diff --git a/manila/api/common.py b/manila/api/common.py
index 605243157f..f14bb55830 100644
--- a/manila/api/common.py
+++ b/manila/api/common.py
@@ -614,7 +614,7 @@ def validate_subnet_create(context, share_network_id, data,
     return share_network, existing_subnets
 
 
-def _check_metadata_properties(metadata=None):
+def check_metadata_properties(metadata=None):
     if not metadata:
         metadata = {}
 
diff --git a/manila/api/openstack/api_version_request.py b/manila/api/openstack/api_version_request.py
index 26b5b0d95a..12c13ef888 100644
--- a/manila/api/openstack/api_version_request.py
+++ b/manila/api/openstack/api_version_request.py
@@ -194,6 +194,7 @@ REST_API_VERSION_HISTORY = """
              promote API.
     * 2.76 - Added 'default_ad_site' field in security service object.
     * 2.77 - Added support for share transfer between different projects.
+    * 2.78 - Added Share Network Subnet Metadata to Metadata API.
 
 """
 
@@ -201,7 +202,7 @@ REST_API_VERSION_HISTORY = """
 # The default api version request is defined to be the
 # minimum version of the API supported.
 _MIN_API_VERSION = "2.0"
-_MAX_API_VERSION = "2.77"
+_MAX_API_VERSION = "2.78"
 DEFAULT_API_VERSION = _MIN_API_VERSION
 
 
diff --git a/manila/api/openstack/rest_api_version_history.rst b/manila/api/openstack/rest_api_version_history.rst
index f333f02b53..03aad792dc 100644
--- a/manila/api/openstack/rest_api_version_history.rst
+++ b/manila/api/openstack/rest_api_version_history.rst
@@ -422,3 +422,8 @@ ____
 2.77
 ----
   Added support for share transfer between different projects.
+
+2.78
+----
+  Added Metadata API methods (GET, PUT, POST, DELETE)
+  to Share Network Subnets.
diff --git a/manila/api/v1/share_metadata.py b/manila/api/v1/share_metadata.py
index 589a4470aa..0d08a33712 100644
--- a/manila/api/v1/share_metadata.py
+++ b/manila/api/v1/share_metadata.py
@@ -134,7 +134,7 @@ class ShareMetadataController(object):
                 _metadata = orig_meta.copy()
                 _metadata.update(metadata_copy)
 
-            api_common._check_metadata_properties(_metadata)
+            api_common.check_metadata_properties(_metadata)
             db.share_metadata_update(context, share['id'],
                                      _metadata, delete)
 
diff --git a/manila/api/v2/metadata.py b/manila/api/v2/metadata.py
index 78e0056a64..40afd306dc 100644
--- a/manila/api/v2/metadata.py
+++ b/manila/api/v2/metadata.py
@@ -27,36 +27,43 @@ class MetadataController(object):
     resource_get = {
         "share": "share_get",
         "share_snapshot": "share_snapshot_get",
+        "share_network_subnet": "share_network_subnet_get",
     }
 
     resource_metadata_get = {
         "share": "share_metadata_get",
         "share_snapshot": "share_snapshot_metadata_get",
+        "share_network_subnet": "share_network_subnet_metadata_get",
     }
 
     resource_metadata_get_item = {
         "share": "share_metadata_get_item",
         "share_snapshot": "share_snapshot_metadata_get_item",
+        "share_network_subnet": "share_network_subnet_metadata_get_item",
     }
 
     resource_metadata_update = {
         "share": "share_metadata_update",
         "share_snapshot": "share_snapshot_metadata_update",
+        "share_network_subnet": "share_network_subnet_metadata_update",
     }
 
     resource_metadata_update_item = {
         "share": "share_metadata_update_item",
         "share_snapshot": "share_snapshot_metadata_update_item",
+        "share_network_subnet": "share_network_subnet_metadata_update_item",
     }
 
     resource_metadata_delete = {
         "share": "share_metadata_delete",
         "share_snapshot": "share_snapshot_metadata_delete",
+        "share_network_subnet": "share_network_subnet_metadata_delete",
     }
 
     resource_policy_get = {
         'share': 'get',
         'share_snapshot': 'get_snapshot',
+        'share_network_subnet': 'show',
     }
 
     def __init__(self):
@@ -65,7 +72,7 @@ class MetadataController(object):
 
     def _get_resource(self, context, resource_id,
                       for_modification=False, parent_id=None):
-        if self.resource_name in ['share']:
+        if self.resource_name in ['share', 'share_network_subnet']:
             # we would allow retrieving some "public" resources
             # across project namespaces excpet share snaphots,
             # project_only=True is hard coded
@@ -114,7 +121,7 @@ class MetadataController(object):
         context = req.environ['manila.context']
         try:
             metadata = body['metadata']
-            common._check_metadata_properties(metadata)
+            common.check_metadata_properties(metadata)
         except (KeyError, TypeError):
             msg = _("Malformed request body")
             raise exc.HTTPBadRequest(explanation=msg)
@@ -140,7 +147,7 @@ class MetadataController(object):
         context = req.environ['manila.context']
         try:
             meta_item = body['metadata']
-            common._check_metadata_properties(meta_item)
+            common.check_metadata_properties(meta_item)
         except (TypeError, KeyError):
             expl = _('Malformed request body')
             raise exc.HTTPBadRequest(explanation=expl)
@@ -171,7 +178,7 @@ class MetadataController(object):
         context = req.environ['manila.context']
         try:
             metadata = body['metadata']
-            common._check_metadata_properties(metadata)
+            common.check_metadata_properties(metadata)
         except (TypeError, KeyError):
             expl = _('Malformed request body')
             raise exc.HTTPBadRequest(explanation=expl)
diff --git a/manila/api/v2/router.py b/manila/api/v2/router.py
index 0dfe82f13e..fcc74f9932 100644
--- a/manila/api/v2/router.py
+++ b/manila/api/v2/router.py
@@ -403,6 +403,48 @@ class APIRouter(manila.api.openstack.APIRouter):
                            action="index",
                            conditions={"method": ["GET"]})
 
