diff --git a/openstack_dashboard/settings.py b/openstack_dashboard/settings.py
index c86a582a34..4e5e8d95d6 100644
--- a/openstack_dashboard/settings.py
+++ b/openstack_dashboard/settings.py
@@ -20,6 +20,7 @@ import glob
 import logging
 import os
 import sys
+import warnings
 
 from django.utils.translation import ugettext_lazy as _
 
@@ -40,6 +41,8 @@ from openstack_dashboard.defaults import *  # noqa: F403,H303
 
 _LOG = logging.getLogger(__name__)
 
+warnings.filterwarnings("default", category=DeprecationWarning)
+
 ROOT_PATH = os.path.dirname(os.path.abspath(__file__))
 
 if ROOT_PATH not in sys.path:
diff --git a/openstack_dashboard/usage/quotas.py b/openstack_dashboard/usage/quotas.py
index e563285154..7986abce96 100644
--- a/openstack_dashboard/usage/quotas.py
+++ b/openstack_dashboard/usage/quotas.py
@@ -13,6 +13,7 @@
 from collections import defaultdict
 import itertools
 import logging
+import warnings
 
 from django.utils.translation import ugettext_lazy as _
 
@@ -361,8 +362,14 @@ def _get_neutron_quota_data(request, qs, disabled_quotas, tenant_id):
     return qs
 
 
+# TODO(amotoki): Deprecated in Ussuri. Drop this in Victoria release or later.
 def _get_tenant_network_usages_legacy(request, usages, disabled_quotas,
                                       tenant_id):
+    warnings.warn(
+        "The legacy way to retrieve neutron resource usage is deprecated "
+        "in Ussuri release. Horizon will depend on 'quota_details' "
+        "neutron extension added in Pike release in future.",
+        DeprecationWarning)
     qs = base.QuotaSet()
     _get_neutron_quota_data(request, qs, disabled_quotas, tenant_id)
     for quota in qs:
diff --git a/releasenotes/notes/deprecate-neutron-quota-legacy-144468a1b269cce8.yaml b/releasenotes/notes/deprecate-neutron-quota-legacy-144468a1b269cce8.yaml
new file mode 100644
index 0000000000..d3a8203614
--- /dev/null
+++ b/releasenotes/notes/deprecate-neutron-quota-legacy-144468a1b269cce8.yaml
@@ -0,0 +1,9 @@
+---
+deprecations:
+  - |
+    The legacy way to retrive neutron resource usages is deprecated.
+    In future, horizon will require ``quota_details`` neutron extension.
+    In the legacy way, horizon list all related resources to count resource usage.
+    It is not efficient and ``quota_details`` neutron extension was added
+    to address it. It was implemented in Pike release and the enough migration
+    period has passed, so we deprecate the legacy way.