attribute
        in a portgroup or the individual domain interface will
        override the setting in the network.</dd>
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    </dl>

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    <h3><a id="elementsConnect">Connectivity</a></h3>
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    <p>
      The next set of elements control how a virtual network is
      provided connectivity to the physical LAN (if at all).
    </p>

    <pre>
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...
&lt;bridge name="virbr0" stp="on" delay="5" macTableManager="libvirt"/&gt;
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&lt;mtu size="9000"/&gt;
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&lt;domain name="example.com" localOnly="no"/&gt;
&lt;forward mode="nat" dev="eth0"/&gt;
...</pre>
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    <dl>
      <dt><code>bridge</code></dt>
      <dd>The <code>name</code> attribute on the <code>bridge</code> element
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        defines the name of a bridge device which will be used to construct
        the virtual network. The virtual machines will be connected to this
        bridge device allowing them to talk to each other. The bridge device
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        may also be connected to the LAN. When defining
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        a new network with a <code>&lt;forward&gt;</code> mode of
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        "nat", "route", or "open" (or an isolated network with
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        no <code>&lt;forward&gt;</code> element), libvirt will
        automatically generate a unique name for the bridge device if
        none is given, and this name will be permanently stored in the
        network configuration so that that the same name will be used
        every time the network is started. For these types of networks
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        (nat, route, open, and isolated), a bridge name beginning with the
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        prefix "virbr" is recommended (and that is what is
        auto-generated), but not enforced.
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        Attribute <code>stp</code> specifies if Spanning Tree Protocol
        is 'on' or 'off' (default is
        'on'). Attribute <code>delay</code> sets the bridge's forward
        delay value in seconds (default is 0).
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        <span class="since">Since 0.3.0</span>
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        <p>
          The <code>macTableManager</code> attribute of the bridge
          element is used to tell libvirt how the bridge's MAC address
          table (used to determine the correct egress port for packets
          based on destination MAC address) will be managed. In the
          default <code>kernel</code> setting, the kernel
          automatically adds and removes entries, typically using
          learning, flooding, and promiscuous mode on the bridge's
          ports in order to determine the proper egress port for
          packets.  When <code>macTableManager</code> is set
          to <code>libvirt</code>, libvirt disables kernel management
          of the MAC table (in the case of the Linux host bridge, this
          means enabling vlan_filtering on the bridge, and disabling
          learning and unicast_filter for all bridge ports), and
          explicitly adds/removes entries to the table according to
          the MAC addresses in the domain interface configurations.
          Allowing libvirt to manage the MAC table can improve
          performance - with a Linux host bridge, for example, turning
          off learning and unicast_flood on ports has its own
          performance advantage, and can also lead to an additional
          boost by permitting the kernel to automatically turn off
          promiscuous mode on some ports of the bridge (in particular,
          the port attaching the bridge to the physical
          network). However, it can also cause some networking setups
          to stop working (e.g. vlan tagging, multicast,
          guest-initiated changes to MAC address) and is not supported
          by older kernels.
          <span class="since">Since 1.2.11, requires kernel 3.17 or
          newer</span>
        </p>
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        <p>
          The optional <code>zone</code> attribute of
          the <code>bridge</code> element is used to specify
          the <a href="https://firewalld.org">firewalld</a>
          zone for the bridge of a network with <code>forward</code>
          mode of "nat", "route", "open", or one with
          no <code>forward</code> specified. By default, the bridges
          of all virtual networks with these forward modes are placed
          in the firewalld zone named "libvirt", which permits
          incoming DNS, DHCP, TFTP, and SSH to the host from guests on
          the network. This behavior can be changed either by
          modifying the libvirt zone (using firewalld management
          tools), or by placing the network in a different zone (which
          will also be managed using firewalld tools).
          <span class="since">Since 5.1.0</span>
        </p>
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      </dd>
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      <dt><code>mtu</code></dt>
      <dd>
        The <code>size</code> attribute of the <code>mtu></code>
        element specifies the Maximum Transmission Unit (MTU) for the
        network. <span class="since">Since 3.1.0</span>. In the case
        of a libvirt-managed network (one with forward mode
        of <code>nat</code>, <code>route</code>, <code>open</code>, or
        no <code>forward</code> element (i.e. an isolated network),
        this will be the MTU assigned to the bridge device when
        libvirt creates it, and thereafter also assigned to all tap
        devices created to connect guest interfaces. Network types not
        specifically mentioned here don't support having an MTU set in
        the libvirt network config. If mtu size is unspecified, the
        default setting for the type of device being used is assumed
        (usually 1500).
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      </dd>
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      <dt><code>domain</code></dt>
      <dd>
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        The <code>name</code> attribute on the <code>domain</code>
        element defines the DNS domain of the DHCP server. This
        element is optional, and is only used for those networks with
        a <code>&lt;forward&gt;</code> mode of "nat" or "route" (or an
        isolated network with no <code>&lt;forward&gt;</code>
        element). <span class="since">Since 0.4.5</span>
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        <p>
          If the optional <code>localOnly</code> attribute on the
          <code>domain</code> element is "yes", then DNS requests under
          this domain will only be resolved by the virtual network's own
          DNS server - they will not be forwarded to the host's upstream
          DNS server.  If <code>localOnly</code> is "no", and by
          default, unresolved requests <b>will</b> be forwarded.
          <span class="since">Since 1.2.12</span>
        </p>
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      </dd>
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      <dt><code>forward</code></dt>
      <dd>Inclusion of the <code>forward</code> element indicates that
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        the virtual network is to be connected to the physical
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        LAN.<span class="since">Since 0.3.0.</span>
        The <code>mode</code> attribute determines the method of
        forwarding. If there is no <code>forward</code> element, the
        network will be isolated from any other network (unless a
        guest connected to that network is acting as a router, of
        course). The following are valid settings
        for <code>mode</code> (if there is a <code>forward</code>
        element but mode is not specified, <code>mode='nat'</code> is
        assumed):
        <dl>
          <dt><code>nat</code></dt>
          <dd>
            All traffic between guests connected to this network and
            the physical network will be forwarded to the physical
            network via the host's IP routing stack, after the guest's
            IP address is translated to appear as the host machine's
            public IP address (a.k.a. Network Address Translation, or
            "NAT"). This allows multiple guests, all having access to
            the physical network, on a host that is only allowed a
            single public IP address. If a network has any IPv6
            addresses defined, the IPv6 traffic will be forwarded
            using plain routing, since IPv6 has no concept of NAT.
            Firewall rules will allow outbound connections to any
            other network device whether ethernet, wireless, dialup,
            or VPN. If the <code>dev</code> attribute is set, the
            firewall rules will restrict forwarding to the named
            device only. Inbound connections from other networks are
            all prohibited; all connections between guests on the same
            network, and to/from the host to the guests, are
            unrestricted and not NATed.<span class="since">Since
            0.4.2</span>
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            <p><span class="since">Since 1.0.3</span> it is possible to
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            specify a public IPv4 address and port range to be used for
            the NAT by using the <code>&lt;nat&gt;</code> subelement.
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            Note that all addresses from the range are used, not just those
            that are in use on the host.
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            The address range is set with the <code>&lt;address&gt;</code>
            subelements and <code>start</code> and <code>stop</code>
            attributes:
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            </p>
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            <pre>
...
  &lt;forward mode='nat'&gt;
    &lt;nat&gt;
      &lt;address start='1.2.3.4' end='1.2.3.10'/&gt;
    &lt;/nat&gt;
  &lt;/forward&gt;
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...</pre>
            <p>
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            A single IPv4 address can be set by setting
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            <code>start</code> and <code>end</code> attributes to
            the same value.
            </p>
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            <p>
            The port range to be used for the <code>&lt;nat&gt;</code> can
            be set via the subelement <code>&lt;port&gt;</code>:
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            </p>
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            <pre>
...
  &lt;forward mode='nat'&gt;
    &lt;nat&gt;
      &lt;port start='500' end='1000'/&gt;
    &lt;/nat&gt;
  &lt;/forward&gt;
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...</pre>
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          </dd>

