[Users] How to add internal networks

Hi, I'm using oVirt 3.2 on a single hosts with only one NIC. Currently there is only the ovirtmgmt network configured. But I need to add more networks, especially some internal networks like 192.168.x.y/24 need to be usable for VMs. From the oVirt Admin Portal this does not seem to be possible. It seems I cannot reuse the ovirtmgmt interface for any other network. Is this true? How am I supposed to add several networks in oVirt if I have just one NIC? Thanks - Frank