Re: howto define which slave provides the mac addr for the bridge

Am Mittwoch, den 23.05.2018, 15:23 +0200 schrieb Thomas Haller:
On Wed, 2018-05-23 at 15:08 +0200, Thomas Haller wrote:
On Wed, 2018-05-23 at 07:16 +0000, thilo cestonaro ts fujitsu com

I want to connect a real ethernet adapter and a virtual ethernet
adapter to a
bridge. The bridge itself is configured to ask a dhcp for an ip

The problem is, that I can't tell the bridge to always use the mac
address of
the real ethernet adapter. Rather than it is more or less luck
one's mac
address the bridge uses. Mostly the address of the virtual adapter
which is not
hardcoded and will be generated at every boot (which is ok, I don't
want to
hardcode this).

Is it possible to define which slave provides the mac addr for the
The first slave which is enslaved? The last slave?
Or can I set a property in the slaves or bridges settings?
Do I need to retrieve the mac addr of the real adapter and assign
via a
script to the bridge?


Which version of NetworkManager is this?

I think if you configure connection.autoconnect-slaves=yes on the
master, activating the master will re-activate the slaves in a
order. With this, the slaves probably should be all

Then, you may also configure connection.autoconnect-priority on the
slaves, to ensure that the order is as you wish.

That should work, but I don't think we test this sufficiently. Hope
it's not broken :)


Beniamino just informed me, that this might not work.

For bond and team devices, kernel chooses as MAC address the MAC
address of the slave that connects first (unless explicitly

For bridge devices, apparently kernel chooses the MAC address of the
slaves, by sorting the MAC addresses like numbers. This means, if you
first activate a slave with numerically higher MAC address, then a
second slave with a lower MAC address, the MAC address of the bridge
master changes. The order in which slaves are enslaved does not matter.

As workaround:

- ensure that the slave's MAC addresses are in a way, that kernel will
pic the right one. Possibly configuring ethernet.cloned-mac-adddress on
the slaves.

- just explicitly configure a MAC address on the bridge master, with

Hi Thomas and Beniamino,

thank you for your infos! So my best solution is, to configure the bridges MAC
address "manually" to the MAC address of the physical adapter.



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