SDN VLAN Zone/Vnet

[aibix]

I have tried to understand VLAN Zone/Vnet in Proxmox SDN. When I setup a VLAN Zone with Vnet (VLAN2001) I get the following setup:



This gets replicated for every VNet I add, no bridge, VLAN or veth pair is ever reused - probably why they named them after the VLAN id.
But why so complicated setup, what purpose does it serve?
Can anyone enlighten me pls?

 

[aibix]

Also the VLAN interface on the PHY interface seems to appear out of thin air (hardcoded probybly) as it is neither defined in /etc/network/interfaces nor in /etc/network/interfaces.d/sdn.

Edit: this is probably done by bridgevlan and/or bridgevlanport from ifupdown2?
Edit2: these seem to be from Proxmox as well as they are not part of ifupdown2 on Debian.

 

[aibix]

I mean, the veth-pair is an "ethernet-cable" between the two bridges "vmbr0v2001" and "vlan2001".
But why are vm/ct not attached to "vmbr0v2001" or even just the vlan-interface itself and be done with it?

I would like to understand the reasoning. In the VlanPlugin.pm are comments hinting at

        # keep vmbrXvY for compatibility with existing network
        # eth0<---->eth0.X----vmbr0v10------vnet---->vm

, but why?

Can someone elaborate about that?