+        for path_prefix in ['/{project_id}', '']:
+            # project_id is optional
+            mapper.connect("subnets_metadata",
+                           "%s/share-networks/{share_network_id}"
+                           "/subnets/{resource_id}/metadata" % path_prefix,
+                           controller=self.resources["share_network_subnets"],
+                           action="create_metadata",
+                           conditions={"method": ["POST"]})
+            mapper.connect("subnets_metadata",
+                           "%s/share-networks/{share_network_id}"
+                           "/subnets/{resource_id}/metadata" % path_prefix,
+                           controller=self.resources["share_network_subnets"],
+                           action="update_all_metadata",
+                           conditions={"method": ["PUT"]})
+            mapper.connect("subnets_metadata",
+                           "%s/share-networks/{share_network_id}"
+                           "/subnets/{resource_id}"
+                           "/metadata/{key}" % path_prefix,
+                           controller=self.resources["share_network_subnets"],
+                           action="update_metadata_item",
+                           conditions={"method": ["POST"]})
+            mapper.connect("subnets_metadata",
+                           "%s/share-networks/{share_network_id}"
+                           "/subnets/{resource_id}/metadata" % path_prefix,
+                           controller=self.resources["share_network_subnets"],
+                           action="index_metadata",
+                           conditions={"method": ["GET"]})
+            mapper.connect("subnets_metadata",
+                           "%s/share-networks/{share_network_id}"
+                           "/subnets/{resource_id}"
+                           "/metadata/{key}" % path_prefix,
+                           controller=self.resources["share_network_subnets"],
+                           action="show_metadata",
+                           conditions={"method": ["GET"]})
+            mapper.connect("subnets_metadata",
+                           "%s/share-networks/{share_network_id}"
+                           "/subnets/{resource_id}"
+                           "/metadata/{key}" % path_prefix,
+                           controller=self.resources["share_network_subnets"],
+                           action="delete_metadata",
+                           conditions={"method": ["DELETE"]})
+
         self.resources["share_servers"] = share_servers.create_resource()
         mapper.resource("share_server",
                         "share-servers",
diff --git a/manila/api/v2/share_network_subnets.py b/manila/api/v2/share_network_subnets.py
index ae403f8ded..19aba3e980 100644
--- a/manila/api/v2/share_network_subnets.py
+++ b/manila/api/v2/share_network_subnets.py
@@ -21,8 +21,10 @@ from oslo_log import log
 import webob
 from webob import exc
 
+from manila.api import common as api_common
 from manila.api.openstack import api_version_request as api_version
 from manila.api.openstack import wsgi
+from manila.api.v2 import metadata as metadata_controller
 from manila.api.views import share_network_subnets as subnet_views
 from manila.db import api as db_api
 from manila import exception
@@ -33,7 +35,8 @@ from manila.share import rpcapi as share_rpcapi
 LOG = log.getLogger(__name__)
 
 
-class ShareNetworkSubnetController(wsgi.Controller):
+class ShareNetworkSubnetController(wsgi.Controller,
+                                   metadata_controller.MetadataController):
     """The Share Network Subnet API controller for the OpenStack API."""
 
     resource_name = 'share_network_subnet'
@@ -116,6 +119,12 @@ class ShareNetworkSubnetController(wsgi.Controller):
             msg = _("Share Network Subnet is missing from the request body.")
             raise exc.HTTPBadRequest(explanation=msg)
         data = body['share-network-subnet']
+
+        if req.api_version_request >= api_version.APIVersionRequest("2.78"):
+            api_common.check_metadata_properties(data.get('metadata'))
+        else:
+            data.pop('metadata', None)
+
         data['share_network_id'] = share_network_id
         multiple_subnet_support = (req.api_version_request >=
                                    api_version.APIVersionRequest("2.70"))
@@ -181,6 +190,49 @@ class ShareNetworkSubnetController(wsgi.Controller):
         return self._view_builder.build_share_network_subnet(
             req, share_network_subnet)
 
+    @wsgi.Controller.api_version("2.78")
+    @wsgi.Controller.authorize("get_metadata")
+    def index_metadata(self, req, share_network_id, resource_id):
+        """Returns the list of metadata for a given share network subnet."""
+        return self._index_metadata(req, resource_id,
+                                    parent_id=share_network_id)
+
+    @wsgi.Controller.api_version("2.78")
+    @wsgi.Controller.authorize("update_metadata")
+    def create_metadata(self, req, share_network_id, resource_id, body):
+        """Create metadata for a given share network subnet."""
+        return self._create_metadata(req, resource_id, body,
+                                     parent_id=share_network_id)
+
+    @wsgi.Controller.api_version("2.78")
+    @wsgi.Controller.authorize("update_metadata")
+    def update_all_metadata(self, req, share_network_id, resource_id, body):
+        """Update entire metadata for a given share network subnet."""
+        return self._update_all_metadata(req, resource_id, body,
+                                         parent_id=share_network_id)
+
+    @wsgi.Controller.api_version("2.78")
+    @wsgi.Controller.authorize("update_metadata")
+    def update_metadata_item(self, req, share_network_id, resource_id, body,
+                             key):
+        """Update metadata item for a given share network subnet."""
+        return self._update_metadata_item(req, resource_id, body, key,
+                                          parent_id=share_network_id)
+
+    @wsgi.Controller.api_version("2.78")
+    @wsgi.Controller.authorize("get_metadata")
+    def show_metadata(self, req, share_network_id, resource_id, key):
+        """Show metadata for a given share network subnet."""
+        return self._show_metadata(req, resource_id, key,
+                                   parent_id=share_network_id)
+
+    @wsgi.Controller.api_version("2.78")
+    @wsgi.Controller.authorize("delete_metadata")
+    def delete_metadata(self, req, share_network_id, resource_id, key):
+        """Delete metadata for a given share network subnet."""
+        return self._delete_metadata(req, resource_id, key,
+                                     parent_id=share_network_id)
+
 
 def create_resource():
     return wsgi.Resource(ShareNetworkSubnetController())
diff --git a/manila/api/views/share_network_subnets.py b/manila/api/views/share_network_subnets.py
index 342ff2bec0..25d071ed53 100644
--- a/manila/api/views/share_network_subnets.py
+++ b/manila/api/views/share_network_subnets.py
@@ -20,6 +20,9 @@ class ViewBuilder(common.ViewBuilder):
     """Model a server API response as a python dictionary."""
 
     _collection_name = 'share_network_subnets'
+    _detail_version_modifiers = [
+        "add_metadata"
+    ]
 
     def build_share_network_subnet(self, request, share_network_subnet):
         return {
@@ -51,3 +54,7 @@ class ViewBuilder(common.ViewBuilder):
         }
         self.update_versioned_resource_dict(request, sns, share_network_subnet)
         return sns
+
+    @common.ViewBuilder.versioned_method("2.78")
+    def add_metadata(self, context, share_network_subnet_dict, sns):
+        share_network_subnet_dict['metadata'] = sns.get('subnet_metadata')
diff --git a/manila/api/views/share_networks.py b/manila/api/views/share_networks.py
index 2c8f5c9afd..bb2a5c4719 100644
--- a/manila/api/views/share_networks.py
+++ b/manila/api/views/share_networks.py
@@ -23,7 +23,8 @@ class ViewBuilder(common.ViewBuilder):
     _detail_version_modifiers = ["add_gateway", "add_mtu", "add_nova_net_id",
                                  "add_subnets",
                                  "add_status_and_sec_service_update_fields",
-                                 "add_network_allocation_update_support_field"]
+                                 "add_network_allocation_update_support_field",
+                                 "add_subnet_with_metadata"]
 
     def build_share_network(self, request, share_network):
         """View of a share network."""
@@ -104,7 +105,7 @@ class ViewBuilder(common.ViewBuilder):
             self.update_versioned_resource_dict(request, sn, share_network)
         return sn
 
