Networking – Understanding Predictable Network Interface Names

devicesnetworkingpcisystemd

So, I've been looking into this systemd "Predictable Network Interface Names" for quite some time and got some understanding on how it works, but I can't for the love of Thor figure out the naming scheme with enpXsY, I know that it's supposed to indicate the physical location of the device, but what exactly does the X and Y mean? Which one is the physical location? What exactly does the other indicate, a bus index, perhaps? I have no idea and really want to know.
I searched high and low and could find nothing explaining in detail how this naming scheme works.

Best Answer

This is described in the man page systemd.net-naming-scheme in later systemd versions. en means ethernet, p means pci, X is the bus number, s means slot, Y is the slot number.

Related Solutions

Linux – way to see the execution tree of systemd

systemd-analyze is your friend. For example systemd-analyze critical-chain outputs blocking tree of daemons. Mine for example:

graphical.target @20.211s
└─multi-user.target @20.211s
  └─nginx.service @19.348s +862ms
    └─network.target @19.347s
      └─NetworkManager.service @10.315s +9.031s
        └─basic.target @10.312s
          └─timers.target @10.311s
            └─systemd-tmpfiles-clean.timer @10.311s
              └─sysinit.target @10.295s
                └─systemd-update-utmp.service @10.167s +127ms
                  └─systemd-tmpfiles-setup.service @10.124s +41ms
                    └─local-fs.target @10.097s
                      └─home-entd-Downloads.mount @10.093s +2ms
                        └─home.mount @9.326s +672ms
                          └─systemd-fsck@dev-sda6.service @8.472s +696ms
                            └─dev-sda6.device @8.471s

NetworkManager in example basically holding entire bootup.

If you want to have more detailed view you can render entire execution chain in a svg file. systemd-analyze plot > something.svg outputs entire chain (120+ modules) as progress bars to high-res svg file which show states, that are blocked and another problems.

Finally you have systemd-analyze dot tool which outputs dot file which outputs entire hierarchy: systemd-analyze dot | dot -Tpng -o stuff.png with dot tool you can output it as ps and svg files too.

All of above tools are built-in in systemd-analyze tool which comes by default with systemd in archlinux at least. I think there is some 3rd party projects dealing with it too.

centos – Disable Predictable Network Interface Names During CentOS 7 Install

You may use the bootloader section in the kickstart file to suppress predictable network interface names. Adding net.ifnames=0 and [if needed] biosdevname=0 to the --append should do what you're asking.

bootloader --location=mbr --append="net.ifnames=0 biosdevname=0"

Note that I've excluded the defaults rhgb quiet crashkernel=auto from the --append, it will work with or without them. You may also exclude the biosdevname package from install and use only net.ifnames=0 in the above.

bootloader --location=mbr --append="net.ifnames=0"
...
%packages --nobase
@core --nodefaults
-biosdevname
%end

Best Answer

Related Solutions

Linux – way to see the execution tree of systemd

centos – Disable Predictable Network Interface Names During CentOS 7 Install

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