          <dt><code>route</code></dt>
          <dd>
            Guest network traffic will be forwarded to the physical
            network via the host's IP routing stack, but without
            having NAT applied. Again, if the <code>dev</code>
            attribute is set, firewall rules will restrict forwarding
            to the named device only. This presumes that the local LAN
            router has suitable routing table entries to return
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            traffic to this host. All incoming and outgoing sessions
            to guest on these networks are unrestricted. (To restrict
            incoming traffic to a guest on a routed network, you can
            configure <a href="formatnwfilter.html">nwfilter rules</a>
            on the guest's interfaces.)
            <span class="since">Since 0.4.2</span>
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          </dd>

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          <dt><code>open</code></dt>
          <dd>
            As with mode='route', guest network traffic will be
            forwarded to the physical network via the host's IP
            routing stack, but there will be no firewall rules added
            to either enable or prevent any of this traffic. When
            forward='open' is set, the <code>dev</code> attribute
            cannot be set (because the forward dev is enforced with
            firewall rules, and the purpose of forward='open' is to
            have a forwarding mode where libvirt doesn't add any
            firewall rules).  This mode presumes that the local LAN
            router has suitable routing table entries to return
            traffic to this host, and that some other management
            system has been used to put in place any necessary
            firewall rules. Although no firewall rules will be added
            for the network, it is of course still possible to add
            restrictions for specific guests using
            <a href="formatnwfilter.html">nwfilter rules</a> on the
            guests' interfaces.)
            <span class="since">Since 2.2.0</span>
          </dd>

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          <dt><code>bridge</code></dt>
          <dd>
            This network describes either 1) an existing host bridge
            that was configured outside of libvirt (if
            a <code>&lt;bridge name='xyz'/&gt;</code> element has been
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            specified, <span class="since">Since 0.9.4</span>), 2) an
            existing Open vSwitch bridge that was configured outside of
            libvirt (if both a <code>&lt;bridge name='xyz'/&gt;</code>
            element <b>and</b> a <code>&lt;virtualport
            type='openvswitch'/&gt;</code> have been
            specified <span class="since">Since 0.10.0</span>) 3) an
            interface or group of interfaces to be used for a "direct"
            connection via macvtap using macvtap's "bridge" mode (if
            the forward element has one or
            more <code>&lt;interface&gt;</code>
            subelements, <span class="since">Since 0.9.4</span>)
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            (see <a href="formatdomain.html#elementsNICSDirect">Direct
            attachment to physical interface</a> for descriptions of
            the various macvtap modes). libvirt doesn't attempt to
            manage the bridge interface at all, thus
            the <code>&lt;bridge&gt;</code> element's <code>stp</code>
            and <code>delay</code> attributes are not allowed; no
            iptables rules, IP addresses, or DHCP/DNS services are
            added; at the IP level, the guest interface appears to be
            directly connected to the physical
            interface.<span class="since">Since 0.9.4</span>
          </dd>
          <dt><code>private</code></dt>
          <dd>
            This network uses a macvtap "direct" connection in
            "private" mode to connect each guest to the network. The
            physical interface to be used will be picked from among
            those listed in <code>&lt;interface&gt;</code> subelements
            of the <code>&lt;forward&gt;</code> element; when using
            802.1Qbh mode (as indicated by
            the <code>&lt;virtualport&gt;</code> type attribute - note
            that this requires an 802.1Qbh-capable hardware switch),
            each physical interface can only be in use by a single
            guest interface at a time; in modes other than 802.1Qbh,
            multiple guest interfaces can share each physical
            interface (libvirt will attempt to balance usage between
            all available interfaces).<span class="since">Since
            0.9.4</span>
          </dd>
          <dt><code>vepa</code></dt>
          <dd>
            This network uses a macvtap "direct" connection in "vepa"
            mode to connect each guest to the network (this requires
            that the physical interfaces used be connected to a
            vepa-capable hardware switch. The physical interface to be
            used will be picked from among those listed
            in <code>&lt;interface&gt;</code> subelements of
            the <code>&lt;forward&gt;</code> element; multiple guest
            interfaces can share each physical interface (libvirt will
            attempt to balance usage between all available
            interfaces).<span class="since">Since 0.9.4</span>
          </dd>
          <dt><code>passthrough</code></dt>
          <dd>
            This network uses a macvtap "direct" connection in
            "passthrough" mode to connect each guest to the network
            (note that this is <i>not</i> the same thing as "PCI
            passthrough"). The physical interface to be used will be
            picked from among those listed
            in <code>&lt;interface&gt;</code> subelements of
            the <code>&lt;forward&gt;</code> element.  Each physical
            interface can only be in use by a single guest interface
            at a time, so libvirt will keep track of which interfaces
            are currently in use, and only assign unused interfaces
            (if there are no available physical interfaces when a
            domain interface is being attached, an error will be
            logged, and the operation causing the attach will fail
            (usually either a domain start, or a hotplug interface
            attach to a domain).<span class="since">Since 0.9.4</span>
          </dd>
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          <dt><code>hostdev</code></dt>
          <dd>
            This network facilitates PCI Passthrough of a network
            device.  A network device is chosen from the interface
            pool and directly assigned to the guest using generic
            device passthrough, after first optionally setting the
            device's MAC address and vlan tag to the configured value,
            and optionally associating the device with an 802.1Qbh
            capable switch using a <code>&lt;virtualport&gt;</code>
            element.  Note that - due to limitations in standard
            single-port PCI ethernet card driver design - only SR-IOV
            (Single Root I/O Virtualization) virtual function (VF)
            devices can be assigned in this manner; to assign a
            standard single-port PCI or PCIe ethernet card to a guest,
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            use the traditional <code>&lt;hostdev&gt;</code> device
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            definition. <span class="since"> Since 0.10.0</span>

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            <p>
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              To force use of a particular type of device assignment,
              a &lt;forward type='hostdev'&gt; interface can have an
              optional <code>driver</code> sub-element with
              a <code>name</code> attribute set to either "vfio" (VFIO
              is a new method of device assignment that is compatible
              with UEFI Secure Boot) or "kvm" (the legacy device
              assignment handled directly by the KVM kernel module)
              <span class="since">Since 1.0.5 (QEMU and KVM only,
              requires kernel 3.6 or newer)</span>. When specified,
              device assignment will fail if the requested method of
              device assignment isn't available on the host. When not
              specified, the default is "vfio" on systems where the
              VFIO driver is available and loaded, and "kvm" on older
              systems, or those where the VFIO driver hasn't been
              loaded <span class="since">Since 1.1.3</span> (prior to
              that the default was always "kvm").
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            </p>

