Optional clean-up
[netvirt.git] / vpnservice / elanmanager / elanmanager-impl / src / main / java / org / opendaylight / netvirt / elan / utils / ElanUtils.java
old mode 100644 (file)
new mode 100755 (executable)
index e14af74..18b3876
@@ -7,10 +7,19 @@
  */
 package org.opendaylight.netvirt.elan.utils;
 
+import com.google.common.base.Optional;
+import com.google.common.util.concurrent.CheckedFuture;
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+
 import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 
@@ -18,13 +27,16 @@ import org.apache.commons.lang3.StringUtils;
 import org.opendaylight.controller.md.sal.binding.api.DataBroker;
 import org.opendaylight.controller.md.sal.binding.api.ReadOnlyTransaction;
 import org.opendaylight.controller.md.sal.binding.api.WriteTransaction;
+import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipService;
 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
 import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
-import org.opendaylight.netvirt.elan.internal.ElanInstanceManager;
 import org.opendaylight.genius.interfacemanager.globals.InterfaceInfo;
 import org.opendaylight.genius.interfacemanager.globals.InterfaceServiceUtil;
+import org.opendaylight.genius.interfacemanager.interfaces.IInterfaceManager;
 import org.opendaylight.genius.itm.globals.ITMConstants;
+import org.opendaylight.genius.mdsalutil.ActionInfo;
+import org.opendaylight.genius.mdsalutil.ActionType;
 import org.opendaylight.genius.mdsalutil.FlowEntity;
 import org.opendaylight.genius.mdsalutil.InstructionInfo;
 import org.opendaylight.genius.mdsalutil.InstructionType;
@@ -35,6 +47,13 @@ import org.opendaylight.genius.mdsalutil.MatchInfo;
 import org.opendaylight.genius.mdsalutil.MetaDataUtil;
 import org.opendaylight.genius.mdsalutil.NwConstants;
 import org.opendaylight.genius.mdsalutil.interfaces.IMdsalApiManager;
+import org.opendaylight.genius.utils.ServiceIndex;
+import org.opendaylight.netvirt.elan.ElanException;
+import org.opendaylight.netvirt.elan.internal.ElanInstanceManager;
+import org.opendaylight.netvirt.elan.internal.ElanInterfaceManager;
+import org.opendaylight.netvirt.elan.l2gw.utils.ElanL2GatewayMulticastUtils;
+import org.opendaylight.netvirt.elan.l2gw.utils.ElanL2GatewayUtils;
+import org.opendaylight.netvirt.elan.l2gw.utils.L2GatewayConnectionUtils;
 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.InterfacesState;
 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface;
 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface.AdminStatus;
@@ -45,39 +64,6 @@ import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.Fl
 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.table.Flow;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.table.FlowBuilder;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.instruction.list.Instruction;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.NodeId;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.Nodes;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.Node;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.NodeKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanDpnInterfaces;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanForwardingTables;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanInstances;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanInterfaceForwardingEntries;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanInterfaces;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanState;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanTagNameMap;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan._interface.forwarding.entries.ElanInterfaceMac;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan._interface.forwarding.entries.ElanInterfaceMacKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.ElanDpnInterfacesList;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.ElanDpnInterfacesListKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.elan.dpn.interfaces.list.DpnInterfaces;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.elan.dpn.interfaces.list.DpnInterfacesKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.forwarding.tables.MacTable;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.forwarding.tables.MacTableBuilder;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.forwarding.tables.MacTableKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.instances.ElanInstance;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.instances.ElanInstanceBuilder;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.instances.ElanInstanceKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.interfaces.ElanInterface;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.interfaces.ElanInterfaceKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.state.Elan;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.state.ElanBuilder;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.state.ElanKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.tag.name.map.ElanTagName;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.tag.name.map.ElanTagNameBuilder;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.tag.name.map.ElanTagNameKey;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.forwarding.entries.MacEntry;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.forwarding.entries.MacEntryKey;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.idmanager.rev160406.AllocateIdInput;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.idmanager.rev160406.AllocateIdInputBuilder;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.idmanager.rev160406.AllocateIdOutput;
@@ -96,6 +82,7 @@ import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.rpc
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.rpcs.rev160406.GetEgressActionsForInterfaceOutput;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.rpcs.rev160406.OdlInterfaceRpcService;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.servicebinding.rev160406.ServiceBindings;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.servicebinding.rev160406.ServiceModeIngress;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.servicebinding.rev160406.ServiceTypeFlowBased;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.servicebinding.rev160406.StypeOpenflow;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.servicebinding.rev160406.StypeOpenflowBuilder;
@@ -119,6 +106,50 @@ import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.itm.rpcs.rev160406.G
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.itm.rpcs.rev160406.ItmRpcService;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.itm.rpcs.rev160406.RemoveTerminatingServiceActionsInput;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.itm.rpcs.rev160406.RemoveTerminatingServiceActionsInputBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.NodeId;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.Nodes;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.Node;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.NodeKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.etree.rev160614.EtreeInstance;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.etree.rev160614.EtreeInstanceBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.etree.rev160614.EtreeInterface;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.etree.rev160614.EtreeInterface.EtreeInterfaceType;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.etree.rev160614.EtreeLeafTag;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.etree.rev160614.EtreeLeafTagName;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.etree.rev160614.EtreeLeafTagNameBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanDpnInterfaces;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanForwardingTables;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanInstances;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanInterfaceForwardingEntries;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanInterfaces;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanState;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.ElanTagNameMap;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.SegmentTypeFlat;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.SegmentTypeVlan;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.SegmentTypeVxlan;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan._interface.forwarding.entries.ElanInterfaceMac;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan._interface.forwarding.entries.ElanInterfaceMacKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.ElanDpnInterfacesList;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.ElanDpnInterfacesListKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.elan.dpn.interfaces.list.DpnInterfaces;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.dpn.interfaces.elan.dpn.interfaces.list.DpnInterfacesKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.forwarding.tables.MacTable;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.forwarding.tables.MacTableBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.forwarding.tables.MacTableKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.instances.ElanInstance;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.instances.ElanInstanceBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.instances.ElanInstanceKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.interfaces.ElanInterface;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.interfaces.ElanInterfaceKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.state.Elan;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.state.ElanBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.state.ElanKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.tag.name.map.ElanTagName;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.tag.name.map.ElanTagNameBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.elan.tag.name.map.ElanTagNameKey;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.forwarding.entries.MacEntry;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.forwarding.entries.MacEntryBuilder;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.elan.rev150602.forwarding.entries.MacEntryKey;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier.InstanceIdentifierBuilder;
@@ -126,36 +157,95 @@ import org.opendaylight.yangtools.yang.common.RpcResult;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.google.common.base.Optional;
-import com.google.common.util.concurrent.CheckedFuture;
-import com.google.common.util.concurrent.FutureCallback;
-import com.google.common.util.concurrent.Futures;
-import com.google.common.util.concurrent.ListenableFuture;
-
 public class ElanUtils {
 
-    private static OdlInterfaceRpcService interfaceMgrRpcService;
-
-    private static ItmRpcService itmRpcService;
-
-    private static IMdsalApiManager mdsalMgr;
+    private static final Logger LOG = LoggerFactory.getLogger(ElanUtils.class);
 
-    private static DataBroker dataBroker;
+    private static Map<String, ElanInstance> elanInstanceLocalCache = new ConcurrentHashMap<>();
+    private static Map<String, ElanInterface> elanInterfaceLocalCache = new ConcurrentHashMap<>();
 
-    private static final Logger logger = LoggerFactory.getLogger(ElanUtils.class);
+    private final DataBroker broker;
+    private final IMdsalApiManager mdsalManager;
+    private final ElanInstanceManager elanInstanceManager;
+    private final OdlInterfaceRpcService interfaceManagerRpcService;
+    private final ItmRpcService itmRpcService;
+    private final ElanL2GatewayUtils elanL2GatewayUtils;
+    private final ElanL2GatewayMulticastUtils elanL2GatewayMulticastUtils;
+    private final L2GatewayConnectionUtils l2GatewayConnectionUtils;
+    private final IInterfaceManager interfaceManager;
 
     public static final FutureCallback<Void> DEFAULT_CALLBACK = new FutureCallback<Void>() {
         @Override
         public void onSuccess(Void result) {
-            logger.debug("Success in Datastore operation");
+            LOG.debug("Success in Datastore operation");
         }
 
         @Override
         public void onFailure(Throwable error) {
-            logger.error("Error in Datastore operation", error);
+            LOG.error("Error in Datastore operation", error);
         }
     };
 
+    public ElanUtils(DataBroker dataBroker, IMdsalApiManager mdsalManager, ElanInstanceManager elanInstanceManager,
+                     OdlInterfaceRpcService interfaceManagerRpcService, ItmRpcService itmRpcService,
+                     ElanInterfaceManager elanInterfaceManager,
+                     EntityOwnershipService entityOwnershipService, IInterfaceManager interfaceManager) {
+        this.broker = dataBroker;
+        this.mdsalManager = mdsalManager;
+        this.elanInstanceManager = elanInstanceManager;
+        this.interfaceManagerRpcService = interfaceManagerRpcService;
+        this.itmRpcService = itmRpcService;
+        this.interfaceManager = interfaceManager;
+
+        elanL2GatewayMulticastUtils =
+                new ElanL2GatewayMulticastUtils(broker, elanInstanceManager, elanInterfaceManager, this);
+        elanL2GatewayUtils = new ElanL2GatewayUtils(broker, itmRpcService, this,
+                entityOwnershipService, elanL2GatewayMulticastUtils);
+        elanL2GatewayMulticastUtils.setEElanL2GatewayUtils(elanL2GatewayUtils);
+        l2GatewayConnectionUtils = new L2GatewayConnectionUtils(broker,
+                elanInstanceManager, entityOwnershipService, this);
+    }
+
+    public ElanL2GatewayUtils getElanL2GatewayUtils() {
+        return elanL2GatewayUtils;
+    }
+
+    public ElanL2GatewayMulticastUtils getElanL2GatewayMulticastUtils() {
+        return elanL2GatewayMulticastUtils;
+    }
+
+    public L2GatewayConnectionUtils getL2GatewayConnectionUtils() {
+        return l2GatewayConnectionUtils;
+    }
+
+    public static void addElanInstanceIntoCache(String elanInstanceName, ElanInstance elanInstance) {
+        elanInstanceLocalCache.put(elanInstanceName, elanInstance);
+    }
+
+    public static void removeElanInstanceFromCache(String elanInstanceName) {
+        elanInstanceLocalCache.remove(elanInstanceName);
+    }
+
+    public static ElanInstance getElanInstanceFromCache(String elanInstanceName) {
+        return elanInstanceLocalCache.get(elanInstanceName);
+    }
+
+    public static Set<String> getAllElanNames() {
+        return elanInstanceLocalCache.keySet();
+    }
+
+    public static void addElanInterfaceIntoCache(String interfaceName, ElanInterface elanInterface) {
+        elanInterfaceLocalCache.put(interfaceName, elanInterface);
+    }
+
+    public static void removeElanInterfaceFromCache(String interfaceName) {
+        elanInterfaceLocalCache.remove(interfaceName);
+    }
+
+    public static ElanInterface getElanInterfaceFromCache(String interfaceName) {
+        return elanInterfaceLocalCache.get(interfaceName);
+    }
+
     /**
      * Uses the IdManager to retrieve a brand new ElanTag.
      *
@@ -165,7 +255,7 @@ public class ElanUtils {
      *            the id key
      * @return the integer
      */
-    public static Integer retrieveNewElanTag(IdManagerService idManager, String idKey) {
+    public static Long retrieveNewElanTag(IdManagerService idManager, String idKey) {
 
         AllocateIdInput getIdInput = new AllocateIdInputBuilder().setPoolName(ElanConstants.ELAN_ID_POOL_NAME)
                 .setIdKey(idKey).build();
@@ -174,34 +264,14 @@ public class ElanUtils {
             Future<RpcResult<AllocateIdOutput>> result = idManager.allocateId(getIdInput);
             RpcResult<AllocateIdOutput> rpcResult = result.get();
             if (rpcResult.isSuccessful()) {
-                return rpcResult.getResult().getIdValue().intValue();
+                return rpcResult.getResult().getIdValue().longValue();
             } else {
-                logger.warn("RPC Call to Allocate Id returned with Errors {}", rpcResult.getErrors());
+                LOG.warn("RPC Call to Allocate Id returned with Errors {}", rpcResult.getErrors());
             }
         } catch (InterruptedException | ExecutionException e) {
-            logger.warn("Exception when Allocating Id",e);
+            LOG.warn("Exception when Allocating Id", e);
         }
-        return 0;
-    }
-
-    public static DataBroker getDataBroker() {
-        return dataBroker;
-    }
-
-    public final static void setIfaceMgrRpcService(OdlInterfaceRpcService rpcService) {
-        interfaceMgrRpcService = rpcService;
-    }
-
-    public final static void setItmRpcService(ItmRpcService itmService) {
-        itmRpcService = itmService;
-    }
-
-    public final static void setDataBroker(DataBroker broker) {
-        dataBroker = broker;
-    }
-
-    public final static void setMdsalManager(IMdsalApiManager mdsalApiManager) {
-        mdsalMgr = mdsalApiManager;
+        return 0L;
     }
 
     public static void releaseId(IdManagerService idManager, String poolName, String idKey) {
@@ -209,69 +279,99 @@ public class ElanUtils {
         Future<RpcResult<Void>> result = idManager.releaseId(releaseIdInput);
     }
 
