[libvirt] Networking with libvirt

I want to setup networking under KVM and with libvirt. I read a lot the last two days, but it is not working as desired. I don't want bridging, I want it with a tap-device created via vde_switch. I cannot figure out what to put in /etc/libvirt/qemu/machine.xml and /etc/ libvirt/qemu/networks/network.xml - there is no really good documentation. /var/log/libvirt/qemu/maschine.log shows a lot of parameters when I start the VM with virsh start machine, but I cannot figure out where to set these values or where to set the defaults. mfg ar -- Hier könnte keine Signatur stehen.