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<topic xml:lang="en-us" id="nichardware">
  <title>Virtual Networking Hardware</title>
  
  <body>
    <p>For each card, you can individually select what kind of <i>hardware</i> will be presented to the virtual machine.
        <ph conkeyref="vbox-conkeyref-phrases/product-name"/> can virtualize the following types of networking hardware: </p>
    <ul>
      <li>
        <p>AMD PCNet PCI II (Am79C970A) Not available on Arm guests.</p>
      </li>
      <li>
        <p>AMD PCNet FAST III (Am79C973), the default setting on x86 guests. Not available on Arm guests.</p>
      </li>
      <li>
        <p>Intel PRO/1000 MT Desktop (82540EM)</p>
      </li>
      <li>
        <p>Intel PRO/1000 T Server (82543GC)</p>
      </li>
      <li>
        <p>Intel PRO/1000 MT Server (82545EM)</p>
      </li>
      <li>
        <p>Paravirtualized network adapter (virtio-net)</p>
      </li>
      <li>
        <p>Ethernet over USB network adapter (usbnet)</p>
      </li>
    </ul>
    <p>The PCNet FAST III is the default because it is supported by nearly all operating systems, as well as by the GNU
      GRUB boot manager. As an exception, the Intel PRO/1000 family adapters are chosen for some guest operating system
      types that no longer ship with drivers for the PCNet card, such as Windows Vista. </p>
    <p>The Intel PRO/1000 MT Desktop type works with Windows Vista and later versions. The T Server variant of the Intel
      PRO/1000 card is recognized by Windows XP guests without additional driver installation. The MT Server variant
      facilitates OVF imports from other platforms. </p>
    <p>The Paravirtualized network adapter (virtio-net) is special. If you select this adapter, then <ph
        conkeyref="vbox-conkeyref-phrases/product-name"/> does <i>not</i> virtualize common networking hardware that is
      supported by common guest operating systems. Instead, <ph conkeyref="vbox-conkeyref-phrases/product-name"/>
      expects a special software interface for virtualized environments to be provided by the guest, thus avoiding the
      complexity of emulating networking hardware and improving network performance. <ph
        conkeyref="vbox-conkeyref-phrases/product-name"/> provides support for the industry-standard <i>virtio</i>
      networking drivers, which are part of the open source KVM project. </p>
    <p>The virtio networking drivers are available for the following guest operating systems: </p>
    <ul>
      <li>
        <p>Linux kernels version 2.6.25 or later can be configured to provide virtio support. Some distributions have
          also back-ported virtio to older kernels. </p>
      </li>
      <li>
        <p>For Windows 2000, XP, and Vista, virtio drivers can be downloaded and installed from the KVM project web
          page: </p>
        <p><ph>http://www.linux-kvm.org/page/WindowsGuestDrivers</ph>.
        </p>
      </li>
    </ul>
    <p><ph conkeyref="vbox-conkeyref-phrases/product-name"/> also has limited support for <i>jumbo frames</i>. These are
      networking packets with more than 1500 bytes of data, provided that you use the Intel card virtualization and
      bridged networking. Jumbo frames are not supported with the AMD networking devices. In those cases, jumbo packets
      will silently be dropped for both the transmit and the receive direction. Guest operating systems trying to use
      this feature will observe this as a packet loss, which may lead to unexpected application behavior in the guest.
      This does not cause problems with guest operating systems in their default configuration, as jumbo frames need to
      be explicitly enabled. </p>
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</topic>
