man/systemd.netdev.xml

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  10   Copyright 2013 Tom Gundersen
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  25
  26 <refentry id="systemd.netdev" conditional='ENABLE_NETWORKD'>
  27
  28   <refentryinfo>
  29     <title>systemd.network</title>
  30     <productname>systemd</productname>
  31
  32     <authorgroup>
  33       <author>
  34         <contrib>Developer</contrib>
  35         <firstname>Tom</firstname>
  36         <surname>Gundersen</surname>
  37         <email>teg@jklm.no</email>
  38       </author>
  39     </authorgroup>
  40   </refentryinfo>
  41
  42   <refmeta>
  43     <refentrytitle>systemd.netdev</refentrytitle>
  44     <manvolnum>5</manvolnum>
  45   </refmeta>
  46
  47   <refnamediv>
  48     <refname>systemd.netdev</refname>
  49     <refpurpose>Virtual Network Device configuration</refpurpose>
  50   </refnamediv>
  51
  52   <refsynopsisdiv>
  53     <para><filename><replaceable>netdev</replaceable>.netdev</filename></para>
  54   </refsynopsisdiv>
  55
  56   <refsect1>
  57     <title>Description</title>
  58
  59     <para>Network setup is performed by
  60     <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  61     </para>
  62
  63     <para>The main Virtual Network Device file must have the extension <filename>.netdev</filename>;
  64     other extensions are ignored. Virtual network devices are created as soon as networkd is
  65     started. If a netdev with the specified name already exists, networkd will use that as-is rather
  66     than create its own. Note that the settings of the pre-existing netdev will not be changed by
  67     networkd.</para>
  68
  69     <para>The <filename>.netdev</filename> files are read from the files located in the system
  70     network directory <filename>/usr/lib/systemd/network</filename>, the volatile runtime network
  71     directory <filename>/run/systemd/network</filename> and the local administration network
  72     directory <filename>/etc/systemd/network</filename>. All configuration files are collectively
  73     sorted and processed in lexical order, regardless of the directories in which they live.
  74     However, files with identical filenames replace each other. Files in <filename>/etc</filename>
  75     have the highest priority, files in <filename>/run</filename> take precedence over files with
  76     the same name in <filename>/usr/lib</filename>. This can be used to override a system-supplied
  77     configuration file with a local file if needed. As a special case, an empty file (file size 0)
  78     or symlink with the same name pointing to <filename>/dev/null</filename> disables the
  79     configuration file entirely (it is "masked").</para>
  80
  81     <para>Along with the netdev file <filename>foo.netdev</filename>, a "drop-in" directory
  82     <filename>foo.netdev.d/</filename> may exist. All files with the suffix <literal>.conf</literal>
  83     from this directory will be parsed after the file itself is parsed. This is useful to alter or
  84     add configuration settings, without having to modify the main configuration file. Each drop-in
  85     file must have appropriate section headers.</para>
  86
  87     <para>In addition to <filename>/etc/systemd/network</filename>, drop-in <literal>.d</literal>
  88     directories can be placed in <filename>/usr/lib/systemd/network</filename> or
  89     <filename>/run/systemd/network</filename> directories. Drop-in files in
  90     <filename>/etc</filename> take precedence over those in <filename>/run</filename> which in turn
  91     take precedence over those in <filename>/usr/lib</filename>. Drop-in files under any of these
  92     directories take precedence over the main netdev file wherever located. (Of course, since
  93     <filename>/run</filename> is temporary and <filename>/usr/lib</filename> is for vendors, it is
  94     unlikely drop-ins should be used in either of those places.)</para>
  95   </refsect1>
  96
  97   <refsect1>
  98     <title>Supported netdev kinds</title>
  99
 100     <para>The following kinds of virtual network devices may be
 101     configured in <filename>.netdev</filename> files:</para>
 102
 103     <table>
 104       <title>Supported kinds of virtual network devices</title>
 105
 106       <tgroup cols='2'>
 107         <colspec colname='kind' />
 108         <colspec colname='explanation' />
 109         <thead><row>
 110           <entry>Kind</entry>
 111           <entry>Description</entry>
 112         </row></thead>
 113         <tbody>
 114           <row><entry><varname>bond</varname></entry>
 115           <entry>A bond device is an aggregation of all its slave devices. See <ulink url="https://www.kernel.org/doc/Documentation/networking/bonding.txt">Linux Ethernet Bonding Driver HOWTO</ulink> for details.Local configuration</entry></row>
 116
 117           <row><entry><varname>bridge</varname></entry>
 118           <entry>A bridge device is a software switch, and each of its slave devices and the bridge itself are ports of the switch.</entry></row>
 119
 120           <row><entry><varname>dummy</varname></entry>
 121           <entry>A dummy device drops all packets sent to it.</entry></row>
 122
 123           <row><entry><varname>gre</varname></entry>
 124           <entry>A Level 3 GRE tunnel over IPv4. See <ulink url="https://tools.ietf.org/html/rfc2784">RFC 2784</ulink> for details.</entry></row>
 125
 126           <row><entry><varname>gretap</varname></entry>
 127           <entry>A Level 2 GRE tunnel over IPv4.</entry></row>
 128
 129           <row><entry><varname>ip6gre</varname></entry>
 130           <entry>A Level 3 GRE tunnel over IPv6.</entry></row>
 131
 132           <row><entry><varname>ip6tnl</varname></entry>
 133           <entry>An IPv4 or IPv6 tunnel over IPv6</entry></row>
 134
 135           <row><entry><varname>ip6gretap</varname></entry>
 136           <entry>A Level 2 GRE tunnel over IPv6.</entry></row>
 137
 138           <row><entry><varname>ipip</varname></entry>
 139           <entry>An IPv4 over IPv4 tunnel.</entry></row>
 140
 141           <row><entry><varname>ipvlan</varname></entry>
 142           <entry>An ipvlan device is a stacked device which receives packets from its underlying device based on IP address filtering.</entry></row>
 143
 144           <row><entry><varname>macvlan</varname></entry>
 145           <entry>A macvlan device is a stacked device which receives packets from its underlying device based on MAC address filtering.</entry></row>
 146
 147           <row><entry><varname>macvtap</varname></entry>
 148           <entry>A macvtap device is a stacked device which receives packets from its underlying device based on MAC address filtering.</entry></row>
 149
 150           <row><entry><varname>sit</varname></entry>
 151           <entry>An IPv6 over IPv4 tunnel.</entry></row>
 152
 153           <row><entry><varname>tap</varname></entry>
 154           <entry>A persistent Level 2 tunnel between a network device and a device node.</entry></row>
 155
 156           <row><entry><varname>tun</varname></entry>
 157           <entry>A persistent Level 3 tunnel between a network device and a device node.</entry></row>
 158
 159           <row><entry><varname>veth</varname></entry>
 160           <entry>An Ethernet tunnel between a pair of network devices.</entry></row>
 161
 162           <row><entry><varname>vlan</varname></entry>
 163           <entry>A VLAN is a stacked device which receives packets from its underlying device based on VLAN tagging. See <ulink url="http://www.ieee802.org/1/pages/802.1Q.html">IEEE 802.1Q</ulink> for details.</entry></row>
 164
 165           <row><entry><varname>vti</varname></entry>
 166           <entry>An IPv4 over IPSec tunnel.</entry></row>
 167
 168           <row><entry><varname>vti6</varname></entry>
 169           <entry>An IPv6 over IPSec tunnel.</entry></row>
 170
 171           <row><entry><varname>vxlan</varname></entry>
 172           <entry>A virtual extensible LAN (vxlan), for connecting Cloud computing deployments.</entry></row>
 173
 174           <row><entry><varname>geneve</varname></entry>
 175           <entry>A GEneric NEtwork Virtualization Encapsulation (GENEVE) netdev driver.</entry></row>
 176
 177           <row><entry><varname>vrf</varname></entry>
 178           <entry>A Virtual Routing and Forwarding (<ulink url="https://www.kernel.org/doc/Documentation/networking/vrf.txt">VRF</ulink>) interface to create separate routing and forwarding domains.</entry></row>
 179
 180           <row><entry><varname>vcan</varname></entry>
 181           <entry>The virtual CAN driver (vcan). Similar to the network loopback devices, vcan offers a virtual local CAN interface.</entry></row>
 182
 183           <row><entry><varname>vxcan</varname></entry>
 184           <entry>The virtual CAN tunnel driver (vxcan). Similar to the virtual ethernet driver veth, vxcan implements a local CAN traffic tunnel between two virtual CAN network devices. When creating a vxcan, two vxcan devices are created as pair. When one end receives the packet it appears on its pair and vice versa. The vxcan can be used for cross namespace communication.
