man/systemd.net-naming-scheme.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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   5
   6 <refentry id="systemd.net-naming-scheme">
   7   <refentryinfo>
   8     <title>systemd.net-naming-scheme</title>
   9     <productname>systemd</productname>
  10   </refentryinfo>
  11
  12   <refmeta>
  13     <refentrytitle>systemd.net-naming-scheme</refentrytitle>
  14     <manvolnum>7</manvolnum>
  15   </refmeta>
  16
  17   <refnamediv>
  18     <refname>systemd.net-naming-scheme</refname>
  19     <refpurpose>Network device naming schemes</refpurpose>
  20   </refnamediv>
  21
  22   <refsect1>
  23     <title>Description</title>
  24
  25     <para>Network interfaces names and MAC addresses may be generated based on certain stable interface
  26     attributes. This is possible when there is enough information about the device to generate those
  27     attributes and the use of this information is configured. This page describes interface naming, i.e. what
  28     possible names may be generated. Those names are generated by the
  29     <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  30     builtin <command>net_id</command> and exported as udev properties
  31     (<varname>ID_NET_NAME_ONBOARD=</varname>, <varname>ID_NET_LABEL_ONBOARD=</varname>,
  32     <varname>ID_NET_NAME_PATH=</varname>, <varname>ID_NET_NAME_SLOT=</varname>).</para>
  33
  34     <para>Names and MAC addresses are derived from various stable device metadata attributes. Newer versions
  35     of udev take more of these attributes into account, improving (and thus possibly changing) the names and
  36     addresses used for the same devices. Different versions of those generation rules are called "naming
  37     schemes". The default naming scheme is chosen at compilation time. Usually this will be the latest
  38     implemented version, but it is also possible to set one of the older versions to preserve
  39     compatibility. This may be useful for example for distributions, which may introduce new versions of
  40     systemd in stable releases without changing the naming scheme. The naming scheme may also be overridden
  41     using the <varname>net.naming-scheme=</varname> kernel command line switch, see
  42     <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  43     Available naming schemes are described below.</para>
  44
  45     <para>After the udev properties have been generated, appropriate udev rules may be used to actually rename
  46     devices based on those properties. See the description of <varname>NamePolicy=</varname> and
  47     <varname>MACAddressPolicy=</varname> in
  48     <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  49
  50     <para>Note that while the concept of network interface naming schemes is primarily relevant in the
  51     context of <filename>systemd-udevd.service</filename>, the
  52     <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  53     container manager also takes it into account when naming network interfaces, see below.</para>
  54   </refsect1>
  55
  56   <refsect1>
  57     <title>Naming</title>
  58
  59     <para>All names start with a two-character prefix that signifies the interface type.</para>
  60
  61     <table>
  62       <title>Two character prefixes based on the type of interface</title>
  63
  64       <tgroup cols='2'>
  65         <thead>
  66           <row>
  67             <entry>Prefix</entry>
  68             <entry>Description</entry>
  69           </row>
  70         </thead>
  71         <tbody>
  72           <row>
  73             <entry><constant>en</constant></entry>
  74             <entry>Ethernet</entry>
  75           </row>
  76           <row>
  77             <entry><constant>ib</constant></entry>
  78             <entry>InfiniBand</entry>
  79           </row>
  80           <row>
  81             <entry><constant>sl</constant></entry>
  82             <entry>Serial line IP (slip)</entry>
  83           </row>
  84           <row>
  85             <entry><constant>wl</constant></entry>
  86             <entry>Wireless local area network (WLAN)</entry>
  87           </row>
  88           <row>
  89             <entry><constant>ww</constant></entry>
  90             <entry>Wireless wide area network (WWAN)</entry>
  91           </row>
  92         </tbody>
  93       </tgroup>
  94     </table>
  95
  96     <para>The udev <command>net_id</command> builtin exports the following udev device properties:</para>
  97
  98     <variablelist>
  99         <varlistentry>
 100           <term><varname>ID_NET_NAME_ONBOARD=<replaceable>prefix</replaceable><constant>o</constant><replaceable>number</replaceable></varname></term>
 101           <term><varname>ID_NET_NAME_ONBOARD=<replaceable>prefix</replaceable><constant>d</constant><replaceable>number</replaceable></varname></term>
 102
 103           <listitem><para>This name is set based on the numeric ordering information given by the firmware
 104           for on-board devices. Different schemes are used depending on the fiemware type, as described in the table below.</para>