-    public static <T extends DataObject> Optional<T> read(DataBroker broker, LogicalDatastoreType datastoreType,
+    /**
+     * Read utility.
+     *
+     * @deprecated Consider using {@link #read2(LogicalDatastoreType, InstanceIdentifier)} with proper exception
+     *             handling instead
+     */
+    @Deprecated
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public <T extends DataObject> Optional<T> read(DataBroker broker, LogicalDatastoreType datastoreType,
             InstanceIdentifier<T> path) {
-        ReadOnlyTransaction tx = (broker != null ) ? broker.newReadOnlyTransaction() : dataBroker.newReadOnlyTransaction();
+        ReadOnlyTransaction tx = broker != null ? broker.newReadOnlyTransaction()
+                : this.broker.newReadOnlyTransaction();
         Optional<T> result = Optional.absent();
         try {
             CheckedFuture<Optional<T>, ReadFailedException> checkedFuture = tx.read(datastoreType, path);
             result = checkedFuture.get();
         } catch (Exception e) {
             throw new RuntimeException(e);
+        } finally {
+            tx.close();
         }
 
         return result;
     }
 
+    public <T extends DataObject> Optional<T> read2(LogicalDatastoreType datastoreType, InstanceIdentifier<T> path)
+            throws ReadFailedException {
+        ReadOnlyTransaction tx = broker.newReadOnlyTransaction();
+        try {
+            CheckedFuture<Optional<T>, ReadFailedException> checkedFuture = tx.read(datastoreType, path);
+            return checkedFuture.checkedGet();
+        } finally {
+            tx.close();
+        }
+    }
 
-    public static <T extends DataObject> void delete(DataBroker broker, LogicalDatastoreType datastoreType, InstanceIdentifier<T> path) {
+    public static <T extends DataObject> void delete(DataBroker broker, LogicalDatastoreType datastoreType,
+            InstanceIdentifier<T> path) {
         WriteTransaction tx = broker.newWriteOnlyTransaction();
         tx.delete(datastoreType, path);
         Futures.addCallback(tx.submit(), DEFAULT_CALLBACK);
     }
 
+    public static <T extends DataObject> void delete(DataBroker broker, LogicalDatastoreType datastoreType,
+            InstanceIdentifier<T> path, FutureCallback<Void> callback) {
+        WriteTransaction tx = broker.newWriteOnlyTransaction();
+        tx.delete(datastoreType, path);
+        Futures.addCallback(tx.submit(), callback);
+    }
 
     public static InstanceIdentifier<ElanInstance> getElanInstanceIdentifier() {
         return InstanceIdentifier.builder(ElanInstances.class).child(ElanInstance.class).build();
     }
 
-    //elan-instances config container
-    public static ElanInstance getElanInstanceByName(String elanInstanceName) {
-        InstanceIdentifier<ElanInstance> elanIdentifierId = getElanInstanceConfigurationDataPath(elanInstanceName);
-        Optional<ElanInstance> elanInstance = read(dataBroker, LogicalDatastoreType.CONFIGURATION, elanIdentifierId);
-        if(elanInstance.isPresent()) {
-            return elanInstance.get();
+    // elan-instances config container
+    public static ElanInstance getElanInstanceByName(DataBroker broker, String elanInstanceName) {
+        ElanInstance elanObj = getElanInstanceFromCache(elanInstanceName);
+        if (elanObj != null) {
+            return elanObj;
         }
-        return null;
+        InstanceIdentifier<ElanInstance> elanIdentifierId = getElanInstanceConfigurationDataPath(elanInstanceName);
+        return MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, elanIdentifierId).orNull();
     }
 
     public static InstanceIdentifier<ElanInstance> getElanInstanceConfigurationDataPath(String elanInstanceName) {
-        return InstanceIdentifier.builder(ElanInstances.class).child(ElanInstance.class, new ElanInstanceKey(elanInstanceName)).build();
+        return InstanceIdentifier.builder(ElanInstances.class)
+                .child(ElanInstance.class, new ElanInstanceKey(elanInstanceName)).build();
     }
 
-    //elan-interfaces Config Container
-    public static ElanInterface getElanInterfaceByElanInterfaceName(String elanInterfaceName) {
-        InstanceIdentifier<ElanInterface> elanInterfaceId = getElanInterfaceConfigurationDataPathId(elanInterfaceName);
-        Optional<ElanInterface> existingElanInterface = read(dataBroker, LogicalDatastoreType.CONFIGURATION, elanInterfaceId);
-        if(existingElanInterface.isPresent()) {
-            return existingElanInterface.get();
+    // elan-interfaces Config Container
+    public static ElanInterface getElanInterfaceByElanInterfaceName(DataBroker broker, String elanInterfaceName) {
+        ElanInterface elanInterfaceObj = getElanInterfaceFromCache(elanInterfaceName);
+        if (elanInterfaceObj != null) {
+            return elanInterfaceObj;
         }
-        return null;
+        InstanceIdentifier<ElanInterface> elanInterfaceId = getElanInterfaceConfigurationDataPathId(elanInterfaceName);
+        return MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, elanInterfaceId).orNull();
+    }
+
+    public static EtreeInterface getEtreeInterfaceByElanInterfaceName(DataBroker broker, String elanInterfaceName) {
+        ElanInterface elanInterface = getElanInterfaceByElanInterfaceName(broker, elanInterfaceName);
+        return elanInterface.getAugmentation(EtreeInterface.class);
     }
 
     public static InstanceIdentifier<ElanInterface> getElanInterfaceConfigurationDataPathId(String interfaceName) {
-        return InstanceIdentifier.builder(ElanInterfaces.class).child(ElanInterface.class,
-                new ElanInterfaceKey(interfaceName)).build();
+        return InstanceIdentifier.builder(ElanInterfaces.class)
+                .child(ElanInterface.class, new ElanInterfaceKey(interfaceName)).build();
     }
 
-    //elan-state Operational container
-    public static Elan getElanByName(String elanInstanceName) {
+    // elan-state Operational container
+    public static Elan getElanByName(DataBroker broker, String elanInstanceName) {
         InstanceIdentifier<Elan> elanIdentifier = getElanInstanceOperationalDataPath(elanInstanceName);
-        Optional<Elan> elanInstance = read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanIdentifier);
-        if(elanInstance.isPresent()) {
-            return elanInstance.get();
-        }
-        return null;
+        return MDSALUtil.read(broker, LogicalDatastoreType.OPERATIONAL, elanIdentifier).orNull();
     }
 
     public static InstanceIdentifier<Elan> getElanInstanceOperationalDataPath(String elanInstanceName) {
@@ -279,66 +379,54 @@ public class ElanUtils {
     }
 
     // grouping of forwarding-entries
-    public static MacEntry getInterfaceMacEntriesOperationalDataPath(String interfaceName, PhysAddress physAddress) {
-        InstanceIdentifier<MacEntry> existingMacEntryId = getInterfaceMacEntriesIdentifierOperationalDataPath(interfaceName, physAddress);
-        Optional<MacEntry> existingInterfaceMacEntry = read(dataBroker, LogicalDatastoreType.OPERATIONAL, existingMacEntryId);
-        if(existingInterfaceMacEntry.isPresent()) {
-            return existingInterfaceMacEntry.get();
-        }
-        return null;
+    public MacEntry getInterfaceMacEntriesOperationalDataPath(String interfaceName, PhysAddress physAddress) {
+        InstanceIdentifier<MacEntry> existingMacEntryId = getInterfaceMacEntriesIdentifierOperationalDataPath(
+                interfaceName, physAddress);
+        return read(broker, LogicalDatastoreType.OPERATIONAL, existingMacEntryId).orNull();
     }
 
-    public static MacEntry getInterfaceMacEntriesOperationalDataPathFromId(InstanceIdentifier identifier) {
-        Optional<MacEntry> existingInterfaceMacEntry = read(dataBroker, LogicalDatastoreType.OPERATIONAL, identifier);
-        if(existingInterfaceMacEntry.isPresent()) {
-            return existingInterfaceMacEntry.get();
-        }
-        return null;
+    public MacEntry getInterfaceMacEntriesOperationalDataPathFromId(InstanceIdentifier identifier) {
+        Optional<MacEntry> existingInterfaceMacEntry = read(broker,
+                LogicalDatastoreType.OPERATIONAL, identifier);
+        return existingInterfaceMacEntry.orNull();
     }
 
-    public static InstanceIdentifier<MacEntry> getInterfaceMacEntriesIdentifierOperationalDataPath(String interfaceName, PhysAddress physAddress) {
-        return InstanceIdentifier.builder(ElanInterfaceForwardingEntries.class).child(ElanInterfaceMac.class,
-                new ElanInterfaceMacKey(interfaceName)).child(MacEntry.class, new MacEntryKey(physAddress)).build();
+    public static InstanceIdentifier<MacEntry> getInterfaceMacEntriesIdentifierOperationalDataPath(String interfaceName,
+            PhysAddress physAddress) {
+        return InstanceIdentifier.builder(ElanInterfaceForwardingEntries.class)
+                .child(ElanInterfaceMac.class, new ElanInterfaceMacKey(interfaceName))
+                .child(MacEntry.class, new MacEntryKey(physAddress)).build();
 
     }
 
-    //elan-forwarding-tables Operational container
-    public static MacEntry getMacTableByElanName(String elanName, PhysAddress physAddress) {
-        InstanceIdentifier<MacEntry> macId =  getMacEntryOperationalDataPath(elanName, physAddress);
-        Optional<MacEntry> existingElanMacEntry = read(dataBroker, LogicalDatastoreType.OPERATIONAL, macId);
-        if(existingElanMacEntry.isPresent()) {
-            return existingElanMacEntry.get();
-        }
-        return null;
+    // elan-forwarding-tables Operational container
+    public Optional<MacEntry> getMacEntryForElanInstance(String elanName, PhysAddress physAddress) {
+        InstanceIdentifier<MacEntry> macId = getMacEntryOperationalDataPath(elanName, physAddress);
+        return read(broker, LogicalDatastoreType.OPERATIONAL, macId);
     }
 
-
-    public static MacEntry getMacEntryFromElanMacId(InstanceIdentifier identifier) {
-        Optional<MacEntry> existingInterfaceMacEntry = read(dataBroker, LogicalDatastoreType.OPERATIONAL, identifier);
-        if(existingInterfaceMacEntry.isPresent()) {
-            return existingInterfaceMacEntry.get();
-        }
-        return null;
+    public MacEntry getMacEntryFromElanMacId(InstanceIdentifier identifier) {
+        Optional<MacEntry> existingInterfaceMacEntry = read(broker,
+                LogicalDatastoreType.OPERATIONAL, identifier);
+        return existingInterfaceMacEntry.orNull();
     }
 
-    public static InstanceIdentifier<MacEntry> getMacEntryOperationalDataPath(String elanName, PhysAddress physAddress) {
-        return InstanceIdentifier.builder(ElanForwardingTables.class).child(MacTable.class,
-                new MacTableKey(elanName)).child(MacEntry.class, new MacEntryKey(physAddress)).build();
+    public static InstanceIdentifier<MacEntry> getMacEntryOperationalDataPath(String elanName,
+            PhysAddress physAddress) {
+        return InstanceIdentifier.builder(ElanForwardingTables.class).child(MacTable.class, new MacTableKey(elanName))
+                .child(MacEntry.class, new MacEntryKey(physAddress)).build();
     }
 
     public static InstanceIdentifier<MacTable> getElanMacTableOperationalDataPath(String elanName) {
-        return InstanceIdentifier.builder(ElanForwardingTables.class).child(MacTable.class,
-                new MacTableKey(elanName)).build();
+        return InstanceIdentifier.builder(ElanForwardingTables.class).child(MacTable.class, new MacTableKey(elanName))
+                .build();
     }
 
-    //elan-interface-forwarding-entries Operational container
-    public static ElanInterfaceMac getElanInterfaceMacByInterfaceName(String interfaceName) {
-        InstanceIdentifier<ElanInterfaceMac> elanInterfaceId = getElanInterfaceMacEntriesOperationalDataPath(interfaceName);
-        Optional<ElanInterfaceMac> existingElanInterface = read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanInterfaceId);
-        if(existingElanInterface.isPresent()) {
-            return existingElanInterface.get();
-        }
-        return null;
+    // elan-interface-forwarding-entries Operational container
+    public ElanInterfaceMac getElanInterfaceMacByInterfaceName(String interfaceName) {
+        InstanceIdentifier<ElanInterfaceMac> elanInterfaceId = getElanInterfaceMacEntriesOperationalDataPath(
+                interfaceName);
+        return read(broker, LogicalDatastoreType.OPERATIONAL, elanInterfaceId).orNull();
     }
 
     /**
@@ -348,9 +436,9 @@ public class ElanUtils {
      *            the interface name
      * @return the elan interface mac addresses
      */
-    public static List<PhysAddress> getElanInterfaceMacAddresses(String interfaceName) {
+    public List<PhysAddress> getElanInterfaceMacAddresses(String interfaceName) {
         List<PhysAddress> macAddresses = new ArrayList<>();
-        ElanInterfaceMac elanInterfaceMac = ElanUtils.getElanInterfaceMacByInterfaceName(interfaceName);
+        ElanInterfaceMac elanInterfaceMac = getElanInterfaceMacByInterfaceName(interfaceName);
         if (elanInterfaceMac != null && elanInterfaceMac.getMacEntry() != null) {
             List<MacEntry> macEntries = elanInterfaceMac.getMacEntry();
             for (MacEntry macEntry : macEntries) {
@@ -360,9 +448,10 @@ public class ElanUtils {
         return macAddresses;
     }
 