 185           </entry></row>
 186
 187         </tbody>
 188       </tgroup>
 189     </table>
 190
 191   </refsect1>
 192
 193   <refsect1>
 194     <title>[Match] Section Options</title>
 195
 196     <para>A virtual network device is only created if the
 197     <literal>[Match]</literal> section matches the current
 198     environment, or if the section is empty. The following keys are
 199     accepted:</para>
 200
 201     <variablelist class='network-directives'>
 202       <varlistentry>
 203         <term><varname>Host=</varname></term>
 204         <listitem>
 205           <para>Matches against the hostname or machine ID of the
 206           host. See <literal>ConditionHost=</literal> in
 207           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 208           for details.
 209           </para>
 210         </listitem>
 211       </varlistentry>
 212       <varlistentry>
 213         <term><varname>Virtualization=</varname></term>
 214         <listitem>
 215           <para>Checks whether the system is executed in a virtualized
 216           environment and optionally test whether it is a specific
 217           implementation. See
 218           <literal>ConditionVirtualization=</literal> in
 219           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 220           for details.
 221           </para>
 222         </listitem>
 223       </varlistentry>
 224       <varlistentry>
 225         <term><varname>KernelCommandLine=</varname></term>
 226         <listitem>
 227           <para>Checks whether a specific kernel command line option
 228           is set (or if prefixed with the exclamation mark unset). See
 229           <literal>ConditionKernelCommandLine=</literal> in
 230           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 231           for details.
 232           </para>
 233         </listitem>
 234       </varlistentry>
 235       <varlistentry>
 236         <term><varname>Architecture=</varname></term>
 237         <listitem>
 238           <para>Checks whether the system is running on a specific
 239           architecture. See <literal>ConditionArchitecture=</literal> in
 240           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 241           for details.
 242           </para>
 243         </listitem>
 244       </varlistentry>
 245     </variablelist>
 246
 247   </refsect1>
 248
 249   <refsect1>
 250     <title>[NetDev] Section Options</title>
 251
 252       <para>The <literal>[NetDev]</literal> section accepts the
 253       following keys:</para>
 254
 255       <variablelist class='network-directives'>
 256         <varlistentry>
 257           <term><varname>Description=</varname></term>
 258           <listitem>
 259             <para>A free-form description of the netdev.</para>
 260           </listitem>
 261         </varlistentry>
 262         <varlistentry>
 263           <term><varname>Name=</varname></term>
 264           <listitem>
 265             <para>The interface name used when creating the netdev.
 266             This option is compulsory.</para>
 267           </listitem>
 268         </varlistentry>
 269         <varlistentry>
 270           <term><varname>Kind=</varname></term>
 271           <listitem>
 272             <para>The netdev kind. This option is compulsory. See the
 273             <literal>Supported netdev kinds</literal> section for the
 274             valid keys.</para>
 275           </listitem>
 276         </varlistentry>
 277         <varlistentry>
 278           <term><varname>MTUBytes=</varname></term>
 279           <listitem>
 280             <para>The maximum transmission unit in bytes to set for
 281             the device. The usual suffixes K, M, G, are supported and
 282             are understood to the base of 1024. This key is not
 283             currently supported for <literal>tun</literal> or
 284             <literal>tap</literal> devices.
 285             </para>
 286           </listitem>
 287         </varlistentry>
 288         <varlistentry>
 289           <term><varname>MACAddress=</varname></term>
 290           <listitem>
 291             <para>The MAC address to use for the device. If none is
 292             given, one is generated based on the interface name and
 293             the
 294             <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 295             This key is not currently supported for
 296             <literal>tun</literal> or <literal>tap</literal> devices.
 297             </para>
 298           </listitem>
 299         </varlistentry>
 300       </variablelist>
 301   </refsect1>
 302
 303     <refsect1>
 304     <title>[Bridge] Section Options</title>
 305
 306       <para>The <literal>[Bridge]</literal> section only applies for
 307       netdevs of kind <literal>bridge</literal>, and accepts the
 308       following keys:</para>
 309
 310       <variablelist class='network-directives'>
 311         <varlistentry>
 312           <term><varname>HelloTimeSec=</varname></term>
 313           <listitem>
 314             <para>HelloTimeSec specifies the number of seconds between two hello packets
 315             sent out by the root bridge and the designated bridges. Hello packets are
 316             used to communicate information about the topology throughout the entire
 317             bridged local area network.</para>
 318           </listitem>
 319         </varlistentry>
 320         <varlistentry>
 321           <term><varname>MaxAgeSec=</varname></term>
 322           <listitem>
 323             <para>MaxAgeSec specifies the number of seconds of maximum message age.
