Re: Bridges and Ethernet Devices

["thilo cestonaro ts fujitsu com" <thilo cestonaro ts fujitsu com>]

Hey Thomas,

Thanks again for your detailed answers!

Cheers,
Thilo


Am Montag, den 15.01.2018, 14:52 +0100 schrieb Thomas Haller:
> On Mon, 2018-01-15 at 10:34 +0000, thilo cestonaro ts fujitsu com
> wrote:
> > Hey all!
> >
> > I have a lack of knowledge about how I'm supposed to work with the
> > network
> > manager.
> >
> > So here is my situation. I have two ethernet devices and multiple
> > bridges.
> > And I want to be able to connect one of the ethernet devices to one
> > bridge and
> > apply a static connection to that bridge then.
> > Afterwards I want to deactive this connection and use any other
> > combination of
> > these two ethernet devices and the bridges to get connected to my
> > network with
> > exactly the same static connection.
> >
> > I want to learn the handling of bridges via network manager so thats
> > more or
> > less just a stupid example.
>
> Hi,
>
> See the D-Bus API:
>
> https://developer.gnome.org/NetworkManager/stable/spec.html
>
> Create connection profiles that are suitable to your need and activate
> them. Also look at the output of `nmcli connection` and `nmcli device`
> to understand what is happening.
>
>
> > How I try to do it is the following (all is done via NM DBus API):
> >
> > # disconncet both ethernet devices
> > disconnect enp0s1, enp0s2
> >
> > # disconnect the old bridge
> > disconnect br1
>
> often, you don't need to explicitly disconnect anything (you might
> though). Just activate what you care about, and NM will take care to
> bring the interface down first.
>
> > # build the new connections
> > add and active connection for new bridge br3 (with static settings)
> > add and active connection for enp0s1 (as slave of br3)
> > add and active connection for enp0s2 (with "/" as connection)
>
>
>
> On a minor note, it's a mistake to do:
>
>   nmcli connection up br0-slave-eth0 && nmcli connection up br0
>
> Either do
>
>   nmcli connection up br0 && nmcli connection up br0-slave-eth0
>
> or better just
>
>   nmcli connection up br0-slave-eth0
>
>
>
> > Is this the way of doing it or how am I supposed to do it?
> >
> > Do I need to delete the old connections?
>
> No, you can have arbitrary many connection profiles.
>
>
> > Is network manager compatible with brctl or should I avoid using
> > brctl when I
> > manage my network devices with network manager?
>
> brctl is deprecated for iproute2. You can use both to look at the
> bridge's state (inspect, not change).
>
> It's probably a bad idea to interfere with NM by modifying the bridge
> using iproute2, but that might work too. Why would you need that? It
> depends what exactly happens, but in general it's not a good idea
> because there are inevitable races.
>
>
>
> > Is there a simple way to show slaves of a bridge with nmcli?
>
>   nmcli -f BRIDGE.SLAVES device show br0
>
>
>
> Use nmcli to understand what's happening, and look at the D-Bus API
> (for example with the "d-feet" program).
>
>
> best,
> Thomas

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