-    @common.ViewBuilder.versioned_method("2.51")
+    @common.ViewBuilder.versioned_method("2.51", "2.77")
     def add_subnets(self, context, network_dict, network):
         subnets = [{
             'id': sns.get('id'),
@@ -152,3 +153,28 @@ class ViewBuilder(common.ViewBuilder):
             self, context, network_dict, network):
         network_dict['network_allocation_update_support'] = network.get(
             'network_allocation_update_support')
+
+    @common.ViewBuilder.versioned_method("2.78")
+    def add_subnet_with_metadata(self, context, network_dict, network):
+        subnets = [{
+            'id': sns.get('id'),
+            'availability_zone': sns.get('availability_zone'),
+            'created_at': sns.get('created_at'),
+            'updated_at': sns.get('updated_at'),
+            'segmentation_id': sns.get('segmentation_id'),
+            'neutron_net_id': sns.get('neutron_net_id'),
+            'neutron_subnet_id': sns.get('neutron_subnet_id'),
+            'ip_version': sns.get('ip_version'),
+            'cidr': sns.get('cidr'),
+            'network_type': sns.get('network_type'),
+            'mtu': sns.get('mtu'),
+            'gateway': sns.get('gateway'),
+            'metadata': sns.get('subnet_metadata'),
+        } for sns in network.get('share_network_subnets')]
+
+        network_dict['share_network_subnets'] = subnets
+        attr_to_remove = [
+            'neutron_net_id', 'neutron_subnet_id', 'network_type',
+            'segmentation_id', 'cidr', 'ip_version', 'gateway', 'mtu']
+        for attr in attr_to_remove:
+            network_dict.pop(attr)
diff --git a/manila/db/api.py b/manila/db/api.py
index a5ded26fe3..1424bba0ce 100644
--- a/manila/db/api.py
+++ b/manila/db/api.py
@@ -1072,10 +1072,11 @@ def share_network_subnet_update(context, network_subnet_id, values):
     return IMPL.share_network_subnet_update(context, network_subnet_id, values)
 
 
-def share_network_subnet_get(context, network_subnet_id, session=None):
+def share_network_subnet_get(context, network_subnet_id, session=None,
+                             parent_id=None):
     """Get requested share network subnet DB record."""
     return IMPL.share_network_subnet_get(context, network_subnet_id,
-                                         session=session)
+                                         session=session, parent_id=parent_id)
 
 
 def share_network_subnet_get_all_with_same_az(context, network_subnet_id,
@@ -1118,8 +1119,47 @@ def share_network_subnet_get_all_by_share_server_id(context, share_server_id):
     return IMPL.share_network_subnet_get_all_by_share_server_id(
         context, share_server_id)
 
+####################
 
-##################
+
+def share_network_subnet_metadata_get(context, share_network_subnet_id,
+                                      **kwargs):
+    """Get all metadata for a share network subnet."""
+    return IMPL.share_network_subnet_metadata_get(context,
+                                                  share_network_subnet_id,
+                                                  **kwargs)
+
+
+def share_network_subnet_metadata_get_item(context, share_network_subnet_id,
+                                           key):
+    """Get metadata item for a share network subnet."""
+    return IMPL.share_network_subnet_metadata_get_item(context,
+                                                       share_network_subnet_id,
+                                                       key)
+
+
+def share_network_subnet_metadata_delete(context, share_network_subnet_id,
+                                         key):
+    """Delete the given metadata item."""
+    IMPL.share_network_subnet_metadata_delete(context, share_network_subnet_id,
+                                              key)
+
+
+def share_network_subnet_metadata_update(context, share_network_subnet_id,
+                                         metadata, delete):
+    """Update metadata if it exists, otherwise create it."""
+    return IMPL.share_network_subnet_metadata_update(context,
+                                                     share_network_subnet_id,
+                                                     metadata, delete)
+
+
+def share_network_subnet_metadata_update_item(context, share_network_subnet_id,
+                                              metadata):
+    """Update metadata item if it exists, otherwise create it."""
+    return IMPL.share_network_subnet_metadata_update_item(
+        context, share_network_subnet_id, metadata)
+
+###################
 
 
 def network_allocation_create(context, values):
diff --git a/manila/db/migrations/alembic/versions/ac0620cbe74d_add_share_network_subnet_metadata.py b/manila/db/migrations/alembic/versions/ac0620cbe74d_add_share_network_subnet_metadata.py
new file mode 100644
index 0000000000..d7b7d5cb75
--- /dev/null
+++ b/manila/db/migrations/alembic/versions/ac0620cbe74d_add_share_network_subnet_metadata.py
@@ -0,0 +1,67 @@
+# 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.
+
+"""Add share network subnet metadata
+
+Revision ID: ac0620cbe74d
+Revises: 1e2d600bf972
+Create Date: 2023-01-07 14:13:25.525968
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'ac0620cbe74d'
+down_revision = '1e2d600bf972'
+
+from alembic import op
+from oslo_log import log
+import sqlalchemy as sql
+
+LOG = log.getLogger(__name__)
+
+share_network_subnet_metadata_table_name = 'share_network_subnet_metadata'
+
+
+def upgrade():
+    context = op.get_context()
+    mysql_dl = context.bind.dialect.name == 'mysql'
+    datetime_type = (sql.dialects.mysql.DATETIME(fsp=6)
+                     if mysql_dl else sql.DateTime)
+    try:
+        op.create_table(
+            share_network_subnet_metadata_table_name,
+            sql.Column('deleted', sql.String(36), default='False'),
+            sql.Column('created_at', datetime_type),
+            sql.Column('updated_at', datetime_type),
+            sql.Column('deleted_at', datetime_type),
+            sql.Column('share_network_subnet_id', sql.String(36),
+                       sql.ForeignKey('share_network_subnets.id'),
+                       nullable=False),
+            sql.Column('key', sql.String(255), nullable=False),
+            sql.Column('value', sql.String(1023), nullable=False),
+            sql.Column('id', sql.Integer, primary_key=True, nullable=False),
+            mysql_engine='InnoDB',
+            mysql_charset='utf8'
+        )
+    except Exception:
+        LOG.error("Table |%s| not created!",
+                  share_network_subnet_metadata_table_name)
+        raise
+
+
+def downgrade():
+    try:
+        op.drop_table(share_network_subnet_metadata_table_name)
+    except Exception:
+        LOG.error("Table |%s| not dropped!",
+                  share_network_subnet_metadata_table_name)
+        raise
diff --git a/manila/db/sqlalchemy/api.py b/manila/db/sqlalchemy/api.py
index 3d60db9a61..316a13a630 100644
--- a/manila/db/sqlalchemy/api.py
+++ b/manila/db/sqlalchemy/api.py
@@ -201,6 +201,20 @@ def require_share_snapshot_exists(f):
     return wrapper
 
 
+def require_share_network_subnet_exists(f):
+    """Decorator to require the specified share network subnet to exist.
+
+    Requires the wrapped function to use context and share_network_subnet_id
+    as their first two arguments.
+    """
+    @wraps(f)
+    def wrapper(context, share_network_subnet_id, *args, **kwargs):
+        share_network_subnet_get(context, share_network_subnet_id)
+        return f(context, share_network_subnet_id, *args, **kwargs)
+    wrapper.__name__ = f.__name__
+    return wrapper
+
+
 def require_share_instance_exists(f):
     """Decorator to require the specified share instance to exist.
 
