Configuring Networking can be one of the most bewildering experiences you will encounter when working with OpenStack. To assist in this we have chosen the simplest production-ready configuration for this guide: the legacy networking in OpenStack Compute, with a flat network, that takes care of DHCP and is made highly available by splitting across multiple hosts. If you require the full software-defined networking stack, see Using Neutron Networking After performing initial configuration of the compute node, install the appropriate packages for compute networking. # apt-get install nova-network # yum install openstack-nova-network # zypper install openstack-nova-network First, set the configuration options needed in nova.conf for the chosen networking mode. # openstack-config --set /etc/nova/nova.conf DEFAULT network_manager nova.network.manager.FlatDHCPManager # openstack-config --set /etc/nova/nova.conf DEFAULT firewall_driver nova.virt.libvirt.firewall.IptablesFirewallDriver # openstack-config --set /etc/nova/nova.conf DEFAULT network_size 254 # openstack-config --set /etc/nova/nova.conf DEFAULT routing_source_ip ADDRESS # openstack-config --set /etc/nova/nova.conf DEFAULT allow_same_net_traffic False # openstack-config --set /etc/nova/nova.conf DEFAULT multi_host True # openstack-config --set /etc/nova/nova.conf DEFAULT send_arp_for_ha True # openstack-config --set /etc/nova/nova.conf DEFAULT share_dhcp_address True # openstack-config --set /etc/nova/nova.conf DEFAULT force_dhcp_release True # openstack-config --set /etc/nova/nova.conf DEFAULT flat_interface eth1 # openstack-config --set /etc/nova/nova.conf DEFAULT flat_network_bridge br100 # openstack-config --set /etc/nova/nova.conf DEFAULT public_interface br100 Edit /etc/nova/nova.conf and add to the [DEFAULT] section. [DEFAULT] ... network_manager=nova.network.manager.FlatDHCPManager firewall_driver=nova.virt.libvirt.firewall.IptablesFirewallDriver network_size=254 routing_source_ip=my_ip allow_same_net_traffic=False multi_host=True send_arp_for_ha=True share_dhcp_address=True force_dhcp_release=True flat_interface = eth1 flat_network_bridge = br100 public_interface = br100 Now, restart the relevant services: # service nova-api restart # service nova-consoleauth restart # service nova-novncproxy restart # service nova-network restart # service openstack-nova-api restart # service openstack-nova-consoleauth restart # service openstack-nova-novncproxy restart # service openstack-nova-network restart # systemctl restart openstack-nova-api.service # systemctl restart openstack-nova-consoleauth.service # systemctl restart openstack-nova-novncproxy.service # systemctl restart openstack-nova-network.service You must run the command that creates the network that the virtual machines use. You only need to run this command once, from a place where your admin user credentials are loaded. # nova network-create vmnet --fixed-range-v4=10.0.0.0/24 --bridge-interface=br100 --multi-host=T