 105
 106             <table>
 107               <title>Onboard naming schemes</title>
 108
 109               <tgroup cols='2'>
 110                 <thead>
 111                   <row>
 112                     <entry>Format</entry>
 113                     <entry>Description</entry>
 114                   </row>
 115                 </thead>
 116
 117                 <tbody>
 118                   <row>
 119                     <entry><replaceable>prefix</replaceable><constant>o</constant><replaceable>number</replaceable></entry>
 120                     <entry>PCI onboard index</entry>
 121                   </row>
 122
 123                   <row>
 124                     <entry><replaceable>prefix</replaceable><constant>d</constant><replaceable>number</replaceable></entry>
 125                     <entry>Devicetree alias index</entry>
 126                   </row>
 127
 128                 </tbody>
 129               </tgroup>
 130             </table>
 131           </listitem>
 132         </varlistentry>
 133
 134         <varlistentry>
 135           <term><varname>ID_NET_LABEL_ONBOARD=<replaceable>prefix</replaceable> <replaceable>label</replaceable></varname></term>
 136
 137           <listitem><para>This property is set based on textual label given by the firmware for on-board
 138           devices. The name consists of the prefix concatenated with the label. This is only available for
 139           PCI devices.
 140           </para>
 141           </listitem>
 142         </varlistentry>
 143
 144         <varlistentry>
 145           <term><varname>ID_NET_NAME_MAC=<replaceable>prefix</replaceable><constant>x</constant><replaceable>AABBCCDDEEFF</replaceable></varname></term>
 146
 147           <listitem><para>This name consists of the prefix, letter <constant>x</constant>, and 12 hexadecimal
 148           digits of the MAC address. It is available if the device has a fixed MAC address. Because this name
 149           is based on an attribute of the card itself, it remains "stable" when the device is moved (even
 150           between machines), but will change when the hardware is replaced.</para>
 151           </listitem>
 152         </varlistentry>
 153
 154         <varlistentry>
 155           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]</varname></term>
 156           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable><constant>v</constant><replaceable>slot</replaceable></varname></term>
 157           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable><constant>x</constant><replaceable>slot</replaceable></varname></term>
 158           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>b</constant><replaceable>number</replaceable></varname></term>
 159           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>u</constant><replaceable>port</replaceable>…[<constant>c</constant><replaceable>config</replaceable>][<constant>i</constant><replaceable>interface</replaceable>]</varname></term>
 160           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>v</constant><replaceable>slot</replaceable></varname></term>
 161
 162           <listitem><para>This property describes the slot position. Different schemes are used depending on
 163           the bus type, as described in the table below. In case of USB, BCMA, and SR-VIO devices, the full
 164           name consists of the prefix, PCI slot identifier, and USB or BCMA or SR-VIO slot identifier. The
 165           first two parts are denoted as "…" in the table below.</para>
 166
 167           <table>
 168             <title>Slot naming schemes</title>
 169
 170             <tgroup cols='2'>
 171               <thead>
 172                 <row>
 173                   <entry>Format</entry>
 174                   <entry>Description</entry>
 175                 </row>
 176               </thead>
 177
 178               <tbody>
 179                 <row>
 180                   <entry><replaceable>prefix</replaceable> [<constant>P</constant><replaceable>domain</replaceable>] <constant>s</constant><replaceable>slot</replaceable> [<constant>f</constant><replaceable>function</replaceable>] [<constant>n</constant><replaceable>port_name</replaceable> | <constant>d</constant><replaceable>dev_port</replaceable>]</entry>
 181                   <entry>PCI slot number</entry>
 182                 </row>
 183
 184                 <row>
 185                   <entry><replaceable>prefix</replaceable> <constant>v</constant><replaceable>slot</replaceable></entry>
 186                   <entry>VIO slot number (IBM PowerVM)</entry>
 187                 </row>
 188
 189                 <row>
 190                   <entry><replaceable>prefix</replaceable> <constant>X</constant><replaceable>number</replaceable></entry>
 191                   <entry>VIF interface number (Xen)</entry>
 192                 </row>
 193
 194                 <row>
 195                   <entry>… <constant>b</constant><replaceable>number</replaceable></entry>
 196                   <entry>Broadcom bus (BCMA) core number</entry>
 197                 </row>
 198
 199                 <row>
