1SYSTEMD.NET-NAMING-SCHEME(7)systemd.net-naming-schemSeYSTEMD.NET-NAMING-SCHEME(7)
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6 systemd.net-naming-scheme - Network device naming schemes
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9 Network interfaces names and MAC addresses may be generated based on
10 certain stable interface attributes. This is possible when there is
11 enough information about the device to generate those attributes and
12 the use of this information is configured. This page describes
13 interface naming, i.e. what possible names may be generated. Those
14 names are generated by the systemd-udevd.service(8) builtin net_id and
15 exported as udev properties (ID_NET_NAME_ONBOARD=,
16 ID_NET_LABEL_ONBOARD=, ID_NET_NAME_PATH=, ID_NET_NAME_SLOT=).
17 Names and MAC addresses are derived from various stable device metadata
19 attributes. Newer versions of udev take more of these attributes into
20 account, improving (and thus possibly changing) the names and addresses
21 used for the same devices. Different versions of those generation rules
22 are called "naming schemes". The default naming scheme is chosen at
23 compilation time. Usually this will be the latest implemented version,
24 but it is also possible to set one of the older versions to preserve
25 compatibility. This may be useful for example for distributions, which
26 may introduce new versions of systemd in stable releases without
27 changing the naming scheme. The naming scheme may also be overridden
28 using the net.naming-scheme= kernel command line switch, see systemd-
29 udevd.service(8). Available naming schemes are described below.
30 After the udev properties have been generated, appropriate udev rules
32 may be used to actually rename devices based on those properties. See
33 the description of NamePolicy= and MACAddressPolicy= in
34 systemd.link(5).
35
37 All names start with a two-character prefix that signifies the
38 interface type.
39 Table 1. Two character prefixes based on the type of interface
41 ┌───────┬────────────────────────────┐
42 │Prefix │ Description │
43 ├───────┼────────────────────────────┤
44 │en │ Ethernet │
45 ├───────┼────────────────────────────┤
46 │ib │ InfiniBand │
47 ├───────┼────────────────────────────┤
48 │sl │ serial line IP (slip) │
49 ├───────┼────────────────────────────┤
50 │wl │ Wireless local area │
51 │ │ network (WLAN) │
52 ├───────┼────────────────────────────┤
53 │ww │ Wireless wide area network │
54 │ │ (WWAN) │
55 └───────┴────────────────────────────┘
56 The udev net_id builtin exports the following udev device properties:
58 ID_NET_NAME_ONBOARD=prefixonumber
60 This name is set based on the ordering information given by the
61 firmware for on-board devices. The name consists of the prefix,
62 letter o, and a number specified by the firmware. This is only
63 available for PCI devices.
64 ID_NET_LABEL_ONBOARD=prefix label
66 This property is set based on label given by the firmware for
67 on-board devices. The name consists of the prefix concatenated with
68 the label. This is only available for PCI devices.
69 ID_NET_NAME_MAC=prefixxAABBCCDDEEFF
71 This name consists of the prefix, letter x, and 12 hexadecimal
72 digits of the MAC address. It is available if the device has a
73 fixed MAC address. Because this name is based on an attribute of
74 the card itself, it remains "stable" when the device is moved (even
75 between machines), but will change when the hardware is replaced.
76 ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port],
78 ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port]bnumber,
79 ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port]uport...[cconfig][iinterface],
80 ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port]vslot
81 This property describes the slot position. Different schemes are
82 used depending on the bus type, as described in the table below. In
83 all cases, PCI slot information must be known. In case of USB,
84 BCMA, and SR-VIO devices, the full name consists of the prefix, PCI
85 slot identifier, and USB or BCMA or SR-VIO slot identifier. The
86 first two parts are denoted as "..." in the table below.
87 Table 2. Slot naming schemes
89 ┌────────────────────────────────────────────────────────────┬──────────────────────────┐
90 │Format │ Description │
91 ├────────────────────────────────────────────────────────────┼──────────────────────────┤
92 │prefix [Pdomain] sslot [ffunction] [nport_name | ddev_port] │ PCI slot number │
93 ├────────────────────────────────────────────────────────────┼──────────────────────────┤
94 │... bnumber │ Broadcom bus (BCMA) core │
95 │ │ number │
96 ├────────────────────────────────────────────────────────────┼──────────────────────────┤
97 │... uport... [cconfig] [iinterface] │ USB port number chain │
98 ├────────────────────────────────────────────────────────────┼──────────────────────────┤
99 │... vslot │ SR-VIO slot number │
100 └────────────────────────────────────────────────────────────┴──────────────────────────┘
101 The PCI domain is only prepended when it is not 0. All
102 multi-function PCI devices will carry the ffunction number in the
103 device name, including the function 0 device. For
104 non-multi-function devices, the number is suppressed if 0. The port
105 name port_name is used, or the port number ddev_port if the name is
106 not known.
