huschi.net

SYSTEMD.NET-NAMING-SCHEME(7systemd.net-naming-scheSYSTEMD.NET-NAMING-SCHEME(7)
NAME
       systemd.net-naming-scheme - Network device naming schemes
DESCRIPTION
       Network interfaces may be renamed to give them predictable names when
       there's enough information to generate appropriate names and the use of
       certain types of names is configured. This page describes the first
       part, i.e. what possible names may be generated. Those names are
       generated by the systemd-udevd.service(8) builtin net_id and exported
       as udev properties (ID_NET_NAME_ONBOARD=, ID_NET_LABEL_ONBOARD=,
       ID_NET_NAME_PATH=, ID_NET_NAME_SLOT=).
       Names are derived from various device metadata attributes. Newer
       versions of udev take more of these attributes into account, improving
       (and thus possibly changing) the names used for the same devices.
       Differents version of the naming 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 overriden using the net.naming-scheme= kernel
       command line switch, see systemd-udevd.service(8). Available naming
       schemes are described below.
       After the udev proprties have been generated, appropriate udev rules
       may be used to actually rename devices based on those properties. See
       the description of NamePolicy= in systemd.link(5).
NAMING
       All names start with a two-character prefix that signifies the
       interface type.
       Table 1. Two character prefixes based on the type of interface
       +-------+----------------------------+
       |Prefix | Description                |
       +-------+----------------------------+
       |en     | Ethernet                   |
       +-------+----------------------------+
       |sl     | serial line IP (slip)      |
       +-------+----------------------------+
       |wl     | Wireless local area        |
       |       | network (WLAN)             |
       +-------+----------------------------+
       |ww     | Wireless wide area network |
       |       | (WWAN)                     |
       +-------+----------------------------+
       The udev net_id builtin exports the following udev device properties:
       ID_NET_NAME_ONBOARD=prefixonumber
           This name is set based on the ordering information given by the
           firmware for on-board devices. The name consists of the prefix,
           letter o, and a number specified by the firmware. This is only
           available for PCI devices.
       ID_NET_LABEL_ONBOARD=prefix label
           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.
       ID_NET_NAME_MAC=prefixxAABBCCDDEEFF
           This name consists of the prefix, letter x, 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.
       ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port],
       ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port]bnumber,
       ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port]uport...[cconfig][iinterface],
       ID_NET_NAME_SLOT=prefix[Pdomain]sslot[ffunction][nport_name|ddev_port]vslot
           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.
           Table 2. Slot naming schemes
           +------------------------------------------------------------+--------------------------+
           |Format                                                      | Description              |
           +------------------------------------------------------------+--------------------------+
           |prefix [Pdomain] sslot [ffunction] [nport_name | ddev_port] | PCI slot number          |
           +------------------------------------------------------------+--------------------------+
           |... bnumber                                                 | Broadcom bus (BCMA) core |
           |                                                            | number                   |
           +------------------------------------------------------------+--------------------------+
           |... uport... [cconfig] [iinterface]                         | USB port number chain    |
           +------------------------------------------------------------+--------------------------+
           |... vslot                                                   | SR-VIO slot number       |
           +------------------------------------------------------------+--------------------------+
           The PCI domain is only prepended when it is not 0. All
           multi-function PCI devices will carry the ffunction number in the
           device name, including the function 0 device. For
           non-multi-function devices, the number is suppressed if 0. The port
           name port_name is used, or the port number ddev_port if the name is
           not known.
           For BCMA devices, the core number is suppressed when 0.
           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.
           SR-IOV virtual devices are named based on the name of the parent
           interface, with a suffix of v and the virtual device number, with
           any leading zeros removed. The bus number is ignored.
           In some configurations a parent PCI bridge of a given network
           controller may be associated with a slot. In such case we don't
           generate this device property to avoid possible naming conflicts.
       ID_NET_NAME_PATH=prefixcbus_id,
       ID_NET_NAME_PATH=prefixavendormodeliinstance,
       ID_NET_NAME_PATH=prefixiaddressnport_name,
       ID_NET_NAME_PATH=prefix[Pdomain]pbussslot[ffunction][nphys_port_name|ddev_port],
       ID_NET_NAME_PATH=prefix[Pdomain]pbussslot[ffunction][nphys_port_name|ddev_port]bnumber,
       ID_NET_NAME_PATH=prefix[Pdomain]pbussslot[ffunction][nphys_port_name|ddev_port]uport...[cconfig][iinterface]
           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.
