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| <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
| "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
| <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
| |
| <refentry id="systemd.net-naming-scheme"> |
| <refentryinfo> |
| <title>systemd.net-naming-scheme</title> |
| <productname>systemd</productname> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle>systemd.net-naming-scheme</refentrytitle> |
| <manvolnum>7</manvolnum> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>systemd.net-naming-scheme</refname> |
| <refpurpose>Network device naming schemes</refpurpose> |
| </refnamediv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para>Network interfaces names and MAC addresses may be generated based on certain stable interface |
| attributes. This is possible when there is enough information about the device to generate those |
| attributes and the use of this information is configured. This page describes interface naming, i.e. what |
| possible names may be generated. Those names are generated by the |
| <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| builtin <command>net_id</command> and exported as udev properties |
| (<varname>ID_NET_NAME_ONBOARD=</varname>, <varname>ID_NET_LABEL_ONBOARD=</varname>, |
| <varname>ID_NET_NAME_PATH=</varname>, <varname>ID_NET_NAME_SLOT=</varname>).</para> |
| |
| <para>Names and MAC addresses are derived from various stable device metadata attributes. Newer versions |
| of udev take more of these attributes into account, improving (and thus possibly changing) the names and |
| addresses used for the same devices. Different versions of those generation rules are called "naming |
| schemes". The default naming scheme is chosen at compilation time. Usually this will be the latest |
| implemented version, but it is also possible to set one of the older versions to preserve |
| compatibility. This may be useful for example for distributions, which may introduce new versions of |
| systemd in stable releases without changing the naming scheme. The naming scheme may also be overridden |
| using the <varname>net.naming-scheme=</varname> kernel command line switch, see |
| <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. |
| Available naming schemes are described below.</para> |
| |
| <para>After the udev properties have been generated, appropriate udev rules may be used to actually rename |
| devices based on those properties. See the description of <varname>NamePolicy=</varname> and |
| <varname>MACAddressPolicy=</varname> in |
| <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Naming</title> |
| |
| <para>All names start with a two-character prefix that signifies the interface type.</para> |
| |
| <table> |
| <title>Two character prefixes based on the type of interface</title> |
| |
| <tgroup cols='2'> |
| <thead> |
| <row> |
| <entry>Prefix</entry> |
| <entry>Description</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry><constant>en</constant></entry> |
| <entry>Ethernet</entry> |
| </row> |
| <row> |
| <entry><constant>ib</constant></entry> |
| <entry>InfiniBand</entry> |
| </row> |
| <row> |
| <entry><constant>sl</constant></entry> |
| <entry>serial line IP (slip)</entry> |
| </row> |
| <row> |
| <entry><constant>wl</constant></entry> |
| <entry>Wireless local area network (WLAN)</entry> |
| </row> |
| <row> |
| <entry><constant>ww</constant></entry> |
| <entry>Wireless wide area network (WWAN)</entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </table> |
| |
| <para>The udev <command>net_id</command> builtin exports the following udev device properties:</para> |
| |
| <variablelist> |
| <varlistentry> |
| <term><varname>ID_NET_NAME_ONBOARD=<replaceable>prefix</replaceable><constant>o</constant><replaceable>number</replaceable></varname></term> |
| |
| <listitem><para>This name is set based on the ordering information given by the firmware for |
| on-board devices. The name consists of the prefix, letter <constant>o</constant>, and a number |
| specified by the firmware. This is only available for PCI devices.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>ID_NET_LABEL_ONBOARD=<replaceable>prefix</replaceable> <replaceable>label</replaceable></varname></term> |
| |