@@ -4611,12 +4625,16 @@ def _network_subnet_get_query(context, session=None):
     if session is None:
         session = get_session()
     return (model_query(context, models.ShareNetworkSubnet, session=session).
-            options(joinedload('share_servers'), joinedload('share_network')))
+            options(joinedload('share_servers'),
+                    joinedload('share_network'),
+                    joinedload('share_network_subnet_metadata')))
 
 
 @require_context
 def share_network_subnet_create(context, values):
     values = ensure_model_dict_has_id(values)
+    values['share_network_subnet_metadata'] = _metadata_refs(
+        values.pop('metadata', {}), models.ShareNetworkSubnetMetadata)
 
     network_subnet_ref = models.ShareNetworkSubnet()
     network_subnet_ref.update(values)
@@ -4635,6 +4653,8 @@ def share_network_subnet_delete(context, network_subnet_id):
         network_subnet_ref = share_network_subnet_get(context,
                                                       network_subnet_id,
                                                       session=session)
+        session.query(models.ShareNetworkSubnetMetadata).filter_by(
+            share_network_subnet_id=network_subnet_id).soft_delete()
         network_subnet_ref.soft_delete(session=session, update_status=True)
 
 
@@ -4652,9 +4672,13 @@ def share_network_subnet_update(context, network_subnet_id, values):
 
 
 @require_context
-def share_network_subnet_get(context, network_subnet_id, session=None):
+def share_network_subnet_get(context, network_subnet_id, session=None,
+                             parent_id=None):
+    kwargs = {'id': network_subnet_id}
+    if parent_id:
+        kwargs['share_network_id'] = parent_id
     result = (_network_subnet_get_query(context, session)
-              .filter_by(id=network_subnet_id)
+              .filter_by(**kwargs)
               .first())
     if result is None:
         raise exception.ShareNetworkSubnetNotFound(
@@ -4740,10 +4764,126 @@ def share_network_subnet_get_all_by_share_server_id(context, share_server_id):
 
     return result
 
-
 ###################
 
 
+@require_context
+@require_share_network_subnet_exists
+def share_network_subnet_metadata_get(context, share_network_subnet_id):
+    session = get_session()
+    return _share_network_subnet_metadata_get(context, share_network_subnet_id,
+                                              session=session)
+
+
+@require_context
+@require_share_network_subnet_exists
+def share_network_subnet_metadata_delete(context, share_network_subnet_id,
+                                         key):
+    session = get_session()
+    meta_ref = _share_network_subnet_metadata_get_item(
+        context, share_network_subnet_id, key, session=session)
+    meta_ref.soft_delete(session=session)
+
+
+@require_context
+@require_share_network_subnet_exists
+def share_network_subnet_metadata_update(context, share_network_subnet_id,
+                                         metadata, delete):
+    session = get_session()
+    return _share_network_subnet_metadata_update(
+        context, share_network_subnet_id, metadata, delete, session=session)
+
+
+def share_network_subnet_metadata_update_item(context, share_network_subnet_id,
+                                              item):
+    session = get_session()
+    return _share_network_subnet_metadata_update(
+        context, share_network_subnet_id, item, delete=False, session=session)
+
+
+def share_network_subnet_metadata_get_item(context, share_network_subnet_id,
+                                           key):
+
+    session = get_session()
+    row = _share_network_subnet_metadata_get_item(
+        context, share_network_subnet_id, key, session=session)
+
+    result = {row['key']: row['value']}
+    return result
+
+
+def _share_network_subnet_metadata_get_query(context, share_network_subnet_id,
+                                             session=None):
+    session = session or get_session()
+    return (model_query(context, models.ShareNetworkSubnetMetadata,
+                        session=session,
+                        read_deleted="no").
+            filter_by(share_network_subnet_id=share_network_subnet_id).
+            options(joinedload('share_network_subnet')))
+
+
+def _share_network_subnet_metadata_get(context, share_network_subnet_id,
+                                       session=None):
+    session = session or get_session()
+    rows = _share_network_subnet_metadata_get_query(
+        context, share_network_subnet_id, session=session).all()
+
+    result = {}
+    for row in rows:
+        result[row['key']] = row['value']
+    return result
+
+
+def _share_network_subnet_metadata_get_item(context, share_network_subnet_id,
+                                            key, session=None):
+    session = session or get_session()
+    result = (_share_network_subnet_metadata_get_query(
+        context, share_network_subnet_id, session=session).
+        filter_by(key=key).first())
+    if not result:
+        raise exception.MetadataItemNotFound
+    return result
+
+
+@oslo_db_api.wrap_db_retry(max_retries=5, retry_on_deadlock=True)
+def _share_network_subnet_metadata_update(context, share_network_subnet_id,
+                                          metadata, delete, session=None):
+    session = session or get_session()
+    delete = strutils.bool_from_string(delete)
+    with session.begin():
+        if delete:
+            original_metadata = _share_network_subnet_metadata_get(
+                context, share_network_subnet_id, session=session)
+            for meta_key, meta_value in original_metadata.items():
+                if meta_key not in metadata:
+                    meta_ref = _share_network_subnet_metadata_get_item(
+                        context, share_network_subnet_id, meta_key,
+                        session=session)
+                    meta_ref.soft_delete(session=session)
+        meta_ref = None
+        # Now update all existing items with new values, or create new meta
+        # objects.
+        for meta_key, meta_value in metadata.items():
+
+            # update the value whether it exists or not.
+            item = {"value": meta_value}
+            meta_ref = _share_network_subnet_metadata_get_query(
+                context, share_network_subnet_id,
+                session=session).filter_by(
+                key=meta_key).first()
+            if not meta_ref:
+                meta_ref = models.ShareNetworkSubnetMetadata()
+                item.update(
+                    {"key": meta_key,
+                     "share_network_subnet_id": share_network_subnet_id})
+            meta_ref.update(item)
+            meta_ref.save(session=session)
+
+        return metadata
+
+#################################
+
+
 def _server_get_query(context, session=None):
     if session is None:
         session = get_session()
diff --git a/manila/db/sqlalchemy/models.py b/manila/db/sqlalchemy/models.py
index d37aaa37e2..5cf7fda4f9 100644
--- a/manila/db/sqlalchemy/models.py
+++ b/manila/db/sqlalchemy/models.py
@@ -1001,7 +1001,7 @@ class ShareNetwork(BASE, ManilaBase):
 class ShareNetworkSubnet(BASE, ManilaBase):
     """Represents a share network subnet used by some resources."""
 
