diff --git a/neutron_lib/api/definitions/__init__.py b/neutron_lib/api/definitions/__init__.py
index 8b5d9e55d..bf2c2525b 100644
--- a/neutron_lib/api/definitions/__init__.py
+++ b/neutron_lib/api/definitions/__init__.py
@@ -51,6 +51,7 @@ from neutron_lib.api.definitions import l3
 from neutron_lib.api.definitions import l3_ext_gw_mode
 from neutron_lib.api.definitions import l3_ext_ha_mode
 from neutron_lib.api.definitions import l3_flavors
+from neutron_lib.api.definitions import l3_port_ip_change_not_allowed
 from neutron_lib.api.definitions import logging
 from neutron_lib.api.definitions import logging_resource
 from neutron_lib.api.definitions import metering
@@ -145,6 +146,7 @@ _ALL_API_DEFINITIONS = {
     l3_ext_gw_mode,
     l3_ext_ha_mode,
     l3_flavors,
+    l3_port_ip_change_not_allowed,
     logging,
     logging_resource,
     metering,
diff --git a/neutron_lib/api/definitions/base.py b/neutron_lib/api/definitions/base.py
index d04775b92..ad9c170af 100644
--- a/neutron_lib/api/definitions/base.py
+++ b/neutron_lib/api/definitions/base.py
@@ -102,6 +102,7 @@ KNOWN_EXTENSIONS = (
     'ip-substring-filtering',
     'l3-ha',
     'l3_agent_scheduler',
+    'l3-port-ip-change-not-allowed',
     'logging',
     'metering',
     'multi-provider',
diff --git a/neutron_lib/api/definitions/l3_port_ip_change_not_allowed.py b/neutron_lib/api/definitions/l3_port_ip_change_not_allowed.py
new file mode 100644
index 000000000..a94fa3aaf
--- /dev/null
+++ b/neutron_lib/api/definitions/l3_port_ip_change_not_allowed.py
@@ -0,0 +1,29 @@
+#    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 l3
+
+
+ALIAS = 'l3-port-ip-change-not-allowed'
+IS_SHIM_EXTENSION = True
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = 'Prevent L3 router ports IP address change extension'
+DESCRIPTION = 'Prevent change of IP address for some L3 router ports'
+UPDATED_TIMESTAMP = '2018-10-09T10:00:00-00:00'
+RESOURCE_ATTRIBUTE_MAP = {}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = [
+    l3.ALIAS
+]
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}
diff --git a/neutron_lib/tests/unit/api/definitions/test_l3_port_ip_change_not_allowed.py b/neutron_lib/tests/unit/api/definitions/test_l3_port_ip_change_not_allowed.py
new file mode 100644
index 000000000..bfcf7277d
--- /dev/null
+++ b/neutron_lib/tests/unit/api/definitions/test_l3_port_ip_change_not_allowed.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 l3_port_ip_change_not_allowed
+from neutron_lib.tests.unit.api.definitions import base
+
+
+class L3PortIPChangeNotAllowedDefinitionTestCase(base.DefinitionBaseTestCase):
+    extension_module = l3_port_ip_change_not_allowed
diff --git a/releasenotes/notes/l3-port-ip-change-not-allow-2c98e13c08b5ee85.yaml b/releasenotes/notes/l3-port-ip-change-not-allow-2c98e13c08b5ee85.yaml
new file mode 100644
index 000000000..2603a526f
--- /dev/null
+++ b/releasenotes/notes/l3-port-ip-change-not-allow-2c98e13c08b5ee85.yaml
@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Directly updating some L3-related port IP addresses does not have any
+    effect on the L3 agent side. As a consequence, these L3-related ports
+    should not allow changing of their IP address. A new shim extension has
+    been added called ``l3-port-ip-change-not-allowed`` to prevent such IP
+    address change. For more information please see bug
+    `1796824 <https://bugs.launchpad.net/neutron/+bug/1796824>`_.