 324             If the last seen (received) hello packet is more than this number of
 325             seconds old, the bridge in question will start the takeover procedure
 326             in attempt to become the Root Bridge itself.</para>
 327           </listitem>
 328         </varlistentry>
 329         <varlistentry>
 330           <term><varname>ForwardDelaySec=</varname></term>
 331           <listitem>
 332             <para>ForwardDelaySec specifies the number of seconds spent in each
 333             of the Listening and Learning states before the Forwarding state is entered.</para>
 334           </listitem>
 335         </varlistentry>
 336         <varlistentry>
 337           <term><varname>AgeingTimeSec=</varname></term>
 338           <listitem>
 339             <para>This specifies the number of seconds a MAC Address will be kept in
 340             the forwarding database after having a packet received from this MAC Address.</para>
 341           </listitem>
 342         </varlistentry>
 343         <varlistentry>
 344           <term><varname>Priority=</varname></term>
 345           <listitem>
 346             <para>The priority of the bridge. An integer between 0 and 65535. A lower value
 347             means higher priority. The bridge having the lowest priority will be elected as root bridge.</para>
 348           </listitem>
 349         </varlistentry>
 350         <varlistentry>
 351           <term><varname>GroupForwardMask=</varname></term>
 352           <listitem>
 353             <para>A 16-bit bitmask represented as an integer which allows forwarding of link
 354             local frames with 802.1D reserved addresses (01:80:C2:00:00:0X). A logical AND
 355             is performed between the specified bitmask and the exponentiation of 2^X, the
 356             lower nibble of the last octet of the MAC address. For example, a value of 8
 357             would allow forwarding of frames addressed to 01:80:C2:00:00:03 (802.1X PAE).</para>
 358           </listitem>
 359         </varlistentry>
 360         <varlistentry>
 361           <term><varname>DefaultPVID=</varname></term>
 362           <listitem>
 363             <para>This specifies the default port VLAN ID of a newly attached bridge port.
 364             Set this to an integer in the range 1–4094 or <literal>none</literal> to disable the PVID.</para>
 365           </listitem>
 366         </varlistentry>
 367         <varlistentry>
 368           <term><varname>MulticastQuerier=</varname></term>
 369           <listitem>
 370             <para>A boolean. This setting controls the IFLA_BR_MCAST_QUERIER option in the kernel.
 371             If enabled, the kernel will send general ICMP queries from a zero source address.
 372             This feature should allow faster convergence on startup, but it causes some
 373             multicast-aware switches to misbehave and disrupt forwarding of multicast packets.
 374             When unset, the kernel's default setting applies.
 375             </para>
 376           </listitem>
 377         </varlistentry>
 378         <varlistentry>
 379           <term><varname>MulticastSnooping=</varname></term>
 380           <listitem>
 381             <para>A boolean. This setting controls the IFLA_BR_MCAST_SNOOPING option in the kernel.
 382             If enabled, IGMP snooping monitors the Internet Group Management Protocol (IGMP) traffic
 383             between hosts and multicast routers. When unset, the kernel's default setting applies.
 384             </para>
 385           </listitem>
 386         </varlistentry>
 387         <varlistentry>
 388           <term><varname>VLANFiltering=</varname></term>
 389           <listitem>
 390             <para>A boolean. This setting controls the IFLA_BR_VLAN_FILTERING option in the kernel.
 391             If enabled, the bridge will be started in VLAN-filtering mode. When unset, the kernel's
 392             default setting applies.
 393             </para>
 394           </listitem>
 395         </varlistentry>
 396           <varlistentry>
 397           <term><varname>STP=</varname></term>
 398           <listitem>
 399             <para>A boolean. This enables the bridge's Spanning Tree Protocol (STP). When unset,
 400             the kernel's default setting applies.
 401             </para>
 402           </listitem>
 403         </varlistentry>
 404       </variablelist>
 405   </refsect1>
 406
 407   <refsect1>
 408     <title>[VLAN] Section Options</title>
 409
 410       <para>The <literal>[VLAN]</literal> section only applies for
 411       netdevs of kind <literal>vlan</literal>, and accepts the
 412       following key:</para>
 413
 414       <variablelist class='network-directives'>
 415         <varlistentry>
 416           <term><varname>Id=</varname></term>
 417           <listitem>
 418             <para>The VLAN ID to use. An integer in the range 0–4094.
 419             This option is compulsory.</para>
 420           </listitem>
 421         </varlistentry>
 422         <varlistentry>
 423           <term><varname>GVRP=</varname></term>
 424           <listitem>
 425             <para>The Generic VLAN Registration Protocol (GVRP) is a protocol that
 426             allows automatic learning of VLANs on a network. A boolean. When unset,
 427             the kernel's default setting applies.</para>
 428           </listitem>
 429         </varlistentry>
 430         <varlistentry>
 431           <term><varname>MVRP=</varname></term>
 432           <listitem>
 433             <para>Multiple VLAN Registration Protocol (MVRP) formerly known as GARP VLAN
 434             Registration Protocol (GVRP) is a standards-based Layer 2 network protocol,
 435             for automatic configuration of VLAN information on switches. It was defined
 436             in the 802.1ak amendment to 802.1Q-2005. A boolean. When unset, the kernel's
 437             default setting applies.</para>
 438           </listitem>
 439         </varlistentry>
 440         <varlistentry>
 441           <term><varname>LooseBinding=</varname></term>
 442           <listitem>
 443             <para>The VLAN loose binding mode, in which only the operational state is passed
 444             from the parent to the associated VLANs, but the VLAN device state is not changed.
 445             A boolean. When unset, the kernel's default setting applies.</para>
 446           </listitem>
 447         </varlistentry>
 448         <varlistentry>
 449           <term><varname>ReorderHeader=</varname></term>
 450           <listitem>
 451             <para>The VLAN reorder header is set VLAN interfaces behave like physical interfaces.
 452             A boolean. When unset, the kernel's default setting applies.</para>
 453           </listitem>
 454         </varlistentry>
 455       </variablelist>
 456   </refsect1>
 457
 458   <refsect1>
 459     <title>[MACVLAN] Section Options</title>
 460
 461     <para>The <literal>[MACVLAN]</literal> section only applies for
 462     netdevs of kind <literal>macvlan</literal>, and accepts the
 463     following key:</para>
 464
 465     <variablelist class='network-directives'>
 466       <varlistentry>
 467         <term><varname>Mode=</varname></term>
 468         <listitem>
 469           <para>The MACVLAN mode to use. The supported options are
 470           <literal>private</literal>,
 471           <literal>vepa</literal>,
 472           <literal>bridge</literal>, and
 473           <literal>passthru</literal>.
 474           </para>
 475         </listitem>
 476       </varlistentry>
 477     </variablelist>
 478
 479   </refsect1>
 480
 481     <refsect1>
 482     <title>[MACVTAP] Section Options</title>
 483
 484     <para>The <literal>[MACVTAP]</literal> section applies for
 485     netdevs of kind <literal>macvtap</literal> and accepts the
 486     same key as <literal>[MACVLAN]</literal>.</para>
 487
 488     </refsect1>
 489
 490   <refsect1>
 491     <title>[IPVLAN] Section Options</title>
 492
 493     <para>The <literal>[IPVLAN]</literal> section only applies for
 494     netdevs of kind <literal>ipvlan</literal>, and accepts the
 495     following key:</para>
 496
 497     <variablelist class='network-directives'>
 498       <varlistentry>
 499         <term><varname>Mode=</varname></term>
 500           <listitem>
 501             <para>The IPVLAN mode to use. The supported options are
 502             <literal>L2</literal> and <literal>L3</literal>.