-    _extra_keys = ['availability_zone']
+    _extra_keys = ['availability_zone', 'subnet_metadata']
 
     __tablename__ = 'share_network_subnets'
     id = Column(String(36), primary_key=True, nullable=False)
@@ -1056,6 +1056,35 @@ class ShareNetworkSubnet(BASE, ManilaBase):
     def share_network_name(self):
         return self.share_network['name']
 
+    @property
+    def subnet_metadata(self):
+        metadata_dict = {}
+        metadata_list = (
+            self.share_network_subnet_metadata)  # pylint: disable=no-member
+        for meta in metadata_list:
+            metadata_dict[meta['key']] = meta['value']
+        return metadata_dict
+
+
+class ShareNetworkSubnetMetadata(BASE, ManilaBase):
+    """Represents a metadata key/value pair for a subnet."""
+    __tablename__ = 'share_network_subnet_metadata'
+    id = Column(Integer, primary_key=True)
+    key = Column(String(255), nullable=False)
+    value = Column(String(1023), nullable=False)
+    deleted = Column(String(36), default='False')
+    share_network_subnet_id = Column(String(36), ForeignKey(
+        'share_network_subnets.id'), nullable=False)
+
+    share_network_subnet = orm.relationship(
+        ShareNetworkSubnet,
+        backref=orm.backref('share_network_subnet_metadata', lazy='immediate'),
+        foreign_keys=share_network_subnet_id,
+        primaryjoin='and_('
+        'ShareNetworkSubnetMetadata.share_network_subnet_id == '
+        'ShareNetworkSubnet.id,'
+        'ShareNetworkSubnetMetadata.deleted == "False")')
+
 
 class ShareServer(BASE, ManilaBase):
     """Represents share server used by share."""
diff --git a/manila/policies/share_network_subnet.py b/manila/policies/share_network_subnet.py
index df281ff9bc..18c90f15a5 100644
--- a/manila/policies/share_network_subnet.py
+++ b/manila/policies/share_network_subnet.py
@@ -48,6 +48,24 @@ deprecated_subnet_index = policy.DeprecatedRule(
     deprecated_reason=DEPRECATED_REASON,
     deprecated_since=versionutils.deprecated.WALLABY
 )
+deprecated_update_subnet_metadata = policy.DeprecatedRule(
+    name=BASE_POLICY_NAME % 'update_metadata',
+    check_str=base.RULE_DEFAULT,
+    deprecated_reason=DEPRECATED_REASON,
+    deprecated_since='ANTELOPE'
+)
+deprecated_delete_subnet_metadata = policy.DeprecatedRule(
+    name=BASE_POLICY_NAME % 'delete_metadata',
+    check_str=base.RULE_DEFAULT,
+    deprecated_reason=DEPRECATED_REASON,
+    deprecated_since='ANTELOPE'
+)
+deprecated_get_subnet_metadata = policy.DeprecatedRule(
+    name=BASE_POLICY_NAME % 'get_metadata',
+    check_str=base.RULE_DEFAULT,
+    deprecated_reason=DEPRECATED_REASON,
+    deprecated_since='ANTELOPE'
+)
 
 
 share_network_subnet_policies = [
@@ -105,6 +123,63 @@ share_network_subnet_policies = [
         ],
         deprecated_rule=deprecated_subnet_index
     ),
+    policy.DocumentedRuleDefault(
+        name=BASE_POLICY_NAME % 'update_metadata',
+        check_str=base.ADMIN_OR_PROJECT_MEMBER,
+        scope_types=['system', 'project'],
+        description="Update share network subnet metadata.",
+        operations=[
+            {
+                'method': 'PUT',
+                'path': '/share-networks/{share_network_id}/subnets/'
+                        '{share_network_subnet_id}/metadata',
+            },
+            {
+                'method': 'POST',
+                'path': '/share-networks/{share_network_id}/subnets/'
+                        '{share_network_subnet_id}/metadata/{key}',
+            },
+            {
+                'method': 'POST',
+                'path': '/share-networks/{share_network_id}/subnets/'
+                        '{share_network_subnet_id}/metadata',
+            },
+        ],
+        deprecated_rule=deprecated_update_subnet_metadata
+    ),
+    policy.DocumentedRuleDefault(
+        name=BASE_POLICY_NAME % 'delete_metadata',
+        check_str=base.ADMIN_OR_PROJECT_MEMBER,
+        scope_types=['system', 'project'],
+        description="Delete share network subnet metadata.",
+        operations=[
+            {
+                'method': 'DELETE',
+                'path': '/share-networks/{share_network_id}/subnets/'
+                        '{share_network_subnet_id}/metadata/{key}',
+            }
+        ],
+        deprecated_rule=deprecated_delete_subnet_metadata
+    ),
+    policy.DocumentedRuleDefault(
+        name=BASE_POLICY_NAME % 'get_metadata',
+        check_str=base.ADMIN_OR_PROJECT_READER,
+        scope_types=['system', 'project'],
+        description="Get share network subnet metadata.",
+        operations=[
+            {
+                'method': 'GET',
+                'path': '/share-networks/{share_network_id}/subnets/'
+                        '{share_network_subnet_id}/metadata',
+            },
+            {
+                'method': 'GET',
+                'path': '/share-networks/{share_network_id}/subnets/'
+                        '{share_network_subnet_id}/metadata/{key}',
+            }
+        ],
+        deprecated_rule=deprecated_get_subnet_metadata
+    ),
 ]
 
 
diff --git a/manila/share/api.py b/manila/share/api.py
index 2fecb525f2..204d2d0d9e 100644
--- a/manila/share/api.py
+++ b/manila/share/api.py
@@ -223,7 +223,7 @@ class API(base.Base):
                az_request_multiple_subnet_support_map=None):
         """Create new share."""
 
-        api_common._check_metadata_properties(metadata)
+        api_common.check_metadata_properties(metadata)
 
         if snapshot_id is not None:
             snapshot = self.get_snapshot(context, snapshot_id)
@@ -1449,7 +1449,7 @@ class API(base.Base):
                         force=False, metadata=None):
         policy.check_policy(context, 'share', 'create_snapshot', share)
         if metadata:
-            api_common._check_metadata_properties(metadata)
+            api_common.check_metadata_properties(metadata)
 
         if ((not force) and (share['status'] != constants.STATUS_AVAILABLE)):
             msg = _("Source share status must be "
@@ -2231,7 +2231,7 @@ class API(base.Base):
             msg = _("Invalid share access level: %s.") % access_level
             raise exception.InvalidShareAccess(reason=msg)
 
-        api_common._check_metadata_properties(metadata)
+        api_common.check_metadata_properties(metadata)
         access_exists = self.db.share_access_check_for_existing_access(
             ctx, share['id'], access_type, access_to)
 