| <listitem><para>This property is set based on label given by the firmware for on-board devices. The |
| name consists of the prefix concatenated with the label. This is only available for PCI devices. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>ID_NET_NAME_MAC=<replaceable>prefix</replaceable><constant>x</constant><replaceable>AABBCCDDEEFF</replaceable></varname></term> |
| |
| <listitem><para>This name consists of the prefix, letter <constant>x</constant>, and 12 hexadecimal |
| digits of the MAC address. It is available if the device has a fixed MAC address. Because this name |
| is based on an attribute of the card itself, it remains "stable" when the device is moved (even |
| between machines), but will change when the hardware is replaced.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <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> |
| <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> |
| <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> |
| <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> |
| |
| <listitem><para>This property describes the slot position. Different schemes are used depending on |
| the bus type, as described in the table below. In all cases, PCI slot information must be known. In |
| case of USB, BCMA, and SR-VIO devices, the full name consists of the prefix, PCI slot identifier, |
| and USB or BCMA or SR-VIO slot identifier. The first two parts are denoted as "…" in the table |
| below.</para> |
| |
| <table> |
| <title>Slot naming schemes</title> |
| |
| <tgroup cols='2'> |
| <thead> |
| <row> |
| <entry>Format</entry> |
| <entry>Description</entry> |
| </row> |
| </thead> |
| |
| <tbody> |
| <row> |
| <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> |
| <entry>PCI slot number</entry> |
| </row> |
| |
| <row> |
| <entry>… <constant>b</constant><replaceable>number</replaceable></entry> |
| <entry>Broadcom bus (BCMA) core number</entry> |
| </row> |
| |
| <row> |
| <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry> |
| <entry>USB port number chain</entry> |
| </row> |
| |
| <row> |
| <entry>… <constant>v</constant><replaceable>slot</replaceable></entry> |
| <entry>SR-VIO slot number</entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </table> |
| |
| <para>The PCI domain is only prepended when it is not 0. All multi-function PCI devices will carry |
| the <constant>f<replaceable>function</replaceable></constant> number in the device name, including |
| the function 0 device. For non-multi-function devices, the number is suppressed if 0. The port name |
| <replaceable>port_name</replaceable> is used, or the port number |
| <constant>d</constant><replaceable>dev_port</replaceable> if the name is not known.</para> |
| |
| <para>For BCMA devices, the core number is suppressed when 0.</para> |
| |
| <para>For USB devices the full chain of port numbers of hubs is composed. If the name gets longer |
| than the maximum number of 15 characters, the name is not exported. The usual USB configuration |
| number 1 and interface number 0 values are suppressed.</para> |
| </listitem> |
| |
| <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of |
| <constant>v</constant> and the virtual device number, with any leading zeros removed. The bus |
| number is ignored. This device type is found in IBM PowerVMs.</para> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>c</constant><replaceable>bus_id</replaceable></varname></term> |
| <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> |
| <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>i</constant><replaceable>address</replaceable><constant>n</constant><replaceable>port_name</replaceable></varname></term> |
| <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> |
| <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> |
| <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> |
| |
| <listitem><para>This property describes the device installation location. Different schemes are |
| used depending on the bus type, as described in the table below. For BCMA and USB devices, PCI path |
| information must known, and the full name consists of the prefix, PCI slot identifier, and USB or |
| BCMA location. The first two parts are denoted as "…" in the table below.</para> |
| |
| <table> |