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            <p>Note that this "intelligent passthrough" of network
            devices is very similar to the functionality of a
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            standard <code>&lt;hostdev&gt;</code> device, the
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            difference being that this method allows specifying a MAC
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            address, vlan tag, and <code>&lt;virtualport&gt;</code>
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            for the passed-through device. If these capabilities are
            not required, if you have a standard single-port PCI,
            PCIe, or USB network card that doesn't support SR-IOV (and
            hence would anyway lose the configured MAC address during
            reset after being assigned to the guest domain), or if you
            are using a version of libvirt older than 0.10.0, you
            should use a standard
            <code>&lt;hostdev&gt;</code> device definition in the
            domain's configuration to assign the device to the guest
            instead of defining an <code>&lt;interface
            type='network'&gt;</code> pointing to a network
            with <code>&lt;forward mode='hostdev'/&gt;</code>.
            </p>
          </dd>
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        </dl>
        As mentioned above, a <code>&lt;forward&gt;</code> element can
        have multiple <code>&lt;interface&gt;</code> subelements, each
        one giving the name of a physical interface that can be used
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        for this network <span class="since">Since 0.9.4</span>:
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        <pre>
...
  &lt;forward mode='passthrough'&gt;
    &lt;interface dev='eth10'/&gt;
    &lt;interface dev='eth11'/&gt;
    &lt;interface dev='eth12'/&gt;
    &lt;interface dev='eth13'/&gt;
    &lt;interface dev='eth14'/&gt;
  &lt;/forward&gt;
...
        </pre>
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        <p>
          <span class="since">since 0.10.0</span>,
          <code>&lt;interface&gt;</code> also has an optional read-only
          attribute - when examining the live configuration of a
          network, the attribute <code>connections</code>, if present,
          specifies the number of guest interfaces currently connected
          via this physical interface.
        </p>
        <p>
          Additionally, <span class="since">since 0.9.10</span>, libvirt
          allows a shorthand for specifying all virtual interfaces
          associated with a single physical function, by using
          the <code>&lt;pf&gt;</code> subelement to call out the
          corresponding physical interface associated with multiple
          virtual interfaces:
        </p>
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        <pre>
...
  &lt;forward mode='passthrough'&gt;
    &lt;pf dev='eth0'/&gt;
  &lt;/forward&gt;
...
        </pre>

        <p>When a guest interface is being constructed, libvirt will pick
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        an interface from this list to use for the connection. In
        modes where physical interfaces can be shared by multiple
        guest interfaces, libvirt will choose the interface that
        currently has the least number of connections. For those modes
        that do not allow sharing of the physical device (in
        particular, 'passthrough' mode, and 'private' mode when using
        802.1Qbh), libvirt will choose an unused physical interface
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        or, if it can't find an unused interface, fail the operation.</p>
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        <p>
          <span class="since">since 0.10.0</span> When using forward
          mode 'hostdev', the interface pool is specified with a list
          of <code>&lt;address&gt;</code> elements, each of which has
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          <code>&lt;type&gt;</code> (must always be <code>'pci'</code>),
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          <code>&lt;domain&gt;</code>, <code>&lt;bus&gt;</code>,
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          <code>&lt;slot&gt;</code>and <code>&lt;function&gt;</code>
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          attributes.
        </p>
        <pre>
...
  &lt;forward mode='hostdev' managed='yes'&gt;
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    &lt;driver name='vfio'/&gt;
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    &lt;address type='pci' domain='0' bus='4' slot='0' function='1'/&gt;
    &lt;address type='pci' domain='0' bus='4' slot='0' function='2'/&gt;
    &lt;address type='pci' domain='0' bus='4' slot='0' function='3'/&gt;
  &lt;/forward&gt;
...
        </pre>

        Alternatively the interface pool can also be defined using a
        single physical function  <code>&lt;pf&gt;</code> subelement to
        call out the  corresponding physical interface associated with
        multiple virtual interfaces (similar to passthrough mode):

        <pre>
...
  &lt;forward mode='hostdev' managed='yes'&gt;
    &lt;pf dev='eth0'/&gt;
  &lt;/forward&gt;
...
        </pre>

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      </dd>
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    </dl>
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    <h5><a id="elementQoS">Quality of service</a></h5>
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<pre>
...
  &lt;forward mode='nat' dev='eth0'/&gt;
  <b>&lt;bandwidth&gt;
    &lt;inbound average='1000' peak='5000' burst='5120'/&gt;
    &lt;outbound average='128' peak='256' burst='256'/&gt;
  &lt;/bandwidth&gt;</b>
...</pre>

      <p>
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        The <code>&lt;bandwidth&gt;</code> element allows setting
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        quality of service for a particular network
        (<span class="since">since 0.9.4</span>). Setting
        <code>bandwidth</code> for a network is supported only
        for networks with a <code>&lt;forward&gt;</code> mode
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        of <code>route</code>, <code>nat</code>, <code>bridge</code>,
        or no mode at all (i.e. an "isolated" network). Setting
        <code>bandwidth</code> is <b>not</b> supported for forward modes
        <code>passthrough</code>, <code>private</code>,
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        or <code>hostdev</code>. Attempts to do this will lead to
        a failure to define the network or to create a transient network.
      </p>
      <p>
        The <code>&lt;bandwidth&gt;</code> element can only be a
        subelement of a domain's <code>&lt;interface&gt;</code>, a
        subelement of a <code>&lt;network&gt;</code>, or a subelement of
        a <code>&lt;portgroup&gt;</code> in a <code>&lt;network&gt;</code>.
      </p>
      <p>
        As a subelement of a domain's <code>&lt;interface&gt;</code>,
        the bandwidth only applies to that one interface of the domain.
        As a subelement of a <code>&lt;network&gt;</code>, the bandwidth
        is a total aggregate bandwidth to/from all guest interfaces attached
        to that network, <b>not</b> to each guest interface individually.
        If a domain's <code>&lt;interface&gt;</code> has
        <code>&lt;bandwidth&gt;</code> element values higher
        than the aggregate for the entire network, then the aggregate
        bandwidth for the <code>&lt;network&gt;</code> takes precedence.
        This is because the two choke points are independent of each other
        where the domain's <code>&lt;interface&gt;</code> bandwidth control
        is applied on the interface's tap device, while the
        <code>&lt;network&gt;</code> bandwidth control is applied on the
        interface part of the bridge device created for that network.
      </p>
      <p>
        As a subelement of a
        <code>&lt;portgroup&gt;</code> in a <code>&lt;network&gt;</code>,
        if a domain's <code>&lt;interface&gt;</code> has a
        <code>portgroup</code> attribute in its
        <code>&lt;source&gt;</code> element <b>and</b> if the
        <code>&lt;interface&gt;</code>
        itself has no <code>&lt;bandwidth&gt;</code> element, then the
        <code>&lt;bandwidth&gt;</code> element of the portgroup will be
        applied individually to each guest interface defined to be a
        member of that portgroup. Any <code>&lt;bandwidth&gt;</code>
        element in the domain's <code>&lt;interface&gt;</code> definition
        will override the setting in the portgroup
        (<span class="since">since 1.0.1</span>).
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      </p>
      <p>
        Incoming and outgoing traffic can be shaped independently. The
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        <code>bandwidth</code> element can have at most one
        <code>inbound</code> and at most one <code>outbound</code>
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        child element. Leaving either of these children elements out
        results in no QoS applied for that traffic direction.  So,
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        when you want to shape only incoming traffic, use
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        <code>inbound</code> only, and vice versa. Each of these
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        elements have one mandatory attribute - <code>average</code> (or
        <code>floor</code> as described below). The attributes are as follows,
        where accepted values for each attribute is an integer number.
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      </p>
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        <dl>
          <dt><code>average</code></dt>
          <dd>
          Specifies the desired average bit rate for the interface
          being shaped (in kilobytes/second).
          </dd>
          <dt><code>peak</code></dt>
          <dd>
          Optional attribute which specifies the maximum rate at
          which the bridge can send data (in kilobytes/second).
          Note the limitation of implementation: this attribute in the
          <code>outbound</code> element is ignored (as Linux ingress
          filters don't know it yet).
          </dd>
          <dt><code>burst</code></dt>
          <dd>
          Optional attribute which specifies the amount of kilobytes that
          can be transmitted in a single burst at <code>peak</code> speed.
          </dd>
          <dt><code>floor</code></dt>
          <dd>
          Optional attribute available only for the <code>inbound</code>
          element. This attribute guarantees minimal throughput for
          shaped interfaces. This, however, requires that all traffic
          goes through one point where QoS decisions can take place, hence
          why this attribute works only for virtual networks for now
          (that is <code>&lt;interface type='network'/&gt;</code> with a
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          forward type of route, nat, open or no forward at all). Moreover, the
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          virtual network the interface is connected to is required to have
          at least inbound QoS set (<code>average</code> at least). If
          using the <code>floor</code> attribute users don't need to specify
          <code>average</code>. However, <code>peak</code> and
          <code>burst</code> attributes still require <code>average</code>.
          Currently, the Linux kernel doesn't allow ingress qdiscs to have
          any classes therefore <code>floor</code> can be applied only
          on <code>inbound</code> and not <code>outbound</code>.
          </dd>
        </dl>

