Legacy networking primarily involves compute nodes. However, you must configure the controller node to use legacy networking. Edit the /etc/nova/nova.conf file and complete the following actions: In the [DEFAULT] section, configure the network and security group APIs: [DEFAULT] ... network_api_class = nova.network.api.API security_group_api = nova Restart the Compute services: # systemctl restart openstack-nova-api.service openstack-nova-scheduler.service \ openstack-nova-conductor.service # service nova-api restart # service nova-scheduler restart # service nova-conductor restart