$ sudo su -
# apt-get update
# apt-get remove network-manager
# apt-get install bridge-utils
Configure /etc/network/interfaces
auto lo
iface lo inet loopback
auto em1
iface em1 inet manual
auto br0
iface br0 inet static
address 192.168.11.196
netmask 255.255.255.0
gateway 192.168.11.1
bridge_ports em1
bridge_stp off
bridge_fd 0
bridge_maxwait 0
And reboot machine.
$ sudo apt-get install uvtool
$ # Maybe needs re-login
$ uvt-simplestreams-libvirt sync release=trusty arch=amd64
$ uvt-kvm create devstack release=trusty \
--bridge br0 --cpu 2 --memory 8096 --disk 100 \
--user-data ~/init-devstack.cfg
$ uvt-kvm create ironic release=trusty \
--bridge br0 --cpu 2 --memory 8096 --disk 100 \
--user-data ~/init-ironic.cfg