-    public static InstanceIdentifier<ElanInterfaceMac> getElanInterfaceMacEntriesOperationalDataPath(String interfaceName) {
-        return InstanceIdentifier.builder(ElanInterfaceForwardingEntries.class).child(ElanInterfaceMac.class,
-                new ElanInterfaceMacKey(interfaceName)).build();
+    public static InstanceIdentifier<ElanInterfaceMac> getElanInterfaceMacEntriesOperationalDataPath(
+            String interfaceName) {
+        return InstanceIdentifier.builder(ElanInterfaceForwardingEntries.class)
+                .child(ElanInterfaceMac.class, new ElanInterfaceMacKey(interfaceName)).build();
     }
 
     /**
@@ -370,31 +459,27 @@ public class ElanUtils {
      * Data retrieved from Elan's operational DS: elan-dpn-interfaces container
      *
      * @param elanInstanceName
-     *          name of the Elan to which the interfaces must belong to
+     *            name of the Elan to which the interfaces must belong to
      * @param dpId
-     *          Id of the DPN where the interfaces are located
-     * @return
+     *            Id of the DPN where the interfaces are located
+     * @return the elan interface Info
      */
-    public static DpnInterfaces getElanInterfaceInfoByElanDpn(String elanInstanceName, BigInteger dpId) {
-        InstanceIdentifier<DpnInterfaces> elanDpnInterfacesId =
-                getElanDpnInterfaceOperationalDataPath(elanInstanceName, dpId);
-        Optional<DpnInterfaces> elanDpnInterfaces = read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfacesId);
-        if ( elanDpnInterfaces.isPresent() ) {
-            return elanDpnInterfaces.get();
-        }
-        return null;
+    public DpnInterfaces getElanInterfaceInfoByElanDpn(String elanInstanceName, BigInteger dpId) {
+        InstanceIdentifier<DpnInterfaces> elanDpnInterfacesId = getElanDpnInterfaceOperationalDataPath(elanInstanceName,
+                dpId);
+        return read(broker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfacesId).orNull();
     }
 
     /**
-     * Returns the InstanceIdentifier that points to the Interfaces of an Elan in a
-     * given DPN in the Operational DS.
-     * Data retrieved from Elans's operational DS: dpn-interfaces list
+     * Returns the InstanceIdentifier that points to the Interfaces of an Elan
+     * in a given DPN in the Operational DS. Data retrieved from Elans's
+     * operational DS: dpn-interfaces list
      *
      * @param elanInstanceName
-     *          name of the Elan to which the interfaces must belong to
+     *            name of the Elan to which the interfaces must belong to
      * @param dpId
-     *          Id of the DPN where the interfaces are located
-     * @return
+     *            Id of the DPN where the interfaces are located
+     * @return the elan dpn interface
      */
     public static InstanceIdentifier<DpnInterfaces> getElanDpnInterfaceOperationalDataPath(String elanInstanceName,
             BigInteger dpId) {
@@ -403,47 +488,55 @@ public class ElanUtils {
                 .child(DpnInterfaces.class, new DpnInterfacesKey(dpId)).build();
     }
 
-    //elan-tag-name-map Operational Container
-    public static ElanTagName getElanInfoByElanTag(long elanTag) {
+    // elan-tag-name-map Operational Container
+    public ElanTagName getElanInfoByElanTag(long elanTag) {
         InstanceIdentifier<ElanTagName> elanId = getElanInfoEntriesOperationalDataPath(elanTag);
-        Optional<ElanTagName> existingElanInfo = ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanId);
-        if(existingElanInfo.isPresent()) {
-            return existingElanInfo.get();
+        Optional<ElanTagName> existingElanInfo = read(broker,
+                LogicalDatastoreType.OPERATIONAL, elanId);
+        return existingElanInfo.orNull();
+    }
+
+    public EtreeLeafTagName getEtreeLeafTagByElanTag(long elanTag) {
+        InstanceIdentifier<ElanTagName> elanId = getElanInfoEntriesOperationalDataPath(elanTag);
+        Optional<ElanTagName> existingElanInfo = read(broker,
+                LogicalDatastoreType.OPERATIONAL, elanId);
+        if (existingElanInfo.isPresent()) {
+            ElanTagName elanTagName = existingElanInfo.get();
+            return elanTagName.getAugmentation(EtreeLeafTagName.class);
         }
         return null;
     }
 
     public static InstanceIdentifier<ElanTagName> getElanInfoEntriesOperationalDataPath(long elanTag) {
-        return InstanceIdentifier.builder(ElanTagNameMap.class).child(ElanTagName.class,
-                new ElanTagNameKey(elanTag)).build();
+        return InstanceIdentifier.builder(ElanTagNameMap.class).child(ElanTagName.class, new ElanTagNameKey(elanTag))
+                .build();
     }
 
     // interface-index-tag operational container
-    public static Optional<IfIndexInterface> getInterfaceInfoByInterfaceTag(long interfaceTag) {
+    public Optional<IfIndexInterface> getInterfaceInfoByInterfaceTag(long interfaceTag) {
         InstanceIdentifier<IfIndexInterface> interfaceId = getInterfaceInfoEntriesOperationalDataPath(interfaceTag);
-        return ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, interfaceId);
+        return read(broker, LogicalDatastoreType.OPERATIONAL, interfaceId);
     }
 
     public static InstanceIdentifier<IfIndexInterface> getInterfaceInfoEntriesOperationalDataPath(long interfaceTag) {
-        return InstanceIdentifier.builder(IfIndexesInterfaceMap.class).child(IfIndexInterface.class,
-                new IfIndexInterfaceKey((int) interfaceTag)).build();
+        return InstanceIdentifier.builder(IfIndexesInterfaceMap.class)
+                .child(IfIndexInterface.class, new IfIndexInterfaceKey((int) interfaceTag)).build();
     }
 
-
-
     public static InstanceIdentifier<ElanDpnInterfacesList> getElanDpnOperationDataPath(String elanInstanceName) {
-        return InstanceIdentifier.builder(ElanDpnInterfaces.class).child(ElanDpnInterfacesList.class,
-                new ElanDpnInterfacesListKey(elanInstanceName)).build();
+        return InstanceIdentifier.builder(ElanDpnInterfaces.class)
+                .child(ElanDpnInterfacesList.class, new ElanDpnInterfacesListKey(elanInstanceName)).build();
     }
 
-    public static  ElanDpnInterfacesList getElanDpnInterfacesList(String elanName) {
+    public ElanDpnInterfacesList getElanDpnInterfacesList(String elanName) {
         InstanceIdentifier<ElanDpnInterfacesList> elanDpnInterfaceId = getElanDpnOperationDataPath(elanName);
-        Optional<ElanDpnInterfacesList> existingElanDpnInterfaces =
-                ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId);
-        if(existingElanDpnInterfaces.isPresent()) {
-            return existingElanDpnInterfaces.get();
-        }
-        return null;
+        return read(broker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId).orNull();
+    }
+
+    public ElanDpnInterfaces getElanDpnInterfacesList() {
+        InstanceIdentifier<ElanDpnInterfaces> elanDpnInterfaceId = InstanceIdentifier.builder(ElanDpnInterfaces.class)
+                .build();
+        return read(broker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId).orNull();
     }
 
     /**
@@ -455,16 +548,16 @@ public class ElanUtils {
      *            the elan instance name
      * @return list of dpIds
      */
-    public static List<BigInteger> getParticipatingDPNsInElanInstance(String elanInstanceName) {
+    public List<BigInteger> getParticipatingDpnsInElanInstance(String elanInstanceName) {
         List<BigInteger> dpIds = new ArrayList<>();
         InstanceIdentifier<ElanDpnInterfacesList> elanDpnInterfaceId = getElanDpnOperationDataPath(elanInstanceName);
-        Optional<ElanDpnInterfacesList> existingElanDpnInterfaces =
-                ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId);
+        Optional<ElanDpnInterfacesList> existingElanDpnInterfaces = read(broker,
+                LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId);
         if (!existingElanDpnInterfaces.isPresent()) {
             return dpIds;
         }
         List<DpnInterfaces> dpnInterfaces = existingElanDpnInterfaces.get().getDpnInterfaces();
-        for (DpnInterfaces dpnInterface: dpnInterfaces) {
+        for (DpnInterfaces dpnInterface : dpnInterfaces) {
             dpIds.add(dpnInterface.getDpId());
         }
         return dpIds;
@@ -481,44 +574,30 @@ public class ElanUtils {
      *            the elan instance name
      * @return true if dpId is already present, otherwise return false
      */
-    public static boolean isDpnAlreadyPresentInElanInstance(BigInteger dpId, String elanInstanceName) {
-        boolean isDpIdPresent = false;
+    public boolean isDpnAlreadyPresentInElanInstance(BigInteger dpId, String elanInstanceName) {
         InstanceIdentifier<ElanDpnInterfacesList> elanDpnInterfaceId = getElanDpnOperationDataPath(elanInstanceName);
-        Optional<ElanDpnInterfacesList> existingElanDpnInterfaces =
-                ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId);
+        Optional<ElanDpnInterfacesList> existingElanDpnInterfaces = read(broker,
+                LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId);
         if (!existingElanDpnInterfaces.isPresent()) {
-            return isDpIdPresent;
+            return false;
         }
         List<DpnInterfaces> dpnInterfaces = existingElanDpnInterfaces.get().getDpnInterfaces();
-        for (DpnInterfaces dpnInterface: dpnInterfaces) {
+        for (DpnInterfaces dpnInterface : dpnInterfaces) {
             if (dpnInterface.getDpId().equals(dpId)) {
-                isDpIdPresent = true;
-                break;
+                return true;
             }
         }
-        return isDpIdPresent;
+        return false;
     }
 
-    public static ElanDpnInterfaces getElanDpnInterfacesList() {
-        InstanceIdentifier<ElanDpnInterfaces> elanDpnInterfaceId =
-                InstanceIdentifier.builder(ElanDpnInterfaces.class).build();
-        Optional<ElanDpnInterfaces> existingElanDpnInterfaces =
-                ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanDpnInterfaceId);
-        if(existingElanDpnInterfaces.isPresent()) {
-            return existingElanDpnInterfaces.get();
-        }
-        return null;
+    public ElanForwardingTables getElanForwardingList() {
+        InstanceIdentifier<ElanForwardingTables> elanForwardingTableId = InstanceIdentifier
+                .builder(ElanForwardingTables.class).build();
+        return read(broker, LogicalDatastoreType.OPERATIONAL, elanForwardingTableId).orNull();
     }
 
-    public static ElanForwardingTables getElanForwardingList() {
-        InstanceIdentifier<ElanForwardingTables> elanForwardingTableId =
-                InstanceIdentifier.builder(ElanForwardingTables.class).build();
-        Optional<ElanForwardingTables> existingElanForwardingList =
-                ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanForwardingTableId);
-        if(existingElanForwardingList.isPresent()) {
-            return existingElanForwardingList.get();
-        }
-        return null;
+    public static long getElanRemoteBroadCastGroupID(long elanTag) {
+        return ElanConstants.ELAN_GID_MIN + (((elanTag % ElanConstants.ELAN_GID_MIN) * 2));
     }
 
     /**
@@ -528,31 +607,34 @@ public class ElanUtils {
      *            the elan name
      * @return the elan mac table
      */
-    public static MacTable getElanMacTable(String elanName) {
+    public MacTable getElanMacTable(String elanName) {
         InstanceIdentifier<MacTable> elanMacTableId = getElanMacTableOperationalDataPath(elanName);
-        Optional<MacTable> existingElanMacTable =
-                ElanUtils.read(dataBroker, LogicalDatastoreType.OPERATIONAL, elanMacTableId);
-        if (existingElanMacTable.isPresent()) {
-            return existingElanMacTable.get();
-        }
-        return null;
+        return read(broker, LogicalDatastoreType.OPERATIONAL, elanMacTableId).orNull();
     }
 
-    public static long getElanLocalBCGID(long elanTag) {
-        return ElanConstants.ELAN_GID_MIN + (((elanTag % ElanConstants.ELAN_GID_MIN) *2) - 1);
+    public static long getElanLocalBCGId(long elanTag) {
+        return ElanConstants.ELAN_GID_MIN + (elanTag % ElanConstants.ELAN_GID_MIN * 2 - 1);
     }
 
-    public static long getElanRemoteBCGID(long elanTag) {
-        return ElanConstants.ELAN_GID_MIN + (((elanTag % ElanConstants.ELAN_GID_MIN) *2));
+    public static long getElanRemoteBCGId(long elanTag) {
+        return ElanConstants.ELAN_GID_MIN + elanTag % ElanConstants.ELAN_GID_MIN * 2;
+    }
+
+    public static long getEtreeLeafLocalBCGId(long etreeLeafTag) {
+        return ElanConstants.ELAN_GID_MIN + (etreeLeafTag % ElanConstants.ELAN_GID_MIN * 2 - 1);
+    }
+
+    public static long getEtreeLeafRemoteBCGId(long etreeLeafTag) {
+        return ElanConstants.ELAN_GID_MIN + etreeLeafTag % ElanConstants.ELAN_GID_MIN * 2;
     }
 
     public static BigInteger getElanMetadataLabel(long elanTag) {
-        return (BigInteger.valueOf(elanTag)).shiftLeft(24);
+        return BigInteger.valueOf(elanTag).shiftLeft(24);
     }
 
-    public static BigInteger getElanMetadataLabel(long elanTag, boolean isSHFlagSet ) {
-        int shBit = (isSHFlagSet) ? 1 : 0;
-        return (BigInteger.valueOf(elanTag)).shiftLeft(24).or(BigInteger.valueOf(shBit));
+    public static BigInteger getElanMetadataLabel(long elanTag, boolean isSHFlagSet) {
+        int shBit = isSHFlagSet ? 1 : 0;
+        return BigInteger.valueOf(elanTag).shiftLeft(24).or(BigInteger.valueOf(shBit));
     }
 
     public static BigInteger getElanMetadataLabel(long elanTag, int lportTag) {
@@ -564,8 +646,7 @@ public class ElanUtils {
     }
 