 503             </para>
 504           </listitem>
 505       </varlistentry>
 506     </variablelist>
 507
 508   </refsect1>
 509
 510   <refsect1>
 511     <title>[VXLAN] Section Options</title>
 512     <para>The <literal>[VXLAN]</literal> section only applies for
 513     netdevs of kind <literal>vxlan</literal>, and accepts the
 514     following keys:</para>
 515
 516     <variablelist class='network-directives'>
 517       <varlistentry>
 518         <term><varname>Id=</varname></term>
 519         <listitem>
 520           <para>The VXLAN ID to use.</para>
 521         </listitem>
 522       </varlistentry>
 523       <varlistentry>
 524         <term><varname>Remote=</varname></term>
 525         <listitem>
 526           <para>Configures destination multicast group IP address.</para>
 527         </listitem>
 528       </varlistentry>
 529       <varlistentry>
 530         <term><varname>Local=</varname></term>
 531         <listitem>
 532           <para>Configures local IP address.</para>
 533         </listitem>
 534       </varlistentry>
 535         <varlistentry>
 536         <term><varname>TOS=</varname></term>
 537         <listitem>
 538           <para>The Type Of Service byte value for a vxlan interface.</para>
 539         </listitem>
 540       </varlistentry>
 541       <varlistentry>
 542         <term><varname>TTL=</varname></term>
 543         <listitem>
 544           <para>A fixed Time To Live N on Virtual eXtensible Local
 545           Area Network packets. N is a number in the range 1–255. 0
 546           is a special value meaning that packets inherit the TTL
 547           value.</para>
 548         </listitem>
 549       </varlistentry>
 550       <varlistentry>
 551         <term><varname>MacLearning=</varname></term>
 552         <listitem>
 553           <para>A boolean. When true, enables dynamic MAC learning
 554           to discover remote MAC addresses.</para>
 555         </listitem>
 556       </varlistentry>
 557       <varlistentry>
 558         <term><varname>FDBAgeingSec=</varname></term>
 559         <listitem>
 560           <para>The lifetime of Forwarding Database entry learnt by
 561           the kernel, in seconds.</para>
 562         </listitem>
 563       </varlistentry>
 564       <varlistentry>
 565         <term><varname>MaximumFDBEntries=</varname></term>
 566         <listitem>
 567           <para>Configures maximum number of FDB entries.</para>
 568         </listitem>
 569       </varlistentry>
 570       <varlistentry>
 571         <term><varname>ReduceARPProxy=</varname></term>
 572         <listitem>
 573           <para>A boolean. When true, bridge-connected VXLAN tunnel
 574           endpoint answers ARP requests from the local bridge on behalf
 575           of remote Distributed Overlay Virtual Ethernet
 576           <ulink url="https://en.wikipedia.org/wiki/Distributed_Overlay_Virtual_Ethernet">
 577           (DVOE)</ulink> clients. Defaults to false.</para>
 578         </listitem>
 579       </varlistentry>
 580       <varlistentry>
 581         <term><varname>L2MissNotification=</varname></term>
 582         <listitem>
 583           <para>A boolean. When true, enables netlink LLADDR miss
 584           notifications.</para>
 585         </listitem>
 586       </varlistentry>
 587       <varlistentry>
 588         <term><varname>L3MissNotification=</varname></term>
 589         <listitem>
 590           <para>A boolean. When true, enables netlink IP address miss
 591           notifications.</para>
 592         </listitem>
 593       </varlistentry>
 594       <varlistentry>
 595         <term><varname>RouteShortCircuit=</varname></term>
 596         <listitem>
 597           <para>A boolean. When true, route short circuiting is turned
 598           on.</para>
 599         </listitem>
 600       </varlistentry>
 601       <varlistentry>
 602         <term><varname>UDPChecksum=</varname></term>
 603         <listitem>
 604           <para>A boolean. When true, transmitting UDP checksums when doing VXLAN/IPv4 is turned on.</para>
 605         </listitem>
 606       </varlistentry>
 607       <varlistentry>
 608         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 609         <listitem>
 610           <para>A boolean. When true, sending zero checksums in VXLAN/IPv6 is turned on.</para>
 611         </listitem>
 612       </varlistentry>
 613       <varlistentry>
 614         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 615         <listitem>
 616           <para>A boolean. When true, receiving zero checksums in VXLAN/IPv6 is turned on.</para>
 617         </listitem>
 618       </varlistentry>
 619       <varlistentry>
 620         <term><varname>RemoteChecksumTx=</varname></term>
 621         <listitem>
 622           <para>A boolean. When true, remote transmit checksum offload of VXLAN is turned on.</para>
 623         </listitem>
 624       </varlistentry>
 625       <varlistentry>
 626         <term><varname>RemoteChecksumRx=</varname></term>
 627         <listitem>
 628           <para>A boolean. When true, remote receive checksum offload in VXLAN is turned on.</para>
 629         </listitem>
 630       </varlistentry>
 631     <varlistentry>
 632       <term><varname>GroupPolicyExtension=</varname></term>
 633       <listitem>
 634         <para>A boolean. When true, it enables Group Policy VXLAN extension security label mechanism
 635         across network peers based on VXLAN. For details about the Group Policy VXLAN, see the
 636         <ulink url="https://tools.ietf.org/html/draft-smith-vxlan-group-policy">
 637         VXLAN Group Policy </ulink> document. Defaults to false.</para>
 638       </listitem>
 639     </varlistentry>
 640     <varlistentry>
 641       <term><varname>DestinationPort=</varname></term>
 642       <listitem>
 643         <para>Configures the default destination UDP port on a per-device basis.
 644         If destination port is not specified then Linux kernel default will be used.
 645         Set destination port 4789 to get the IANA assigned value. If not set or if the
 646         destination port is assigned the empty string the default port of 4789 is used.</para>
 647       </listitem>
 648     </varlistentry>
 649     <varlistentry>
 650       <term><varname>PortRange=</varname></term>
 651         <listitem>
 652           <para>Configures VXLAN port range. VXLAN bases source
 653           UDP port based on flow to help the receiver to be able
 654           to load balance based on outer header flow. It
 655           restricts the port range to the normal UDP local
 656           ports, and allows overriding via configuration.</para>
 657         </listitem>
 658       </varlistentry>
 659     <varlistentry>
 660       <term><varname>FlowLabel=</varname></term>
 661         <listitem>
 662           <para>Specifies the flow label to use in outgoing packets.
