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