     /**
-     * Setting INTERNAL_TUNNEL_TABLE, SMAC, DMAC, UDMAC in this DPN and also in
-     * other DPNs.
+     * Setting INTERNAL_TUNNEL_TABLE, SMAC, DMAC, UDMAC in this DPN and optionally in other DPNs.
      *
      * @param elanInfo
      *            the elan info
@@ -575,87 +656,110 @@ public class ElanUtils {
      *            the mac timeout
      * @param macAddress
      *            the mac address
+     * @param configureRemoteFlows
+     *            true if remote dmac flows should be configured as well
+     * @param writeFlowGroupTx
+     *            the flow group tx
+     * @throws ElanException in case of issues creating the flow objects
      */
-    public static void setupMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, long macTimeout,
-            String macAddress) {
-        synchronized (macAddress) {
-            logger.info("Acquired lock for mac : " + macAddress + ". Proceeding with install operation.");
-            setupKnownSmacFlow(elanInfo, interfaceInfo, macTimeout, macAddress, mdsalMgr);
-            setupOrigDmacFlows(elanInfo, interfaceInfo, macAddress, mdsalMgr, dataBroker);
+    public void setupMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo,
+                              long macTimeout, String macAddress, boolean configureRemoteFlows,
+                              WriteTransaction writeFlowGroupTx) throws ElanException {
+        synchronized (getElanMacKey(elanInfo.getElanTag(), macAddress)) {
+            setupKnownSmacFlow(elanInfo, interfaceInfo, macTimeout, macAddress, mdsalManager,
+                writeFlowGroupTx);
+            setupOrigDmacFlows(elanInfo, interfaceInfo, macAddress, configureRemoteFlows, mdsalManager,
+                broker, writeFlowGroupTx);
         }
     }
 
-    public static void setupDMacFlowonRemoteDpn(ElanInstance elanInfo, InterfaceInfo interfaceInfo, BigInteger dstDpId,
-            String macAddress) {
-        synchronized (macAddress) {
-            logger.info("Acquired lock for mac : " + macAddress + "Proceeding with install operation.");
-            setupOrigDmacFlowsonRemoteDpn(elanInfo, interfaceInfo, dstDpId, macAddress);
+    public void setupDMacFlowonRemoteDpn(ElanInstance elanInfo, InterfaceInfo interfaceInfo, BigInteger dstDpId,
+            String macAddress, WriteTransaction writeFlowTx) throws ElanException {
+        synchronized (getElanMacKey(elanInfo.getElanTag(), macAddress)) {
+            LOG.debug("Acquired lock for mac : " + macAddress + ". Proceeding with install operation.");
+            setupOrigDmacFlowsonRemoteDpn(elanInfo, interfaceInfo, dstDpId, macAddress, writeFlowTx);
         }
     }
 
-
     /**
-     * Inserts a Flow in SMAC table to state that the MAC has already been learnt.
-     *
-     * @param elanInfo
-     * @param interfaceInfo
-     * @param macTimeout
-     * @param macAddress
-     * @param mdsalApiManager
+     * Inserts a Flow in SMAC table to state that the MAC has already been
+     * learnt.
      */
-    private static void setupKnownSmacFlow(ElanInstance elanInfo, InterfaceInfo interfaceInfo, long macTimeout,
-            String macAddress, IMdsalApiManager mdsalApiManager) {
+    private void setupKnownSmacFlow(ElanInstance elanInfo, InterfaceInfo interfaceInfo, long macTimeout,
+            String macAddress, IMdsalApiManager mdsalApiManager, WriteTransaction writeFlowGroupTx) {
         FlowEntity flowEntity = buildKnownSmacFlow(elanInfo, interfaceInfo, macTimeout, macAddress);
-        mdsalApiManager.installFlow(flowEntity);
-        if (logger.isDebugEnabled()) {
-            logger.debug("Known Smac flow entry created for elan Name:{}, logical Interface port:{} and mac address:{}",
-                         elanInfo.getElanInstanceName(), elanInfo.getDescription(), macAddress);
-        }
+        mdsalApiManager.addFlowToTx(flowEntity, writeFlowGroupTx);
+        LOG.debug("Known Smac flow entry created for elan Name:{}, logical Interface port:{} and mac address:{}",
+                elanInfo.getElanInstanceName(), elanInfo.getDescription(), macAddress);
     }
 
-    public static FlowEntity buildKnownSmacFlow(ElanInstance elanInfo, InterfaceInfo interfaceInfo, long macTimeout, String macAddress) {
-        BigInteger dpId = interfaceInfo.getDpId();
+    public FlowEntity buildKnownSmacFlow(ElanInstance elanInfo, InterfaceInfo interfaceInfo, long macTimeout,
+            String macAddress) {
         int lportTag = interfaceInfo.getInterfaceTag();
-        long elanTag = elanInfo.getElanTag();
         // Matching metadata and eth_src fields
         List<MatchInfo> mkMatches = new ArrayList<>();
         mkMatches.add(new MatchInfo(MatchFieldType.metadata, new BigInteger[] {
-                ElanUtils.getElanMetadataLabel(elanInfo.getElanTag(), lportTag),
-                ElanUtils.getElanMetadataMask() }));
+                getElanMetadataLabel(elanInfo.getElanTag(), lportTag), getElanMetadataMask() }));
         mkMatches.add(new MatchInfo(MatchFieldType.eth_src, new String[] { macAddress }));
         List<InstructionInfo> mkInstructions = new ArrayList<>();
-        mkInstructions.add(new InstructionInfo(InstructionType.goto_table, new long[] { ElanConstants.ELAN_DMAC_TABLE }));
+        mkInstructions.add(new InstructionInfo(InstructionType.goto_table, new long[] { NwConstants.ELAN_DMAC_TABLE }));
 
-        FlowEntity flowEntity = MDSALUtil.buildFlowEntity(dpId, ElanConstants.ELAN_SMAC_TABLE,
-                getKnownDynamicmacFlowRef(ElanConstants.ELAN_SMAC_TABLE, dpId, lportTag, macAddress, elanTag),
-                20, elanInfo.getDescription(), (int)macTimeout, 0, ElanConstants.COOKIE_ELAN_KNOWN_SMAC.add(BigInteger.valueOf(elanTag)),
-                mkMatches, mkInstructions);
+        BigInteger dpId = interfaceInfo.getDpId();
+        long elanTag = getElanTag(broker, elanInfo, interfaceInfo);
+        FlowEntity flowEntity = MDSALUtil.buildFlowEntity(dpId, NwConstants.ELAN_SMAC_TABLE,
+                getKnownDynamicmacFlowRef(NwConstants.ELAN_SMAC_TABLE, dpId, lportTag, macAddress, elanTag), 20,
+                elanInfo.getDescription(), (int) macTimeout, 0,
+                ElanConstants.COOKIE_ELAN_KNOWN_SMAC.add(BigInteger.valueOf(elanTag)), mkMatches, mkInstructions);
         flowEntity.setStrictFlag(true);
-        flowEntity.setSendFlowRemFlag(macTimeout != 0); //If Mac timeout is 0, the flow wont be deleted automatically, so no need to get notified
+        flowEntity.setSendFlowRemFlag(macTimeout != 0); // If Mac timeout is 0,
+                                                        // the flow wont be
+                                                        // deleted
+                                                        // automatically, so no
+                                                        // need to get notified
         return flowEntity;
     }
 
+    private static Long getElanTag(DataBroker broker, ElanInstance elanInfo, InterfaceInfo interfaceInfo) {
+        EtreeInterface etreeInterface = getEtreeInterfaceByElanInterfaceName(broker, interfaceInfo.getInterfaceName());
+        if (etreeInterface == null || etreeInterface.getEtreeInterfaceType() == EtreeInterfaceType.Root) {
+            return elanInfo.getElanTag();
+        } else { // Leaf
+            EtreeInstance etreeInstance = elanInfo.getAugmentation(EtreeInstance.class);
+            if (etreeInstance == null) {
+                LOG.warn("EtreeInterface {} is connected to a non-Etree network: {}",
+                         interfaceInfo.getInterfaceName(), elanInfo.getElanInstanceName());
+                return elanInfo.getElanTag();
+            } else {
+                return etreeInstance.getEtreeLeafTagVal().getValue();
+            }
+        }
+    }
+
     /**
-     * Installs a Flow in INTERNAL_TUNNEL_TABLE of the affected DPN that sends the packet through the specified
-     * interface if the tunnel_id matches the interface's lportTag
+     * Installs a Flow in INTERNAL_TUNNEL_TABLE of the affected DPN that sends
+     * the packet through the specified interface if the tunnel_id matches the
+     * interface's lportTag.
      *
      * @param interfaceInfo
+     *            the interface info
      * @param mdsalApiManager
+     *            the mdsal API manager
+     * @param writeFlowGroupTx
+     *            the writeFLowGroup tx
      */
-    public static void setupTermDmacFlows(InterfaceInfo interfaceInfo, IMdsalApiManager mdsalApiManager) {
+    public void setupTermDmacFlows(InterfaceInfo interfaceInfo, IMdsalApiManager mdsalApiManager,
+            WriteTransaction writeFlowGroupTx) {
         BigInteger dpId = interfaceInfo.getDpId();
         int lportTag = interfaceInfo.getInterfaceTag();
         Flow flow = MDSALUtil.buildFlowNew(NwConstants.INTERNAL_TUNNEL_TABLE,
                 getIntTunnelTableFlowRef(NwConstants.INTERNAL_TUNNEL_TABLE, lportTag), 5,
-                String.format("%s:%d","ITM Flow Entry ",lportTag), 0, 0,
+                String.format("%s:%d", "ITM Flow Entry ", lportTag), 0, 0,
                 ITMConstants.COOKIE_ITM.add(BigInteger.valueOf(lportTag)),
                 getTunnelIdMatchForFilterEqualsLPortTag(lportTag),
                 getInstructionsInPortForOutGroup(interfaceInfo.getInterfaceName()));
-        mdsalApiManager.installFlow(dpId, flow);
-        if (logger.isDebugEnabled()) {
-            logger.debug("Terminating service table flow entry created on dpn:{} for logical Interface port:{}",
-                         dpId, interfaceInfo.getPortName());
-        }
+        mdsalApiManager.addFlowToTx(dpId, flow, writeFlowGroupTx);
+        LOG.debug("Terminating service table flow entry created on dpn:{} for logical Interface port:{}", dpId,
+                interfaceInfo.getPortName());
     }
 
     /**
@@ -663,8 +767,10 @@ public class ElanUtils {
      * consisting in tableId + elanTag.
      *
      * @param tableId
+     *            table Id
      * @param elanTag
-     * @return
+     *            elan Tag
+     * @return the Internal tunnel
      */
     public static String getIntTunnelTableFlowRef(short tableId, int elanTag) {
         return new StringBuffer().append(tableId).append(elanTag).toString();
@@ -672,37 +778,36 @@ public class ElanUtils {
 
     /**
      * Constructs the Matches that checks that the tunnel_id field contains a
-     * specific lportTag
+     * specific lportTag.
      *
      * @param lportTag
      *            lportTag that must be checked against the tunnel_id field
-     * @return
+     * @return the list of match Info
      */
     public static List<MatchInfo> getTunnelIdMatchForFilterEqualsLPortTag(int lportTag) {
         List<MatchInfo> mkMatches = new ArrayList<>();
         // Matching metadata
-        mkMatches.add(new MatchInfo(MatchFieldType.tunnel_id, new BigInteger[] {
-                BigInteger.valueOf(lportTag)}));
+        mkMatches.add(new MatchInfo(MatchFieldType.tunnel_id, new BigInteger[] { BigInteger.valueOf(lportTag) }));
         return mkMatches;
     }
 
     /**
-     * Constructs the Instructions that take the packet over a given interface
+     * Constructs the Instructions that take the packet over a given interface.
      *
      * @param ifName
-     *          Name of the interface where the packet must be sent over. It can
-     *          be a local interface or a tunnel interface (internal or external)
-     * @return
+     *            Name of the interface where the packet must be sent over. It
+     *            can be a local interface or a tunnel interface (internal or
+     *            external)
+     * @return the Instruction
      */
-    public static List<Instruction> getInstructionsInPortForOutGroup(String ifName) {
+    public List<Instruction> getInstructionsInPortForOutGroup(String ifName) {
         List<Instruction> mkInstructions = new ArrayList<>();
-        List<Action> actions = ElanUtils.getEgressActionsForInterface(ifName, /*tunnelKey*/ null );
+        List<Action> actions = getEgressActionsForInterface(ifName, /* tunnelKey */ null);
 
         mkInstructions.add(MDSALUtil.buildApplyActionsInstruction(actions));
         return mkInstructions;
     }
 