 663           The valid range is 0-1048575.
 664           </para>
 665         </listitem>
 666       </varlistentry>
 667     </variablelist>
 668   </refsect1>
 669   <refsect1>
 670     <title>[GENEVE] Section Options</title>
 671     <para>The <literal>[GENEVE]</literal> section only applies for
 672     netdevs of kind <literal>geneve</literal>, and accepts the
 673     following keys:</para>
 674
 675     <variablelist class='network-directives'>
 676       <varlistentry>
 677         <term><varname>Id=</varname></term>
 678         <listitem>
 679           <para>Specifies the Virtual Network Identifier (VNI) to use. Ranges [0-16777215].</para>
 680         </listitem>
 681       </varlistentry>
 682       <varlistentry>
 683         <term><varname>Remote=</varname></term>
 684         <listitem>
 685           <para>Specifies the unicast destination IP address to use in outgoing packets.</para>
 686         </listitem>
 687       </varlistentry>
 688       <varlistentry>
 689         <term><varname>TOS=</varname></term>
 690         <listitem>
 691           <para>Specifies the TOS value to use in outgoing packets. Ranges [1-255].</para>
 692         </listitem>
 693       </varlistentry>
 694       <varlistentry>
 695         <term><varname>TTL=</varname></term>
 696         <listitem>
 697           <para>Specifies the TTL value to use in outgoing packets. Ranges [1-255].</para>
 698         </listitem>
 699       </varlistentry>
 700       <varlistentry>
 701         <term><varname>UDPChecksum=</varname></term>
 702         <listitem>
 703           <para>A boolean. When true, specifies if UDP checksum is calculated for transmitted packets over IPv4.</para>
 704         </listitem>
 705       </varlistentry>
 706       <varlistentry>
 707         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 708         <listitem>
 709           <para>A boolean. When true, skip UDP checksum calculation for transmitted packets over IPv6.</para>
 710         </listitem>
 711       </varlistentry>
 712       <varlistentry>
 713         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 714         <listitem>
 715           <para>A boolean. When true, allows incoming UDP packets over IPv6 with zero checksum field.</para>
 716         </listitem>
 717       </varlistentry>
 718     <varlistentry>
 719       <term><varname>DestinationPort=</varname></term>
 720       <listitem>
 721         <para>Specifies destination port. Defaults to 6081. If not set or assigned the empty string, the default
 722         port of 6081 is used.</para>
 723       </listitem>
 724     </varlistentry>
 725     <varlistentry>
 726       <term><varname>FlowLabel=</varname></term>
 727         <listitem>
 728           <para>Specifies the flow label to use in outgoing packets.</para>
 729         </listitem>
 730       </varlistentry>
 731     </variablelist>
 732   </refsect1>
 733   <refsect1>
 734     <title>[Tunnel] Section Options</title>
 735
 736     <para>The <literal>[Tunnel]</literal> section only applies for
 737     netdevs of kind
 738     <literal>ipip</literal>,
 739     <literal>sit</literal>,
 740     <literal>gre</literal>,
 741     <literal>gretap</literal>,
 742     <literal>ip6gre</literal>,
 743     <literal>ip6gretap</literal>,
 744     <literal>vti</literal>,
 745     <literal>vti6</literal>, and
 746     <literal>ip6tnl</literal> and accepts
 747     the following keys:</para>
 748
 749     <variablelist class='network-directives'>
 750       <varlistentry>
 751         <term><varname>Local=</varname></term>
 752         <listitem>
 753           <para>A static local address for tunneled packets. It must
 754           be an address on another interface of this host.</para>
 755         </listitem>
 756       </varlistentry>
 757       <varlistentry>
 758         <term><varname>Remote=</varname></term>
 759         <listitem>
 760           <para>The remote endpoint of the tunnel.</para>
 761         </listitem>
 762       </varlistentry>
 763       <varlistentry>
 764         <term><varname>TOS=</varname></term>
 765         <listitem>
 766           <para>The Type Of Service byte value for a tunnel interface.
 767           For details about the TOS, see the
 768           <ulink url="http://tools.ietf.org/html/rfc1349"> Type of
 769           Service in the Internet Protocol Suite </ulink> document.
 770           </para>
 771         </listitem>
 772       </varlistentry>
 773       <varlistentry>
 774         <term><varname>TTL=</varname></term>
 775         <listitem>
 776           <para>A fixed Time To Live N on tunneled packets. N is a
 777           number in the range 1–255. 0 is a special value meaning that
 778           packets inherit the TTL value. The default value for IPv4
 779           tunnels is: inherit. The default value for IPv6 tunnels is
 780           64.</para>
 781         </listitem>
 782       </varlistentry>
 783       <varlistentry>
 784         <term><varname>DiscoverPathMTU=</varname></term>
 785         <listitem>
 786           <para>A boolean. When true, enables Path MTU Discovery on
 787           the tunnel.</para>
 788         </listitem>
 789       </varlistentry>
 790       <varlistentry>
 791         <term><varname>IPv6FlowLabel=</varname></term>
 792         <listitem>
 793           <para>Configures the 20-bit flow label (see <ulink url="https://tools.ietf.org/html/rfc6437">
 794           RFC 6437</ulink>) field in the IPv6 header (see <ulink url="https://tools.ietf.org/html/rfc2460">
 795           RFC 2460</ulink>), which is used by a node to label packets of a flow.
 796           It is only used for IPv6 tunnels.
 797           A flow label of zero is used to indicate packets that have
 798           not been labeled.
 799           It can be configured to a value in the range 0–0xFFFFF, or be
 800           set to <literal>inherit</literal>, in which case the original flowlabel is used.</para>
 801         </listitem>
 802       </varlistentry>
 803       <varlistentry>
 804         <term><varname>CopyDSCP=</varname></term>
 805         <listitem>
 806           <para>A boolean. When true, the Differentiated Service Code
 807           Point (DSCP) field will be copied to the inner header from
 808           outer header during the decapsulation of an IPv6 tunnel
 809           packet. DSCP is a field in an IP packet that enables different
 810           levels of service to be assigned to network traffic.
 811           Defaults to <literal>no</literal>.
 812           </para>
 813         </listitem>
 814       </varlistentry>
 815       <varlistentry>
 816         <term><varname>EncapsulationLimit=</varname></term>
 817         <listitem>
 818           <para>The Tunnel Encapsulation Limit option specifies how many additional
 819           levels of encapsulation are permitted to be prepended to the packet.
 820           For example, a Tunnel Encapsulation Limit option containing a limit
 821           value of zero means that a packet carrying that option may not enter
 822           another tunnel before exiting the current tunnel.
 823           (see <ulink url="https://tools.ietf.org/html/rfc2473#section-4.1.1"> RFC 2473</ulink>).