 200                   <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry>
 201                   <entry>USB port number chain</entry>
 202                 </row>
 203
 204                 <row>
 205                   <entry>… <constant>v</constant><replaceable>slot</replaceable></entry>
 206                   <entry>SR-VIO slot number</entry>
 207                 </row>
 208               </tbody>
 209             </tgroup>
 210           </table>
 211
 212           <para>The PCI domain is only prepended when it is not 0. All multi-function PCI devices will carry
 213           the <constant>f<replaceable>function</replaceable></constant> number in the device name, including
 214           the function 0 device. For non-multi-function devices, the number is suppressed if 0. The port name
 215           <replaceable>port_name</replaceable> is used, or the port number
 216           <constant>d</constant><replaceable>dev_port</replaceable> if the name is not known.</para>
 217
 218           <para>For BCMA devices, the core number is suppressed when 0.</para>
 219
 220           <para>For USB devices the full chain of port numbers of hubs is composed. If the name gets longer
 221           than the maximum number of 15 characters, the name is not exported. The usual USB configuration
 222           number 1 and interface number 0 values are suppressed.</para>
 223
 224           <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of
 225           <constant>v</constant> and the virtual device number, with any leading zeros removed. The bus
 226           number is ignored.</para>
 227
 228           <para>In some configurations a parent PCI bridge of a given network controller may be associated
 229           with a slot. In such case we don't generate this device property to avoid possible naming conflicts.</para>
 230           </listitem>
 231         </varlistentry>
 232
 233         <varlistentry>
 234           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>c</constant><replaceable>bus_id</replaceable></varname></term>
 235           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>a</constant><replaceable>vendor</replaceable><replaceable>model</replaceable><constant>i</constant><replaceable>instance</replaceable></varname></term>
 236           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>i</constant><replaceable>address</replaceable><constant>n</constant><replaceable>port_name</replaceable></varname></term>
 237           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]</varname></term>
 238           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>b</constant><replaceable>number</replaceable></varname></term>
 239           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>u</constant><replaceable>port</replaceable>…[<constant>c</constant><replaceable>config</replaceable>][<constant>i</constant><replaceable>interface</replaceable>]</varname></term>
 240
 241           <listitem><para>This property describes the device installation location. Different schemes are
 242           used depending on the bus type, as described in the table below. For BCMA and USB devices, PCI path
 243           information must known, and the full name consists of the prefix, PCI slot identifier, and USB or
 244           BCMA location. The first two parts are denoted as "…" in the table below.</para>
 245
 246           <table>
 247             <title>Path naming schemes</title>
 248
 249             <tgroup cols='2'>
 250               <thead>
 251                 <row>
 252                   <entry>Format</entry>
 253                   <entry>Description</entry>
 254                 </row>
 255               </thead>
 256
 257               <tbody>
 258                 <row>
 259                   <entry><replaceable>prefix</replaceable> <constant>c</constant><replaceable>bus_id</replaceable></entry>
 260                   <entry>CCW or grouped CCW device identifier</entry>
 261                 </row>
 262
 263                 <row>
 264                   <entry><replaceable>prefix</replaceable> <constant>a</constant><replaceable>vendor</replaceable> <replaceable>model</replaceable> <constant>i</constant><replaceable>instance</replaceable></entry>
 265                   <entry>ACPI path names for ARM64 platform devices</entry>
 266                 </row>
 267
 268                 <row>
 269                   <entry><replaceable>prefix</replaceable> <constant>i</constant><replaceable>address</replaceable> <constant>n</constant><replaceable>port_name</replaceable></entry>
 270                   <entry>Netdevsim (simulated networking device) device number and port name</entry>
 271                 </row>
 272
 273                 <row>
 274                   <entry><replaceable>prefix</replaceable> [<constant>P</constant><replaceable>domain</replaceable>] <constant>p</constant><replaceable>bus</replaceable> <constant>s</constant><replaceable>slot</replaceable> [<constant>f</constant><replaceable>function</replaceable>] [<constant>n</constant><replaceable>phys_port_name</replaceable> | <constant>d</constant><replaceable>dev_port</replaceable>]</entry>