-
     /**
      * Returns the list of Actions to be taken when sending the packet through
      * an Elan interface. Note that this interface can refer to an ElanInterface
@@ -717,241 +822,367 @@ public class ElanUtils {
      *            the tunnel key
      * @return the egress actions for interface
      */
-    public static List<Action> getEgressActionsForInterface(String ifName, Long tunnelKey) {
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public List<Action> getEgressActionsForInterface(String ifName, Long tunnelKey) {
         List<Action> listAction = new ArrayList<>();
         try {
-            GetEgressActionsForInterfaceInput getEgressActionInput =
-                    new GetEgressActionsForInterfaceInputBuilder().setIntfName(ifName).setTunnelKey(tunnelKey).build();
-            Future<RpcResult<GetEgressActionsForInterfaceOutput>> result =
-                    interfaceMgrRpcService.getEgressActionsForInterface(getEgressActionInput);
+            GetEgressActionsForInterfaceInput getEgressActionInput = new GetEgressActionsForInterfaceInputBuilder()
+                    .setIntfName(ifName).setTunnelKey(tunnelKey).build();
+            Future<RpcResult<GetEgressActionsForInterfaceOutput>> result = interfaceManagerRpcService
+                    .getEgressActionsForInterface(getEgressActionInput);
             RpcResult<GetEgressActionsForInterfaceOutput> rpcResult = result.get();
             if (!rpcResult.isSuccessful()) {
-                logger.warn("RPC Call to Get egress actions for interface {} returned with Errors {}",
-                            ifName, rpcResult.getErrors());
+                LOG.warn("RPC Call to Get egress actions for interface {} returned with Errors {}", ifName,
+                        rpcResult.getErrors());
             } else {
-                List<org.opendaylight.yang.gen.v1.urn.opendaylight.action.types.rev131112.action.list.Action> actions =
-                        rpcResult.getResult().getAction();
+                List<Action> actions = rpcResult.getResult().getAction();
                 listAction = actions;
             }
-        } catch (InterruptedException | ExecutionException e) {
-            logger.warn("Exception when egress actions for interface {}", ifName, e);
+        } catch (Exception e) {
+            LOG.warn("Exception when egress actions for interface {}", ifName, e);
         }
         return listAction;
     }
 
-    private static void setupOrigDmacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, String macAddress,
-            IMdsalApiManager mdsalApiManager, DataBroker broker) {
+    private void setupOrigDmacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, String macAddress,
+                                    boolean configureRemoteFlows, IMdsalApiManager mdsalApiManager,
+                                    DataBroker broker, WriteTransaction writeFlowGroupTx)
+                                    throws ElanException {
         BigInteger dpId = interfaceInfo.getDpId();
         String ifName = interfaceInfo.getInterfaceName();
         long ifTag = interfaceInfo.getInterfaceTag();
         String elanInstanceName = elanInfo.getElanInstanceName();
+
+        Long elanTag = getElanTag(broker, elanInfo, interfaceInfo);
+
+        setupLocalDmacFlow(elanTag, dpId, ifName, macAddress, elanInstanceName, mdsalApiManager, ifTag,
+                writeFlowGroupTx);
+        LOG.debug("Dmac flow entry created for elan Name:{}, logical port Name:{} mand mac address:{} "
+                                    + "on dpn:{}", elanInstanceName, interfaceInfo.getPortName(), macAddress, dpId);
+
+        if (!configureRemoteFlows) {
+            return;
+        }
+
         List<DpnInterfaces> elanDpns = getInvolvedDpnsInElan(elanInstanceName);
-        if (elanDpns != null) {
-            Long elanTag = elanInfo.getElanTag();
-            for (DpnInterfaces elanDpn : elanDpns) {
-                if (elanDpn.getDpId().equals(dpId)) {
-                    // On the local DPN set up a direct output flow
-                    setupLocalDmacFlow(elanTag, dpId, ifName, macAddress, elanInstanceName, mdsalApiManager, ifTag);
-                    logger.debug("Dmac flow entry created for elan Name:{}, logical port Name:{} and mac address:{} on dpn:{}",
-                                 elanInstanceName, interfaceInfo.getPortName(), macAddress, dpId);
-                } else {
-                    // Check for the Remote DPN present in Inventory Manager
-                    if (isDpnPresent(elanDpn.getDpId())) {
-                        // For remote DPNs a flow is needed to indicate that packets of this ELAN going to this MAC
-                        // need to be forwarded through the appropiated ITM tunnel
-                        setupRemoteDmacFlow(elanDpn.getDpId(),   // srcDpn (the remote DPN in this case)
-                                            dpId,                // dstDpn (the local DPN)
-                                            interfaceInfo.getInterfaceTag(), // lportTag of the local interface
-                                            elanTag,             // identifier of the Elan
-                                            macAddress,          // MAC to be programmed in remote DPN
-                                            elanInstanceName);
-                        logger.debug("Dmac flow entry created for elan Name:{}, logical port Name:{} and mac address:{} on dpn:{}",
-                                     elanInstanceName, interfaceInfo.getPortName(), macAddress, elanDpn.getDpId());
-                    }
-                }
+        if (elanDpns == null) {
+            return;
+        }
+
+        for (DpnInterfaces elanDpn : elanDpns) {
+
+            if (elanDpn.getDpId().equals(dpId)) {
+                continue;
+            }
+
+            // Check for the Remote DPN present in Inventory Manager
+            if (!isDpnPresent(elanDpn.getDpId())) {
+                continue;
             }
 
-            // TODO (eperefr): Make sure that the same is performed against the ElanDevices.
+            // For remote DPNs a flow is needed to indicate that
+            // packets of this ELAN going to this MAC
+            // need to be forwarded through the appropiated ITM
+            // tunnel
+            setupRemoteDmacFlow(elanDpn.getDpId(), // srcDpn (the remote DPN in this case)
+                    dpId, // dstDpn (the local DPN)
+                    interfaceInfo.getInterfaceTag(), // lportTag of the local interface
+                    elanTag, // identifier of the Elan
+                    macAddress, // MAC to be programmed in remote DPN
+                    elanInstanceName, writeFlowGroupTx, ifName, elanInfo);
+            LOG.debug("Dmac flow entry created for elan Name:{}, logical port Name:{} and mac address:{} on"
+                        + " dpn:{}", elanInstanceName, interfaceInfo.getPortName(), macAddress, elanDpn.getDpId());
         }
+
+        // TODO: Make sure that the same is performed against the ElanDevices.
     }
 
-    private static void setupOrigDmacFlowsonRemoteDpn(ElanInstance elanInfo, InterfaceInfo interfaceInfo, BigInteger dstDpId, String macAddress) {
+    private void setupOrigDmacFlowsonRemoteDpn(ElanInstance elanInfo, InterfaceInfo interfaceInfo,
+            BigInteger dstDpId, String macAddress, WriteTransaction writeFlowTx) throws ElanException {
         BigInteger dpId = interfaceInfo.getDpId();
         String elanInstanceName = elanInfo.getElanInstanceName();
         List<DpnInterfaces> remoteFEs = getInvolvedDpnsInElan(elanInstanceName);
-        for(DpnInterfaces remoteFE: remoteFEs) {
+        for (DpnInterfaces remoteFE : remoteFEs) {
             Long elanTag = elanInfo.getElanTag();
             if (remoteFE.getDpId().equals(dstDpId)) {
                 // Check for the Remote DPN present in Inventory Manager
-                setupRemoteDmacFlow(dstDpId, dpId, interfaceInfo.getInterfaceTag(), elanTag, macAddress, elanInstanceName);
-                if (logger.isDebugEnabled()) {
-                    logger.debug("Dmac flow entry created for elan Name:{}, logical port Name:{} and mac address {} on dpn:{}", elanInstanceName, interfaceInfo.getPortName(), macAddress, remoteFE.getDpId());
-                }
+                setupRemoteDmacFlow(dstDpId, dpId, interfaceInfo.getInterfaceTag(), elanTag, macAddress,
+                        elanInstanceName, writeFlowTx, interfaceInfo.getInterfaceName(), elanInfo);
+                LOG.debug("Dmac flow entry created for elan Name:{}, logical port Name:{} and mac address {} on dpn:{}",
+                        elanInstanceName, interfaceInfo.getPortName(), macAddress, remoteFE.getDpId());
                 break;
             }
         }
     }
 
-
     @SuppressWarnings("unchecked")
-    public static List<DpnInterfaces> getInvolvedDpnsInElan(String elanName) {
-        List<DpnInterfaces> dpns = ElanInstanceManager.getElanInstanceManager().getElanDPNByName(elanName);
+    public List<DpnInterfaces> getInvolvedDpnsInElan(String elanName) {
+        List<DpnInterfaces> dpns = elanInstanceManager.getElanDPNByName(elanName);
         if (dpns == null) {
             return Collections.emptyList();
         }
         return dpns;
     }
 
-    private static void setupLocalDmacFlow(long elanTag, BigInteger dpId, String ifName, String macAddress,
-                                           String displayName, IMdsalApiManager mdsalApiManager, long ifTag) {
+    private void setupLocalDmacFlow(long elanTag, BigInteger dpId, String ifName, String macAddress,
+            String displayName, IMdsalApiManager mdsalApiManager, long ifTag, WriteTransaction writeFlowGroupTx) {
         Flow flowEntity = buildLocalDmacFlowEntry(elanTag, dpId, ifName, macAddress, displayName, ifTag);
-        mdsalApiManager.installFlow(dpId, flowEntity);
+        mdsalApiManager.addFlowToTx(dpId, flowEntity, writeFlowGroupTx);
+        installEtreeLocalDmacFlow(elanTag, dpId, ifName, macAddress, displayName, mdsalApiManager, ifTag,
+                writeFlowGroupTx);
+    }
+
+    private void installEtreeLocalDmacFlow(long elanTag, BigInteger dpId, String ifName, String macAddress,
+            String displayName, IMdsalApiManager mdsalApiManager, long ifTag, WriteTransaction writeFlowGroupTx) {
+        EtreeInterface etreeInterface = getEtreeInterfaceByElanInterfaceName(broker, ifName);
+        if (etreeInterface != null) {
+            if (etreeInterface.getEtreeInterfaceType() == EtreeInterfaceType.Root) {
+                EtreeLeafTagName etreeTagName = getEtreeLeafTagByElanTag(elanTag);
+                if (etreeTagName == null) {
+                    LOG.warn("Interface {} seems like it belongs to Etree but etreeTagName from elanTag {} is null",
+                             ifName, elanTag);
+                } else {
+                    Flow flowEntity = buildLocalDmacFlowEntry(etreeTagName.getEtreeLeafTag().getValue(), dpId, ifName,
+                            macAddress, displayName, ifTag);
+                    mdsalApiManager.addFlowToTx(dpId, flowEntity, writeFlowGroupTx);
+                }
+            }
+        }
+    }
 
+    public static String getKnownDynamicmacFlowRef(short tableId, BigInteger dpId, long lporTag, String macAddress,
+            long elanTag) {
+        return new StringBuffer().append(tableId).append(elanTag).append(dpId).append(lporTag).append(macAddress)
+                .toString();
     }
 
-    public static String getKnownDynamicmacFlowRef(short tableId, BigInteger dpId, long lporTag, String macAddress, long elanTag) {
-        return new StringBuffer().append(tableId).append(elanTag).append(dpId).append(lporTag).append(macAddress).toString();
+    public static String getKnownDynamicmacFlowRef(short tableId, BigInteger dpId, BigInteger remoteDpId,
+            String macAddress, long elanTag) {
+        return new StringBuffer().append(tableId).append(elanTag).append(dpId).append(remoteDpId).append(macAddress)
+                .toString();
     }
 
-    public static String getKnownDynamicmacFlowRef(short tableId, BigInteger dpId, BigInteger remoteDpId, String macAddress, long elanTag) {
-        return new StringBuffer().append(tableId).append(elanTag).append(dpId).append(remoteDpId).append(macAddress).toString();
+    public static String getKnownDynamicmacFlowRef(short tableId, BigInteger dpId, String macAddress, long elanTag) {
+        return new StringBuffer().append(tableId).append(elanTag).append(dpId).append(macAddress).toString();
     }
 
     private static String getKnownDynamicmacFlowRef(short elanDmacTable, BigInteger dpId, String extDeviceNodeId,
             String dstMacAddress, long elanTag, boolean shFlag) {
-        return new StringBuffer().append(elanDmacTable).append(elanTag).append(dpId)
-                                 .append(extDeviceNodeId).append(dstMacAddress).append(shFlag)
-                                 .toString();
+        return new StringBuffer().append(elanDmacTable).append(elanTag).append(dpId).append(extDeviceNodeId)
+                .append(dstMacAddress).append(shFlag).toString();
     }
 
     /**
-     * Builds the flow to be programmed in the DMAC table of the local DPN (that is, where the MAC is attached to).
-     * This flow consists in:
+     * Builds the flow to be programmed in the DMAC table of the local DPN (that
+     * is, where the MAC is attached to). This flow consists in:
      *
-     *  Match:
-     *     + elanTag in metadata
-     *     + packet goes to a MAC locally attached
-     *  Actions:
-     *     + optionally, pop-vlan + set-vlan-id
-     *     + output to ifName's portNumber
+     * <p>Match: + elanTag in metadata + packet goes to a MAC locally attached
+     * Actions: + optionally, pop-vlan + set-vlan-id + output to ifName's
+     * portNumber
      *
-     * @param elanTag the elan tag
-     * @param dpId the dp id
-     * @param ifName the if name
-     * @param macAddress the mac address
-     * @param displayName the display name
-     * @param ifTag the if tag
+     * @param elanTag
+     *            the elan tag
+     * @param dpId
+     *            the dp id
+     * @param ifName
+     *            the if name
+     * @param macAddress
+     *            the mac address
+     * @param displayName
+     *            the display name
+     * @param ifTag
+     *            the if tag
      * @return the flow
      */
-    public static Flow buildLocalDmacFlowEntry(long elanTag, BigInteger dpId, String ifName, String macAddress,
-                                               String displayName, long ifTag) {
+    public Flow buildLocalDmacFlowEntry(long elanTag, BigInteger dpId, String ifName, String macAddress,
+            String displayName, long ifTag) {
         List<MatchInfo> mkMatches = new ArrayList<>();
         mkMatches.add(new MatchInfo(MatchFieldType.metadata,
-                new BigInteger[] { ElanUtils.getElanMetadataLabel(elanTag), MetaDataUtil.METADATA_MASK_SERVICE }));
+                new BigInteger[] { getElanMetadataLabel(elanTag), MetaDataUtil.METADATA_MASK_SERVICE }));
         mkMatches.add(new MatchInfo(MatchFieldType.eth_dst, new String[] { macAddress }));
 