 824           The valid range is 0–255 and <literal>none</literal>. Defaults to 4.
 825         </para>
 826         </listitem>
 827       </varlistentry>
 828       <varlistentry>
 829         <term><varname>Key=</varname></term>
 830         <listitem>
 831           <para>The <varname>Key=</varname> parameter specifies the same key to use in
 832           both directions (<varname>InputKey=</varname> and <varname>OutputKey=</varname>).
 833           The <varname>Key=</varname> is either a number or an IPv4 address-like dotted quad.
 834           It is used as mark-configured SAD/SPD entry as part of the lookup key (both in data
 835           and control path) in ip xfrm (framework used to implement IPsec protocol).
 836           See <ulink url="http://man7.org/linux/man-pages/man8/ip-xfrm.8.html">
 837           ip-xfrm — transform configuration</ulink> for details. It is only used for VTI/VTI6
 838           tunnels.</para>
 839         </listitem>
 840       </varlistentry>
 841       <varlistentry>
 842         <term><varname>InputKey=</varname></term>
 843         <listitem>
 844           <para>The <varname>InputKey=</varname> parameter specifies the key to use for input.
 845           The format is same as <varname>Key=</varname>. It is only used for VTI/VTI6 tunnels.</para>
 846         </listitem>
 847       </varlistentry>
 848       <varlistentry>
 849         <term><varname>OutputKey=</varname></term>
 850         <listitem>
 851           <para>The <varname>OutputKey=</varname> parameter specifies the key to use for output.
 852           The format is same as <varname>Key=</varname>. It is only used for VTI/VTI6 tunnels.</para>
 853         </listitem>
 854       </varlistentry>
 855       <varlistentry>
 856         <term><varname>Mode=</varname></term>
 857         <listitem>
 858           <para>An <literal>ip6tnl</literal> tunnel can be in one of three
 859           modes
 860           <literal>ip6ip6</literal> for IPv6 over IPv6,
 861           <literal>ipip6</literal> for IPv4 over IPv6 or
 862           <literal>any</literal> for either.
 863           </para>
 864         </listitem>
 865       </varlistentry>
 866       <varlistentry>
 867         <term><varname>Independent=</varname></term>
 868         <listitem>
 869           <para>A boolean. When true tunnel does not require .network file. Created as "tunnel@NONE".
 870           Defaults to <literal>false</literal>.
 871           </para>
 872         </listitem>
 873       </varlistentry>
 874     </variablelist>
 875   </refsect1>
 876   <refsect1>
 877     <title>[Peer] Section Options</title>
 878
 879       <para>The <literal>[Peer]</literal> section only applies for
 880       netdevs of kind <literal>veth</literal> and accepts the
 881       following keys:</para>
 882
 883       <variablelist class='network-directives'>
 884         <varlistentry>
 885           <term><varname>Name=</varname></term>
 886           <listitem>
 887             <para>The interface name used when creating the netdev.
 888             This option is compulsory.</para>
 889           </listitem>
 890         </varlistentry>
 891         <varlistentry>
 892           <term><varname>MACAddress=</varname></term>
 893           <listitem>
 894             <para>The peer MACAddress, if not set, it is generated in
 895             the same way as the MAC address of the main
 896             interface.</para>
 897           </listitem>
 898         </varlistentry>
 899       </variablelist>
 900   </refsect1>
 901   <refsect1>
 902   <title>[VXCAN] Section Options</title>
 903       <para>The <literal>[VXCAN]</literal> section only applies for
 904       netdevs of kind <literal>vxcan</literal> and accepts the
 905       following key:</para>
 906
 907       <variablelist class='network-directives'>
 908         <varlistentry>
 909           <term><varname>Peer=</varname></term>
 910           <listitem>
 911             <para>The peer interface name used when creating the netdev.
 912             This option is compulsory.</para>
 913           </listitem>
 914         </varlistentry>
 915       </variablelist>
 916   </refsect1>
 917   <refsect1>
 918     <title>[Tun] Section Options</title>
 919
 920     <para>The <literal>[Tun]</literal> section only applies for
 921     netdevs of kind <literal>tun</literal>, and accepts the following
 922     keys:</para>
 923
 924     <variablelist class='network-directives'>
 925       <varlistentry>
 926         <term><varname>OneQueue=</varname></term>
 927         <listitem><para>Takes a boolean argument. Configures whether
 928         all packets are queued at the device (enabled), or a fixed
 929         number of packets are queued at the device and the rest at the
 930         <literal>qdisc</literal>. Defaults to
 931         <literal>no</literal>.</para>
 932         </listitem>
 933       </varlistentry>
 934       <varlistentry>
 935         <term><varname>MultiQueue=</varname></term>
 936         <listitem><para>Takes a boolean argument. Configures whether
 937         to use multiple file descriptors (queues) to parallelize
 938         packets sending and receiving. Defaults to
 939         <literal>no</literal>.</para>
 940         </listitem>
 941       </varlistentry>
 942       <varlistentry>
 943         <term><varname>PacketInfo=</varname></term>
 944         <listitem><para>Takes a boolean argument. Configures whether
 945         packets should be prepended with four extra bytes (two flag
 946         bytes and two protocol bytes). If disabled, it indicates that
 947         the packets will be pure IP packets. Defaults to
 948         <literal>no</literal>.</para>
 949         </listitem>
 950       </varlistentry>
 951       <varlistentry>
 952         <term><varname>VNetHeader=</varname></term>
 953         <listitem><para>Takes a boolean argument. Configures
 954         IFF_VNET_HDR flag for a tap device. It allows sending
 955         and receiving larger Generic Segmentation Offload (GSO)
 956         packets. This may increase throughput significantly.
 957         Defaults to
 958         <literal>no</literal>.</para>
 959         </listitem>
 960       </varlistentry>
 961       <varlistentry>
 962         <term><varname>User=</varname></term>
 963         <listitem><para>User to grant access to the
 964         <filename>/dev/net/tun</filename> device.</para>
 965         </listitem>
 966       </varlistentry>
 967       <varlistentry>
 968         <term><varname>Group=</varname></term>
 969         <listitem><para>Group to grant access to the
 970         <filename>/dev/net/tun</filename> device.</para>
 971         </listitem>
 972       </varlistentry>
 973
 974     </variablelist>
 975
 976   </refsect1>
 977
 978   <refsect1>
 979     <title>[Tap] Section Options</title>
 980
 981     <para>The <literal>[Tap]</literal> section only applies for
 982     netdevs of kind <literal>tap</literal>, and accepts the same keys
 983     as the <literal>[Tun]</literal> section.</para>
 984   </refsect1>
 985
 986   <refsect1>
 987     <title>[Bond] Section Options</title>
 988
 989     <para>The <literal>[Bond]</literal> section accepts the following
 990     key:</para>
 991
 992     <variablelist class='network-directives'>
 993       <varlistentry>
 994         <term><varname>Mode=</varname></term>
 995         <listitem>
 996           <para>Specifies one of the bonding policies. The default is
 997           <literal>balance-rr</literal> (round robin). Possible values are
 998           <literal>balance-rr</literal>,
 999           <literal>active-backup</literal>,
1000           <literal>balance-xor</literal>,
1001           <literal>broadcast</literal>,
1002           <literal>802.3ad</literal>,
1003           <literal>balance-tlb</literal>, and
1004           <literal>balance-alb</literal>.