@@ -2413,7 +2413,7 @@ class API(base.Base):
     def update_share_access_metadata(self, context, access_id, metadata):
         """Updates share access metadata."""
         try:
-            api_common._check_metadata_properties(metadata)
+            api_common.check_metadata_properties(metadata)
         except exception.InvalidMetadata:
             raise exception.InvalidMetadata()
         except exception.InvalidMetadataSize:
diff --git a/manila/share/manager.py b/manila/share/manager.py
index 89c98ffe33..6f3735b9fe 100644
--- a/manila/share/manager.py
+++ b/manila/share/manager.py
@@ -4209,6 +4209,7 @@ class ShareManager(manager.SchedulerDependentManager):
                 'admin_network_allocations': admin_network_allocations,
                 'backend_details': share_server.get('backend_details'),
                 'network_type': share_network_subnet['network_type'],
+                'subnet_metadata': share_network_subnet['subnet_metadata']
             })
         return network_info
 
diff --git a/manila/tests/api/v2/test_share_network_subnets.py b/manila/tests/api/v2/test_share_network_subnets.py
index 2d7be05e76..cd3b6a9dc4 100644
--- a/manila/tests/api/v2/test_share_network_subnets.py
+++ b/manila/tests/api/v2/test_share_network_subnets.py
@@ -62,8 +62,10 @@ class ShareNetworkSubnetControllerTest(test.TestCase):
                                             mock.Mock(return_value=fake_az))
         self.share_network = db_utils.create_share_network(
             name='fake_network', id='fake_sn_id')
+        self.subnet_metadata = {'fake_key': 'fake_value'}
         self.subnet = db_utils.create_share_network_subnet(
-            share_network_id=self.share_network['id'])
+            share_network_id=self.share_network['id'],
+            metadata=self.subnet_metadata)
         self.share_server = db_utils.create_share_server(
             share_network_subnets=[self.subnet])
         self.share = db_utils.create_share()
@@ -212,27 +214,35 @@ class ShareNetworkSubnetControllerTest(test.TestCase):
         self.mock_policy_check.assert_called_once_with(
             context, self.resource_name, 'delete')
 
-    def _setup_create_test_request_body(self):
+    def _setup_create_test_request_body(self, metadata=False):
         body = {
             'share_network_id': self.share_network['id'],
             'availability_zone': fake_az['name'],
             'neutron_net_id': 'fake_nn_id',
             'neutron_subnet_id': 'fake_nsn_id'
         }
+        if metadata:
+            body['metadata'] = self.subnet_metadata
         return body
 
     @ddt.data({'version': "2.51", 'has_share_servers': False},
               {'version': "2.70", 'has_share_servers': False},
-              {'version': "2.70", 'has_share_servers': True})
+              {'version': "2.70", 'has_share_servers': True},
+              {'version': "2.78", 'has_share_servers': False})
     @ddt.unpack
     def test_subnet_create(self, version, has_share_servers):
         req = fakes.HTTPRequest.blank('/subnets', version=version)
         multiple_subnet_support = (req.api_version_request >=
                                    api_version.APIVersionRequest("2.70"))
+        metadata_support = (req.api_version_request >=
+                            api_version.APIVersionRequest("2.78"))
+
         context = req.environ['manila.context']
         body = {
-            'share-network-subnet': self._setup_create_test_request_body()
+            'share-network-subnet': self._setup_create_test_request_body(
+                metadata=metadata_support)
         }
+
         sn_id = body['share-network-subnet']['share_network_id']
         expected_subnet = copy.deepcopy(self.subnet)
         if has_share_servers:
@@ -251,6 +261,8 @@ class ShareNetworkSubnetControllerTest(test.TestCase):
         mock_share_network_subnet_get = self.mock_object(
             db_api, 'share_network_subnet_get',
             mock.Mock(return_value=expected_subnet))
+        mock_check_metadata_properties = self.mock_object(
+            common, 'check_metadata_properties')
 
         fake_data = body['share-network-subnet']
         fake_data['share_network_id'] = self.share_network['id']
@@ -273,6 +285,8 @@ class ShareNetworkSubnetControllerTest(test.TestCase):
             'mtu': expected_subnet.get('mtu'),
             'gateway': expected_subnet.get('gateway')
         }
+        if metadata_support:
+            view_subnet['metadata'] = self.subnet_metadata
         self.assertEqual(view_subnet, res['share_network_subnet'])
         mock_share_network_subnet_get.assert_called_once_with(
             context, expected_subnet['id'])
@@ -285,6 +299,8 @@ class ShareNetworkSubnetControllerTest(test.TestCase):
         else:
             mock_subnet_create.assert_called_once_with(
                 context, fake_data)
+        self.assertEqual(metadata_support,
+                         mock_check_metadata_properties.called)
 
     @ddt.data({'exception1': exception.ServiceIsDown(service='fake_srv'),
                'exc_raise': exc.HTTPInternalServerError},
@@ -475,3 +491,87 @@ class ShareNetworkSubnetControllerTest(test.TestCase):
                           req,
                           self.share_network['id'])
         mock_sn_get.assert_called_once_with(context, self.share_network['id'])
+
+    def test_index_metadata(self):
+        req = fakes.HTTPRequest.blank('/subnets/', version="2.78")
+        mock_index = self.mock_object(
+            self.controller, '_index_metadata',
+            mock.Mock(return_value='fake_metadata'))
+
+        result = self.controller.index_metadata(req, self.share_network['id'],
+                                                self.subnet['id'])
+
+        self.assertEqual('fake_metadata', result)
+        mock_index.assert_called_once_with(req, self.subnet['id'],
+                                           parent_id=self.share_network['id'])
+
+    def test_create_metadata(self):
+        req = fakes.HTTPRequest.blank('/subnets/', version="2.78")
+        mock_index = self.mock_object(
+            self.controller, '_create_metadata',
+            mock.Mock(return_value='fake_metadata'))
+
+        body = 'fake_metadata_body'
+        result = self.controller.create_metadata(req, self.share_network['id'],
+                                                 self.subnet['id'], body)
+
+        self.assertEqual('fake_metadata', result)
+        mock_index.assert_called_once_with(req, self.subnet['id'], body,
+                                           parent_id=self.share_network['id'])
+
+    def test_update_all_metadata(self):
+        req = fakes.HTTPRequest.blank('/subnets/', version="2.78")
+        mock_index = self.mock_object(
+            self.controller, '_update_all_metadata',
+            mock.Mock(return_value='fake_metadata'))
+
+        body = 'fake_metadata_body'
+        result = self.controller.update_all_metadata(
+            req, self.share_network['id'], self.subnet['id'], body)
+
+        self.assertEqual('fake_metadata', result)
+        mock_index.assert_called_once_with(req, self.subnet['id'], body,
+                                           parent_id=self.share_network['id'])
+
+    def test_update_metadata_item(self):
+        req = fakes.HTTPRequest.blank('/subnets/', version="2.78")
+        mock_index = self.mock_object(
+            self.controller, '_update_metadata_item',
+            mock.Mock(return_value='fake_metadata'))
+
+        body = 'fake_metadata_body'
+        key = 'fake_key'
+        result = self.controller.update_metadata_item(
+            req, self.share_network['id'], self.subnet['id'], body, key)
+
+        self.assertEqual('fake_metadata', result)
+        mock_index.assert_called_once_with(req, self.subnet['id'], body, key,
+                                           parent_id=self.share_network['id'])
+
+    def test_show_metadata(self):
+        req = fakes.HTTPRequest.blank('/subnets/', version="2.78")
+        mock_index = self.mock_object(
+            self.controller, '_show_metadata',
+            mock.Mock(return_value='fake_metadata'))
+
+        key = 'fake_key'
+        result = self.controller.show_metadata(
+            req, self.share_network['id'], self.subnet['id'], key)
+
+        self.assertEqual('fake_metadata', result)
+        mock_index.assert_called_once_with(req, self.subnet['id'], key,
+                                           parent_id=self.share_network['id'])
+
+    def test_delete_metadata(self):
+        req = fakes.HTTPRequest.blank('/subnets/', version="2.78")
+        mock_index = self.mock_object(
+            self.controller, '_delete_metadata',
+            mock.Mock(return_value='fake_metadata'))
+
+        key = 'fake_key'
+        result = self.controller.delete_metadata(
+            req, self.share_network['id'], self.subnet['id'], key)
+
+        self.assertEqual('fake_metadata', result)
+        mock_index.assert_called_once_with(req, self.subnet['id'], key,
+                                           parent_id=self.share_network['id'])
diff --git a/manila/tests/api/views/test_share_network_subnets.py b/manila/tests/api/views/test_share_network_subnets.py
index 6f9fe3953e..9a26819134 100644
--- a/manila/tests/api/views/test_share_network_subnets.py
+++ b/manila/tests/api/views/test_share_network_subnets.py
@@ -16,6 +16,7 @@
 
