diff --git a/src/main/java/org/opencord/cordmcast/CordMcast.java b/src/main/java/org/opencord/cordmcast/CordMcast.java
index c965476..078bcbf 100644
--- a/src/main/java/org/opencord/cordmcast/CordMcast.java
+++ b/src/main/java/org/opencord/cordmcast/CordMcast.java
@@ -41,6 +41,8 @@
 import org.onosproject.core.ApplicationId;
 import org.onosproject.core.CoreService;
 import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.PortNumber;
 import org.onosproject.net.config.ConfigFactory;
 import org.onosproject.net.config.NetworkConfigEvent;
 import org.onosproject.net.config.NetworkConfigListener;
@@ -48,6 +50,7 @@
 import org.onosproject.net.config.basics.SubjectFactories;
 import org.onosproject.net.flow.DefaultTrafficSelector;
 import org.onosproject.net.flow.DefaultTrafficTreatment;
+import org.onosproject.net.flow.FlowRuleService;
 import org.onosproject.net.flow.TrafficSelector;
 import org.onosproject.net.flowobjective.DefaultForwardingObjective;
 import org.onosproject.net.flowobjective.DefaultNextObjective;
@@ -81,6 +84,7 @@
 import java.util.Dictionary;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.Properties;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -105,7 +109,7 @@
     private static final int DEFAULT_REST_TIMEOUT_MS = 1000;
     private static final int DEFAULT_PRIORITY = 500;
     private static final short DEFAULT_MCAST_VLAN = 4000;
-    private static final String DEFAULT_SYNC_HOST = "10.90.0.8:8181";
+    private static final String DEFAULT_SYNC_HOST = "";
     private static final String DEFAULT_USER = "karaf";
     private static final String DEFAULT_PASSWORD = "karaf";
     private static final boolean DEFAULT_VLAN_ENABLED = true;
@@ -131,12 +135,15 @@
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected NetworkConfigRegistry networkConfig;
 
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected FlowRuleService flowRuleService;
+
     protected McastListener listener = new InternalMulticastListener();
     private InternalNetworkConfigListener configListener =
             new InternalNetworkConfigListener();
 
     //TODO: move this to a ec map
-    private Map<IpAddress, Integer> groups = Maps.newConcurrentMap();
+    private Map<NextKey, Integer> groups = Maps.newConcurrentMap();
 
     private ApplicationId appId;
     private ApplicationId coreAppId;
@@ -207,9 +214,19 @@
         componentConfigService.unregisterProperties(getClass(), false);
         mcastService.removeListener(listener);
         networkConfig.removeListener(configListener);
+        networkConfig.unregisterConfigFactory(cordMcastConfigFactory);
+        clearGroups();
         log.info("Stopped");
     }
 
+    public void clearGroups() {
+        groups.keySet().forEach(d -> {
+            flowObjectiveService.next(d.getDevice(), nextObject(groups.get(d), PortNumber.ANY, NextType.Remove));
+        });
+        flowRuleService.removeFlowRulesById(appId);
+        groups.clear();
+    }
+
     @Modified
     public void modified(ComponentContext context) {
         Dictionary<?, ?> properties = context != null ? context.getProperties() : new Properties();
@@ -271,7 +288,47 @@
         }
     }
 
+    private enum NextType { AddNew, AddToExisting, Remove, RemoveFromExisting };
+
+
+    private NextObjective nextObject(Integer id, PortNumber port, NextType nextType) {
+        DefaultNextObjective.Builder build = DefaultNextObjective.builder()
+                .fromApp(appId)
+                .addTreatment(DefaultTrafficTreatment.builder().setOutput(port).build())
+                .withType(NextObjective.Type.BROADCAST)
+                .withId(id);
+        ObjectiveContext content = new ObjectiveContext() {
+            @Override
+            public void onSuccess(Objective objective) {
+                //TODO: change to debug
+                log.info("Next Objective {} installed", objective.id());
+            }
+
+            @Override
+            public void onError(Objective objective, ObjectiveError error) {
+                //TODO: change to debug
+                log.info("Next Objective {} failed, because {}",
+                        objective.id(),
+                        error);
+            }
+        };
+
+        switch (nextType) {
+            case AddNew:
+                return build.add(content);
+            case AddToExisting:
+                return build.addToExisting(content);
+            case Remove:
+                return build.remove(content);
+            case RemoveFromExisting:
+                return build.removeFromExisting(content);
+            default:
+                return null;
+        }
+    }
+
     private void unprovisionGroup(McastRouteInfo info) {
+
         if (info.sinks().isEmpty()) {
             removeRemoteRoute(info.route());
         }
@@ -282,28 +339,12 @@
         }
         ConnectPoint loc = info.sink().get();
 