| <title>Path naming schemes</title> |
| |
| <tgroup cols='2'> |
| <thead> |
| <row> |
| <entry>Format</entry> |
| <entry>Description</entry> |
| </row> |
| </thead> |
| |
| <tbody> |
| <row> |
| <entry><replaceable>prefix</replaceable> <constant>c</constant><replaceable>bus_id</replaceable></entry> |
| <entry>CCW or grouped CCW device identifier</entry> |
| </row> |
| |
| <row> |
| <entry><replaceable>prefix</replaceable> <constant>a</constant><replaceable>vendor</replaceable> <replaceable>model</replaceable> <constant>i</constant><replaceable>instance</replaceable></entry> |
| <entry>ACPI path names for ARM64 platform devices</entry> |
| </row> |
| |
| <row> |
| <entry><replaceable>prefix</replaceable> <constant>i</constant><replaceable>address</replaceable> <constant>n</constant><replaceable>port_name</replaceable></entry> |
| <entry>Netdevsim (simulated networking device) device number and port name</entry> |
| </row> |
| |
| <row> |
| <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> |
| <entry>PCI geographical location</entry> |
| </row> |
| |
| <row> |
| <entry>… <constant>b</constant><replaceable>number</replaceable></entry> |
| <entry>Broadcom bus (BCMA) core number</entry> |
| </row> |
| |
| <row> |
| <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry> |
| <entry>USB port number chain</entry> |
| </row> |
| |
| </tbody> |
| </tgroup> |
| </table> |
| |
| <para>CCW and grouped CCW devices are found in IBM System Z mainframes. Any leading zeros and |
| dots are suppressed.</para> |
| |
| <para>For PCI, BCMA, and USB devices, the same rules as described above for slot naming are |
| used.</para> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| </refsect1> |
| |
| <refsect1> |
| <title>History</title> |
| |
| <para>The following "naming schemes" have been defined:</para> |
| |
| <variablelist> |
| <varlistentry> |
| <term><constant>v238</constant></term> |
| |
| <listitem><para>This is the naming naming that was implemented in systemd 238.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>v239</constant></term> |
| |
| <listitem><para>Naming was changed for virtual network interfaces created with SR-IOV and NPAR and |
| for devices where the PCI network controller device does not have a slot number associated.</para> |
| |
| <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of |
| <literal>v<replaceable>port</replaceable></literal>, where <replaceable>port</replaceable> is the |
| virtual device number. Previously those virtual devices were named as if completely independent. |
| </para> |
| |
| <para>The ninth and later NPAR virtual devices are named following the scheme used for the first |
| eight NPAR partitions. Previously those devices were not renamed and the kernel default |
| ("eth<replaceable>N</replaceable>") was used.</para> |
| |
| <para>Names are also generated for PCI devices where the PCI network controller device does not |
| have an associated slot number itself, but one of its parents does. Previously those devices were |
| not renamed and the kernel default was used.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>v240</constant></term> |
| |
| <listitem><para>The <literal>ib</literal> prefix and stable names for infiniband devices are |
| introduced. Previously those devices were not renamed.</para> |
| |
| <para>The ACPI index field (used in <varname>ID_NET_NAME_ONBOARD=</varname>) is now also used when |
| 0.</para> |
| |
| <para>A new naming policy <varname>NamePolicy=keep</varname> was introduced. With this policy, if |
| the network device name was already set by userspace, the device will not be renamed |
| again. Previously, this naming policy applied implicitly, and now it must be explicitly |
| requested. Effectively, this means that network devices will be renamed according to the |
| configuration, even if they have been renamed already, if <constant>keep</constant> is not |
| specified as the naming policy in the <filename index="false">.link</filename> file. See |
| <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| for a description of <varname>NamePolicy=</varname>.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>v241</constant></term> |
| |
| <listitem><para><option>MACAddressPolicy=persistent</option> was extended to set MAC addresses |
