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. This setup uses "multi-host" functionality: the networking is configured to be highly available by splitting networking functionality across multiple hosts. As a result, there is no single network controller that acts as a single point of failure. Because each compute node is configured for networking in this setup, no additional networking configuration is required on the controller. 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 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 /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 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 Provide a local metadata service that will be reachable from instances on this compute node. This step is only necessary 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 Finally, you have to create a network that virtual machines can use. You only need to do this once for the entire installation, not for each compute node. Run the nova network-create command anywhere your admin user credentials are loaded. # source keystonerc # nova network-create vmnet --fixed-range-v4=10.0.0.0/24 \ --bridge-interface=br100 --multi-host=T