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      <p>
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        Attributes <code>average</code>, <code>peak</code>, and
        <code>burst</code> are available
        <span class="since">since 0.9.4</span>, while the
        <code>floor</code> attribute is available
        <span class="since">since 1.0.1</span>.
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      </p>
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    <h5><a id="elementVlanTag">Setting VLAN tag (on supported network types only)</a></h5>
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<pre>
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&lt;network&gt;
  &lt;name&gt;ovs-net&lt;/name&gt;
  &lt;forward mode='bridge'/&gt;
  &lt;bridge name='ovsbr0'/&gt;
  &lt;virtualport type='openvswitch'&gt;
    &lt;parameters interfaceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/&gt;
  &lt;/virtualport&gt;
  <b>&lt;vlan trunk='yes'&gt;</b>
    <b>&lt;tag id='42' nativeMode='untagged'/&gt;</b>
    <b>&lt;tag id='47'/&gt;</b>
  <b>&lt;/vlan&gt;</b>
  &lt;portgroup name='dontpanic'&gt;
    <b>&lt;vlan&gt;</b>
      <b>&lt;tag id='42'/&gt;</b>
    <b>&lt;/vlan&gt;</b>
  &lt;/portgroup&gt;
&lt;/network&gt;
</pre>
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    <p>
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      If (and only if) the network connection used by the guest
      supports VLAN tagging transparent to the guest, an
      optional <code>&lt;vlan&gt;</code> element can specify one or
      more VLAN tags to apply to the guest's network
      traffic <span class="since">Since 0.10.0</span>. Network
      connections that support guest-transparent VLAN tagging include
      1) type='bridge' interfaces connected to an Open vSwitch bridge
      <span class="since">Since 0.10.0</span>, 2) SRIOV Virtual
      Functions (VF) used via type='hostdev' (direct device
      assignment) <span class="since">Since 0.10.0</span>, and 3)
      SRIOV VFs used via type='direct' with mode='passthrough'
      (macvtap "passthru" mode) <span class="since">Since
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      1.3.5</span>. All other connection types, including standard
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      linux bridges and libvirt's own virtual networks, <b>do not</b>
      support it. 802.1Qbh (vn-link) and 802.1Qbg (VEPA) switches
      provide their own way (outside of libvirt) to tag guest traffic
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      onto a specific VLAN. Each tag is given in a
      separate <code>&lt;tag&gt;</code> subelement
      of <code>&lt;vlan&gt;</code> (for example: <code>&lt;tag
      id='42'/&gt;</code>). For VLAN trunking of multiple tags (which
      is supported only on Open vSwitch connections),
      multiple <code>&lt;tag&gt;</code> subelements can be specified,
      which implies that the user wants to do VLAN trunking on the
      interface for all the specified tags. In the case that VLAN
      trunking of a single tag is desired, the optional
      attribute <code>trunk='yes'</code> can be added to the toplevel
      <code>&lt;vlan&gt;</code> element to differentiate trunking of a
      single tag from normal tagging.
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    </p>
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    <p>
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      For network connections using Open vSwitch it is also possible
      to configure 'native-tagged' and 'native-untagged' VLAN modes
      <span class="since">Since 1.1.0.</span> This is done with the
      optional <code>nativeMode</code> attribute on
      the <code>&lt;tag&gt;</code> subelement: <code>nativeMode</code>
      may be set to 'tagged' or 'untagged'. The <code>id</code>
      attribute of the <code>&lt;tag&gt;</code> subelement
      containing <code>nativeMode</code> sets which VLAN is considered
      to be the "native" VLAN for this interface, and
      the <code>nativeMode</code> attribute determines whether or not
      traffic for that VLAN will be tagged.
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    </p>
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    <p>
      <code>&lt;vlan&gt;</code> elements can also be specified in
      a <code>&lt;portgroup&gt;</code> element, as well as directly in
      a domain's <code>&lt;interface&gt;</code> element. In the case
      that a vlan tag is specified in multiple locations, the setting
      in <code>&lt;interface&gt;</code> takes precedence, followed by
      the setting in the <code>&lt;portgroup&gt;</code> selected by
      the interface config. The <code>&lt;vlan&gt;</code>
      in <code>&lt;network&gt;</code> will be selected only if none is
      given in <code>&lt;portgroup&gt;</code>
      or <code>&lt;interface&gt;</code>.
    </p>

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    <h5><a id="elementPort">Isolating ports from one another</a></h5>

<pre>
&lt;network&gt;
  &lt;name&gt;isolated-ports&lt;/name&gt;
  &lt;forward mode='bridge'/&gt;
  &lt;bridge name='br0'/&gt;
  &lt;port isolated='yes'/&gt;
&lt;/network&gt;
</pre>

    <p>
      <span class="since">Since 6.1.0.</span> The <code>port</code>
      element property <code>isolated</code>, when set
      to <code>yes</code> (default setting is <code>no</code>) is used
      to isolate the network traffic of each guest on the network from
      all other guests connected to the network; it does not have an
      effect on communication between the guests and the host, or
      between the guests and destinations beyond this network. This
      setting is only supported for networks that use a Linux host
      bridge to connect guest interfaces via a standard tap device
      (i.e. those with a forward mode of nat, route, open, bridge, or
      no forward mode).
    </p>

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    <h5><a id="elementsPortgroup">Portgroups</a></h5>
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<pre>
...
  &lt;forward mode='private'/&gt;
    &lt;interface dev="eth20"/&gt;
    &lt;interface dev="eth21"/&gt;
    &lt;interface dev="eth22"/&gt;
    &lt;interface dev="eth23"/&gt;
    &lt;interface dev="eth24"/&gt;
  &lt;/forward&gt;
  <b>&lt;portgroup name='engineering' default='yes'&gt;
    &lt;virtualport type='802.1Qbh'&gt;
      &lt;parameters profileid='test'/&gt;
    &lt;/virtualport&gt;
    &lt;bandwidth&gt;
      &lt;inbound average='1000' peak='5000' burst='5120'/&gt;
      &lt;outbound average='1000' peak='5000' burst='5120'/&gt;
    &lt;/bandwidth&gt;
  &lt;/portgroup&gt;</b>
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  <b>&lt;portgroup name='sales' trustGuestRxFilters='no'&gt;
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    &lt;virtualport type='802.1Qbh'&gt;
      &lt;parameters profileid='salestest'/&gt;
    &lt;/virtualport&gt;
    &lt;bandwidth&gt;
      &lt;inbound average='500' peak='2000' burst='2560'/&gt;
      &lt;outbound average='128' peak='256' burst='256'/&gt;
    &lt;/bandwidth&gt;
  &lt;/portgroup&gt;</b>
...</pre>

