diff --git a/nova/conf/network.py b/nova/conf/network.py
index 3995327417fe..7b22afe60bb2 100644
--- a/nova/conf/network.py
+++ b/nova/conf/network.py
@@ -486,7 +486,7 @@ with the name 'share_address'.
     # NOTE(stephenfin): This should move to True for a cycle before being
     # removed.
     cfg.BoolOpt('use_neutron',
-        default=False,
+        default=True,
         deprecated_for_removal=True,
         deprecated_since='15.0.0',
         deprecated_reason="""
diff --git a/nova/tests/functional/api_sample_tests/test_security_groups.py b/nova/tests/functional/api_sample_tests/test_security_groups.py
index 8988bc426505..0f9d96f3144b 100644
--- a/nova/tests/functional/api_sample_tests/test_security_groups.py
+++ b/nova/tests/functional/api_sample_tests/test_security_groups.py
@@ -60,9 +60,9 @@ def fake_create_security_group(self, context, name, description):
 
 class SecurityGroupsJsonTest(test_servers.ServersSampleBase):
     sample_dir = 'os-security-groups'
+    USE_NEUTRON = True
 
     def setUp(self):
-        self.flags(use_neutron=True)
         self.neutron = fixtures.NeutronFixture(self)
         self.useFixture(self.neutron)
         super(SecurityGroupsJsonTest, self).setUp()
diff --git a/nova/tests/functional/integrated_helpers.py b/nova/tests/functional/integrated_helpers.py
index be40118da408..c12d7a8a6e5b 100644
--- a/nova/tests/functional/integrated_helpers.py
+++ b/nova/tests/functional/integrated_helpers.py
@@ -63,11 +63,18 @@ def generate_new_element(items, prefix, numeric=False):
 class _IntegratedTestBase(test.TestCase):
     REQUIRES_LOCKING = True
     ADMIN_API = False
+    # Override this in subclasses which use the NeutronFixture. New tests
+    # should rely on Neutron since nova-network is deprecated. The default
+    # value of False here is only temporary while we update the existing
+    # functional tests to use Neutron.
+    USE_NEUTRON = False
 
     def setUp(self):
         super(_IntegratedTestBase, self).setUp()
 
         self.flags(verbose=True)
+        # TODO(mriedem): Fix the functional tests to work with Neutron.
+        self.flags(use_neutron=self.USE_NEUTRON)
 
         nova.tests.unit.image.fake.stub_out_image_service(self)
         self._setup_services()
diff --git a/nova/tests/functional/regressions/test_bug_1522536.py b/nova/tests/functional/regressions/test_bug_1522536.py
index 237b7e0ca8f6..3a2c864d882d 100644
--- a/nova/tests/functional/regressions/test_bug_1522536.py
+++ b/nova/tests/functional/regressions/test_bug_1522536.py
@@ -12,8 +12,6 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-from oslo_config import cfg
-
 import nova.scheduler.utils
 import nova.servicegroup
 from nova import test
@@ -23,8 +21,6 @@ from nova.tests.unit import cast_as_call
 import nova.tests.unit.image.fake
 from nova.tests.unit import policy_fixture
 
-CONF = cfg.CONF
-
 
 class TestServerGet(test.TestCase):
     REQUIRES_LOCKING = True
@@ -32,6 +28,7 @@ class TestServerGet(test.TestCase):
     def setUp(self):
         super(TestServerGet, self).setUp()
         self.useFixture(policy_fixture.RealPolicyFixture())
+        self.useFixture(nova_fixtures.NeutronFixture(self))
         api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1'))
 
@@ -43,8 +40,6 @@ class TestServerGet(test.TestCase):
         self.start_service('conductor')
         self.flags(driver='chance_scheduler', group='scheduler')
         self.start_service('scheduler')
-        self.network = self.start_service('network',
-                                          manager=CONF.network_manager)
         self.compute = self.start_service('compute')
 
         self.useFixture(cast_as_call.CastAsCall(self.stubs))
diff --git a/nova/tests/functional/regressions/test_bug_1548980.py b/nova/tests/functional/regressions/test_bug_1548980.py
index 2d7d79c9cde5..5dfbe0098313 100644
--- a/nova/tests/functional/regressions/test_bug_1548980.py
+++ b/nova/tests/functional/regressions/test_bug_1548980.py
@@ -14,8 +14,6 @@
 
 import time
 
-from oslo_config import cfg
-
 import nova.scheduler.utils
 import nova.servicegroup
 from nova import test
@@ -25,8 +23,6 @@ from nova.tests.unit import cast_as_call
 import nova.tests.unit.image.fake
 from nova.tests.unit import policy_fixture
 
