Configuring networking can be a bewildering experience. The following example shows the simplest production-ready configuration that is available: the legacy networking in OpenStack Compute, with a flat network, that takes care of DHCP. This set up uses multi-host functionality. Networking is configured to be highly available by distributing networking functionality across multiple hosts. As a result, no single network controller acts as a single point of failure. This process configures each compute node for networking. You must complete some minimal configuration on the controller. If you need the full software-defined networking stack, see . Install the appropriate packages for compute networking: # apt-get install nova-network # yum install openstack-nova-network # zypper install openstack-nova-network Edit the nova.conf file to define the 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 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 eth1 # openstack-config --set /etc/nova/nova.conf DEFAULT network_api_class nova.network.api.API # openstack-config --set /etc/nova/nova.conf DEFAULT security_group_api nova # openstack-config --set /etc/nova/nova.conf DEFAULT rabbit_host controller # openstack-config --set /etc/nova/nova.conf database connection mysql://nova:NOVA_DBPASS@controller/nova Edit the /etc/nova/nova.conf file and add these lines to the [DEFAULT] section: [DEFAULT] ... network_manager=nova.network.manager.FlatDHCPManager firewall_driver=nova.virt.libvirt.firewall.IptablesFirewallDriver network_size=254 allow_same_net_traffic=False multi_host=True send_arp_for_ha=True share_dhcp_address=True force_dhcp_release=True flat_network_bridge=br100 flat_interface=eth1 public_interface=eth1 rabbit_host=controller In the multi-host scenario, you also need to configure the database access. Edit /etc/nova/nova.conf and set the connection variable in the [database] section. [database] connection = mysql://nova:NOVA_DBPASS@controller/nova Provide a local metadata service that is reachable from instances on this compute node. Perform this step only on compute nodes that do not run the nova-api service. # yum install openstack-nova-api # service openstack-nova-metadata-api start # chkconfig openstack-nova-metadata-api on Restart the network service: # service nova-network restart Start the network service and configure it to start when the system boots: # service openstack-nova-network restart # chkconfig openstack-nova-network on Create a network that virtual machines can use. Do this once for the entire installation and not on each compute node. Run the nova network-create command on the controller: # source keystonerc # nova network-create vmnet --fixed-range-v4=10.0.0.0/24 \ --bridge-interface=br100 --multi-host=T