    <p>
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      <span class="since">Since 0.9.4</span>
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      A portgroup provides a method of easily putting guest
      connections to the network into different classes, with each
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      class potentially having a different level/type of service.
      <span class="since">Since 0.9.4</span> Each
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      network can have multiple portgroup elements (and one of those
      can optionally be designated as the 'default' portgroup for the
      network), and each portgroup has a name, as well as various
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      attributes and subelements associated with it. The currently supported
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      subelements are <code>&lt;bandwidth&gt;</code>
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      (described <a href="formatnetwork.html#elementQoS">here</a>)
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      and <code>&lt;virtualport&gt;</code>
      (documented <a href="formatdomain.html#elementsNICSDirect">here</a>).
      If a domain interface definition specifies a portgroup (by
      adding a <code>portgroup</code> attribute to
      the <code>&lt;source&gt;</code> subelement), that portgroup's
      info will be merged into the interface's configuration. If no
      portgroup is given in the interface definition, and one of the
      network's portgroups has <code>default='yes'</code>, that
      default portgroup will be used. If no portgroup is given in the
      interface definition, and there is no default portgroup, then
      none will be used. Any <code>&lt;bandwidth&gt;</code>
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      specified directly in the domain XML will take precedence over
      any setting in the chosen portgroup. if
      a <code>&lt;virtualport&gt;</code> is specified in the portgroup
      (and/or directly in the network definition), the multiple
      virtualports will be merged, and any parameter that is specified
      in more than one virtualport, and is not identical, will be
      considered an error, and will prevent the interface from
      starting.
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    </p>
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    <p>
      portgroups also support the optional
      parameter <code>trustGuestRxFilters</code> which can be used to
      set that attribute of the same name for each domain interface
      using this portgroup (<span class="since">since
      1.2.10</span>). See
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      the <a href="formatdomain.html#elementsNICS">Network
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      interfaces</a> section of the domain XML documentation for more
      details. Note that an explicit setting of this attribute in the
      portgroup overrides the network-wide setting, and an explicit
      setting in the individual domain interface will override the
      setting in the portgroup.
    </p>
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    <h5><a id="elementsStaticroute">Static Routes</a></h5>
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    <p>
      Static route definitions are used to provide routing information
      to the virtualization host for networks which are not directly
      reachable from the virtualization host, but *are* reachable from
      a guest domain that is itself reachable from the
      host <span class="since">since 1.0.6</span>.
    </p>

    <p>
      As shown in <a href="formatnetwork.html#examplesNoGateway">this
      example</a>, it is possible to define a virtual network
      interface with no IPv4 or IPv6 addresses.  Such networks are
      useful to provide host connectivity to networks which are only
      reachable via a guest.  A guest with connectivity both to the
      guest-only network and to another network that is directly
      reachable from the host can act as a gateway between the
      networks.  A static route added to the "host-visible" network
      definition provides the routing information so that IP packets
      can be sent from the virtualization host to guests on the hidden
      network.
    </p>

    <p>
      Here is a fragment of a definition which shows the static
      route specification as well as the  IPv4 and IPv6 definitions
      for network addresses which are referred to in the
      <code>gateway</code> gateway address specifications.  Note
      that the third static route specification includes the
      <code>metric</code> attribute specification with a value of 2.
      This particular route would *not* be preferred if there was
      another existing rout on the system with the same address and
      prefix but with a lower value for the metric. If there is a
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      route in the host system configuration that should be overridden
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      by a route in a virtual network whenever the virtual network is
      running, the configuration for the system-defined route should
      be modified to have a higher metric, and the route on the
      virtual network given a lower metric (for example, the default
      metric of "1").
    </p>

    <pre>
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...
  &lt;ip address="192.168.122.1" netmask="255.255.255.0"&gt;
    &lt;dhcp&gt;
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      &lt;range start="192.168.122.128" end="192.168.122.254"/&gt;
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    &lt;/dhcp&gt;
  &lt;/ip&gt;
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  &lt;route address="192.168.222.0" prefix="24" gateway="192.168.122.2"/&gt;
  &lt;ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64"/&gt;
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  &lt;route family="ipv6" address="2001:db8:ca2:3::" prefix="64" gateway="2001:db8:ca2:2::2"/&gt;
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  &lt;route family="ipv6" address="2001:db9:4:1::" prefix="64" gateway="2001:db8:ca2:2::3" metric='2'/&gt;
887
...
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    </pre>

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    <h3><a id="elementsAddress">Addressing</a></h3>
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    <p>
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      The final set of elements define the addresses (IPv4 and/or
      IPv6, as well as MAC) to be assigned to the bridge device
      associated with the virtual network, and optionally enable DHCP
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      services. These elements are only valid for isolated networks
      (no <code>forward</code> element specified), and for those with
      a forward mode of 'route' or 'nat'.
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    </p>

    <pre>
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...
&lt;mac address='00:16:3E:5D:C7:9E'/&gt;
&lt;domain name="example.com"/&gt;
&lt;dns&gt;
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  &lt;txt name="example" value="example value"/&gt;
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  &lt;forwarder addr="8.8.8.8"/&gt;
  &lt;forwarder domain='example.com' addr="8.8.4.4"/&gt;
  &lt;forwarder domain='www.example.com'/&gt;
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  &lt;srv service='name' protocol='tcp' domain='test-domain-name' target='.'
    port='1024' priority='10' weight='10'/&gt;
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  &lt;host ip='192.168.122.2'&gt;
    &lt;hostname&gt;myhost&lt;/hostname&gt;
    &lt;hostname&gt;myhostalias&lt;/hostname&gt;
  &lt;/host&gt;
&lt;/dns&gt;
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&lt;ip address="192.168.122.1" netmask="255.255.255.0" localPtr="yes"&gt;
918
  &lt;dhcp&gt;
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    &lt;range start="192.168.122.100" end="192.168.122.254"/&gt;
    &lt;host mac="00:16:3e:77:e2:ed" name="foo.example.com" ip="192.168.122.10"/&gt;
    &lt;host mac="00:16:3e:3e:a9:1a" name="bar.example.com" ip="192.168.122.11"/&gt;
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  &lt;/dhcp&gt;
&lt;/ip&gt;
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&lt;ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64" localPtr="yes"/&gt;
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&lt;route family="ipv6" address="2001:db9:ca1:1::" prefix="64" gateway="2001:db8:ca2:2::2"/&gt;
926
</pre>
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    <dl>
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      <dt><code>mac</code></dt>
      <dd>The <code>address</code> attribute defines a MAC
        (hardware) address formatted as 6 groups of 2-digit
        hexadecimal numbers, the groups separated by colons
        (eg, <code>"52:54:00:1C:DA:2F"</code>).  This MAC address is
        assigned to the bridge device when it is created.  Generally
        it is best to not specify a MAC address when creating a
        network - in this case, if a defined MAC address is needed for
        proper operation, libvirt will automatically generate a random
        MAC address and save it in the config. Allowing libvirt to
        generate the MAC address will assure that it is compatible
        with the idiosyncrasies of the platform where libvirt is
        running. <span class="since">Since 0.8.8</span>
      </dd>
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      <dt><code>dns</code></dt>
      <dd> The dns element of a network contains configuration
        information for the virtual network's DNS
        server <span class="since">Since 0.9.3</span>.