-CONF = cfg.CONF
-
 
 class TestServerGet(test.TestCase):
     REQUIRES_LOCKING = True
@@ -34,6 +30,7 @@ class TestServerGet(test.TestCase):
     def setUp(self):
         super(TestServerGet, self).setUp()
         self.useFixture(policy_fixture.RealPolicyFixture())
+        self.useFixture(nova_fixtures.NeutronFixture(self))
         api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1'))
 
@@ -51,8 +48,6 @@ class TestServerGet(test.TestCase):
         self.start_service('conductor')
         self.flags(driver='chance_scheduler', group='scheduler')
         self.start_service('scheduler')
-        self.network = self.start_service('network',
-                                          manager=CONF.network_manager)
         self.compute = self.start_service('compute')
         self.consoleauth = self.start_service('consoleauth')
 
diff --git a/nova/tests/functional/regressions/test_bug_1558866.py b/nova/tests/functional/regressions/test_bug_1558866.py
index 495e9063f43f..9f2ab46e4129 100644
--- a/nova/tests/functional/regressions/test_bug_1558866.py
+++ b/nova/tests/functional/regressions/test_bug_1558866.py
@@ -29,6 +29,7 @@ class TestServerGet(test.TestCase):
     def setUp(self):
         super(TestServerGet, self).setUp()
         self.useFixture(policy_fixture.RealPolicyFixture())
+        self.useFixture(nova_fixtures.NeutronFixture(self))
         api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1'))
 
diff --git a/nova/tests/functional/regressions/test_bug_1595962.py b/nova/tests/functional/regressions/test_bug_1595962.py
index fb32a18b35ee..71368bcb9e85 100644
--- a/nova/tests/functional/regressions/test_bug_1595962.py
+++ b/nova/tests/functional/regressions/test_bug_1595962.py
@@ -17,7 +17,7 @@ import time
 import fixtures
 import mock
 
-import nova.conf
+import nova
 from nova import test
 from nova.tests import fixtures as nova_fixtures
 from nova.tests.unit import cast_as_call
@@ -27,15 +27,13 @@ from nova.tests.unit.virt.libvirt import fakelibvirt
 from nova.virt.libvirt import guest as libvirt_guest
 
 
-CONF = nova.conf.CONF
-
-
 class TestSerialConsoleLiveMigrate(test.TestCase):
     REQUIRES_LOCKING = True
 
     def setUp(self):
         super(TestSerialConsoleLiveMigrate, self).setUp()
         self.useFixture(policy_fixture.RealPolicyFixture())
+        self.useFixture(nova_fixtures.NeutronFixture(self))
         api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1'))
         # Replace libvirt with fakelibvirt
@@ -70,8 +68,6 @@ class TestSerialConsoleLiveMigrate(test.TestCase):
         self.start_service('conductor')
         self.flags(driver='chance_scheduler', group='scheduler')
         self.start_service('scheduler')
-        self.network = self.start_service('network',
-                                          manager=CONF.network_manager)
         self.compute = self.start_service('compute', host='test_compute1')
         self.consoleauth = self.start_service('consoleauth')
 
diff --git a/nova/tests/functional/regressions/test_bug_1620248.py b/nova/tests/functional/regressions/test_bug_1620248.py
index f787b7be6f4d..8bcc606ef6d2 100644
--- a/nova/tests/functional/regressions/test_bug_1620248.py
+++ b/nova/tests/functional/regressions/test_bug_1620248.py
@@ -10,16 +10,12 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-from oslo_config import cfg
-
 from nova import test
 from nova.tests import fixtures as nova_fixtures
 from nova.tests.unit import cast_as_call
 import nova.tests.unit.image.fake
 from nova.tests.unit import policy_fixture
 