1005           </para>
1006         </listitem>
1007       </varlistentry>
1008
1009       <varlistentry>
1010         <term><varname>TransmitHashPolicy=</varname></term>
1011         <listitem>
1012           <para>Selects the transmit hash policy to use for slave
1013           selection in balance-xor, 802.3ad, and tlb modes. Possible
1014           values are
1015           <literal>layer2</literal>,
1016           <literal>layer3+4</literal>,
1017           <literal>layer2+3</literal>,
1018           <literal>encap2+3</literal>, and
1019           <literal>encap3+4</literal>.
1020           </para>
1021         </listitem>
1022       </varlistentry>
1023
1024       <varlistentry>
1025         <term><varname>LACPTransmitRate=</varname></term>
1026         <listitem>
1027           <para>Specifies the rate with which link partner transmits
1028           Link Aggregation Control Protocol Data Unit packets in
1029           802.3ad mode. Possible values are <literal>slow</literal>,
1030           which requests partner to transmit LACPDUs every 30 seconds,
1031           and <literal>fast</literal>, which requests partner to
1032           transmit LACPDUs every second. The default value is
1033           <literal>slow</literal>.</para>
1034         </listitem>
1035       </varlistentry>
1036
1037       <varlistentry>
1038         <term><varname>MIIMonitorSec=</varname></term>
1039         <listitem>
1040           <para>Specifies the frequency that Media Independent
1041           Interface link monitoring will occur. A value of zero
1042           disables MII link monitoring. This value is rounded down to
1043           the nearest millisecond. The default value is 0.</para>
1044         </listitem>
1045       </varlistentry>
1046
1047       <varlistentry>
1048         <term><varname>UpDelaySec=</varname></term>
1049         <listitem>
1050           <para>Specifies the delay before a link is enabled after a
1051           link up status has been detected. This value is rounded down
1052           to a multiple of MIIMonitorSec. The default value is
1053           0.</para>
1054         </listitem>
1055       </varlistentry>
1056
1057       <varlistentry>
1058         <term><varname>DownDelaySec=</varname></term>
1059         <listitem>
1060           <para>Specifies the delay before a link is disabled after a
1061           link down status has been detected. This value is rounded
1062           down to a multiple of MIIMonitorSec. The default value is
1063           0.</para>
1064         </listitem>
1065       </varlistentry>
1066
1067       <varlistentry>
1068         <term><varname>LearnPacketIntervalSec=</varname></term>
1069         <listitem>
1070           <para>Specifies the number of seconds between instances where the bonding
1071           driver sends learning packets to each slave peer switch.
1072           The valid range is 1–0x7fffffff; the default value is 1. This option
1073           has an effect only for the balance-tlb and balance-alb modes.</para>
1074         </listitem>
1075       </varlistentry>
1076
1077       <varlistentry>
1078         <term><varname>AdSelect=</varname></term>
1079         <listitem>
1080           <para>Specifies the 802.3ad aggregation selection logic to use. Possible values are
1081           <literal>stable</literal>,
1082           <literal>bandwidth</literal> and
1083           <literal>count</literal>.
1084           </para>
1085         </listitem>
1086       </varlistentry>
1087
1088       <varlistentry>
1089         <term><varname>FailOverMACPolicy=</varname></term>
1090         <listitem>
1091           <para>Specifies whether the active-backup mode should set all slaves to
1092           the same MAC address at the time of enslavement or, when enabled, to perform special handling of the
1093           bond's MAC address in accordance with the selected policy. The default policy is none.
1094           Possible values are
1095           <literal>none</literal>,
1096           <literal>active</literal> and
1097           <literal>follow</literal>.
1098           </para>
1099         </listitem>
1100       </varlistentry>
1101
1102       <varlistentry>
1103         <term><varname>ARPValidate=</varname></term>
1104         <listitem>
1105           <para>Specifies whether or not ARP probes and replies should be
1106           validated in any mode that supports ARP monitoring, or whether
1107           non-ARP traffic should be filtered (disregarded) for link
1108           monitoring purposes. Possible values are
1109           <literal>none</literal>,
1110           <literal>active</literal>,
1111           <literal>backup</literal> and
1112           <literal>all</literal>.
1113           </para>
1114         </listitem>
1115       </varlistentry>
1116
1117       <varlistentry>
1118         <term><varname>ARPIntervalSec=</varname></term>
1119         <listitem>
1120           <para>Specifies the ARP link monitoring frequency in milliseconds.
1121           A value of 0 disables ARP monitoring. The default value is 0.
1122           </para>
1123         </listitem>
1124       </varlistentry>
1125
1126       <varlistentry>
1127         <term><varname>ARPIPTargets=</varname></term>
1128         <listitem>
1129           <para>Specifies the IP addresses to use as ARP monitoring peers when
1130           ARPIntervalSec is greater than 0. These are the targets of the ARP request
1131           sent to determine the health of the link to the targets.
1132           Specify these values in IPv4 dotted decimal format. At least one IP
1133           address must be given for ARP monitoring to function. The
1134           maximum number of targets that can be specified is 16. The
1135           default value is no IP addresses.
1136           </para>
1137         </listitem>
1138       </varlistentry>
1139
1140       <varlistentry>
1141         <term><varname>ARPAllTargets=</varname></term>
1142         <listitem>
1143           <para>Specifies the quantity of ARPIPTargets that must be reachable
1144           in order for the ARP monitor to consider a slave as being up.
1145           This option affects only active-backup mode for slaves with
1146           ARPValidate enabled. Possible values are
1147           <literal>any</literal> and
1148           <literal>all</literal>.
1149           </para>
1150         </listitem>
1151       </varlistentry>
1152
1153       <varlistentry>
1154         <term><varname>PrimaryReselectPolicy=</varname></term>
1155         <listitem>
1156           <para>Specifies the reselection policy for the primary slave.  This
1157           affects how the primary slave is chosen to become the active slave
1158           when failure of the active slave or recovery of the primary slave
1159           occurs. This option is designed to prevent flip-flopping between
1160           the primary slave and other slaves.  Possible values are
1161           <literal>always</literal>,
1162           <literal>better</literal> and
1163           <literal>failure</literal>.
1164           </para>
1165         </listitem>
1166       </varlistentry>
1167
1168       <varlistentry>
1169         <term><varname>ResendIGMP=</varname></term>
1170         <listitem>
1171           <para>Specifies the number of IGMP membership reports to be issued after
1172           a failover event. One membership report is issued immediately after
1173           the failover, subsequent packets are sent in each 200ms interval.