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        <p>
          The dns element can have an optional <code>enable</code>
          attribute <span class="since">Since 2.2.0</span>.
          If <code>enable</code> is "no", then no DNS server will be
          setup by libvirt for this network (and any other
          configuration in <code>&lt;dns&gt;</code> will be ignored).
          If <code>enable</code> is "yes" or unspecified (including
          the complete absence of any <code>&lt;dns&gt;</code>
          element) then a DNS server will be setup by libvirt to
          listen on all IP addresses specified in the network's
          configuration.
        </p>
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        <p>
          The dns element
          can have an optional <code>forwardPlainNames</code>
          attribute <span class="since">Since 1.1.2</span>.
          If <code>forwardPlainNames</code> is "no", then DNS resolution
          requests for names that are not qualified with a domain
          (i.e. names with no "." character) will not be forwarded to
          the host's upstream DNS server - they will only be resolved if
          they are known locally within the virtual network's own DNS
          server. If <code>forwardPlainNames</code> is "yes",
          unqualified names <b>will</b> be forwarded to the upstream DNS
          server if they can't be resolved by the virtual network's own
          DNS server.
        </p>

        Currently supported sub-elements of <code>&lt;dns&gt;</code> are:
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        <dl>
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          <dt><code>forwarder</code></dt>
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          <dd>The dns element can have 0 or
            more <code>&lt;forwarder&gt;</code> elements.  Each
            forwarder element defines an alternate DNS server to use
            for some, or all, DNS requests sent to this network's DNS
            server. There are two attributes - <code>domain</code>,
            and <code>addr</code>; at least one of these must be
            specified in any <code>&lt;forwarder&gt;</code>
            element. If both <code>domain</code> and <code>addr</code>
            are specified, then all requests that match the given
            domain will be forwarded to the DNS server at addr. If
            only <code>domain</code> is specified, then all matching
            domains will be resolved locally (or via the host's
            standard DNS forwarding if they can't be resolved
            locally). If an <code>addr</code> is specified by itself,
            then all DNS requests to the network's DNS server will be
            forwarded to the DNS server at that address with no
            exceptions. <code>addr</code> <span class="since">Since
            1.1.3</span>, <code>domain</code> <span class="since">Since
            2.2.0</span>.
997
          </dd>
998 999 1000 1001 1002 1003 1004 1005
          <dt><code>txt</code></dt>
          <dd>A <code>dns</code> element can have 0 or more <code>txt</code> elements.
            Each txt element defines a DNS TXT record and has two attributes, both
            required: a name that can be queried via dns, and a value that will be
            returned when that name is queried. names cannot contain embedded spaces
            or commas. value is a single string that can contain multiple values
            separated by commas. <span class="since">Since 0.9.3</span>
          </dd>
1006 1007 1008 1009 1010 1011 1012 1013
          <dt><code>host</code></dt>
          <dd>The <code>host</code> element within <code>dns</code> is the
            definition of DNS hosts to be passed to the DNS service. The IP
            address is identified by the <code>ip</code> attribute and the names
            for that IP address are identified in the <code>hostname</code>
            sub-elements of the <code>host</code> element.
            <span class="since">Since 0.9.3</span>
          </dd>
1014
        </dl>
1015 1016 1017 1018 1019
        <dl>
          <dt><code>srv</code></dt>
          <dd>The <code>dns</code> element can have also 0 or more <code>srv</code>
            record elements. Each <code>srv</code> record element defines a DNS SRV record
            and has 2 mandatory and 5 optional attributes. The mandatory attributes
1020 1021 1022 1023
            are service <code>name</code> and <code>protocol</code> (tcp, udp)
            and the optional attributes are <code>target</code>,
            <code>port</code>, <code>priority</code>, <code>weight</code> and
            <code>domain</code> as defined in DNS server SRV RFC (RFC 2782).
1024 1025 1026
            <span class="since">Since 0.9.9</span>
          </dd>
        </dl>
1027
      </dd>
1028 1029
      <dt><code>ip</code></dt>
      <dd>The <code>address</code> attribute defines an IPv4 address in
1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041
        dotted-decimal format, or an IPv6 address in standard colon-separated
        hexadecimal format, that will be configured on the bridge device
        associated with the virtual network. To the guests this IPv4 address
        will be their IPv4 default route. For IPv6, the default route is
        established via Router Advertisement. For IPv4 addresses, the
        <code>netmask</code> attribute defines the significant bits of the
        network address, again specified in dotted-decimal format. For IPv6
        addresses, and as an alternate method for IPv4 addresses, the
        significant bits of the network address can be specified with the
        <code>prefix</code> attribute, which is an integer (for example,
        <code>netmask='255.255.255.0'</code> could also be given as
        <code>prefix='24'</code>). The <code>family</code> attribute is used
1042
        to specify the type of address - <code>ipv4</code> or
1043 1044
        <code>ipv6</code>; if no <code>family</code> is given,
        <code>ipv4</code> is assumed. More than one address of each family can
1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056
        be defined for a network. The optional <code>localPtr</code> attribute
        (<span class="since">since 3.0.0</span>) configures the DNS server to
        not forward any reverse DNS requests for IP addresses from the network
        configured by the <code>address</code> and
        <code>netmask</code>/<code>prefix</code> attributes. For some unusual
        network prefixes (not divisible by 8 for IPv4 or not divisible by 4 for
        IPv6) libvirt may be unable to compute the PTR domain automatically.
        The <code>ip</code> element is supported <span class="since">since
        0.3.0</span>. IPv6, multiple addresses on a single network,
        <code>family</code>, and <code>prefix</code> are supported
        <span class="since">since 0.8.7</span>. The <code>ip</code> element may
        contain the following elements:
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        <dl>
          <dt><code>tftp</code></dt>
1060 1061 1062 1063 1064
          <dd>The optional <code>tftp</code> element and its mandatory
            <code>root</code> attribute enable TFTP services. The attribute
            specifies the path to the root directory served via TFTP. The
            <code>tftp</code> element is not supported for IPv6 addresses,
            and can only be specified on a single IPv4 address per network.
1065 1066 1067 1068
            <span class="since">Since 0.7.1</span>
          </dd>

