diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 0e75b05f423a..5cbcd532c4ac 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -73,6 +73,7 @@ from nova.openstack.common import log as logging
 from nova.openstack.common import periodic_task
 from nova.openstack.common import rpc
 from nova.openstack.common.rpc import common as rpc_common
+from nova.openstack.common import strutils
 from nova.openstack.common import timeutils
 from nova import paths
 from nova import safe_utils
@@ -1238,6 +1239,12 @@ class ComputeManager(manager.Manager):
                         dhcp_options=dhcp_options)
                 LOG.debug(_('Instance network_info: |%s|'), nwinfo,
                           instance=instance)
+                # NOTE(alaski): This can be done more cleanly once we're sure
+                # we'll receive an object.
+                sys_meta = utils.metadata_to_dict(instance['system_metadata'])
+                sys_meta['network_allocated'] = 'True'
+                self._instance_update(context, instance['uuid'],
+                        system_metadata=sys_meta)
                 return nwinfo
             except Exception:
                 exc_info = sys.exc_info()
@@ -1260,10 +1267,10 @@ class ComputeManager(manager.Manager):
     def _build_networks_for_instance(self, context, instance,
             requested_networks, security_groups):
 
-        # May have been allocated previously and rescheduled to this host
-        network_info = self._get_instance_nw_info(context, instance)
-        if len(network_info) > 0:
-            return network_info
+        # If we're here from a reschedule the network may already be allocated.
+        if strutils.bool_from_string(
+                instance.system_metadata.get('network_allocated', 'False')):
+            return self._get_instance_nw_info(context, instance)
 
         if not self.is_neutron_security_groups:
             security_groups = []
@@ -1722,6 +1729,9 @@ class ComputeManager(manager.Manager):
             raise exception.RescheduledException(
                     instance_uuid=instance.uuid, reason=str(e))
 
+        # NOTE(alaski): This is only useful during reschedules, remove it now.
+        instance.system_metadata.pop('network_allocated', None)
+
         instance.power_state = self._get_power_state(context, instance)
         instance.vm_state = vm_states.ACTIVE
         instance.task_state = None
@@ -1799,6 +1809,8 @@ class ComputeManager(manager.Manager):
             requested_networks):
         try:
             self._deallocate_network(context, instance, requested_networks)
+            instance.system_metadata['network_allocated'] = 'False'
+            instance.save()
         except Exception:
             msg = _('Failed to deallocate networks')
             LOG.exception(msg, instance=instance)
diff --git a/nova/tests/compute/test_compute_mgr.py b/nova/tests/compute/test_compute_mgr.py
index 72e68f556634..059456909395 100644
--- a/nova/tests/compute/test_compute_mgr.py
+++ b/nova/tests/compute/test_compute_mgr.py
@@ -53,9 +53,10 @@ class ComputeManagerUnitTestCase(test.NoDBTestCase):
 
         nwapi = self.compute.network_api
         self.mox.StubOutWithMock(nwapi, 'allocate_for_instance')
+        self.mox.StubOutWithMock(self.compute, '_instance_update')
         self.mox.StubOutWithMock(time, 'sleep')
 
-        instance = {}
+        instance = fake_instance.fake_db_instance(system_metadata={})
         is_vpn = 'fake-is-vpn'
         req_networks = 'fake-req-networks'
         macs = 'fake-macs'
@@ -79,6 +80,8 @@ class ComputeManagerUnitTestCase(test.NoDBTestCase):
                 requested_networks=req_networks, macs=macs,
                 security_groups=sec_groups,
                 dhcp_options=dhcp_options).AndReturn(final_result)
+        self.compute._instance_update(self.context, instance['uuid'],
+                system_metadata={'network_allocated': 'True'})
 
         self.mox.ReplayAll()
 
@@ -1383,28 +1386,47 @@ class ComputeManagerBuildInstanceTestCase(test.NoDBTestCase):
                 self.compute._cleanup_build_resources, self.context,
                 self.instance, self.block_device_mapping)
 
-    def test_build_networks_if_none_found(self):
+    def test_build_networks_if_not_allocated(self):
+        instance = fake_instance.fake_instance_obj(self.context,
+                system_metadata={},
+                expected_attrs=['system_metadata'])
+
         self.mox.StubOutWithMock(self.compute, '_get_instance_nw_info')
         self.mox.StubOutWithMock(self.compute, '_allocate_network')
-        self.compute._get_instance_nw_info(self.context,
-                self.instance).AndReturn(self.network_info)
-        self.compute._allocate_network(self.context, self.instance,
+        self.compute._allocate_network(self.context, instance,
                 self.requested_networks, None, self.security_groups, None)
         self.mox.ReplayAll()
 
-        self.compute._build_networks_for_instance(self.context, self.instance,
+        self.compute._build_networks_for_instance(self.context, instance,
+                self.requested_networks, self.security_groups)
+
+    def test_build_networks_if_allocated_false(self):
+        instance = fake_instance.fake_instance_obj(self.context,
+                system_metadata=dict(network_allocated='False'),
+                expected_attrs=['system_metadata'])
+
+        self.mox.StubOutWithMock(self.compute, '_get_instance_nw_info')
+        self.mox.StubOutWithMock(self.compute, '_allocate_network')
+        self.compute._allocate_network(self.context, instance,
+                self.requested_networks, None, self.security_groups, None)
+        self.mox.ReplayAll()
+
+        self.compute._build_networks_for_instance(self.context, instance,
                 self.requested_networks, self.security_groups)
 
     def test_return_networks_if_found(self):
+        instance = fake_instance.fake_instance_obj(self.context,
+                system_metadata=dict(network_allocated='True'),
+                expected_attrs=['system_metadata'])
+
         def fake_network_info():
             return network_model.NetworkInfo([{'address': '123.123.123.123'}])
 
         self.mox.StubOutWithMock(self.compute, '_get_instance_nw_info')
         self.mox.StubOutWithMock(self.compute, '_allocate_network')
-        self.compute._get_instance_nw_info(self.context,
-                self.instance).AndReturn(
+        self.compute._get_instance_nw_info(self.context, instance).AndReturn(
                     network_model.NetworkInfoAsyncWrapper(fake_network_info))
         self.mox.ReplayAll()
 
-        self.compute._build_networks_for_instance(self.context, self.instance,
+        self.compute._build_networks_for_instance(self.context, instance,
                 self.requested_networks, self.security_groups)