         List<Instruction> mkInstructions = new ArrayList<>();
         List<Action> actions = getEgressActionsForInterface(ifName, /* tunnelKey */ null);
         mkInstructions.add(MDSALUtil.buildApplyActionsInstruction(actions));
-        Flow flow = MDSALUtil.buildFlowNew(ElanConstants.ELAN_DMAC_TABLE,
-                getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, dpId, ifTag, macAddress, elanTag), 20,
+        Flow flow = MDSALUtil.buildFlowNew(NwConstants.ELAN_DMAC_TABLE,
+                getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpId, ifTag, macAddress, elanTag), 20,
                 displayName, 0, 0, ElanConstants.COOKIE_ELAN_KNOWN_DMAC.add(BigInteger.valueOf(elanTag)), mkMatches,
                 mkInstructions);
 
         return flow;
     }
 
-    public static void setupRemoteDmacFlow(BigInteger srcDpId, BigInteger destDpId, int lportTag, long elanTag, String macAddress,
-                                           String displayName) {
-        Flow flowEntity = buildRemoteDmacFlowEntry(srcDpId, destDpId, lportTag, elanTag, macAddress, displayName);
-        mdsalMgr.installFlow(srcDpId, flowEntity);
+    public void setupRemoteDmacFlow(BigInteger srcDpId, BigInteger destDpId, int lportTag, long elanTag,
+            String macAddress, String displayName, WriteTransaction writeFlowGroupTx, String interfaceName,
+            ElanInstance elanInstance) throws ElanException {
+        Flow flowEntity = buildRemoteDmacFlowEntry(srcDpId, destDpId, lportTag, elanTag, macAddress, displayName,
+                elanInstance);
+        mdsalManager.addFlowToTx(srcDpId, flowEntity, writeFlowGroupTx);
+        setupEtreeRemoteDmacFlow(srcDpId, destDpId, lportTag, elanTag, macAddress, displayName, interfaceName,
+                writeFlowGroupTx, elanInstance);
+    }
+
+    private void setupEtreeRemoteDmacFlow(BigInteger srcDpId, BigInteger destDpId, int lportTag, long elanTag,
+                                String macAddress, String displayName, String interfaceName,
+                                WriteTransaction writeFlowGroupTx, ElanInstance elanInstance) throws ElanException {
+        Flow flowEntity;
+        EtreeInterface etreeInterface = getEtreeInterfaceByElanInterfaceName(broker, interfaceName);
+        if (etreeInterface != null) {
+            if (etreeInterface.getEtreeInterfaceType() == EtreeInterfaceType.Root) {
+                EtreeLeafTagName etreeTagName = getEtreeLeafTagByElanTag(elanTag);
+                if (etreeTagName == null) {
+                    LOG.warn("Interface " + interfaceName
+                            + " seems like it belongs to Etree but etreeTagName from elanTag " + elanTag + " is null.");
+                } else {
+                    flowEntity = buildRemoteDmacFlowEntry(srcDpId, destDpId, lportTag,
+                            etreeTagName.getEtreeLeafTag().getValue(), macAddress, displayName, elanInstance);
+                    mdsalManager.addFlowToTx(srcDpId, flowEntity, writeFlowGroupTx);
+                }
+            }
+        }
     }
 
     /**
-     * Builds a Flow to be programmed in a remote DPN's DMAC table.
-     * This flow consists in:
-     *  Match:
-     *    + elanTag in packet's metadata
-     *    + packet going to a MAC known to be located in another DPN
-     *  Actions:
-     *    + set_tunnel_id(lportTag)
-     *    + output ITM internal tunnel interface with the other DPN
+     * Builds a Flow to be programmed in a remote DPN's DMAC table. This flow
+     * consists in: Match: + elanTag in packet's metadata + packet going to a
+     * MAC known to be located in another DPN Actions: + set_tunnel_id(lportTag)
+     * + output ITM internal tunnel interface with the other DPN
      *
      * @param srcDpId
+     *            the src Dpn Id
      * @param destDpId
+     *            dest Dp Id
      * @param lportTag
+     *            lport Tag
      * @param elanTag
+     *            elan Tag
      * @param macAddress
+     *            macAddress
      * @param displayName
-     * @return
+     *            display Name
+     * @return the flow remote Dmac
+     * @throws ElanException in case of issues creating the flow objects
      */
-    public static Flow buildRemoteDmacFlowEntry(BigInteger srcDpId, BigInteger destDpId, int lportTag, long elanTag,
-                                                 String macAddress, String displayName) {
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public Flow buildRemoteDmacFlowEntry(BigInteger srcDpId, BigInteger destDpId, int lportTag, long elanTag,
+            String macAddress, String displayName, ElanInstance elanInstance) throws ElanException {
         List<MatchInfo> mkMatches = new ArrayList<>();
         mkMatches.add(new MatchInfo(MatchFieldType.metadata,
-                                    new BigInteger[]{ ElanUtils.getElanMetadataLabel(elanTag),
-                                                      MetaDataUtil.METADATA_MASK_SERVICE }));
+                new BigInteger[] { getElanMetadataLabel(elanTag), MetaDataUtil.METADATA_MASK_SERVICE }));
         mkMatches.add(new MatchInfo(MatchFieldType.eth_dst, new String[] { macAddress }));
 
         List<Instruction> mkInstructions = new ArrayList<>();
 
-        //List of Action for the provided Source and Destination DPIDs
+        // List of Action for the provided Source and Destination DPIDs
         try {
-            List<Action> actions = getInternalItmEgressAction(srcDpId, destDpId, lportTag);
+            List<Action> actions = null;
+            if (isVlan(elanInstance) || isFlat(elanInstance)) {
+                String interfaceName = getExternalElanInterface(elanInstance.getElanInstanceName(), srcDpId);
+                if (null == interfaceName) {
+                    LOG.error("buildRemoteDmacFlowEntry: Could not find interfaceName for {} {}", srcDpId,
+                            elanInstance);
+                }
+                actions = getEgressActionsForInterface(interfaceName, null);
+            } else {
+                actions = getInternalTunnelItmEgressAction(srcDpId, destDpId, lportTag);
+            }
             mkInstructions.add(MDSALUtil.buildApplyActionsInstruction(actions));
         } catch (Exception e) {
-            logger.error("Interface Not Found exception");
+            LOG.error("Could not get egress actions to add to flow for srcDpId=" + srcDpId + ", destDpId=" + destDpId
+                    + ", lportTag=" + lportTag, e);
         }
 
-
-        Flow flow = MDSALUtil.buildFlowNew(ElanConstants.ELAN_DMAC_TABLE,
-                getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, srcDpId, destDpId, macAddress, elanTag),
-                20,  /* prio */
-                displayName, 0,   /* idleTimeout */
-                0,   /* hardTimeout */
+        Flow flow = MDSALUtil.buildFlowNew(NwConstants.ELAN_DMAC_TABLE,
+                getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, srcDpId, destDpId, macAddress, elanTag),
+                20, /* prio */
+                displayName, 0, /* idleTimeout */
+                0, /* hardTimeout */
                 ElanConstants.COOKIE_ELAN_KNOWN_DMAC.add(BigInteger.valueOf(elanTag)), mkMatches, mkInstructions);
 
         return flow;
 
     }
 
-    public static void deleteMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, MacEntry macEntry) {
+    public void deleteMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, MacEntry macEntry,
+            WriteTransaction deleteFlowGroupTx) {
         if (elanInfo == null || interfaceInfo == null) {
             return;
         }
         String macAddress = macEntry.getMacAddress().getValue();
-        synchronized (macAddress) {
-            logger.info("Acquired lock for mac : " + macAddress + "Proceeding with remove operation.");
-            deleteMacFlows(elanInfo, interfaceInfo,  macAddress, /* alsoDeleteSMAC */ true);
+        synchronized (getElanMacKey(elanInfo.getElanTag(), macAddress)) {
+            deleteMacFlows(elanInfo, interfaceInfo, macAddress, /* alsoDeleteSMAC */ true, deleteFlowGroupTx);
         }
     }
 
-    public static void deleteMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, String macAddress, boolean deleteSmac) {
+    public void deleteMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, String macAddress,
+            boolean deleteSmac, WriteTransaction deleteFlowGroupTx) {
         String elanInstanceName = elanInfo.getElanInstanceName();
-        long ifTag = interfaceInfo.getInterfaceTag();
         List<DpnInterfaces> remoteFEs = getInvolvedDpnsInElan(elanInstanceName);
         BigInteger srcdpId = interfaceInfo.getDpId();
-        for (DpnInterfaces dpnInterface: remoteFEs) {
+        boolean isFlowsRemovedInSrcDpn = false;
+        for (DpnInterfaces dpnInterface : remoteFEs) {
             Long elanTag = elanInfo.getElanTag();
             BigInteger dstDpId = dpnInterface.getDpId();
-            if (dstDpId.equals(srcdpId)) {
-                if(deleteSmac) {
-                    mdsalMgr.removeFlow(srcdpId, MDSALUtil.buildFlow(ElanConstants.ELAN_SMAC_TABLE,
-                            getKnownDynamicmacFlowRef(ElanConstants.ELAN_SMAC_TABLE, srcdpId, ifTag, macAddress, elanTag)));
-                }
-                mdsalMgr.removeFlow(srcdpId, MDSALUtil.buildFlow(ElanConstants.ELAN_DMAC_TABLE,
-                        getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, srcdpId, ifTag, macAddress, elanTag)));
-                if (logger.isDebugEnabled()) {
-                    logger.debug("All the required flows deleted for elan:{}, logical Interface port:{} and mac address:{} on dpn:{}", elanInstanceName, interfaceInfo.getPortName(), macAddress, srcdpId);
-                }
-            } else if (isDpnPresent(dstDpId)) {
-                mdsalMgr.removeFlow(dstDpId, MDSALUtil.buildFlow(ElanConstants.ELAN_DMAC_TABLE,
-                        getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, dstDpId, srcdpId, macAddress, elanTag)));
-                if (logger.isDebugEnabled()) {
-                    logger.debug("Dmac flow entry deleted for elan:{}, logical interface port:{} and mac address:{} on dpn:{}", elanInstanceName, interfaceInfo.getPortName(), macAddress, dstDpId);
-                }
+            if (executeDeleteMacFlows(elanInfo, interfaceInfo, macAddress, deleteSmac, elanInstanceName, srcdpId,
+                    elanTag, dstDpId, deleteFlowGroupTx)) {
+                isFlowsRemovedInSrcDpn = true;
             }
+            executeEtreeDeleteMacFlows(elanInfo, interfaceInfo, macAddress, deleteSmac, elanInstanceName, srcdpId,
+                    elanTag, dstDpId, deleteFlowGroupTx);
+        }
+        if (!isFlowsRemovedInSrcDpn) {
+            deleteSmacAndDmacFlows(elanInfo, interfaceInfo, macAddress, deleteSmac, deleteFlowGroupTx);
+        }
+    }
+
+    private void executeEtreeDeleteMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, String macAddress,
+            boolean deleteSmac, String elanInstanceName, BigInteger srcdpId, Long elanTag, BigInteger dstDpId,
+            WriteTransaction deleteFlowGroupTx) {
+        EtreeLeafTagName etreeLeafTag = getEtreeLeafTagByElanTag(elanTag);
+        if (etreeLeafTag != null) {
+            executeDeleteMacFlows(elanInfo, interfaceInfo, macAddress, deleteSmac, elanInstanceName, srcdpId,
+                    etreeLeafTag.getEtreeLeafTag().getValue(), dstDpId, deleteFlowGroupTx);
+        }
+    }
+
+    private boolean executeDeleteMacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, String macAddress,
+            boolean deleteSmac, String elanInstanceName, BigInteger srcdpId, Long elanTag, BigInteger dstDpId,
+            WriteTransaction deleteFlowGroupTx) {
+        boolean isFlowsRemovedInSrcDpn = false;
+        if (dstDpId.equals(srcdpId)) {
+            isFlowsRemovedInSrcDpn = true;
+            deleteSmacAndDmacFlows(elanInfo, interfaceInfo, macAddress, deleteSmac, deleteFlowGroupTx);
+        } else if (isDpnPresent(dstDpId)) {
+            mdsalManager
+                    .removeFlowToTx(dstDpId,
+                            MDSALUtil.buildFlow(NwConstants.ELAN_DMAC_TABLE, getKnownDynamicmacFlowRef(
+                                    NwConstants.ELAN_DMAC_TABLE, dstDpId, srcdpId, macAddress, elanTag)),
+                            deleteFlowGroupTx);
+            LOG.debug("Dmac flow entry deleted for elan:{}, logical interface port:{} and mac address:{} on dpn:{}",
+                    elanInstanceName, interfaceInfo.getPortName(), macAddress, dstDpId);
+        }
+        return isFlowsRemovedInSrcDpn;
+    }
+
+    private void deleteSmacAndDmacFlows(ElanInstance elanInfo, InterfaceInfo interfaceInfo, String macAddress,
+            boolean deleteSmac, WriteTransaction deleteFlowGroupTx) {
+        String elanInstanceName = elanInfo.getElanInstanceName();
+        long ifTag = interfaceInfo.getInterfaceTag();
+        BigInteger srcdpId = interfaceInfo.getDpId();
+        Long elanTag = elanInfo.getElanTag();
+        if (deleteSmac) {
+            mdsalManager
+                    .removeFlowToTx(srcdpId,
+                            MDSALUtil.buildFlow(NwConstants.ELAN_SMAC_TABLE, getKnownDynamicmacFlowRef(
+                                    NwConstants.ELAN_SMAC_TABLE, srcdpId, ifTag, macAddress, elanTag)),
+                            deleteFlowGroupTx);
         }
+        mdsalManager.removeFlowToTx(srcdpId,
+                MDSALUtil.buildFlow(NwConstants.ELAN_DMAC_TABLE,
+                        getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, srcdpId, ifTag, macAddress, elanTag)),
+                deleteFlowGroupTx);
+        LOG.debug("All the required flows deleted for elan:{}, logical Interface port:{} and MAC address:{} on dpn:{}",
+                elanInstanceName, interfaceInfo.getPortName(), macAddress, srcdpId);
     }
 