          <dt><code>dhcp</code></dt>
1069 1070 1071 1072 1073 1074
          <dd>The presence of this element enables DHCP services on the
            virtual network. The <code>dhcp</code> element is supported for
            both IPv4 (<span class="since">since 0.3.0</span>) and IPv6
            (<span class="since">since 1.0.1</span>), but only for one IP
            address of each type per network. The following sub-elements are
            supported:
1075 1076 1077 1078
            <dl>
              <dt><code>range</code></dt>
              <dd>The <code>start</code> and <code>end</code> attributes on the
                <code>range</code> element specify the boundaries of a pool of
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                addresses to be provided to DHCP clients. These two addresses
1080
                must lie within the scope of the network defined on the parent
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                <code>ip</code> element.  There may be zero or more
                <code>range</code> elements specified.
                <span class="since">Since 0.3.0</span>
1084 1085
              </dd>
              <dt><code>host</code></dt>
1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102
              <dd>Within the <code>dhcp</code> element there may be zero or
                more <code>host</code> elements. These specify hosts which will
                be given names and predefined IP addresses by the built-in DHCP
                server. Any IPv4 <code>host</code> element must specify the MAC
                address of the host to be assigned a given name (via the
                <code>mac</code> attribute), the IP to be assigned to that host
                (via the <code>ip</code> attribute), and the name itself (the
                <code>name</code> attribute). The IPv6 <code>host</code>
                element differs slightly from that for IPv4: there is no
                <code>mac</code> attribute since a MAC address has no defined
                meaning in IPv6. Instead, the <code>name</code> attribute is
                used to identify the host to be assigned the IPv6 address. For
                DHCPv6, the name is the plain name of the client host sent by the
                client to the server. Note that this method of assigning a
                specific IP address can also be used for IPv4 instead of the
                <code>mac</code> attribute.
                <span class="since">Since 0.4.5</span>
1103 1104
              </dd>
              <dt><code>bootp</code></dt>
1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116
              <dd>The optional <code>bootp</code> element specifies BOOTP
                options to be provided by the DHCP server for IPv4 only. Two
                attributes are supported: <code>file</code> is mandatory and
                gives the file to be used for the boot image;
                <code>server</code> is optional and gives the address of the
                TFTP server from which the boot image will be fetched.
                <code>server</code> defaults to the same host that runs the
                DHCP server, as is the case when the <code>tftp</code> element
                is used. The BOOTP options currently have to be the same for
                all address ranges and statically assigned addresses. <span
                class="since">Since 0.7.1</span> (<code>server</code>
                <span class="since">since 0.7.3</span>)
1117 1118 1119 1120
              </dd>
            </dl>
          </dd>
        </dl>
1121
      </dd>
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    </dl>
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1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145
    <h3><a id="elementsNamespaces">Network namespaces</a></h3>

    <p>
      A special XML namespace is available for passing options directly to the
      underlying dnsmasq configuration file. Usage of XML namespaces comes with no
      support guarantees, so use at your own risk.
    </p>

    <p>
      This example XML will pass the option strings <code>foo=bar</code> and
      <code>cname=*.foo.example.com,master.example.com</code> directly to the
      underlying dnsmasq instance.
      <pre>
&lt;network xmlns:dnsmasq='http://libvirt.org/schemas/network/dnsmasq/1.0'&gt;
  ...
  &lt;dnsmasq:options&gt;
    &lt;dnsmasq:option value="foo=bar"/&gt;
    &lt;dnsmasq:option value="cname=*.foo.example.com,master.example.com"/&gt;
  &lt;/dnsmasq:options&gt;
&lt;/network&gt;</pre>
    </p>

1146
    <h2><a id="examples">Example configuration</a></h2>
1147

1148
    <h3><a id="examplesNAT">NAT based network</a></h3>
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    <p>
      This example is the so called "default" virtual network. It is
      provided and enabled out-of-the-box for all libvirt installations.
      This is a configuration that allows guest OS to get outbound
      connectivity regardless of whether the host uses ethernet, wireless,
      dialup, or VPN networking without requiring any specific admin
      configuration. In the absence of host networking, it at least allows
      guests to talk directly to each other.
    </p>

1160
    <pre>
1161 1162
&lt;network&gt;
  &lt;name&gt;default&lt;/name&gt;
1163
  &lt;bridge name="virbr0"/&gt;
1164 1165 1166
  &lt;forward mode="nat"/&gt;
  &lt;ip address="192.168.122.1" netmask="255.255.255.0"&gt;
    &lt;dhcp&gt;
1167
      &lt;range start="192.168.122.2" end="192.168.122.254"/&gt;
1168 1169
    &lt;/dhcp&gt;
  &lt;/ip&gt;
1170
  &lt;ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64"/&gt;
1171
&lt;/network&gt;</pre>
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    <p>
      Below is a variation of the above example which adds an IPv6
      dhcp range definition.
    </p>

    <pre>
1180 1181
&lt;network&gt;
  &lt;name&gt;default6&lt;/name&gt;
1182
  &lt;bridge name="virbr0"/&gt;
1183 1184 1185
  &lt;forward mode="nat"/&gt;
  &lt;ip address="192.168.122.1" netmask="255.255.255.0"&gt;
    &lt;dhcp&gt;
1186
      &lt;range start="192.168.122.2" end="192.168.122.254"/&gt;
1187 1188
    &lt;/dhcp&gt;
  &lt;/ip&gt;
1189
  &lt;ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64"&gt;
1190
    &lt;dhcp&gt;
1191
      &lt;range start="2001:db8:ca2:2:1::10" end="2001:db8:ca2:2:1::ff"/&gt;
1192 1193 1194
    &lt;/dhcp&gt;
  &lt;/ip&gt;
&lt;/network&gt;</pre>
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1196
    <h3><a id="examplesRoute">Routed network config</a></h3>
1197

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    <p>
      This is a variant on the default network which routes traffic
      from the virtual network to the LAN without applying any NAT.
      It requires that the IP address range be pre-configured in the
      routing tables of the router on the host network. This example
      further specifies that guest traffic may only go out via the
      <code>eth1</code> host network device.
    </p>

1207
    <pre>
1208 1209
&lt;network&gt;
  &lt;name&gt;local&lt;/name&gt;
1210
  &lt;bridge name="virbr1"/&gt;
1211 1212 1213
  &lt;forward mode="route" dev="eth1"/&gt;
  &lt;ip address="192.168.122.1" netmask="255.255.255.0"&gt;
    &lt;dhcp&gt;
1214
      &lt;range start="192.168.122.2" end="192.168.122.254"/&gt;
1215 1216
    &lt;/dhcp&gt;
  &lt;/ip&gt;
1217
  &lt;ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64"/&gt;
1218
&lt;/network&gt;</pre>
1219

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    <p>
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      Below is another IPv6 variation.  Instead of a dhcp range being
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      specified, this example has a couple of IPv6 host definitions.
1223 1224 1225 1226 1227
      Note that most of the dhcp host definitions use an "id" (client
      id or DUID) since this has proven to be a more reliable way
      of specifying the interface and its association with an IPv6
      address.  The first is a DUID-LLT, the second a DUID-LL, and
      the third a DUID-UUID.  <span class="since">Since 1.0.3</span>
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    </p>

    <pre>
1231 1232
&lt;network&gt;
  &lt;name&gt;local6&lt;/name&gt;
1233
  &lt;bridge name="virbr1"/&gt;
1234 1235 1236
  &lt;forward mode="route" dev="eth1"/&gt;
  &lt;ip address="192.168.122.1" netmask="255.255.255.0"&gt;
    &lt;dhcp&gt;
1237
      &lt;range start="192.168.122.2" end="192.168.122.254"/&gt;
1238 1239
    &lt;/dhcp&gt;
  &lt;/ip&gt;
1240
  &lt;ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64"&gt;
1241
    &lt;dhcp&gt;
1242 1243 1244
      &lt;host name="paul" ip="2001:db8:ca2:2:3::1"/&gt;
      &lt;host id="0:1:0:1:18:aa:62:fe:0:16:3e:44:55:66" ip="2001:db8:ca2:2:3::2"/&gt;
      &lt;host id="0:3:0:1:0:16:3e:11:22:33" name="ralph" ip="2001:db8:ca2:2:3::3"/&gt;
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      &lt;host id="0:4:7e:7d:f0:7d:a8:bc:c5:d2:13:32:11:ed:16:ea:84:63"
        name="badbob" ip="2001:db8:ca2:2:3::4"/&gt;
1247 1248 1249
    &lt;/dhcp&gt;
  &lt;/ip&gt;
&lt;/network&gt;</pre>
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1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263
    <p>
      Below is yet another IPv6 variation.  This variation has only
      IPv6 defined with DHCPv6 on the primary IPv6 network.  A static
      link if defined for a second IPv6 network which will not be
      directly visible on the bridge interface but there will be a
      static route defined for this network via the specified
      gateway. Note that the gateway address must be directly
      reachable via (on the same subnet as) one of the &lt;ip&gt;
      addresses defined for this &lt;network&gt;.
      <span class="since">Since 1.0.6</span>
    </p>

