diff --git a/neutron/plugins/ml2/plugin.py b/neutron/plugins/ml2/plugin.py
index 15deaf5b5f0..2b26e735f1c 100644
--- a/neutron/plugins/ml2/plugin.py
+++ b/neutron/plugins/ml2/plugin.py
@@ -708,32 +708,30 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
 
         return [self._fields(net, fields) for net in nets]
 
-    def _delete_ports(self, context, ports):
-        for port in ports:
+    def _delete_ports(self, context, port_ids):
+        for port_id in port_ids:
             try:
-                self.delete_port(context, port.id)
-            except (exc.PortNotFound, sa_exc.ObjectDeletedError):
-                context.session.expunge(port)
+                self.delete_port(context, port_id)
+            except exc.PortNotFound:
                 # concurrent port deletion can be performed by
                 # release_dhcp_port caused by concurrent subnet_delete
-                LOG.info(_LI("Port %s was deleted concurrently"), port.id)
+                LOG.info(_LI("Port %s was deleted concurrently"), port_id)
             except Exception:
                 with excutils.save_and_reraise_exception():
                     LOG.exception(_LE("Exception auto-deleting port %s"),
-                                  port.id)
+                                  port_id)
 
-    def _delete_subnets(self, context, subnets):
-        for subnet in subnets:
+    def _delete_subnets(self, context, subnet_ids):
+        for subnet_id in subnet_ids:
             try:
-                self.delete_subnet(context, subnet.id)
-            except (exc.SubnetNotFound, sa_exc.ObjectDeletedError):
-                context.session.expunge(subnet)
+                self.delete_subnet(context, subnet_id)
+            except exc.SubnetNotFound:
                 LOG.info(_LI("Subnet %s was deleted concurrently"),
-                         subnet.id)
+                         subnet_id)
             except Exception:
                 with excutils.save_and_reraise_exception():
                     LOG.exception(_LE("Exception auto-deleting subnet %s"),
-                                  subnet.id)
+                                  subnet_id)
 
     def delete_network(self, context, id):
         # REVISIT(rkukura) The super(Ml2Plugin, self).delete_network()
@@ -797,6 +795,9 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                         # network record, so explicit removal is not necessary.
                         LOG.debug("Committing transaction")
                         break
+
+                    port_ids = [port.id for port in ports]
+                    subnet_ids = [subnet.id for subnet in subnets]
             except os_db_exception.DBError as e:
                 with excutils.save_and_reraise_exception() as ctxt:
                     if isinstance(e.inner_exception, sql_exc.IntegrityError):
@@ -804,8 +805,8 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                         LOG.warning(_LW("A concurrent port creation has "
                                         "occurred"))
                         continue
-            self._delete_ports(context, ports)
-            self._delete_subnets(context, subnets)
+            self._delete_ports(context, port_ids)
+            self._delete_subnets(context, subnet_ids)
 
         try:
             self.mechanism_manager.delete_network_postcommit(mech_context)
diff --git a/neutron/tests/unit/plugins/ml2/test_plugin.py b/neutron/tests/unit/plugins/ml2/test_plugin.py
index 56c0a3d270b..7dc84b50c41 100644
--- a/neutron/tests/unit/plugins/ml2/test_plugin.py
+++ b/neutron/tests/unit/plugins/ml2/test_plugin.py
@@ -24,7 +24,6 @@ import webob
 
 from oslo_db import exception as db_exc
 from oslo_utils import uuidutils
-from sqlalchemy.orm import exc as sqla_exc
 
 from neutron.callbacks import registry
 from neutron.common import constants
@@ -220,18 +219,12 @@ class TestMl2NetworksV2(test_plugin.TestNetworksV2,
         with mock.patch.object(plugin, "delete_port",
                                side_effect=exc.PortNotFound(port_id="123")):
             plugin._delete_ports(mock.MagicMock(), [mock.MagicMock()])
-        with mock.patch.object(plugin, "delete_port",
-                               side_effect=sqla_exc.ObjectDeletedError(None)):
-            plugin._delete_ports(mock.MagicMock(), [mock.MagicMock()])
 
     def test_subnet_delete_helper_tolerates_failure(self):
         plugin = manager.NeutronManager.get_plugin()
         with mock.patch.object(plugin, "delete_subnet",
                                side_effect=exc.SubnetNotFound(subnet_id="1")):
             plugin._delete_subnets(mock.MagicMock(), [mock.MagicMock()])
-        with mock.patch.object(plugin, "delete_subnet",
-                               side_effect=sqla_exc.ObjectDeletedError(None)):
-            plugin._delete_subnets(mock.MagicMock(), [mock.MagicMock()])
 
     def _create_and_verify_networks(self, networks):
         for net_idx, net in enumerate(networks):