-        NextObjective next = DefaultNextObjective.builder()
-                .fromApp(appId)
-                .addTreatment(DefaultTrafficTreatment.builder().setOutput(loc.port()).build())
-                .withType(NextObjective.Type.BROADCAST)
-                .withId(groups.get(info.route().group()))
-                .removeFromExisting(new ObjectiveContext() {
-                    @Override
-                    public void onSuccess(Objective objective) {
-                        //TODO: change to debug
-                        log.info("Next Objective {} installed", objective.id());
-                    }
-
-                    @Override
-                    public void onError(Objective objective, ObjectiveError error) {
-                        //TODO: change to debug
-                        log.info("Next Objective {} failed, because {}",
-                                objective.id(),
-                                error);
-                    }
-                });
-
-        flowObjectiveService.next(loc.deviceId(), next);
+        NextKey key = new NextKey(loc.deviceId(), info.route().group());
+        if (groups.get(key) == null) {
+            log.warn("No groups on device: {}", loc.deviceId());
+            return;
+        }
+        flowObjectiveService.next(loc.deviceId(), nextObject(groups.get(key), loc.port(), NextType.RemoveFromExisting));
     }
 
     private void provisionGroup(McastRoute route, ConnectPoint sink) {
@@ -318,37 +359,16 @@
         }
 
         final AtomicBoolean sync = new AtomicBoolean(false);
-
-        Integer nextId = groups.computeIfAbsent(route.group(), (g) -> {
+        NextKey key = new NextKey(sink.deviceId(), route.group());
+        Integer nextId = groups.computeIfAbsent(key, (g) -> {
             Integer id = flowObjectiveService.allocateNextId();
 
-            NextObjective next = DefaultNextObjective.builder()
-                    .fromApp(appId)
-                    .addTreatment(DefaultTrafficTreatment.builder().setOutput(sink.port()).build())
-                    .withType(NextObjective.Type.BROADCAST)
-                    .withId(id)
-                    .add(new ObjectiveContext() {
-                        @Override
-                        public void onSuccess(Objective objective) {
-                            //TODO: change to debug
-                            log.info("Next Objective {} installed", objective.id());
-                        }
-
-                        @Override
-                        public void onError(Objective objective, ObjectiveError error) {
-                            //TODO: change to debug
-                            log.info("Next Objective {} failed, because {}",
-                                    objective.id(),
-                                    error);
-                        }
-                    });
-
-            flowObjectiveService.next(sink.deviceId(), next);
+            flowObjectiveService.next(sink.deviceId(), nextObject(id, sink.port(), NextType.AddNew));
 
             TrafficSelector.Builder mcast = DefaultTrafficSelector.builder()
                     .matchInPort(oltInfo.get().uplink())
                     .matchEthType(Ethernet.TYPE_IPV4)
-                    .matchIPDst(g.toIpPrefix());
+                    .matchIPDst(route.group().toIpPrefix());
 
             if (vlanEnabled) {
                 mcast.matchVlanId(VlanId.vlanId((short) mcastVlan));
@@ -383,28 +403,7 @@
         });
 
         if (!sync.get()) {
-            NextObjective next = DefaultNextObjective.builder()
-                    .fromApp(appId)
-                    .addTreatment(DefaultTrafficTreatment.builder().setOutput(sink.port()).build())
-                    .withType(NextObjective.Type.BROADCAST)
-                    .withId(nextId)
-                    .addToExisting(new ObjectiveContext() {
-                        @Override
-                        public void onSuccess(Objective objective) {
-                            //TODO: change to debug
-                            log.info("Next Objective {} installed", objective.id());
-                        }
-
-                        @Override
-                        public void onError(Objective objective, ObjectiveError error) {
-                            //TODO: change to debug
-                            log.info("Next Objective {} failed, because {}",
-                                    objective.id(),
-                                    error);
-                        }
-                    });
-
-            flowObjectiveService.next(sink.deviceId(), next);
+            flowObjectiveService.next(sink.deviceId(), nextObject(nextId, sink.port(), NextType.AddToExisting));
         }
 
         addRemoteRoute(route, sink);
@@ -524,6 +523,12 @@
                     if (event.configClass().equals(CORD_MCAST_CONFIG_CLASS)) {
                         McastConfig config = networkConfig.getConfig(coreAppId, CORD_MCAST_CONFIG_CLASS);
                         if (config != null) {
+                            //TODO: Simply remove flows/groups, hosts will response period query
+                            // and re-sent IGMP report, so the flows can be rebuild.
+                            // However, better to remove and re-add mcast flow rules here
+                            if (mcastVlan != config.egressVlan().toShort() && vlanEnabled) {
+                                clearGroups();
+                            }
                             mcastVlan = config.egressVlan().toShort();
                         }
                     }
@@ -537,5 +542,36 @@
             }
         }
     }
+
+    private class NextKey {
+        private DeviceId device;
+        private IpAddress group;
+        public NextKey(DeviceId deviceId, IpAddress groupAddress) {
+            device = deviceId;
+            group = groupAddress;
+        }
+
+        public DeviceId getDevice() {
+            return device;
+        }
+
+        public int hashCode() {
+            return com.google.common.base.Objects.hashCode(new Object[]{this.device, this.group});
+        }
+
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            } else if (!(obj instanceof NextKey)) {
+                return false;
+            } else {
+                NextKey that = (NextKey) obj;
+                return this.getClass() == that.getClass() &&
+                        Objects.equals(this.device, that.device) &&
+                        Objects.equals(this.group, that.group);
+            }
+        }
+    }
 }
 
+