diff --git a/api-ref/source/v2/routers.inc b/api-ref/source/v2/routers.inc
index 4a4a7e482..6c3444f47 100644
--- a/api-ref/source/v2/routers.inc
+++ b/api-ref/source/v2/routers.inc
@@ -52,6 +52,17 @@ Resource timestamps
 The ``standard-attr-timestamp`` extension adds the ``created_at`` and
 ``updated_at`` attributes to all resources that have standard attributes.
 
+Router admin state down before update extension
+===============================================
+
+The ``router-admin-state-down-before-update`` extension adds the requirement
+that the administrative state of a distributed virtual router (DVR) be set to
+DOWN (``admin_state_up=False``) prior to modifying the ``distributed``
+parameter of the router. The API will return an error response code of 400 if
+the router's ``distributed`` attribute is modified without first setting the
+router's ``admin_state_up=False``.
+This extension requires the ``dvr`` extension.
+
 Router availability zone extension
 ==================================
 
diff --git a/neutron_lib/api/definitions/__init__.py b/neutron_lib/api/definitions/__init__.py
index 12cf041f6..345ca66c1 100644
--- a/neutron_lib/api/definitions/__init__.py
+++ b/neutron_lib/api/definitions/__init__.py
@@ -86,6 +86,7 @@ from neutron_lib.api.definitions import qos_rule_type_details
 from neutron_lib.api.definitions import qos_rules_alias
 from neutron_lib.api.definitions import rbac_security_groups
 from neutron_lib.api.definitions import revisionifmatch
+from neutron_lib.api.definitions import router_admin_state_down_before_update
 from neutron_lib.api.definitions import router_availability_zone
 from neutron_lib.api.definitions import router_interface_fip
 from neutron_lib.api.definitions import routerservicetype
@@ -191,6 +192,7 @@ _ALL_API_DEFINITIONS = {
     qos_rules_alias,
     rbac_security_groups,
     revisionifmatch,
+    router_admin_state_down_before_update,
     router_availability_zone,
     router_interface_fip,
     routerservicetype,
diff --git a/neutron_lib/api/definitions/router_admin_state_down_before_update.py b/neutron_lib/api/definitions/router_admin_state_down_before_update.py
new file mode 100644
index 000000000..49cb19ade
--- /dev/null
+++ b/neutron_lib/api/definitions/router_admin_state_down_before_update.py
@@ -0,0 +1,28 @@
+#    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 dvr as dvr_apidef
+
+ALIAS = 'router-admin-state-down-before-update'
+IS_SHIM_EXTENSION = True
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = "Enforce Router's Admin State Down Before Update Extension"
+DESCRIPTION = ('Ensure that the admin state of a router is DOWN '
+               '(admin_state_up=False) before updating the distributed '
+               'attribute')
+UPDATED_TIMESTAMP = '2019-07-02T15:56:00'
+RESOURCE_ATTRIBUTE_MAP = {}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = [dvr_apidef.ALIAS]
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}
diff --git a/neutron_lib/tests/unit/api/definitions/test_admin_state_down_before_update.py b/neutron_lib/tests/unit/api/definitions/test_admin_state_down_before_update.py
new file mode 100644
index 000000000..4f8b6698f
--- /dev/null
+++ b/neutron_lib/tests/unit/api/definitions/test_admin_state_down_before_update.py
@@ -0,0 +1,18 @@
+#    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 router_admin_state_down_before_update
+from neutron_lib.tests.unit.api.definitions import base
+
+
+class AdminStateDownToUpdateDefinitionTestCase(base.DefinitionBaseTestCase):
+    extension_module = router_admin_state_down_before_update
diff --git a/releasenotes/notes/admin-state-down-before-update-c06fb3a551fe499f.yaml b/releasenotes/notes/admin-state-down-before-update-c06fb3a551fe499f.yaml
new file mode 100644
index 000000000..2a74c6549
--- /dev/null
+++ b/releasenotes/notes/admin-state-down-before-update-c06fb3a551fe499f.yaml
@@ -0,0 +1,5 @@
+---
+features:
+  - Router API is modified through a regime API extension to neutron-lib that
+    enforces the admin state of a router be DOWN (admin_state_up=False) prior
+    to modifying the distributed attribute of the router.