network device names change w/kernel version

[Andrew Ruthven]

On Thu, 2025-05-08 at 08:54 +0200, Steffen Grunewald wrote:
> On Wed, 2025-05-07 at 13:49:45 -0700, andrew bezella wrote:
> > hello -
> > 
> > i'm running into a situation where the systemd network device naming
> > changes with kernel version (bookworm/6.1 vs trixie/6.12 in this case).
> > this is possibly related to a change/update in devlink support in the
> > i40e driver[1] although i haven't found a "smoking gun" changelog
> > entry.

It isn't the i40e driver, it is a change to "predictable interface names" in
systemd. See https://systemd.io/PREDICTABLE_INTERFACE_NAMES/ . I don't find
them so predictable, especially when there can be many interfaces in a host,
and the PCIe slot layout can vary a lot.

> 
> Have you considered using the systemd.link (5) mechanism, and choosing
> a non-"eth*" name?

This is pretty much the approach we use, using enX as the interface names
(ordered by the physical layout looking at the rear of a server). You can't
use ethX as systemd refuses to rename things to ethX now. And can't use enoX
for a similar reason.

After a system is built the first time, we add the, ahem, udev file, to our
FAI profile so on a rebuild we get consistent interface naming. I'll switch
to systemd.link at some point in time.


Cheers,
Andrew

-- 
Andrew Ruthven, Wellington, New Zealand
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