diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py
index 454d54cabbdc..b9faa61ad269 100644
--- a/nova/db/sqlalchemy/api.py
+++ b/nova/db/sqlalchemy/api.py
@@ -1168,6 +1168,13 @@ def fixed_ip_associate(context, address, instance_uuid, network_id=None,
 @main_context_manager.writer
 def fixed_ip_associate_pool(context, network_id, instance_uuid=None,
                             host=None, virtual_interface_id=None):
+    """allocate a fixed ip out of a fixed ip network pool.
+
+    This allocates an unallocated fixed ip out of a specified
+    network. We sort by updated_at to hand out the oldest address in
+    the list.
+
+    """
     if instance_uuid and not uuidutils.is_uuid_like(instance_uuid):
         raise exception.InvalidUUID(uuid=instance_uuid)
 
@@ -1179,6 +1186,7 @@ def fixed_ip_associate_pool(context, network_id, instance_uuid=None,
                            filter_by(instance_uuid=None).\
                            filter_by(host=None).\
                            filter_by(leased=False).\
+                           order_by(asc(models.FixedIp.updated_at)).\
                            first()
 
     if not fixed_ip_ref:
diff --git a/nova/tests/unit/db/test_db_api.py b/nova/tests/unit/db/test_db_api.py
index 6a1d8ac25ff0..601e2d9fdad0 100644
--- a/nova/tests/unit/db/test_db_api.py
+++ b/nova/tests/unit/db/test_db_api.py
@@ -4794,6 +4794,27 @@ class FixedIPTestCase(BaseInstanceTypeTestCase):
         fixed_ip = db.fixed_ip_get_by_address(self.ctxt, address)
         self.assertEqual(fixed_ip['instance_uuid'], instance_uuid)
 
+    def test_fixed_ip_associate_pool_order(self):
+        """Test that fixed_ip always uses oldest fixed_ip.
+
+        We should always be using the fixed ip with the oldest
+        updated_at.
+        """
+        instance_uuid = self._create_instance()
+        network = db.network_create_safe(self.ctxt, {})
+        self.addCleanup(timeutils.clear_time_override)
+        start = timeutils.utcnow()
+        for i in range(1, 4):
+            now = start - datetime.timedelta(hours=i)
+            timeutils.set_time_override(now)
+            address = self.create_fixed_ip(
+                updated_at=now,
+                address='10.1.0.%d' % i,
+                network_id=network['id'])
+        db.fixed_ip_associate_pool(self.ctxt, network['id'], instance_uuid)
+        fixed_ip = db.fixed_ip_get_by_address(self.ctxt, address)
+        self.assertEqual(fixed_ip['instance_uuid'], instance_uuid)
+
     def test_fixed_ip_associate_pool_succeeds_fip_ref_network_id_is_none(self):
         instance_uuid = self._create_instance()
         network = db.network_create_safe(self.ctxt, {})