 import ddt
 
+from manila.api.openstack import api_version_request as api_version
 from manila.api.views import share_network_subnets
 from manila import test
 from manila.tests.api import fakes
@@ -31,11 +32,13 @@ class ViewBuilderTestCase(test.TestCase):
         self.share_network = db_utils.create_share_network(
             name='fake_network', id='fake_sn_id')
 
-    def _validate_is_detail_return(self, result):
+    def _validate_is_detail_return(self, result, metadata_support=False):
         expected_keys = ['id', 'created_at', 'updated_at', 'neutron_net_id',
                          'neutron_subnet_id', 'network_type', 'cidr',
                          'segmentation_id', 'ip_version', 'share_network_id',
                          'availability_zone', 'gateway', 'mtu']
+        if metadata_support:
+            expected_keys.append('metadata')
 
         for key in expected_keys:
             self.assertIn(key, result)
@@ -58,13 +61,19 @@ class ViewBuilderTestCase(test.TestCase):
             result['share_network_subnet']['availability_zone'])
         self._validate_is_detail_return(result['share_network_subnet'])
 
-    def test_build_share_network_subnets(self):
-        req = fakes.HTTPRequest.blank('/subnets', version='2.51')
+    @ddt.data("2.51", "2.78")
+    def test_build_share_network_subnets(self, microversion):
+        metadata_support = (api_version.APIVersionRequest(microversion) >=
+                            api_version.APIVersionRequest('2.78'))
+
+        req = fakes.HTTPRequest.blank('/subnets', version=microversion)
 
         share_network = db_utils.create_share_network(
             name='fake_network', id='fake_sn_id_1')
+
+        expected_metadata = {'fake_key': 'fake_value'}
         subnet = db_utils.create_share_network_subnet(
-            share_network_id=share_network['id'])
+            share_network_id=share_network['id'], metadata=expected_metadata)
 
         result = self.builder.build_share_network_subnets(req, [subnet])
 
@@ -72,4 +81,7 @@ class ViewBuilderTestCase(test.TestCase):
         self.assertEqual(1, len(result['share_network_subnets']))
         subnet_list = result['share_network_subnets']
         for subnet in subnet_list:
-            self._validate_is_detail_return(subnet)
+            self._validate_is_detail_return(subnet,
+                                            metadata_support=metadata_support)
+            if metadata_support:
+                self.assertEqual(expected_metadata, subnet['metadata'])
diff --git a/manila/tests/api/views/test_share_networks.py b/manila/tests/api/views/test_share_networks.py
index 98e6583fbb..d3ebbd9af9 100644
--- a/manila/tests/api/views/test_share_networks.py
+++ b/manila/tests/api/views/test_share_networks.py
@@ -13,6 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import copy
 import ddt
 import itertools
 
@@ -145,6 +146,9 @@ class ViewBuilderTestCase(test.TestCase):
         network_allocation_update_support = (
             api_version.APIVersionRequest(microversion) >=
             api_version.APIVersionRequest('2.69'))
+        subnet_metadata_support = (
+            api_version.APIVersionRequest(microversion) >=
+            api_version.APIVersionRequest('2.78'))
 
         req = fakes.HTTPRequest.blank('/share-networks', version=microversion)
         expected_networks_list = []
@@ -158,8 +162,30 @@ class ViewBuilderTestCase(test.TestCase):
                 'description': share_network.get('description'),
             }
             if subnets_support:
-                share_network.update({'share_network_subnets': []})
-                expected_data.update({'share_network_subnets': []})
+                expected_subnet = {
+                    'id': 'fake_subnet_id',
+                    'availability_zone': 'fake_az',
+                    'created_at': share_network.get('created_at'),
+                    'updated_at': share_network.get('updated_at'),
+                    'segmentation_id': share_network.get('segmentation_id'),
+                    'neutron_net_id': share_network.get('neutron_net_id'),
+                    'neutron_subnet_id': share_network.get(
+                        'neutron_subnet_id'),
+                    'ip_version': share_network.get('ip_version'),
+                    'cidr': share_network.get('cidr'),
+                    'network_type': share_network.get('network_type'),
+                    'mtu': share_network.get('mtu'),
+                    'gateway': share_network.get('gateway'),
+                }
+                subnet = expected_subnet
+                if subnet_metadata_support:
+                    subnet = copy.deepcopy(expected_subnet)
+                    expected_subnet['metadata'] = {'fake_key': 'fake_value'}
+                    subnet['subnet_metadata'] = expected_subnet['metadata']
+
+                expected_data.update(
+                    {'share_network_subnets': [expected_subnet]})
+                share_network.update({'share_network_subnets': [subnet]})
             else:
                 if default_net_info_support:
                     network_data = {
diff --git a/manila/tests/db/migrations/alembic/migrations_data_checks.py b/manila/tests/db/migrations/alembic/migrations_data_checks.py
index e547f2c97a..4d210f7db6 100644
--- a/manila/tests/db/migrations/alembic/migrations_data_checks.py
+++ b/manila/tests/db/migrations/alembic/migrations_data_checks.py
@@ -3253,3 +3253,58 @@ class AddSnapshotMetadata(BaseMigrationChecks):
     def check_downgrade(self, engine):
         self.test_case.assertRaises(sa_exc.NoSuchTableError, utils.load_table,
                                     self.new_table_name, engine)
+
+
+@map_to_migration('ac0620cbe74d')
+class AddSubnetMetadata(BaseMigrationChecks):
+    share_subnet_id = uuidutils.generate_uuid()
+    new_table_name = 'share_network_subnet_metadata'
+
+    def setup_upgrade_data(self, engine):
+        # Setup Share network.
+        share_network_data = {
+            'id': uuidutils.generate_uuid(),
+            'user_id': 'fake',
+            'project_id': 'fake'
+        }
+        network_table = utils.load_table('share_networks', engine)
+        engine.execute(network_table.insert(share_network_data))
+
+        # Setup share network subnet.
+        share_network_subnet_data = {
+            'id': self.share_subnet_id,
+            'share_network_id': share_network_data['id']
+        }
+        network_table = utils.load_table('share_network_subnets', engine)
+        engine.execute(network_table.insert(share_network_subnet_data))
+
+    def check_upgrade(self, engine, data):
+        data = {
+            'id': 1,
+            'key': 't' * 255,
+            'value': 'v' * 1023,
+            'share_network_subnet_id': self.share_subnet_id,
+            'deleted': 'False',
+        }
+
+        new_table = utils.load_table(self.new_table_name, engine)
+        engine.execute(new_table.insert(data))
+
+        item = engine.execute(
+            new_table.select().where(new_table.c.id == data['id'])).first()
+        self.test_case.assertTrue(hasattr(item, 'id'))
+        self.test_case.assertEqual(data['id'], item['id'])
+        self.test_case.assertTrue(hasattr(item, 'key'))
+        self.test_case.assertEqual(data['key'], item['key'])
+        self.test_case.assertTrue(hasattr(item, 'value'))
+        self.test_case.assertEqual(data['value'], item['value'])
+        self.test_case.assertTrue(hasattr(item, 'share_network_subnet_id'))
+        self.test_case.assertEqual(self.share_subnet_id,
+                                   item['share_network_subnet_id'])
+        self.test_case.assertTrue(hasattr(item, 'deleted'))
+        self.test_case.assertEqual('False', item['deleted'])
+
+    def check_downgrade(self, engine):
+        self.test_case.assertRaises(sa_exc.NoSuchTableError,
+                                    utils.load_table,
+                                    self.new_table_name, engine)
diff --git a/manila/tests/db/sqlalchemy/test_api.py b/manila/tests/db/sqlalchemy/test_api.py
index 8caf6ede90..3648ed4a2e 100644
--- a/manila/tests/db/sqlalchemy/test_api.py
+++ b/manila/tests/db/sqlalchemy/test_api.py
@@ -3149,6 +3149,64 @@ class ShareNetworkSubnetDatabaseAPITestCase(BaseDatabaseAPITestCase):
             db_api.share_network_subnet_get_all_by_share_server_id,
             self.fake_context, 'share_server_id')
 
