diff --git a/ryu/app/simple_isolation.py b/ryu/app/simple_isolation.py
index 3535e73e..b17fd14d 100644
--- a/ryu/app/simple_isolation.py
+++ b/ryu/app/simple_isolation.py
@@ -52,6 +52,12 @@ class SimpleIsolation(app_manager.RyuApp):
 
     @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
     def switch_features_handler(self, ev):
+        msg = ev.msg
+        datapath = msg.datapath
+
+        datapath.send_delete_all_flows()
+        datapath.send_barrier()
+
         self.mac2port.dpid_add(ev.msg.datapath_id)
         self.nw.add_datapath(ev.msg)
 
diff --git a/ryu/controller/handler.py b/ryu/controller/handler.py
index 9fc4e5ab..14f67580 100644
--- a/ryu/controller/handler.py
+++ b/ryu/controller/handler.py
@@ -191,23 +191,6 @@ class ConfigHandler(object):
             )
         datapath.send_msg(set_config)
 
-        #
-        # drop all flows in order to put datapath into unknown state
-        #
-        datapath.send_delete_all_flows()
-
-        datapath.send_barrier()
-
-        # We had better to move on to the main state after getting the
-        # response of the barrier since it guarantees that the switch
-        # is in the known state (all the flows were removed). However,
-        # cbench doesn't work because it ignores the barrier. Also,
-        # the above "known" state doesn't always work (for example,
-        # the secondary controller should not remove all the flows in
-        # the case of HA configuration). Let's move on to the main
-        # state here for now. I guess that we need API to enable
-        # applications to initialize switches in their own ways.
-
         LOG.debug('move onto main mode')
         ev.msg.datapath.ev_q.set_dispatcher(MAIN_DISPATCHER)