Network Interface Naming

People often get confused by the network interfaces naming as earlier we used to see traditional naming conventions like eth0, eth1 and so on ..

Starting with v197 systemd/udev will automatically assign predictable, stable network interface names for all local Ethernet, WLAN and WWAN interfaces. This is a departure from the traditional interface naming scheme (“eth0”, “eth1”, “wlan0”, …), but should fix real problems.

Basic idea is that unlike previous *nix naming scheme where probing for hardware occurs in no particular order and may change between reboots, here interface name depends on physical location of hardware and can be predicted/guessed by looking at lspci or lshw output.

Two character prefixes based on the type of interface:
* en -- ethernet
* sl -- serial line IP (slip)
* wl -- wlan
* ww -- wwan
* ib -- Infiniband

1. Names incorporating Firmware/BIOS provided index numbers for on-board devices (example: eno1)
2. Names incorporating Firmware/BIOS provided PCI Express hotplug slot index numbers (example: ens1)
3. Names incorporating physical/geographical location of the connector of the hardware (example: enp2s0)
4. Names incorporating the interfaces’s MAC address (example: enx78e7d1ea46da)
5. Classic, unpredictable kernel-native ethX naming (example: eth0)

With this new scheme you now get:

• Stable interface names across reboots
• Stable interface names even when hardware is added or removed, i.e. no re-enumeration takes place (to the level the firmware permits this)
• Stable interface names when kernels or drivers are updated/changed
• Stable interface names even if you have to replace broken ethernet cards by new ones
• The names are automatically determined without user configuration, they just work
• The interface names are fully predictable, i.e. just by looking at lspci you can figure out what the interface is going to be called
• Fully stateless operation, changing the hardware configuration will not result in changes in /etc
• Compatibility with read-only root
• The network interface naming now follows more closely the scheme used for aliasing block device nodes and other device nodes in /dev via symlinks
• Applicability to both x86 and non-x86 machines
• The same on all distributions that adopted systemd/udev
• It’s easy to opt out of the scheme

Hope you like the tutorial. Please let me know your feedback in the response section.

Happy learning!