1. Create a new libvirt network (other than your default 198.162.x.x) file:

  $ cat openstackvms.xml 
  <network>
    <name>openstackvms</name>
    <uuid>d0e9964a-f91a-40c0-b769-a609aee41bf2</uuid>
    <forward mode='nat'>
      <nat>
        <port start='1024' end='65535'/>
      </nat>
    </forward>
    <bridge name='virbr1' stp='on' delay='0' />
    <mac address='52:54:00:60:f8:6e'/>
    <ip address='192.169.142.1' netmask='255.255.255.0'>
      <dhcp>
        <range start='192.169.142.2' end='192.169.142.254' />
      </dhcp>
    </ip>
  </network>


2. Define the above network:

  $ virsh net-define openstackvms.xml


3. Start the network and enable it for "autostart"

  $ virsh net-start openstackvms
  $ virsh net-autostart openstackvms


4. List your libvirt networks to see if it reflects:

  $ virsh net-list
  Name                 State      Autostart     Persistent
  ----------------------------------------------------------
  default              active     yes           yes
  openstackvms         active     yes           yes


5. Optionally, list your bridge devices:

  $ brctl show
  bridge name     bridge id               STP enabled     interfaces
  virbr0          8000.5254003339b3       yes             virbr0-nic
  virbr1          8000.52540060f86e       yes             virbr1-nic