diff --git a/api-ref/source/v2/intro.inc b/api-ref/source/v2/intro.inc
index 9c063c7fb..45de9c1b8 100644
--- a/api-ref/source/v2/intro.inc
+++ b/api-ref/source/v2/intro.inc
@@ -378,6 +378,12 @@ the background.
 To determine if sorting is supported, a user can check whether the 'sorting'
 extension API is available.
 
+Starting from Rocky release, the Networking API performs validation on
+sorting attributes if the API extension ``sort-key-validation`` is available.
+If an API request contains an unknown or unsupported sort key,
+the server will return a ``400`` response instead of silently ignoring
+the invalid input.
+
 
 .. _Extensions:
 
diff --git a/neutron_lib/api/definitions/__init__.py b/neutron_lib/api/definitions/__init__.py
index 4081b04a1..a7a3a957d 100644
--- a/neutron_lib/api/definitions/__init__.py
+++ b/neutron_lib/api/definitions/__init__.py
@@ -79,6 +79,7 @@ from neutron_lib.api.definitions import segment
 from neutron_lib.api.definitions import segments_peer_subnet_host_routes
 from neutron_lib.api.definitions import servicetype
 from neutron_lib.api.definitions import sfc
+from neutron_lib.api.definitions import sort_key_validation
 from neutron_lib.api.definitions import sorting
 from neutron_lib.api.definitions import standard_attr_segment
 from neutron_lib.api.definitions import subnet
@@ -164,6 +165,7 @@ _ALL_API_DEFINITIONS = {
     segments_peer_subnet_host_routes,
     servicetype,
     sfc,
+    sort_key_validation,
     sorting,
     standard_attr_segment,
     subnet,
diff --git a/neutron_lib/api/definitions/base.py b/neutron_lib/api/definitions/base.py
index 4490425c3..d42f5bfeb 100644
--- a/neutron_lib/api/definitions/base.py
+++ b/neutron_lib/api/definitions/base.py
@@ -116,6 +116,7 @@ KNOWN_EXTENSIONS = (
     'security-group',
     'segment',
     'service-type',
+    'sort-key-validation',
     'sorting',
     'standard-attr-description',
     'standard-attr-revisions',
diff --git a/neutron_lib/api/definitions/sort_key_validation.py b/neutron_lib/api/definitions/sort_key_validation.py
new file mode 100644
index 000000000..350b0a6c7
--- /dev/null
+++ b/neutron_lib/api/definitions/sort_key_validation.py
@@ -0,0 +1,27 @@
+#    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 sorting
+
+
+ALIAS = 'sort-key-validation'
+IS_SHIM_EXTENSION = True
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = 'Sort keys validation'
+DESCRIPTION = 'Provides validation on sort keys.'
+UPDATED_TIMESTAMP = '2018-07-04T10:00:00-00:00'
+RESOURCE_ATTRIBUTE_MAP = {}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = [sorting.ALIAS]
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}
diff --git a/neutron_lib/tests/unit/api/definitions/test_sort_key_validation.py b/neutron_lib/tests/unit/api/definitions/test_sort_key_validation.py
new file mode 100644
index 000000000..650f63b52
--- /dev/null
+++ b/neutron_lib/tests/unit/api/definitions/test_sort_key_validation.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 sort_key_validation as apidef
+from neutron_lib.tests.unit.api.definitions import base
+
+
+class SortKeyValidationiDefinitionTestCase(base.DefinitionBaseTestCase):
+    extension_module = apidef
diff --git a/releasenotes/notes/add-api-extension-sort-key-validation-b42f5839671fe5f5.yaml b/releasenotes/notes/add-api-extension-sort-key-validation-b42f5839671fe5f5.yaml
new file mode 100644
index 000000000..3af695536
--- /dev/null
+++ b/releasenotes/notes/add-api-extension-sort-key-validation-b42f5839671fe5f5.yaml
@@ -0,0 +1,12 @@
+---
+features:
+  - |
+    Add API extension ``sort-key-validation``. This extension indicates if the
+    server supports validation on sorting.
+other:
+  - |
+    API extension ``sort-key-validation`` relies on the ``is_sort_key`` keyword
+    in the ``RESOURCE_ATTRIBUTE_MAP`` to judge if an attribute can be used as
+    sort key. Neutron plugins which want to support sort key validation
+    needs to set ``is_sort_key`` to ``True`` for each attribute in their
+    resource attribute map.