    <pre>
1264 1265
&lt;network&gt;
  &lt;name&gt;net7&lt;/name&gt;
1266
  &lt;bridge name="virbr7"/&gt;
1267
  &lt;forward mode="route"/&gt;
1268
  &lt;ip family="ipv6" address="2001:db8:ca2:7::1" prefix="64"&gt;
1269
    &lt;dhcp&gt;
1270
      &lt;range start="2001:db8:ca2:7::100" end="2001:db8:ca2::1ff"/&gt;
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      &lt;host id="0:4:7e:7d:f0:7d:a8:bc:c5:d2:13:32:11:ed:16:ea:84:63"
        name="lucas" ip="2001:db8:ca2:2:3::4"/&gt;
1273 1274
    &lt;/dhcp&gt;
  &lt;/ip&gt;
1275
  &lt;route family="ipv6" address="2001:db8:ca2:8::" prefix="64" gateway="2001:db8:ca2:7::4"/&gt;
1276
&lt;/network&gt;</pre>
1277

1278
    <h3><a id="examplesPrivate">Isolated network config</a></h3>
1279

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    <p>
      This variant provides a completely isolated private network
      for guests. The guests can talk to each other, and the host
      OS, but cannot reach any other machines on the LAN, due to
      the omission of the <code>forward</code> element in the XML
      description.
    </p>

1288
    <pre>
1289 1290
&lt;network&gt;
  &lt;name&gt;private&lt;/name&gt;
1291
  &lt;bridge name="virbr2"/&gt;
1292 1293
  &lt;ip address="192.168.152.1" netmask="255.255.255.0"&gt;
    &lt;dhcp&gt;
1294
      &lt;range start="192.168.152.2" end="192.168.152.254"/&gt;
1295 1296
    &lt;/dhcp&gt;
  &lt;/ip&gt;
1297
  &lt;ip family="ipv6" address="2001:db8:ca2:3::1" prefix="64"/&gt;
1298
&lt;/network&gt;</pre>
1299

1300
    <h3><a id="examplesPrivate6">Isolated IPv6 network config</a></h3>
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    <p>
      This variation of an isolated network defines only IPv6.
1304 1305 1306 1307 1308
      Note that most of the dhcp host definitions use an "id" (client
      id or DUID) since this has proven to be a more reliable way
      of specifying the interface and its association with an IPv6
      address.  The first is a DUID-LLT, the second a DUID-LL, and
      the third a DUID-UUID.  <span class="since">Since 1.0.3</span>
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    </p>

    <pre>
1312 1313
&lt;network&gt;
  &lt;name&gt;sixnet&lt;/name&gt;
1314 1315
  &lt;bridge name="virbr6"/&gt;
  &lt;ip family="ipv6" address="2001:db8:ca2:6::1" prefix="64"&gt;
1316
    &lt;dhcp&gt;
1317 1318 1319
      &lt;host name="peter" ip="2001:db8:ca2:6:6::1"/&gt;
      &lt;host id="0:1:0:1:18:aa:62:fe:0:16:3e:44:55:66" ip="2001:db8:ca2:6:6::2"/&gt;
      &lt;host id="0:3:0:1:0:16:3e:11:22:33" name="dariusz" ip="2001:db8:ca2:6:6::3"/&gt;
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      &lt;host id="0:4:7e:7d:f0:7d:a8:bc:c5:d2:13:32:11:ed:16:ea:84:63"
        name="anita" ip="2001:db8:ca2:6:6::4"/&gt;
1322 1323 1324
    &lt;/dhcp&gt;
  &lt;/ip&gt;
&lt;/network&gt;</pre>
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1326
    <h3><a id="examplesBridge">Using an existing host bridge</a></h3>
1327 1328

    <p>
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      <span class="since">Since 0.9.4</span>
1330 1331 1332 1333 1334 1335 1336 1337
      This shows how to use a pre-existing host bridge "br0". The
      guests will effectively be directly connected to the physical
      network (i.e. their IP addresses will all be on the subnet of
      the physical network, and there will be no restrictions on
      inbound or outbound connections).
    </p>

    <pre>
1338 1339 1340 1341 1342
&lt;network&gt;
  &lt;name&gt;host-bridge&lt;/name&gt;
  &lt;forward mode="bridge"/&gt;
  &lt;bridge name="br0"/&gt;
&lt;/network&gt;</pre>
1343

1344
    <h3><a id="examplesDirect">Using a macvtap "direct" connection</a></h3>
1345 1346

    <p>
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      <span class="since">Since 0.9.4, QEMU and KVM only, requires
      Linux kernel 2.6.34 or newer</span>
1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367
      This shows how to use macvtap to connect to the physical network
      directly through one of a group of physical devices (without
      using a host bridge device). As with the host bridge network,
      the guests will effectively be directly connected to the
      physical network so their IP addresses will all be on the subnet
      of the physical network, and there will be no restrictions on
      inbound or outbound connections. Note that, due to a limitation
      in the implementation of macvtap, these connections do not allow
      communication directly between the host and the guests - if you
      require this you will either need the attached physical switch
      to be operating in a mirroring mode (so that all traffic coming
      to the switch is reflected back to the host's interface), or
      provide alternate means for this communication (e.g. a second
      interface on each guest that is connected to an isolated
      network). The other forward modes that use macvtap (private,
      vepa, and passthrough) would be used in a similar fashion.
    </p>

    <pre>
1368 1369 1370 1371 1372 1373 1374 1375 1376 1377
&lt;network&gt;
  &lt;name&gt;direct-macvtap&lt;/name&gt;
  &lt;forward mode="bridge"&gt;
    &lt;interface dev="eth20"/&gt;
    &lt;interface dev="eth21"/&gt;
    &lt;interface dev="eth22"/&gt;
    &lt;interface dev="eth23"/&gt;
    &lt;interface dev="eth24"/&gt;
  &lt;/forward&gt;
&lt;/network&gt;</pre>
1378

1379
    <h3><a id="examplesNoGateway">Network config with no gateway addresses</a></h3>
1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391

    <p>
    A valid network definition can contain no IPv4 or IPv6 addresses.  Such a definition
    can be used for a "very private" or "very isolated" network since it will not be
    possible to communicate with the virtualization host via this network.  However,
    this virtual network interface can be used for communication between virtual guest
    systems.  This works for IPv4 and <span class="since">(Since 1.0.1)</span> IPv6.
    However, the new ipv6='yes' must be added for guest-to-guest IPv6
    communication.
    </p>

    <pre>
1392 1393 1394
&lt;network ipv6='yes'&gt;
  &lt;name&gt;nogw&lt;/name&gt;
  &lt;uuid&gt;7a3b7497-1ec7-8aef-6d5c-38dff9109e93&lt;/uuid&gt;
1395
  &lt;bridge name="virbr2" stp="on" delay="0"/&gt;
1396 1397
  &lt;mac address='00:16:3E:5D:C7:9E'/&gt;
&lt;/network&gt;</pre>
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