+    def test_share_network_subnet_metadata_get(self):
+        metadata = {'a': 'b', 'c': 'd'}
+
+        subnet_1 = db_api.share_network_subnet_create(
+            self.fake_context, self.subnet_dict)
+        db_api.share_network_subnet_metadata_update(
+            self.fake_context, share_network_subnet_id=subnet_1['id'],
+            metadata=metadata, delete=False)
+        self.assertEqual(
+            metadata, db_api.share_network_subnet_metadata_get(
+                self.fake_context, share_network_subnet_id=subnet_1['id']))
+
+    def test_share_network_subnet_metadata_get_item(self):
+        metadata = {'a': 'b', 'c': 'd'}
+        key = 'a'
+        shouldbe = {'a': 'b'}
+        subnet_1 = db_api.share_network_subnet_create(
+            self.fake_context, self.subnet_dict)
+        db_api.share_network_subnet_metadata_update(
+            self.fake_context, share_network_subnet_id=subnet_1['id'],
+            metadata=metadata, delete=False)
+        self.assertEqual(
+            shouldbe, db_api.share_network_subnet_metadata_get_item(
+                self.fake_context, share_network_subnet_id=subnet_1['id'],
+                key=key))
+
+    def test_share_network_subnet_metadata_update(self):
+        metadata1 = {'a': '1', 'c': '2'}
+        metadata2 = {'a': '3', 'd': '5'}
+        should_be = {'a': '3', 'c': '2', 'd': '5'}
+        subnet_1 = db_api.share_network_subnet_create(
+            self.fake_context, self.subnet_dict)
+        db_api.share_network_subnet_metadata_update(
+            self.fake_context, share_network_subnet_id=subnet_1['id'],
+            metadata=metadata1, delete=False)
+        db_api.share_network_subnet_metadata_update(
+            self.fake_context, share_network_subnet_id=subnet_1['id'],
+            metadata=metadata2, delete=False)
+        self.assertEqual(
+            should_be, db_api.share_network_subnet_metadata_get(
+                self.fake_context, share_network_subnet_id=subnet_1['id']))
+
+    def test_share_network_subnet_metadata_delete(self):
+        key = 'a'
+        metadata = {'a': '1', 'c': '2'}
+        should_be = {'c': '2'}
+        subnet_1 = db_api.share_network_subnet_create(
+            self.fake_context, self.subnet_dict)
+        db_api.share_network_subnet_metadata_update(
+            self.fake_context, share_network_subnet_id=subnet_1['id'],
+            metadata=metadata, delete=False)
+        db_api.share_network_subnet_metadata_delete(
+            self.fake_context, share_network_subnet_id=subnet_1['id'],
+            key=key)
+        self.assertEqual(
+            should_be, db_api.share_network_subnet_metadata_get(
+                self.fake_context, share_network_subnet_id=subnet_1['id']))
+
 
 @ddt.ddt
 class SecurityServiceDatabaseAPITestCase(BaseDatabaseAPITestCase):
diff --git a/manila/tests/share/test_manager.py b/manila/tests/share/test_manager.py
index 0cbc81101e..1bb8056ee1 100644
--- a/manila/tests/share/test_manager.py
+++ b/manila/tests/share/test_manager.py
@@ -3861,7 +3861,8 @@ class ShareManagerTestCase(test.TestCase):
             cidr='fake_cidr',
             neutron_net_id='fake_neutron_net_id',
             neutron_subnet_id='fake_neutron_subnet_id',
-            network_type='fake_network_type')
+            network_type='fake_network_type',
+            subnet_metadata={'fake_key': 'fake_value'})
         expected = [dict(
             server_id=fake_share_server['id'],
             segmentation_id=fake_share_network_subnet['segmentation_id'],
@@ -3874,7 +3875,8 @@ class ShareManagerTestCase(test.TestCase):
             admin_network_allocations=(
                 fake_network_allocations_get_for_share_server(label='admin')),
             backend_details=fake_share_server['backend_details'],
-            network_type=fake_share_network_subnet['network_type'])]
+            network_type=fake_share_network_subnet['network_type'],
+            subnet_metadata=fake_share_network_subnet['subnet_metadata'])]
 
         network_info = self.share_manager._form_server_setup_info(
             self.context, fake_share_server, fake_share_network,
diff --git a/releasenotes/notes/add_share_network_subnet_metadata-ddee482d93030fc3.yaml b/releasenotes/notes/add_share_network_subnet_metadata-ddee482d93030fc3.yaml
new file mode 100644
index 0000000000..95203c7c63
--- /dev/null
+++ b/releasenotes/notes/add_share_network_subnet_metadata-ddee482d93030fc3.yaml
@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Adds share network subnet metadata capabilities including
+    create, update all, update single, show and delete metadata.