           Table 3. Path naming schemes
           +----------------------------------------------------------------------+---------------------------+
           |Format                                                                | Description               |
           +----------------------------------------------------------------------+---------------------------+
           |prefix cbus_id                                                        | CCW or grouped CCW device |
           |                                                                      | identifier                |
           +----------------------------------------------------------------------+---------------------------+
           |prefix avendor model iinstance                                        | ACPI path names for ARM64 |
           |                                                                      | platform devices          |
           +----------------------------------------------------------------------+---------------------------+
           |prefix [Pdomain] pbus sslot [ffunction] [nphys_port_name | ddev_port] | PCI geographical location |
           +----------------------------------------------------------------------+---------------------------+
           |... bnumber                                                           | Broadcom bus (BCMA) core  |
           |                                                                      | number                    |
           +----------------------------------------------------------------------+---------------------------+
           |... uport... [cconfig] [iinterface]                                   | USB port number chain     |
           +----------------------------------------------------------------------+---------------------------+
           CCW and grouped CCW devices are found in IBM System Z mainframes.
           Any leading zeros and dots are suppressed.
           For PCI, BCMA, and USB devices, the same rules as described above
           for slot naming are used.
HISTORY
       The following "naming schemes" have been defined:
       rhel-8.0
           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.
           SR-IOV virtual devices are named based on the name of the parent
           interface, with a suffix of "vport", where port is the virtual
           device number. Previously those virtual devices were named as if
           completely independent.
           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 ("ethN") was used.
           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.
       rhel-8.1
           Same as naming scheme rhel-8.0.
       rhel-8.2
           Same as naming scheme rhel-8.0.
       rhel-8.3
           Same as naming scheme rhel-8.0.
       rhel-8.4
           If the PCI slot is assocated with PCI bridge and that has multiple
           child network controllers then all of them might derive the same
           value of ID_NET_NAME_SLOT property. That could cause naming
           conflict if the property is selected as a device name. Now, we
           detect the situation, slot - bridge relation, and we don't produce
           the ID_NET_NAME_SLOT property to avoid possible naming conflict.
       rhel-8.5
           Same as naming scheme rhel-8.4.
       rhel-8.6
           Same as naming scheme rhel-8.4.
       rhel-8.7
           PCI hotplug slot names for the s390 PCI driver are a hexadecimal
           representation of the function_id device attribute. This attribute
           is now used to build the ID_NET_NAME_SLOT. Before that, all slot
           names were parsed as decimal numbers, which could either result in
           an incorrect value of the ID_NET_NAME_SLOT property or none at all.
           Some firmware and hypervisor implementations report unreasonable
           high numbers for the onboard index. To prevent the generation of
           bogus onbard interface names, index numbers greater than 16381
           (2^14-1) were ignored. For s390 PCI devices index values up to
           65535 (2^16-1) are valid. To account for that, the limit is
           increased to now 65535.
       rhel-8.8
           Same as naming scheme rhel-8.7.
       rhel-8.9
           Same as naming scheme rhel-8.7.
       rhel-8.10
           Same as naming scheme rhel-8.7.
       Note that latest may be used to denote the latest scheme known to this
       particular version of systemd.
EXAMPLES
       Example 1. Using udevadm test-builtin to display device properties
           $ udevadm test-builtin net_id /sys/class/net/enp0s31f6
           ...
           Using default interface naming scheme 'rhel-8.3'.
           ID_NET_NAMING_SCHEME=rhel-8.3
           ID_NET_NAME_MAC=enx54ee75cb1dc0
           ID_OUI_FROM_DATABASE=Wistron InfoComm(Kunshan)Co.,Ltd.
           ID_NET_NAME_PATH=enp0s31f6
           ...
       Example 2. PCI Ethernet card with firmware index "1"
           ID_NET_NAME_ONBOARD=eno1
           ID_NET_NAME_ONBOARD_LABEL=enEthernet Port 1
       Example 3. PCI Ethernet card in hotplug slot with firmware index number
           # /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
       Example 4. PCI Ethernet multi-function card with 2 ports
           # /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
       Example 5. PCI WLAN card
           # /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/wlp3s0
           ID_NET_NAME_MAC=wlx0024d7e31130
           ID_NET_NAME_PATH=wlp3s0
       Example 6. USB built-in 3G modem
           # /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
       Example 7. USB Android phone
           # /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
       Example 8. s390 grouped CCW interface
           # /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0
           ID_NET_NAME_MAC=enx026d3c00000a
           ID_NET_NAME_PATH=encf5f0
SEE ALSO
       udev(7), udevadm(8), the original page describing stable interface
       names[1]
NOTES
        1. the original page describing stable interface names
           https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames
systemd 239                                       SYSTEMD.NET-NAMING-SCHEME(7)