[libvirt-users] virtual subnet

Hello all, I need to setup a virtual subnet to create a test AD domain (server + clients): guests need to talk to each other, they need to reach the internet through a virtual router with nat (virbr0?), broadcasts must not reach the host nor the physical network (because of conflicts with the existing real AD domain) and libvirt must NOT offer a dhcp service inside the virtual subnet. What kind of networking model should I look at?