[PLUG] adding network name alias

Ben Koenig techkoenig at gmail.com
Mon Feb 15 05:35:32 UTC 2021


Just some thoughts... If I'm reading the document on freedesktop.org 
correctly then this new system does not actually solve the problem it 
claims to be solving. Specifically this part here:


"...The following different naming schemes for network interfaces are 
now supported by udev natively:

 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)

By default, systemd v197 will now name interfaces following policy 1) if 
that information from the firmware is applicable and available, falling 
back to 2) if that information from the firmware is applicable and 
available, falling back to 3) if applicable, falling back to 5) in all 
other cases. Policy 4) is not used by default, but is available if the 
user chooses so."


End quote. The whole problem is that the eth# is designated by the order 
in which hardware is enumerated. This is unpredictable. However, relying 
on the firmware/BIOS to define index numbers and falling back if not 
properly defined is also unpredictable. Not only will this change from 
one hardware configuration to the next but it is also subject to change 
for a very large number of different reasons.


They are essentially removing an unpredictable system and replacing it 
with another unpredictable system. I would argue that the old way is 
actually better because of the simplicity of how it decides. Going with 
the new process you now have to ask an additional question about the 
nature of your hardware and such information may not be readily available.


Problem remains unsolved. Whoever funded the development of this feature 
should probably ask for their money back. Unless of course their goal 
was to destablize the Linux platform, in which case, Good Job!

-Ben



On 2/14/21 1:00 PM, Chuck Hast wrote:
> I too have never figured out what was gained by going to
> "predictable names" as far as I am concerned it is the
> definition of oxymoron. I always knew what eth0 or eth1
> or whatever the original names were, these things though
> on a given machine will USUALLY come up the same but
> they change from machine to machine.  I have 3 machines
> here and all 3 of them have different names for eth0....
>
> As they say in Costa Rica "predictable names" turas...
>
>
> On Sat, Feb 13, 2021 at 8:33 PM Russell Senior <russell at personaltelco.net>
> wrote:
>
>> https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
>>
>> Given the plenitude of schemes (!) that are supported, this system
>> deserves the word "predictable" about as much as USB deserves the word
>> "universal".
>>
>> On Sat, Feb 13, 2021 at 6:28 PM Russell Senior
>> <russell at personaltelco.net> wrote:
>>>> There are ways to rename the interface back to eth0, but
>>>> I assume this breaks other things,
>>> It doesn't break anything. I routinely turn off the silly "predictable"
>> names.
>>> I use the technique of adding:
>>>
>>> GRUB_CMDLINE_LINUX_DEFAULT="net.ifnames=0"
>>>
>>> to my /etc/default/grub file, and after running:
>>>
>>> sudo update-grub2 (or equivalent) you are good for the long haul.
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>



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