107 For BCMA devices, the core number is suppressed when 0.
109 For USB devices the full chain of port numbers of hubs is composed.
111 If the name gets longer than the maximum number of 15 characters,
112 the name is not exported. The usual USB configuration number 1 and
113 interface number 0 values are suppressed.
114 SR-IOV virtual devices are named based on the name of the parent
116 interface, with a suffix of v and the virtual device number, with
117 any leading zeros removed. The bus number is ignored. This device
118 type is found in IBM PowerVMs.
119 ID_NET_NAME_PATH=prefixcbus_id,
121 ID_NET_NAME_PATH=prefixavendormodeliinstance,
122 ID_NET_NAME_PATH=prefixiaddressnport_name,
123 ID_NET_NAME_PATH=prefix[Pdomain]pbussslot[ffunction][nphys_port_name|ddev_port],
124 ID_NET_NAME_PATH=prefix[Pdomain]pbussslot[ffunction][nphys_port_name|ddev_port]bnumber,
125 ID_NET_NAME_PATH=prefix[Pdomain]pbussslot[ffunction][nphys_port_name|ddev_port]uport...[cconfig][iinterface]
126 This property describes the device installation location. Different
127 schemes are used depending on the bus type, as described in the
128 table below. For BCMA and USB devices, PCI path information must
129 known, and the full name consists of the prefix, PCI slot
130 identifier, and USB or BCMA location. The first two parts are
131 denoted as "..." in the table below.
132 Table 3. Path naming schemes
134 ┌──────────────────────────────────────────────────────────────────────┬───────────────────────────┐
135 │Format │ Description │
136 ├──────────────────────────────────────────────────────────────────────┼───────────────────────────┤
137 │prefix cbus_id │ CCW or grouped CCW device │
138 │ │ identifier │
139 ├──────────────────────────────────────────────────────────────────────┼───────────────────────────┤
140 │prefix avendor model iinstance │ ACPI path names for ARM64 │
141 │ │ platform devices │
142 ├──────────────────────────────────────────────────────────────────────┼───────────────────────────┤
143 │prefix iaddress nport_name │ Netdevsim (simulated │
144 │ │ networking device) device │
145 │ │ number and port name │
146 ├──────────────────────────────────────────────────────────────────────┼───────────────────────────┤
147 │prefix [Pdomain] pbus sslot [ffunction] [nphys_port_name | ddev_port] │ PCI geographical location │
148 ├──────────────────────────────────────────────────────────────────────┼───────────────────────────┤
149 │... bnumber │ Broadcom bus (BCMA) core │
150 │ │ number │
151 ├──────────────────────────────────────────────────────────────────────┼───────────────────────────┤
152 │... uport... [cconfig] [iinterface] │ USB port number chain │
153 └──────────────────────────────────────────────────────────────────────┴───────────────────────────┘
154 CCW and grouped CCW devices are found in IBM System Z mainframes.
155 Any leading zeros and dots are suppressed.
156 For PCI, BCMA, and USB devices, the same rules as described above
158 for slot naming are used.
159
161 The following "naming schemes" have been defined:
162 v238
164 This is the naming scheme that was implemented in systemd 238.
165 v239
167 Naming was changed for virtual network interfaces created with
168 SR-IOV and NPAR and for devices where the PCI network controller
169 device does not have a slot number associated.
170 SR-IOV virtual devices are named based on the name of the parent
172 interface, with a suffix of "vport", where port is the virtual
173 device number. Previously those virtual devices were named as if
174 completely independent.
175 The ninth and later NPAR virtual devices are named following the
177 scheme used for the first eight NPAR partitions. Previously those
178 devices were not renamed and the kernel default ("ethN") was used.
179 Names are also generated for PCI devices where the PCI network
181 controller device does not have an associated slot number itself,
182 but one of its parents does. Previously those devices were not
183 renamed and the kernel default was used.
