Virtual Networking— KVM, NetworkManager, Bridge Interfaces, VLAN Interfaces, etc

Fedora Discussion,

I’ve recently gotten a new workstation and it has significantly more resources than I had before, so I would like to run some VMs in the background on my workstation. However, I am running into issues with the virtual networking setup.

Previously, I always used the default NAT network with KVM, but now I am hoping I can configure networking so I can attach the VMs to different VLANS using 802.1Q tagging. I want the VM to be directly accessible from other hosts on the network, so NAT networking is not a good option here. I have a dedicated interface on my machine for VM traffic, and I control the switch I am connected to, so I should be able to make the necessary configurations.

What I am finding is that I can attach a VM to a bridge interface, which is in turn connected to a physical interface, and it that works. But that setup is without VLAN tagging (connected to “access” port in Cisco speak). I also find I can configure a VLAN sub-interface under my physical adapter and put an IP address on that, and my host machine can correctly communicate with external hosts out on the VLAN. But whenever I try to combine VLAN tagging with bridging, the setup doesn’t work!

I guess I am mostly looking for some direction here. Most of the documentation I can find for this subject online focuses on RHEL and ifcfg files (no longer valid on Fedora), and every guide uses a different mix of commands which adds to the confusion.

How have others implemented similar setups on Fedora? Is NetworkManager getting in the way? Should I switch to systemd-networkd? Just use ip and bridge command?

Thanks,

Ross

@manbart,

Are you using libvirt?

All the features you discuss should be available sticking with NetworkManager in fedora. The linux bridge supports vlan tags. I’ve use openvswitch for this as well.

There is a bunch of configuration to get it all working nicely with systemd, networkmanager, libvirt and kvm.

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