NetworkManager is now able to configure veth interfaces throught the
NMSettingVeth. Veth interfaces only have "peer" property.
In order to support Veth interfaces in NetworkManager the design need
to pass the following requirements:
* Veth setting only has "peer" attribute.
* Ethernet profiles must be applicable to Veth interfaces.
* When creating a veth interface, the peer will be managed by
NetworkManager but will not have a profile.
* Veth connection can reapply only if the peer has not been modified.
* In order to modify the veth peer, NetworkManager must deactivate the
connection and create a new one with peer modified.
In general, it should support the basis of veth interfaces but without
breaking any existing feature or use case. The users that are using veth
interfaces as ethernet should not notice anything changed unless they
specified the veth peer setting.
Creating a Veth interface in NetworkManager is useful even without the
support for namespaces for some use cases, e.g "connecting one side of
the veth to an OVS bridge and the other side to a Linux bridge" this is
done when using OVN kubernetes [1][2]. In addition, it would provide
persistent configuration and rollback support for Veth interfaces.
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1885605
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1894139
Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
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