| based on the device name. Previously addresses were only based on the |
| <varname index="false">ID_NET_NAME_*</varname> attributes, which meant that interface names would |
| never be generated for virtual devices. Now a persistent address will be generated for most |
| devices, including in particular bridges.</para> |
| |
| <para>Note: when userspace does not set a MAC address for a bridge device, the kernel will |
| initially assign a random address, and then change it when the first device is enslaved to the |
| bridge. With this naming policy change, bridges get a persistent MAC address based on the bridge |
| name instead of the first enslaved device.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>v243</constant></term> |
| |
| <listitem><para>Support for renaming netdevsim (simulated networking) devices was added. Previously |
| those devices were not renamed.</para> |
| |
| <para>Previously two-letter interface type prefix was prepended to |
| <varname>ID_NET_LABEL_ONBOARD=</varname>. This is not done anymore.</para></listitem> |
| </varlistentry> |
| </variablelist> |
| |
| <para>Note that <constant>latest</constant> may be used to denote the latest scheme known (to this |
| particular version of systemd.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Examples</title> |
| |
| <example> |
| <title>Using <command>udevadm test-builtin</command> to display device properties</title> |
| |
| <programlisting>$ udevadm test-builtin net_id /sys/class/net/enp0s31f6 |
| ... |
| Using default interface naming scheme 'v243'. |
| ID_NET_NAMING_SCHEME=v243 |
| ID_NET_NAME_MAC=enx54ee75cb1dc0 |
| ID_OUI_FROM_DATABASE=Wistron InfoComm(Kunshan)Co.,Ltd. |
| ID_NET_NAME_PATH=enp0s31f6 |
| ...</programlisting> |
| </example> |
| |
| <example> |
| <title>PCI Ethernet card with firmware index "1"</title> |
| |
| <programlisting>ID_NET_NAME_ONBOARD=eno1 |
| ID_NET_NAME_ONBOARD_LABEL=Ethernet Port 1 |
| </programlisting> |
| </example> |
| |
| <example> |
| <title>PCI Ethernet card in hotplug slot with firmware index number</title> |
| |
| <programlisting># /sys/devices/pci0000:00/0000:00:1c.3/0000:05:00.0/net/ens1 |
| ID_NET_NAME_MAC=enx000000000466 |
| ID_NET_NAME_PATH=enp5s0 |
| ID_NET_NAME_SLOT=ens1</programlisting> |
| </example> |
| |
| <example> |
| <title>PCI Ethernet multi-function card with 2 ports</title> |
| |
| <programlisting># /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/enp2s0f0 |
| ID_NET_NAME_MAC=enx78e7d1ea46da |
| ID_NET_NAME_PATH=enp2s0f0 |
| |
| # /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.1/net/enp2s0f1 |
| ID_NET_NAME_MAC=enx78e7d1ea46dc |
| ID_NET_NAME_PATH=enp2s0f1</programlisting> |
| </example> |
| |
| <example> |
| <title>PCI WLAN card</title> |
| |
| <programlisting># /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/wlp3s0 |
| ID_NET_NAME_MAC=wlx0024d7e31130 |
| ID_NET_NAME_PATH=wlp3s0</programlisting> |
| </example> |
| |
| <example> |
| <title>PCI IB host adapter with 2 ports</title> |
| |
| <programlisting># /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.0/net/ibp21s0f0 |
| ID_NET_NAME_PATH=ibp21s0f0 |
| |
| # /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.1/net/ibp21s0f1 |
| ID_NET_NAME_PATH=ibp21s0f1</programlisting> |
| </example> |
| |
| <example> |
| <title>USB built-in 3G modem</title> |
| |
| <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.4/2-1.4:1.6/net/wwp0s29u1u4i6 |
| ID_NET_NAME_MAC=wwx028037ec0200 |
| ID_NET_NAME_PATH=wwp0s29u1u4i6</programlisting> |
| </example> |
| |
| <example> |
| <title>USB Android phone</title> |
| |
| <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/net/enp0s29u1u2 |
| ID_NET_NAME_MAC=enxd626b3450fb5 |
| ID_NET_NAME_PATH=enp0s29u1u2</programlisting> |
| </example> |
| |
| <example> |
| <title>s390 grouped CCW interface</title> |
| |
| <programlisting># /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0 |
| ID_NET_NAME_MAC=enx026d3c00000a |
| ID_NET_NAME_PATH=encf5f0</programlisting> |
| </example> |
| </refsect1> |
| |
| <refsect1> |
| <title>See Also</title> |
| <para> |
| <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <ulink url="https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames">the |
| original page describing stable interface names</ulink> |
| </para> |
| </refsect1> |
| |
| </refentry> |