-CONF = cfg.CONF
-
 
 class TestServerUpdate(test.TestCase):
     REQUIRES_LOCKING = True
@@ -27,6 +23,7 @@ class TestServerUpdate(test.TestCase):
     def setUp(self):
         super(TestServerUpdate, self).setUp()
         self.useFixture(policy_fixture.RealPolicyFixture())
+        self.useFixture(nova_fixtures.NeutronFixture(self))
         # Simulate requests coming in before the instance is scheduled by
         # using a no-op for conductor build_instances
         self.useFixture(nova_fixtures.NoopConductorFixture())
diff --git a/nova/tests/functional/test_metadata.py b/nova/tests/functional/test_metadata.py
index 0ebf369e3f5b..1e7ff1e92988 100644
--- a/nova/tests/functional/test_metadata.py
+++ b/nova/tests/functional/test_metadata.py
@@ -68,6 +68,9 @@ class MetadataTest(test.TestCase):
         # NOTE(mikal): We could create a network and a fixed IP here, but it
         # turns out to be heaps of fiddly boiler plate code, so let's just
         # fake it and hope mriedem doesn't notice.
+        # TODO(mriedem): Make this all work with the Neutron fixture.
+        self.flags(use_neutron=False)
+
         def fake_get_fixed_ip_by_address(self, ctxt, address):
             return {'instance_uuid': instance.uuid}
 
diff --git a/nova/tests/functional/test_server_group.py b/nova/tests/functional/test_server_group.py
index 7c9335f9b5b8..0e75973de942 100644
--- a/nova/tests/functional/test_server_group.py
+++ b/nova/tests/functional/test_server_group.py
@@ -16,7 +16,6 @@
 import time
 
 import mock
-from oslo_config import cfg
 
 from nova import context
 from nova import db
@@ -32,8 +31,6 @@ import nova.scheduler.utils
 import nova.servicegroup
 import nova.tests.unit.image.fake
 
-CONF = cfg.CONF
-
 # An alternate project id
 PROJECT_ID_ALT = "616c6c796f7572626173656172656f73"
 
@@ -70,6 +67,7 @@ class ServerGroupTestBase(test.TestCase,
         self.flags(report_interval=self._report_interval)
 
         self.useFixture(policy_fixture.RealPolicyFixture())
+        self.useFixture(nova_fixtures.NeutronFixture(self))
 
         api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1'))
@@ -111,7 +109,6 @@ class ServerGroupTestV21(ServerGroupTestBase):
     def setUp(self):
         super(ServerGroupTestV21, self).setUp()
 
-        self.start_service('network', manager=CONF.network_manager)
         self.compute = self.start_service('compute')
 
         # NOTE(gibi): start a second compute host to be able to test affinity
diff --git a/nova/tests/functional/wsgi/test_servers.py b/nova/tests/functional/wsgi/test_servers.py
index 63a6f026ddcc..964e09e8592f 100644
--- a/nova/tests/functional/wsgi/test_servers.py
+++ b/nova/tests/functional/wsgi/test_servers.py
@@ -38,6 +38,7 @@ class ServersPreSchedulingTestCase(test.TestCase):
         fake_image.stub_out_image_service(self)
         self.useFixture(policy_fixture.RealPolicyFixture())
         self.useFixture(nova_fixtures.NoopConductorFixture())
+        self.useFixture(nova_fixtures.NeutronFixture(self))
         api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1'))
 
diff --git a/releasenotes/notes/ocata-use-neutron-by-default-7a836e65e1c3ccaf.yaml b/releasenotes/notes/ocata-use-neutron-by-default-7a836e65e1c3ccaf.yaml
new file mode 100644
index 000000000000..0d437c28b2c6
--- /dev/null
+++ b/releasenotes/notes/ocata-use-neutron-by-default-7a836e65e1c3ccaf.yaml
@@ -0,0 +1,9 @@
+---
+prelude: >
+    Neutron is now the default configuration for new deployments.
+upgrade:
+  - |
+    The nova-network service was deprecated in the 14.0.0 Newton release. In
+    the 15.0.0 Ocata release, nova-network will only work in a Cells v1
+    deployment. The Neutron networking service is now the default configuration
+    for new deployments based on the ``use_neutron`` configuration option.