 275                   <entry>PCI geographical location</entry>
 276                 </row>
 277
 278                 <row>
 279                   <entry>… <constant>b</constant><replaceable>number</replaceable></entry>
 280                   <entry>Broadcom bus (BCMA) core number</entry>
 281                 </row>
 282
 283                 <row>
 284                   <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry>
 285                   <entry>USB port number chain</entry>
 286                 </row>
 287
 288               </tbody>
 289             </tgroup>
 290           </table>
 291
 292           <para>CCW and grouped CCW devices are found in IBM System Z mainframes. Any leading zeros and
 293           dots are suppressed.</para>
 294
 295           <para>For PCI, BCMA, and USB devices, the same rules as described above for slot naming are
 296           used.</para>
 297           </listitem>
 298         </varlistentry>
 299     </variablelist>
 300   </refsect1>
 301
 302   <refsect1>
 303     <title>History</title>
 304
 305     <para>The following "naming schemes" have been defined (which may be chosen at system boot-up time via
 306     the <varname>net.naming-scheme=</varname> kernel command line switch, see above):</para>
 307
 308     <variablelist>
 309         <varlistentry>
 310           <term><constant>v238</constant></term>
 311
 312           <listitem><para>This is the naming scheme that was implemented in systemd 238.</para></listitem>
 313         </varlistentry>
 314
 315         <varlistentry>
 316           <term><constant>v239</constant></term>
 317
 318           <listitem><para>Naming was changed for virtual network interfaces created with SR-IOV and NPAR and
 319           for devices where the PCI network controller device does not have a slot number associated.</para>
 320
 321           <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of
 322           <literal>v<replaceable>port</replaceable></literal>, where <replaceable>port</replaceable> is the
 323           virtual device number. Previously those virtual devices were named as if completely independent.
 324           </para>
 325
 326           <para>The ninth and later NPAR virtual devices are named following the scheme used for the first
 327           eight NPAR partitions. Previously those devices were not renamed and the kernel default
 328           ("eth<replaceable>N</replaceable>") was used.</para>
 329
 330           <para>Names are also generated for PCI devices where the PCI network controller device does not
 331           have an associated slot number itself, but one of its parents does. Previously those devices were
 332           not renamed and the kernel default was used.</para>
 333           </listitem>
 334         </varlistentry>
 335
 336         <varlistentry>
 337           <term><constant>v240</constant></term>
 338
 339           <listitem><para>The <literal>ib</literal> prefix and stable names for infiniband devices are
 340           introduced. Previously those devices were not renamed.</para>
 341
 342           <para>The ACPI index field (used in <varname>ID_NET_NAME_ONBOARD=</varname>) is now also used when
 343           0.</para>
 344
 345           <para>A new naming policy <varname>NamePolicy=keep</varname> was introduced. With this policy, if
 346           the network device name was already set by userspace, the device will not be renamed
 347           again. Previously, this naming policy applied implicitly, and now it must be explicitly
 348           requested. Effectively, this means that network devices will be renamed according to the
 349           configuration, even if they have been renamed already, if <constant>keep</constant> is not
 350           specified as the naming policy in the <filename index="false">.link</filename> file. See
 351           <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 352           for a description of <varname>NamePolicy=</varname>.</para></listitem>
 353         </varlistentry>
 354
 355         <varlistentry>
 356           <term><constant>v241</constant></term>
 357
 358           <listitem><para><option>MACAddressPolicy=persistent</option> was extended to set MAC addresses
 359           based on the device name. Previously addresses were only based on the
 360           <varname index="false">ID_NET_NAME_*</varname> attributes, which meant that interface names would
 361           never be generated for virtual devices. Now a persistent address will be generated for most
 362           devices, including in particular bridges.</para>
 363
 364           <para>Note: when userspace does not set a MAC address for a bridge device, the kernel will
 365           initially assign a random address, and then change it when the first device is enslaved to the
 366           bridge. With this naming policy change, bridges get a persistent MAC address based on the bridge
 367           name instead of the first enslaved device.</para></listitem>
 368         </varlistentry>
 369
 370         <varlistentry>
 371           <term><constant>v243</constant></term>