1174           The valid range is 0–255. Defaults to 1. A value of 0
1175           prevents the IGMP membership report from being issued in response
1176           to the failover event.
1177           </para>
1178         </listitem>
1179       </varlistentry>
1180
1181       <varlistentry>
1182         <term><varname>PacketsPerSlave=</varname></term>
1183         <listitem>
1184           <para>Specify the number of packets to transmit through a slave before
1185             moving to the next one. When set to 0, then a slave is chosen at
1186             random. The valid range is 0–65535. Defaults to 1. This option
1187             only has effect when in balance-rr mode.
1188           </para>
1189         </listitem>
1190       </varlistentry>
1191
1192       <varlistentry>
1193         <term><varname>GratuitousARP=</varname></term>
1194         <listitem>
1195           <para>Specify the number of peer notifications (gratuitous ARPs and
1196             unsolicited IPv6 Neighbor Advertisements) to be issued after a
1197             failover event.  As soon as the link is up on the new slave,
1198             a peer notification is sent on the  bonding device and each
1199             VLAN sub-device.  This is repeated at each link monitor interval
1200             (ARPIntervalSec or MIIMonitorSec, whichever is active) if the number is
1201             greater than 1. The valid range is 0–255. The default value is 1.
1202             These options affect only the active-backup mode.
1203           </para>
1204         </listitem>
1205       </varlistentry>
1206
1207       <varlistentry>
1208         <term><varname>AllSlavesActive=</varname></term>
1209         <listitem>
1210           <para>A boolean. Specifies that duplicate frames (received on inactive ports)
1211           should be dropped when false, or delivered when true. Normally, bonding will drop
1212           duplicate frames (received on inactive ports), which is desirable for
1213           most users. But there are some times it is nice to allow duplicate
1214           frames to be delivered. The default value is false (drop duplicate frames
1215           received on inactive ports).
1216           </para>
1217         </listitem>
1218       </varlistentry>
1219
1220       <varlistentry>
1221         <term><varname>MinLinks=</varname></term>
1222         <listitem>
1223           <para>Specifies the minimum number of links that must be active before
1224           asserting carrier. The default value is 0.
1225           </para>
1226         </listitem>
1227       </varlistentry>
1228     </variablelist>
1229
1230     <para>For more detail information see
1231     <ulink url="https://www.kernel.org/doc/Documentation/networking/bonding.txt">
1232     Linux Ethernet Bonding Driver HOWTO</ulink></para>
1233
1234   </refsect1>
1235
1236   <refsect1>
1237     <title>Example</title>
1238     <example>
1239       <title>/etc/systemd/network/25-bridge.netdev</title>
1240
1241       <programlisting>[NetDev]
1242 Name=bridge0
1243 Kind=bridge</programlisting>
1244     </example>
1245
1246     <example>
1247       <title>/etc/systemd/network/25-vlan1.netdev</title>
1248
1249       <programlisting>[Match]
1250 Virtualization=no
1251
1252 [NetDev]
1253 Name=vlan1
1254 Kind=vlan
1255
1256 [VLAN]
1257 Id=1</programlisting>
1258     </example>
1259     <example>
1260       <title>/etc/systemd/network/25-ipip.netdev</title>
1261       <programlisting>[NetDev]
1262 Name=ipip-tun
1263 Kind=ipip
1264 MTUBytes=1480
1265
1266 [Tunnel]
1267 Local=192.168.223.238
1268 Remote=192.169.224.239
1269 TTL=64</programlisting>
1270     </example>
1271     <example>
1272       <title>/etc/systemd/network/25-tap.netdev</title>
1273       <programlisting>[NetDev]
1274 Name=tap-test
1275 Kind=tap
1276
1277 [Tap]
1278 MultiQueue=true
1279 PacketInfo=true</programlisting> </example>
1280
1281     <example>
1282       <title>/etc/systemd/network/25-sit.netdev</title>
1283       <programlisting>[NetDev]
1284 Name=sit-tun
1285 Kind=sit
1286 MTUBytes=1480
1287
1288 [Tunnel]
1289 Local=10.65.223.238
1290 Remote=10.65.223.239</programlisting>
1291     </example>
1292
1293     <example>
1294       <title>/etc/systemd/network/25-gre.netdev</title>
1295       <programlisting>[NetDev]
1296 Name=gre-tun
1297 Kind=gre
1298 MTUBytes=1480
1299
1300 [Tunnel]
1301 Local=10.65.223.238
1302 Remote=10.65.223.239</programlisting>
1303     </example>
1304
1305     <example>
1306       <title>/etc/systemd/network/25-vti.netdev</title>
1307
1308       <programlisting>[NetDev]
1309 Name=vti-tun
1310 Kind=vti
1311 MTUBytes=1480
1312
1313 [Tunnel]
1314 Local=10.65.223.238
1315 Remote=10.65.223.239</programlisting>
1316     </example>
1317
1318     <example>
1319       <title>/etc/systemd/network/25-veth.netdev</title>
1320       <programlisting>[NetDev]
1321 Name=veth-test
1322 Kind=veth
1323
1324 [Peer]
1325 Name=veth-peer</programlisting>
1326     </example>
1327
1328     <example>
1329       <title>/etc/systemd/network/25-bond.netdev</title>
1330       <programlisting>[NetDev]
1331 Name=bond1
1332 Kind=bond
1333
1334 [Bond]
1335 Mode=802.3ad
1336 TransmitHashPolicy=layer3+4
1337 MIIMonitorSec=1s
1338 LACPTransmitRate=fast
1339 </programlisting>
1340     </example>
1341
1342     <example>
1343       <title>/etc/systemd/network/25-dummy.netdev</title>
1344       <programlisting>[NetDev]
1345 Name=dummy-test
1346 Kind=dummy
1347 MACAddress=12:34:56:78:9a:bc</programlisting>
1348     </example>
1349     <example>
1350       <title>/etc/systemd/network/25-vrf.netdev</title>
1351       <para>Create a VRF interface with table 42.</para>
1352       <programlisting>[NetDev]
1353 Name=vrf-test
1354 Kind=vrf
1355
1356 [VRF]
1357 Table=42</programlisting>
1358     </example>
1359
1360     <example>
1361       <title>/etc/systemd/network/25-macvtap.netdev</title>
1362       <para>Create a MacVTap device.</para>
1363       <programlisting>[NetDev]
1364 Name=macvtap-test
1365 Kind=macvtap
1366       </programlisting>
1367     </example>
1368   </refsect1>
1369   <refsect1>
1370     <title>See Also</title>
1371     <para>
1372       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1373       <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1374       <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1375       <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1376     </para>
1377   </refsect1>
1378
1379 </refentry>