DK> Well, I think we still need the bridge to exist on the system, to DK> be able to use the virtual network available on the machine. In DK> order to see whether the bridge is really required to be present DK> on the machine. Sure, but we can rely on libvirt to handle that for us. DK> Though I have not specified the bridge info anywhere in the config DK> file , the libvirt assigned its own bridge "vnet0" , see the dump DK> below: Right. DK> 1) brought the vnet0 down DK> 2) deleted the bridge DK> 3) tried creating the KVM guest with the following network information This isn't a valid thing to do, though. If the user goes behind libvirt and breaks the networking config, then I think the expectation is that things will not work :) DK> and got the following error while creating the guest DK> virsh create new_kvm_net.xml DK> libvir: QEMU error : internal error Failed to add tap interface DK> vnet%d' to bridge 'vnet0' : Operation not supported DK> error: Failed to create domain from new_kvm_net.xml This is because libvirtd tried to attach the domain's ethernet adapter to a bridge that no longer exists. This _should_ fail and it does. DK> Is there any other way to create the virtual network where it does DK> not bother to have a bridge to exist? I'm not sure what you're asking here, but as far as I can tell, things are behaving as they should. -- Dan Smith IBM Linux Technology Center Open Hypervisor Team email: danms@us.ibm.com