Hi Michal
Thank you for the clarification. Also I am sorry for being a bit salty. I will look more into the linux kernel bridge module.
Best Regards
On Wed, 26 Oct 2022, 09:10 Michal Prívozník, <mprivozn@xxxxxxxxxx> wrote:
On 10/25/22 17:03, Armin Lepir wrote:
> Hi
>
> I am using libvrt for the first time. Im building a KVM for multiple
> Virtual OS instances.
>
> The problem i have is with your official documentation for Virtual
> Networking.
>
> https://wiki.libvirt.org/page/VirtualNetworking
> <https://wiki.libvirt.org/page/VirtualNetworking>
>
Please note that our wiki page is obsolete and we tried to move
everything into our knowledge base articles:
https://libvirt.org/kbase/
We're keeping the wiki around though, because maybe not everything was
moved.
>
> The following is wrong:
>
> The default mode is BRIDGE + NAT.
>
> Optional mode is ROUTING.
>
>
> It should be:
>
> The default mode is ROUTING + NAT.
>
> Optional mode is BRIDGE.
>
>
> As far as i know a bridge operates on the Layer2.
>
> IP and NAT operate on the Layer3.
>
> NAT can not operate on the L2.
>
> Please tell me that im wrong and explain how am i wrong.
If we'd be talking about bare metal network components then you are 100%
correct. Except, the Linux bridge is more than just plain L2 bridge. It
can have an IP address, route traffic, serve as network interface (when
a host is sending a packet to a guest, the packet is injected into said
bridge).
What the wiki page is trying to say, that by default you'll get this
'default' network which uses this Linux 'bridge' + NAT. Optionally, you
can define new network, or modify the existing one to switch to so
called routed mode.
Hope this clears things up.
Michal
