diff --git a/neutron_lib/api/definitions/__init__.py b/neutron_lib/api/definitions/__init__.py
index 25802cf8c..6c534dc3c 100644
--- a/neutron_lib/api/definitions/__init__.py
+++ b/neutron_lib/api/definitions/__init__.py
@@ -11,6 +11,7 @@
 # under the License.
 
 from neutron_lib.api.definitions import agent
+from neutron_lib.api.definitions import auto_allocated_topology
 from neutron_lib.api.definitions import bgpvpn
 from neutron_lib.api.definitions import bgpvpn_routes_control
 from neutron_lib.api.definitions import data_plane_status
@@ -39,6 +40,7 @@ from neutron_lib.api.definitions import trunk_details
 
 _ALL_API_DEFINITIONS = {
     agent,
+    auto_allocated_topology,
     bgpvpn,
     bgpvpn_routes_control,
     data_plane_status,
diff --git a/neutron_lib/api/definitions/auto_allocated_topology.py b/neutron_lib/api/definitions/auto_allocated_topology.py
new file mode 100644
index 000000000..f5b65cdb7
--- /dev/null
+++ b/neutron_lib/api/definitions/auto_allocated_topology.py
@@ -0,0 +1,55 @@
+# Copyright 2015-2016 Hewlett Packard Enterprise Development Company, LP
+#
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from neutron_lib.api import converters
+from neutron_lib.api.definitions import constants
+from neutron_lib.api.definitions import l3
+from neutron_lib.api.definitions import network
+
+ALIAS = 'auto-allocated-topology'
+LABEL = ALIAS
+IS_SHIM_EXTENSION = False
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = 'Auto Allocated Topology Services'
+API_PREFIX = ''
+DESCRIPTION = 'Auto Allocated Topology Services.'
+UPDATED_TIMESTAMP = '2016-01-01T00:00:00-00:00'
+RESOURCE_NAME = 'auto_allocated_topology'
+COLLECTION_NAME = 'auto_allocated_topologies'
+RESOURCE_ATTRIBUTE_MAP = {
+    COLLECTION_NAME: {
+        'id': {'allow_post': False, 'allow_put': False,
+               'validate': {'type:uuid': None},
+               'is_visible': True},
+        'tenant_id': {'allow_post': False, 'allow_put': False,
+                      'validate': {'type:uuid': None},
+                      'is_visible': True},
+    },
+    network.COLLECTION_NAME: {
+        constants.IS_DEFAULT: {
+            'allow_post': True,
+            'allow_put': True,
+            'default': False,
+            'is_visible': True,
+            'convert_to': converters.convert_to_boolean,
+            'enforce_policy': True,
+            'required_by_policy': True}},
+}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = [l3.ALIAS, 'subnet_allocation', 'external-net']
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}
diff --git a/neutron_lib/api/definitions/constants.py b/neutron_lib/api/definitions/constants.py
index 374771878..53258ece2 100644
--- a/neutron_lib/api/definitions/constants.py
+++ b/neutron_lib/api/definitions/constants.py
@@ -27,3 +27,6 @@ FW_VALID_ACTION_VALUES = [FWAAS_ALLOW, FWAAS_DENY, FWAAS_REJECT]
 # Firewall Protocol List
 
 FW_PROTOCOL_VALUES = list(constants.IPTABLES_PROTOCOL_MAP.keys()) + [None]
+
+# a default resource, such as auto allocated topology is_default network
+IS_DEFAULT = 'is_default'
diff --git a/neutron_lib/tests/unit/api/definitions/test_auto_allocated_topology.py b/neutron_lib/tests/unit/api/definitions/test_auto_allocated_topology.py
new file mode 100644
index 000000000..de5c1c308
--- /dev/null
+++ b/neutron_lib/tests/unit/api/definitions/test_auto_allocated_topology.py
@@ -0,0 +1,22 @@
+# All rights reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from neutron_lib.api.definitions import auto_allocated_topology
+from neutron_lib.tests.unit.api.definitions import base
+
+
+class AutoTopologyDefinitionTestCase(base.DefinitionBaseTestCase):
+    extension_module = auto_allocated_topology
+    extension_resources = (auto_allocated_topology.COLLECTION_NAME,)
+    extension_attributes = ()
diff --git a/releasenotes/notes/rehome-autotopology-apidef-4a77e8ba0c783f7e.yaml b/releasenotes/notes/rehome-autotopology-apidef-4a77e8ba0c783f7e.yaml
new file mode 100644
index 000000000..8c86c72d8
--- /dev/null
+++ b/releasenotes/notes/rehome-autotopology-apidef-4a77e8ba0c783f7e.yaml
@@ -0,0 +1,4 @@
+---
+features:
+  - The neutron ``auto-allocated-topology`` extension's API definition is now
+    available as ``neutron_lib.api.definitions.auto_allocated_topology``.