184 v240
186 The "ib" prefix and stable names for infiniband devices are
187 introduced. Previously those devices were not renamed.
188 The ACPI index field (used in ID_NET_NAME_ONBOARD=) is now also
190 used when 0.
191 A new naming policy NamePolicy=keep was introduced. With this
193 policy, if the network device name was already set by userspace,
194 the device will not be renamed again. Previously, this naming
195 policy applied implicitly, and now it must be explicitly requested.
196 Effectively, this means that network devices will be renamed
197 according to the configuration, even if they have been renamed
198 already, if keep is not specified as the naming policy in the .link
199 file. See systemd.link(5) for a description of NamePolicy=.
200 v241
202 MACAddressPolicy=persistent was extended to set MAC addresses based
203 on the device name. Previously addresses were only based on the
204 ID_NET_NAME_* attributes, which meant that interface names would
205 never be generated for virtual devices. Now a persistent address
206 will be generated for most devices, including in particular
207 bridges.
208 Note: when userspace does not set a MAC address for a bridge
210 device, the kernel will initially assign a random address, and then
211 change it when the first device is enslaved to the bridge. With
212 this naming policy change, bridges get a persistent MAC address
213 based on the bridge name instead of the first enslaved device.
214 v243
216 Support for renaming netdevsim (simulated networking) devices was
217 added. Previously those devices were not renamed.
218 Previously two-letter interface type prefix was prepended to
220 ID_NET_LABEL_ONBOARD=. This is not done anymore.
221 Note that latest may be used to denote the latest scheme known (to this
223 particular version of systemd.
224
226 Example 1. Using udevadm test-builtin to display device properties
227 $ udevadm test-builtin net_id /sys/class/net/enp0s31f6
229 ...
230 Using default interface naming scheme 'v243'.
231 ID_NET_NAMING_SCHEME=v243
232 ID_NET_NAME_MAC=enx54ee75cb1dc0
233 ID_OUI_FROM_DATABASE=Wistron InfoComm(Kunshan)Co.,Ltd.
234 ID_NET_NAME_PATH=enp0s31f6
235 ...
236 Example 2. PCI Ethernet card with firmware index "1"
238 ID_NET_NAME_ONBOARD=eno1
240 ID_NET_NAME_ONBOARD_LABEL=Ethernet Port 1
241 Example 3. PCI Ethernet card in hotplug slot with firmware index number
244 # /sys/devices/pci0000:00/0000:00:1c.3/0000:05:00.0/net/ens1
246 ID_NET_NAME_MAC=enx000000000466
247 ID_NET_NAME_PATH=enp5s0
248 ID_NET_NAME_SLOT=ens1
249 Example 4. PCI Ethernet multi-function card with 2 ports
251 # /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/enp2s0f0
253 ID_NET_NAME_MAC=enx78e7d1ea46da
254 ID_NET_NAME_PATH=enp2s0f0
255 # /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.1/net/enp2s0f1
257 ID_NET_NAME_MAC=enx78e7d1ea46dc
258 ID_NET_NAME_PATH=enp2s0f1
259 Example 5. PCI WLAN card
261 # /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/wlp3s0
263 ID_NET_NAME_MAC=wlx0024d7e31130
264 ID_NET_NAME_PATH=wlp3s0
265 Example 6. PCI IB host adapter with 2 ports
267 # /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.0/net/ibp21s0f0
269 ID_NET_NAME_PATH=ibp21s0f0
270 # /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.1/net/ibp21s0f1
272 ID_NET_NAME_PATH=ibp21s0f1
273 Example 7. USB built-in 3G modem
275 # /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.4/2-1.4:1.6/net/wwp0s29u1u4i6
277 ID_NET_NAME_MAC=wwx028037ec0200
278 ID_NET_NAME_PATH=wwp0s29u1u4i6
279 Example 8. USB Android phone
281 # /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/net/enp0s29u1u2
283 ID_NET_NAME_MAC=enxd626b3450fb5
284 ID_NET_NAME_PATH=enp0s29u1u2
285 Example 9. s390 grouped CCW interface
287 # /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0
289 ID_NET_NAME_MAC=enx026d3c00000a
290 ID_NET_NAME_PATH=encf5f0
291
293 udev(7), udevadm(8), the original page describing stable interface
294 names[1]
295
297 1. the original page describing stable interface names
298 https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames
299systemd 243 SYSTEMD.NET-NAMING-SCHEME(7)