 372
 373           <listitem><para>Support for renaming netdevsim (simulated networking) devices was added. Previously
 374           those devices were not renamed.</para>
 375
 376           <para>Previously two-letter interface type prefix was prepended to
 377           <varname>ID_NET_LABEL_ONBOARD=</varname>. This is not done anymore.</para></listitem>
 378         </varlistentry>
 379
 380         <varlistentry>
 381           <term><constant>v245</constant></term>
 382
 383           <listitem><para>When
 384           <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 385           derives the name for the host side of the network interface created with
 386           <option>--network-veth</option> from the container name it previously simply truncated the result
 387           at 15 characters if longer (since that's the maximum length for network interface names). From now
 388           on, for any interface name that would be longer than 15 characters the last 4 characters are set to
 389           a 24bit hash value of the full interface name. This way network interface name collisions between
 390           multiple similarly named containers (who only differ in container name suffix) should be less
 391           likely (but still possible, since the 24bit hash value is very small).</para></listitem>
 392         </varlistentry>
 393
 394         <varlistentry>
 395           <term><constant>v247</constant></term>
 396
 397           <listitem><para>When a PCI slot is associated with a PCI bridge that has multiple child network
 398           controllers, the same value of the <varname>ID_NET_NAME_SLOT</varname> property might be derived
 399           for those controllers. This would cause a naming conflict if the property is selected as the device
 400           name. Now, we detect this situation and don't produce the <varname>ID_NET_NAME_SLOT</varname>
 401           property.</para></listitem>
 402         </varlistentry>
 403
 404         <varlistentry>
 405           <term><constant>v249</constant></term>
 406
 407           <listitem><para>PCI hotplug slot names for the s390 PCI driver are a hexadecimal representation
 408           of the <filename>function_id</filename> device attribute. This attribute is now used to build the
 409           <varname>ID_NET_NAME_SLOT</varname>. Before that, all slot names were parsed as decimal
 410           numbers, which could either result in an incorrect value of the <varname>ID_NET_NAME_SLOT</varname>
 411           property or none at all.</para>
 412
 413           <para>Some firmware and hypervisor implementations report unreasonably high numbers for the onboard
 414           index. To prevent the generation of bogus onbard interface names, index numbers greater than 16381
 415           (2¹⁴-1) were ignored. For s390 PCI devices index values up to 65535 (2¹⁶-1) are valid. To account
 416           for that, the limit was increased to 65535.</para>
 417
 418           <para>The udev rule <varname>NAME=</varname> replaces <literal>:</literal>,
 419           <literal>/</literal>, and <literal>%</literal> with an underscore (<literal>_</literal>), and
 420           refuses strings which contain only numerics.</para>
 421           </listitem>
 422         </varlistentry>
 423
 424         <varlistentry>
 425           <term><constant>v250</constant></term>
 426
 427           <listitem><para>Added naming scheme for Xen netfront "vif" interfaces based on the guest side
 428           VIF number set from the Xen config (or the interface index in AWS EC2).</para>
 429           </listitem>
 430         </varlistentry>
 431
 432         <varlistentry>
 433           <term><constant>v251</constant></term>
 434
 435           <listitem><para>Since version <constant>v247</constant> we no longer set
 436           <varname>ID_NET_NAME_SLOT</varname> if we detect that a PCI device associated with a slot is a PCI
 437           bridge as that would create naming conflict when there are more child devices on that bridge. Now,
 438           this is relaxed and we will use slot information to generate the name based on it but only if
 439           the PCI device has multiple functions. This is safe because distinct function number is a part of
 440           the device name for multifunction devices.</para>
 441           </listitem>
 442         </varlistentry>
 443
 444         <varlistentry>
 445           <term><constant>v252</constant></term>
 446
 447           <listitem><para>Added naming scheme for platform devices with devicetree aliases.</para>
 448           </listitem>
 449         </varlistentry>
 450
 451       </variablelist>
 452
 453     <para>Note that <constant>latest</constant> may be used to denote the latest scheme known (to this
 454     particular version of systemd).</para>
 455   </refsect1>
 456
 457   <refsect1>
 458     <title>Examples</title>
 459
 460     <example>
 461       <title>Using <command>udevadm test-builtin</command> to display device properties</title>
 462
 463       <programlisting>$ udevadm test-builtin net_id /sys/class/net/enp0s31f6
 464 ...
