[libvirt-users] defining directly to the wan/lan

I have a fedora system configured and running with virsh using kvm/qemu. All I want is to have a fixed ipaddress for that virtual machine. I know that there is the Host and Guest sides to the network. The host has virbr0 interface, which i guess is a bridge. Seem when ever I define a interface to the guest with a type=routed it hoses my other interfaces on the host and requires a console reboot -- completely hanging the network. I'm no networking expert, but there must be a simple N step procedure for defining a static IPaddress to route to a guest machine? Has anyone got this working and have a procedure. My network has 2 nic, eth0 and eth1 (10.0.0.253 and 10.0.1.253), one nic has a route to an nfs machine, the other passes through a linux based router to the wan. I can alias the 10.0.1.253 (eth0) to another address in the subnet, like 10.0.1.251 (eth0:0) and would like to use it in some way to connect to the guest -- I have the nat/routing working fine from the router to eth0:0. The network for libvirt is confusing. It not obvious which side (guest or host) your defining and seem to keep multiple definitions around, even after a restart of libvirtd.service. An help would be great!