Comment by dbaxps for controller>neutron net-create ext-net --shared --router:external=True 503-{u'NeutronError': {u'message': u'Unable to create the network. No tenant network is available for allocation.', u'type': u'NoNetworkAvailable', u'detail': u''}} I refer Openstack Document install openstack icehouse on ubuntu 14.04. I do not know where the wrong. view the Log File: controller>cat /var/log/neutron/server.log 2014-05-09 15:34:47.144 989 INFO neutron.wsgi [-] (989) accepted ('10.0.0.251', 46917) 2014-05-09 15:34:47.147 989 INFO urllib3.connectionpool [-] Starting new HTTP connection (1): controller 2014-05-09 15:34:47.258 989 ERROR neutron.api.v2.resource [req-eeb01f6a-9b04-4c20-a118-9303ee7b794a None] create failed 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource Traceback (most recent call last): 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource File "/usr/lib/python2.7/dist-packages/neutron/api/v2/resource.py", line 87, in resource 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource result = method(request=request, **args) 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource File "/usr/lib/python2.7/dist-packages/neutron/api/v2/base.py", line 419, in create 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource obj = obj_creator(request.context, **kwargs) 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/plugin.py", line 384, in create_network 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource segment = self.type_manager.allocate_tenant_segment(session) 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/managers.py", line 96, in allocate_tenant_segment 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource raise exc.NoNetworkAvailable() 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource NoNetworkAvailable: Unable to create the network. No tenant network is available for allocation. 2014-05-09 15:34:47.258 989 TRACE neutron.api.v2.resource 2014-05-09 15:34:47.264 989 INFO neutron.wsgi [req-eeb01f6a-9b04-4c20-a118-9303ee7b794a None] 10.0.0.251 - - [09/May/2014 15:34:47] "POST /v2.0/networks.json HTTP/1.1" 503 360 0.118819 controller>ps aux | grep neutron neutron 2587 0.2 4.0 211936 52140 ? Ss 17:06 0:07 /usr/bin/python /usr/bin/neutron-server --config-file /etc/neutron/neutron.conf --log-file /var/log/neutron/server.log --config-file /etc/neutron/plugins/ml2/ml2_conf.ini root 3356 0.0 0.0 11744 924 pts/1 S+ 17:57 0:00 grep --color=auto neutron controller neutron.conf file: [DEFAULT] verbose = True state_path = /var/lib/neutron lock_path = $state_path/lock core_plugin = ml2 service_plugins = router allow_overlapping_ips = True notify_nova_on_port_status_changes = True notify_nova_on_port_data_changes = True nova_url = http://controller:8774/v2 nova_admin_username = nova nova_admin_tenant_id = 36bf9ca9fbee42a5abad0d0ad2a69e02 nova_admin_password = nova nova_admin_auth_url = http://controller:35357/v2.0 auth_strategy = keystone rpc_backend = neutron.openstack.common.rpc.impl_kombu rabbit_host = controller rabbit_password = guest rabbit_userid = guest notification_driver = neutron.openstack.common.notifier.rpc_notifier [quotas] [agent] root_helper = sudo /usr/bin/neutron-rootwrap /etc/neutron/rootwrap.conf [keystone_authtoken] auth_uri = http://controller:5000 auth_host = controller auth_port = 35357 ... (more)

*Your issue seems to be addresed by:-
* 1 [GRE tunnels not being created](https://ask.openstack.org/en/question/6598/gre-tunnels-not-being-created/)
2. [ ML2 driver with GRE not working on multi-node installation](https://ask.openstack.org/en/question/24962/ml2-driver-with-gre-not-working-on-multi-node-installation/)