diff --git a/neutron/plugins/ml2/plugin.py b/neutron/plugins/ml2/plugin.py
index ef56846d3fd..9e9e5cc4cfd 100644
--- a/neutron/plugins/ml2/plugin.py
+++ b/neutron/plugins/ml2/plugin.py
@@ -1080,7 +1080,8 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
         need_network_update_notify = False
 
         with db_api.CONTEXT_WRITER.using(context):
-            original_network = self.get_network(context, id)
+            db_network = self._get_network(context, id)
+            original_network = self.get_network(context, id, net_db=db_network)
             self._update_provider_network_attributes(
                 context, original_network, net_data)
 
@@ -1091,12 +1092,6 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                                                           updated_network)
             self._process_l3_update(context, updated_network, net_data)
 
-            # ToDO(QoS): This would change once EngineFacade moves out
-            db_network = self._get_network(context, id)
-            # Expire the db_network in current transaction, so that the join
-            # relationship can be updated.
-            context.session.expire(db_network)
-
             if mtuw_apidef.MTU in net_data:
                 db_network.mtu = self._get_network_mtu(db_network)
                 # agents should now update all ports to reflect new MTU
@@ -1138,10 +1133,9 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
         return updated_network
 
     @db_api.retry_if_session_inactive()
-    def get_network(self, context, id, fields=None):
+    def get_network(self, context, id, fields=None, net_db=None):
         with db_api.CONTEXT_READER.using(context):
-            net_db = self._get_network(context, id)
-
+            net_db = net_db or self._get_network(context, id)
             net_data = self._make_network_dict(net_db, context=context)
             self.type_manager.extend_network_dict_provider(context, net_data)