     /**
@@ -964,68 +1195,100 @@ public class ElanUtils {
      *            the id manager
      * @param elanInstanceAdded
      *            the elan instance added
+     * @param elanInterfaces
+     *            the elan interfaces
+     * @param tx
+     *            transaction
      */
     public static void updateOperationalDataStore(DataBroker broker, IdManagerService idManager,
-            ElanInstance elanInstanceAdded) {
+            ElanInstance elanInstanceAdded, List<String> elanInterfaces, WriteTransaction tx) {
         String elanInstanceName = elanInstanceAdded.getElanInstanceName();
-        long elanTag = ElanUtils.retrieveNewElanTag(idManager, elanInstanceName);
-        Elan elanInfo = new ElanBuilder().setName(elanInstanceName).setKey(new ElanKey(elanInstanceName)).build();
+        Long elanTag = elanInstanceAdded.getElanTag();
+        if (elanTag == null || elanTag == 0L) {
+            elanTag = retrieveNewElanTag(idManager, elanInstanceName);
+        }
+        Elan elanInfo = new ElanBuilder().setName(elanInstanceName).setElanInterfaces(elanInterfaces)
+                .setKey(new ElanKey(elanInstanceName)).build();
 
-        //Add the ElanState in the elan-state operational data-store
-        MDSALUtil.syncWrite(broker, LogicalDatastoreType.OPERATIONAL,
-                ElanUtils.getElanInstanceOperationalDataPath(elanInstanceName), elanInfo);
+        // Add the ElanState in the elan-state operational data-store
+        tx.put(LogicalDatastoreType.OPERATIONAL, getElanInstanceOperationalDataPath(elanInstanceName),
+                elanInfo, true);
 
-        //Add the ElanMacTable in the elan-mac-table operational data-store
+        // Add the ElanMacTable in the elan-mac-table operational data-store
         MacTable elanMacTable = new MacTableBuilder().setKey(new MacTableKey(elanInstanceName)).build();
-        MDSALUtil.syncWrite(broker, LogicalDatastoreType.OPERATIONAL,
-                ElanUtils.getElanMacTableOperationalDataPath(elanInstanceName), elanMacTable);
-
-        ElanTagName elanTagName = new ElanTagNameBuilder().setElanTag(elanTag).setKey(new ElanTagNameKey(elanTag))
-                .setName(elanInstanceName).build();
+        tx.put(LogicalDatastoreType.OPERATIONAL, getElanMacTableOperationalDataPath(elanInstanceName),
+                elanMacTable, true);
+
+        ElanTagNameBuilder elanTagNameBuilder = new ElanTagNameBuilder().setElanTag(elanTag)
+                .setKey(new ElanTagNameKey(elanTag)).setName(elanInstanceName);
+        long etreeLeafTag = -1;
+        if (isEtreeInstance(elanInstanceAdded)) {
+            etreeLeafTag = retrieveNewElanTag(idManager, elanInstanceName + ElanConstants.LEAVES_POSTFIX);
+            EtreeLeafTagName etreeLeafTagName = new EtreeLeafTagNameBuilder()
+                    .setEtreeLeafTag(new EtreeLeafTag(etreeLeafTag)).build();
+            elanTagNameBuilder.addAugmentation(EtreeLeafTagName.class, etreeLeafTagName);
+            addTheLeafTagAsElanTag(broker, elanInstanceName, etreeLeafTag, tx);
+        }
+        ElanTagName elanTagName = elanTagNameBuilder.build();
 
-        //Add the ElanTag to ElanName in the elan-tag-name Operational data-store
-        MDSALUtil.syncWrite(broker, LogicalDatastoreType.OPERATIONAL,
-                ElanUtils.getElanInfoEntriesOperationalDataPath(elanTag), elanTagName);
+        // Add the ElanTag to ElanName in the elan-tag-name Operational
+        // data-store
+        tx.put(LogicalDatastoreType.OPERATIONAL,
+                getElanInfoEntriesOperationalDataPath(elanTag), elanTagName);
 
-        // Updates the ElanInstance Config DS by setting the just adquired elanTag
-        ElanInstance elanInstanceWithTag = new ElanInstanceBuilder().setElanInstanceName(elanInstanceName)
+        // Updates the ElanInstance Config DS by setting the just acquired
+        // elanTag
+        ElanInstanceBuilder elanInstanceBuilder = new ElanInstanceBuilder().setElanInstanceName(elanInstanceName)
                 .setDescription(elanInstanceAdded.getDescription())
-                .setMacTimeout(elanInstanceAdded.getMacTimeout() == null ?  ElanConstants.DEFAULT_MAC_TIME_OUT
+                .setMacTimeout(elanInstanceAdded.getMacTimeout() == null ? ElanConstants.DEFAULT_MAC_TIME_OUT
                         : elanInstanceAdded.getMacTimeout())
-                .setKey(elanInstanceAdded.getKey()).setElanTag(elanTag).build();
-        MDSALUtil.syncUpdate(broker, LogicalDatastoreType.CONFIGURATION,
-                getElanInstanceConfigurationDataPath(elanInstanceName), elanInstanceWithTag);
+                .setKey(elanInstanceAdded.getKey()).setElanTag(elanTag);
+        if (isEtreeInstance(elanInstanceAdded)) {
+            EtreeInstance etreeInstance = new EtreeInstanceBuilder().setEtreeLeafTagVal(new EtreeLeafTag(etreeLeafTag))
+                    .build();
+            elanInstanceBuilder.addAugmentation(EtreeInstance.class, etreeInstance);
+        }
+        ElanInstance elanInstanceWithTag = elanInstanceBuilder.build();
+        tx.merge(LogicalDatastoreType.CONFIGURATION, getElanInstanceConfigurationDataPath(elanInstanceName),
+                elanInstanceWithTag, true);
+    }
+
+    private static void addTheLeafTagAsElanTag(DataBroker broker, String elanInstanceName, long etreeLeafTag,
+            WriteTransaction tx) {
+        ElanTagName etreeTagAsElanTag = new ElanTagNameBuilder().setElanTag(etreeLeafTag)
+                .setKey(new ElanTagNameKey(etreeLeafTag)).setName(elanInstanceName).build();
+        tx.put(LogicalDatastoreType.OPERATIONAL,
+                getElanInfoEntriesOperationalDataPath(etreeLeafTag), etreeTagAsElanTag);
+    }
+
+    private static boolean isEtreeInstance(ElanInstance elanInstanceAdded) {
+        return elanInstanceAdded.getAugmentation(EtreeInstance.class) != null;
     }
 
-    public static boolean isDpnPresent(BigInteger dpnId) {
-        String dpn = String.format("%s:%s", "openflow",dpnId);
+    public boolean isDpnPresent(BigInteger dpnId) {
+        String dpn = String.format("%s:%s", "openflow", dpnId);
         NodeId nodeId = new NodeId(dpn);
 
         InstanceIdentifier<Node> node = InstanceIdentifier.builder(Nodes.class).child(Node.class, new NodeKey(nodeId))
                 .build();
-        Optional<Node> nodePresent = read(dataBroker, LogicalDatastoreType.OPERATIONAL, node);
-        return (nodePresent.isPresent());
+        return read(broker, LogicalDatastoreType.OPERATIONAL, node).isPresent();
     }
 
     public static ServicesInfo getServiceInfo(String elanInstanceName, long elanTag, String interfaceName) {
         int priority = ElanConstants.ELAN_SERVICE_PRIORITY;
         int instructionKey = 0;
         List<Instruction> instructions = new ArrayList<>();
-        instructions.add(MDSALUtil.buildAndGetWriteMetadaInstruction(ElanUtils.getElanMetadataLabel(elanTag), MetaDataUtil.METADATA_MASK_SERVICE, ++instructionKey));
-        instructions.add(MDSALUtil.buildAndGetGotoTableInstruction(ElanConstants.ELAN_SMAC_TABLE, ++instructionKey));
-
-        ServicesInfo serviceInfo = InterfaceServiceUtil.buildServiceInfo(String.format("%s.%s", elanInstanceName, interfaceName), ElanConstants.ELAN_SERVICE_INDEX,
-                priority, ElanConstants.COOKIE_ELAN_INGRESS_TABLE, instructions);
+        instructions.add(MDSALUtil.buildAndGetWriteMetadaInstruction(getElanMetadataLabel(elanTag),
+                MetaDataUtil.METADATA_MASK_SERVICE, ++instructionKey));
+        instructions.add(MDSALUtil.buildAndGetGotoTableInstruction(NwConstants.ELAN_SMAC_TABLE, ++instructionKey));
+
+        short serviceIndex = ServiceIndex.getIndex(NwConstants.ELAN_SERVICE_NAME, NwConstants.ELAN_SERVICE_INDEX);
+        ServicesInfo serviceInfo = InterfaceServiceUtil.buildServiceInfo(
+                String.format("%s.%s", elanInstanceName, interfaceName), serviceIndex, priority,
+                NwConstants.COOKIE_ELAN_INGRESS_TABLE, instructions);
         return serviceInfo;
     }
 
-    public static <T extends DataObject> void delete(DataBroker broker, LogicalDatastoreType datastoreType,
-            InstanceIdentifier<T> path, FutureCallback<Void> callback) {
-        WriteTransaction tx = broker.newWriteOnlyTransaction();
-        tx.delete(datastoreType, path);
-        Futures.addCallback(tx.submit(), callback);
-    }
-
     public static <T extends DataObject> void syncWrite(DataBroker broker, LogicalDatastoreType datastoreType,
             InstanceIdentifier<T> path, T data) {
         WriteTransaction tx = broker.newWriteOnlyTransaction();
@@ -1034,22 +1297,23 @@ public class ElanUtils {
         try {
             futures.get();
         } catch (InterruptedException | ExecutionException e) {
-            logger.error("Error writing to datastore (path, data) : ({}, {})", path, data);
+            LOG.error("Error writing to datastore (path, data) : ({}, {})", path, data);
             throw new RuntimeException(e.getMessage());
         }
     }
 
-
     public static BoundServices getBoundServices(String serviceName, short servicePriority, int flowPriority,
             BigInteger cookie, List<Instruction> instructions) {
-        StypeOpenflowBuilder augBuilder = new StypeOpenflowBuilder().setFlowCookie(cookie).setFlowPriority(flowPriority).setInstruction(instructions);
-        return new BoundServicesBuilder().setKey(new BoundServicesKey(servicePriority))
-                .setServiceName(serviceName).setServicePriority(servicePriority)
-                .setServiceType(ServiceTypeFlowBased.class).addAugmentation(StypeOpenflow.class, augBuilder.build()).build();
+        StypeOpenflowBuilder augBuilder = new StypeOpenflowBuilder().setFlowCookie(cookie).setFlowPriority(flowPriority)
+                .setInstruction(instructions);
+        return new BoundServicesBuilder().setKey(new BoundServicesKey(servicePriority)).setServiceName(serviceName)
+                .setServicePriority(servicePriority).setServiceType(ServiceTypeFlowBased.class)
+                .addAugmentation(StypeOpenflow.class, augBuilder.build()).build();
     }
 
     public static InstanceIdentifier<BoundServices> buildServiceId(String vpnInterfaceName, short serviceIndex) {
-        return InstanceIdentifier.builder(ServiceBindings.class).child(ServicesInfo.class, new ServicesInfoKey(vpnInterfaceName))
+        return InstanceIdentifier.builder(ServiceBindings.class)
+                .child(ServicesInfo.class, new ServicesInfoKey(vpnInterfaceName, ServiceModeIngress.class))
                 .child(BoundServices.class, new BoundServicesKey(serviceIndex)).build();
     }
 
@@ -1064,26 +1328,44 @@ public class ElanUtils {
      *            the tunnel key
      * @return the list
      */
-    public static List<Action> buildItmEgressActions(String tunnelIfaceName, Long tunnelKey) {
-        List<Action> result = Collections.emptyList();
+    public List<Action> buildTunnelItmEgressActions(String tunnelIfaceName, Long tunnelKey) {
         if (tunnelIfaceName != null && !tunnelIfaceName.isEmpty()) {
+            return buildItmEgressActions(tunnelIfaceName, tunnelKey);
+        }
+
+        return Collections.emptyList();
+    }
+
+    /**
+     * Builds the list of actions to be taken when sending the packet over
+     * external port such as tunnel, physical port etc.
+     *
+     * @param interfaceName
+     *            the interface name
+     * @param tunnelKey
+     *            can be VNI for VxLAN tunnel interfaces, Gre Key for GRE
+     *            tunnels, etc.
+     * @return the list
+     */
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public List<Action> buildItmEgressActions(String interfaceName, Long tunnelKey) {
+        List<Action> result = Collections.emptyList();
+        try {
             GetEgressActionsForInterfaceInput getEgressActInput = new GetEgressActionsForInterfaceInputBuilder()
-                    .setIntfName(tunnelIfaceName).setTunnelKey(tunnelKey).build();
-
-            Future<RpcResult<GetEgressActionsForInterfaceOutput>> egressActionsOutputFuture =
-                    interfaceMgrRpcService.getEgressActionsForInterface(getEgressActInput);
-            try {
-                if (egressActionsOutputFuture.get().isSuccessful()) {
-                    GetEgressActionsForInterfaceOutput egressActionsOutput = egressActionsOutputFuture.get().getResult();
-                    result = egressActionsOutput.getAction();
-                }
-            } catch (InterruptedException | ExecutionException e) {
-                logger.error("Error in RPC call getEgressActionsForInterface {}", e);
+                    .setIntfName(interfaceName).setTunnelKey(tunnelKey).build();
+
+            Future<RpcResult<GetEgressActionsForInterfaceOutput>> egressActionsOutputFuture = interfaceManagerRpcService
+                    .getEgressActionsForInterface(getEgressActInput);
+            if (egressActionsOutputFuture.get().isSuccessful()) {
+                GetEgressActionsForInterfaceOutput egressActionsOutput = egressActionsOutputFuture.get().getResult();
+                result = egressActionsOutput.getAction();
             }
+        } catch (Exception e) {
+            LOG.error("Error in RPC call getEgressActionsForInterface {}", e);
         }
 