 465 Using default interface naming scheme 'v243'.
 466 ID_NET_NAMING_SCHEME=v243
 467 ID_NET_NAME_MAC=enx54ee75cb1dc0
 468 ID_OUI_FROM_DATABASE=Wistron InfoComm(Kunshan)Co.,Ltd.
 469 ID_NET_NAME_PATH=enp0s31f6
 470 ...</programlisting>
 471     </example>
 472
 473     <example>
 474       <title>PCI Ethernet card with firmware index "1"</title>
 475
 476       <programlisting>ID_NET_NAME_ONBOARD=eno1
 477 ID_NET_NAME_ONBOARD_LABEL=Ethernet Port 1
 478       </programlisting>
 479     </example>
 480
 481     <example>
 482       <title>PCI Ethernet card in hotplug slot with firmware index number</title>
 483
 484       <programlisting># /sys/devices/pci0000:00/0000:00:1c.3/0000:05:00.0/net/ens1
 485 ID_NET_NAME_MAC=enx000000000466
 486 ID_NET_NAME_PATH=enp5s0
 487 ID_NET_NAME_SLOT=ens1</programlisting>
 488     </example>
 489
 490     <example>
 491       <title>PCI Ethernet multi-function card with 2 ports</title>
 492
 493       <programlisting># /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/enp2s0f0
 494 ID_NET_NAME_MAC=enx78e7d1ea46da
 495 ID_NET_NAME_PATH=enp2s0f0
 496
 497 # /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.1/net/enp2s0f1
 498 ID_NET_NAME_MAC=enx78e7d1ea46dc
 499 ID_NET_NAME_PATH=enp2s0f1</programlisting>
 500     </example>
 501
 502     <example>
 503       <title>PCI WLAN card</title>
 504
 505       <programlisting># /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/wlp3s0
 506 ID_NET_NAME_MAC=wlx0024d7e31130
 507 ID_NET_NAME_PATH=wlp3s0</programlisting>
 508     </example>
 509
 510     <example>
 511       <title>PCI IB host adapter with 2 ports</title>
 512
 513       <programlisting># /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.0/net/ibp21s0f0
 514 ID_NET_NAME_PATH=ibp21s0f0
 515
 516 # /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.1/net/ibp21s0f1
 517 ID_NET_NAME_PATH=ibp21s0f1</programlisting>
 518     </example>
 519
 520     <example>
 521       <title>USB built-in 3G modem</title>
 522
 523       <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.4/2-1.4:1.6/net/wwp0s29u1u4i6
 524 ID_NET_NAME_MAC=wwx028037ec0200
 525 ID_NET_NAME_PATH=wwp0s29u1u4i6</programlisting>
 526     </example>
 527
 528     <example>
 529       <title>USB Android phone</title>
 530
 531       <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/net/enp0s29u1u2
 532 ID_NET_NAME_MAC=enxd626b3450fb5
 533 ID_NET_NAME_PATH=enp0s29u1u2</programlisting>
 534     </example>
 535
 536     <example>
 537       <title>s390 grouped CCW interface</title>
 538
 539       <programlisting># /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0
 540 ID_NET_NAME_MAC=enx026d3c00000a
 541 ID_NET_NAME_PATH=encf5f0</programlisting>
 542     </example>
 543   </refsect1>
 544
 545   <refsect1>
 546     <title>See Also</title>
 547     <para>
 548       <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 549       <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 550       <ulink url="https://systemd.io/PREDICTABLE_INTERFACE_NAMES">Predictable Network Interface Names</ulink>,
 551       <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 552     </para>
 553   </refsect1>
 554
 555 </refentry>