-        if ( result == null || result.size() == 0 ) {
-            logger.warn("Could not build Egress actions for interface {} and tunnelId {}", tunnelIfaceName, tunnelKey);
+        if (result == null || result.size() == 0) {
+            LOG.warn("Could not build Egress actions for interface {} and tunnelId {}", interfaceName, tunnelKey);
         }
         return result;
     }
@@ -1102,25 +1384,25 @@ public class ElanUtils {
      *            Vni to be stamped on the VxLAN Header.
      * @return the external itm egress action
      */
-    public static List<Action> getExternalItmEgressAction(BigInteger srcDpnId, NodeId torNode, long vni ) {
+    public List<Action> getExternalTunnelItmEgressAction(BigInteger srcDpnId, NodeId torNode, long vni) {
         List<Action> result = Collections.emptyList();
 
         GetExternalTunnelInterfaceNameInput input = new GetExternalTunnelInterfaceNameInputBuilder()
-                .setDestinationNode(torNode.getValue()).setSourceNode(srcDpnId.toString()).setTunnelType(TunnelTypeVxlan.class).build();
-        Future<RpcResult<GetExternalTunnelInterfaceNameOutput>> output =
-                itmRpcService.getExternalTunnelInterfaceName(input);
+                .setDestinationNode(torNode.getValue()).setSourceNode(srcDpnId.toString())
+                .setTunnelType(TunnelTypeVxlan.class).build();
+        Future<RpcResult<GetExternalTunnelInterfaceNameOutput>> output = itmRpcService
+                .getExternalTunnelInterfaceName(input);
         try {
             if (output.get().isSuccessful()) {
                 GetExternalTunnelInterfaceNameOutput tunnelInterfaceNameOutput = output.get().getResult();
                 String tunnelIfaceName = tunnelInterfaceNameOutput.getInterfaceName();
-                if ( logger.isDebugEnabled() )
-                    logger.debug("Received tunnelInterfaceName from getTunnelInterfaceName RPC {}", tunnelIfaceName);
+                LOG.debug("Received tunnelInterfaceName from getTunnelInterfaceName RPC {}", tunnelIfaceName);
 
-                result = buildItmEgressActions(tunnelIfaceName, vni);
+                result = buildTunnelItmEgressActions(tunnelIfaceName, vni);
             }
 
         } catch (InterruptedException | ExecutionException e) {
-            logger.error("Error in RPC call getTunnelInterfaceName {}", e);
+            LOG.error("Error in RPC call getTunnelInterfaceName {}", e);
         }
 
         return result;
@@ -1141,69 +1423,82 @@ public class ElanUtils {
      *            serviceId to be sent on the VxLAN header.
      * @return the internal itm egress action
      */
-    public static List<Action> getInternalItmEgressAction(BigInteger sourceDpnId, BigInteger destinationDpnId,
+    public List<Action> getInternalTunnelItmEgressAction(BigInteger sourceDpnId, BigInteger destinationDpnId,
             long serviceTag) {
         List<Action> result = Collections.emptyList();
 
-        logger.debug("In getInternalItmEgressAction Action source {}, destination {}, elanTag {}",
-                     sourceDpnId, destinationDpnId, serviceTag);
+        LOG.debug("In getInternalItmEgressAction Action source {}, destination {}, elanTag {}", sourceDpnId,
+                destinationDpnId, serviceTag);
         Class<? extends TunnelTypeBase> tunType = TunnelTypeVxlan.class;
         GetTunnelInterfaceNameInput input = new GetTunnelInterfaceNameInputBuilder()
                 .setDestinationDpid(destinationDpnId).setSourceDpid(sourceDpnId).setTunnelType(tunType).build();
-        Future<RpcResult<GetTunnelInterfaceNameOutput>> output = itmRpcService.getTunnelInterfaceName(input);
+        Future<RpcResult<GetTunnelInterfaceNameOutput>> output = itmRpcService
+                .getTunnelInterfaceName(input);
         try {
             if (output.get().isSuccessful()) {
                 GetTunnelInterfaceNameOutput tunnelInterfaceNameOutput = output.get().getResult();
                 String tunnelIfaceName = tunnelInterfaceNameOutput.getInterfaceName();
-                logger.debug("Received tunnelInterfaceName from getTunnelInterfaceName RPC {}", tunnelIfaceName);
+                LOG.debug("Received tunnelInterfaceName from getTunnelInterfaceName RPC {}", tunnelIfaceName);
 
-                result = buildItmEgressActions(tunnelIfaceName, serviceTag);
+                result = buildTunnelItmEgressActions(tunnelIfaceName, serviceTag);
             }
         } catch (InterruptedException | ExecutionException e) {
-            logger.error("Error in RPC call getTunnelInterfaceName {}", e);
+            LOG.error("Error in RPC call getTunnelInterfaceName {}", e);
         }
 
         return result;
     }
 
+    /**
+     * Build the list of actions to be taken when sending the packet to external
+     * (physical) port.
+     *
+     * @param interfaceName
+     *            Interface name
+     * @return the external port itm egress actions
+     */
+    public List<Action> getExternalPortItmEgressAction(String interfaceName) {
+        return buildItmEgressActions(interfaceName, null);
+    }
+
     public static List<MatchInfo> getTunnelMatchesForServiceId(int elanTag) {
         List<MatchInfo> mkMatches = new ArrayList<>();
         // Matching metadata
-        mkMatches.add(new MatchInfo(MatchFieldType.tunnel_id, new BigInteger[]{BigInteger.valueOf(elanTag)}));
+        mkMatches.add(new MatchInfo(MatchFieldType.tunnel_id, new BigInteger[] { BigInteger.valueOf(elanTag) }));
 
         return mkMatches;
     }
 
-    public static void removeTerminatingServiceAction(BigInteger destDpId, int serviceId) {
-        RemoveTerminatingServiceActionsInput input = new RemoveTerminatingServiceActionsInputBuilder().setDpnId(destDpId).setServiceId(serviceId).build();
-        Future<RpcResult<Void>> futureObject = itmRpcService.removeTerminatingServiceActions(input);
+    public void removeTerminatingServiceAction(BigInteger destDpId, int serviceId) {
+        RemoveTerminatingServiceActionsInput input = new RemoveTerminatingServiceActionsInputBuilder()
+                .setDpnId(destDpId).setServiceId(serviceId).build();
+        Future<RpcResult<Void>> futureObject = itmRpcService
+                .removeTerminatingServiceActions(input);
         try {
             RpcResult<Void> result = futureObject.get();
             if (result.isSuccessful()) {
-                logger.debug("Successfully completed removeTerminatingServiceActions");
+                LOG.debug("Successfully completed removeTerminatingServiceActions");
             } else {
-                logger.debug("Failure in removeTerminatingServiceAction RPC call");
+                LOG.debug("Failure in removeTerminatingServiceAction RPC call");
             }
         } catch (InterruptedException | ExecutionException e) {
-            logger.error("Error in RPC call removeTerminatingServiceActions {}", e);
+            LOG.error("Error in RPC call removeTerminatingServiceActions {}", e);
         }
     }
 
-    public static void createTerminatingServiceActions(BigInteger destDpId, int serviceId, List<Action> actions) {
+    public void createTerminatingServiceActions(BigInteger destDpId, int serviceId, List<Action> actions) {
         List<Instruction> mkInstructions = new ArrayList<>();
         mkInstructions.add(MDSALUtil.buildApplyActionsInstruction(actions));
-        CreateTerminatingServiceActionsInput input = new CreateTerminatingServiceActionsInputBuilder().setDpnId(destDpId).setServiceId(serviceId).setInstruction(mkInstructions).build();
+        CreateTerminatingServiceActionsInput input = new CreateTerminatingServiceActionsInputBuilder()
+                .setDpnId(destDpId).setServiceId(serviceId).setInstruction(mkInstructions).build();
 
         itmRpcService.createTerminatingServiceActions(input);
     }
 
     public static TunnelList buildInternalTunnel(DataBroker broker) {
-        InstanceIdentifier<TunnelList> tunnelListInstanceIdentifier = InstanceIdentifier.builder(TunnelList.class).build();
-        Optional<TunnelList> tunnelList = read(broker, LogicalDatastoreType.CONFIGURATION, tunnelListInstanceIdentifier);
-        if (tunnelList.isPresent()) {
-            return tunnelList.get();
-        }
-        return null;
+        InstanceIdentifier<TunnelList> tunnelListInstanceIdentifier = InstanceIdentifier.builder(TunnelList.class)
+                .build();
+        return MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, tunnelListInstanceIdentifier).orNull();
     }
 
     /**
@@ -1217,17 +1512,12 @@ public class ElanUtils {
      *            the datastore type
      * @return the external tunnel
      */
-    public static ExternalTunnel getExternalTunnel(String sourceDevice, String destinationDevice,
+    public ExternalTunnel getExternalTunnel(String sourceDevice, String destinationDevice,
             LogicalDatastoreType datastoreType) {
-        ExternalTunnel externalTunnel = null;
-        Class<? extends TunnelTypeBase> tunType = TunnelTypeVxlan.class ;
+        Class<? extends TunnelTypeBase> tunType = TunnelTypeVxlan.class;
         InstanceIdentifier<ExternalTunnel> iid = InstanceIdentifier.builder(ExternalTunnelList.class)
                 .child(ExternalTunnel.class, new ExternalTunnelKey(destinationDevice, sourceDevice, tunType)).build();
-        Optional<ExternalTunnel> tunnelList = read(dataBroker, datastoreType, iid);
-        if (tunnelList.isPresent()) {
-            externalTunnel = tunnelList.get();
-        }
-        return externalTunnel;
+        return read(broker, datastoreType, iid).orNull();
     }
 
     /**
@@ -1239,7 +1529,7 @@ public class ElanUtils {
      *            the datastore type
      * @return the external tunnel
      */
-    public static ExternalTunnel getExternalTunnel(String interfaceName, LogicalDatastoreType datastoreType) {
+    public ExternalTunnel getExternalTunnel(String interfaceName, LogicalDatastoreType datastoreType) {
         ExternalTunnel externalTunnel = null;
         List<ExternalTunnel> externalTunnels = getAllExternalTunnels(datastoreType);
         for (ExternalTunnel tunnel : externalTunnels) {
@@ -1254,19 +1544,14 @@ public class ElanUtils {
     /**
      * Gets the all external tunnels.
      *
+     * @param datastoreType
+     *            the data store type
      * @return the all external tunnels
      */
-    public static List<ExternalTunnel> getAllExternalTunnels(LogicalDatastoreType datastoreType) {
-        List<ExternalTunnel> result = null;
+    public List<ExternalTunnel> getAllExternalTunnels(LogicalDatastoreType datastoreType) {
         InstanceIdentifier<ExternalTunnelList> iid = InstanceIdentifier.builder(ExternalTunnelList.class).build();
-        Optional<ExternalTunnelList> tunnelList = read(dataBroker, datastoreType, iid);
-        if (tunnelList.isPresent()) {
-            result = tunnelList.get().getExternalTunnel();
-        }
-        if (result == null) {
-            result = Collections.emptyList();
-        }
-        return result;
+        return read(broker, datastoreType, iid).transform(ExternalTunnelList::getExternalTunnel).or(
+                Collections.emptyList());
     }
 
     /**
@@ -1287,11 +1572,13 @@ public class ElanUtils {
      *            MAC to be installed in remoteDpId's DMAC table
      * @param displayName
      *            the display name
+     * @throws ElanException in case of issues creating the flow objects
      */
-    public static void installDmacFlowsToInternalRemoteMac(BigInteger localDpId, BigInteger remoteDpId, long lportTag,
-            long elanTag, String macAddress, String displayName) {
-        Flow flow = buildDmacFlowForInternalRemoteMac(localDpId, remoteDpId, lportTag, elanTag, macAddress, displayName);
-        mdsalMgr.installFlow(remoteDpId, flow);
+    public void installDmacFlowsToInternalRemoteMac(BigInteger localDpId, BigInteger remoteDpId, int lportTag,
+            long elanTag, String macAddress, String displayName) throws ElanException {
+        Flow flow = buildDmacFlowForInternalRemoteMac(localDpId, remoteDpId, lportTag, elanTag, macAddress,
+                displayName);
+        mdsalManager.installFlow(remoteDpId, flow);
     }
 
     /**
@@ -1313,136 +1600,202 @@ public class ElanUtils {
      *            the mac address
      * @param displayName
      *            the display name
+     * @param interfaceName
+     *            the interface name
+     *
+     * @return the dmac flows
+     * @throws ElanException in case of issues creating the flow objects
      */
-    public static List<ListenableFuture<Void>> installDmacFlowsToExternalRemoteMac(BigInteger dpnId,
-            String extDeviceNodeId, Long elanTag, Long vni, String macAddress, String displayName) {
+    public List<ListenableFuture<Void>> installDmacFlowsToExternalRemoteMac(BigInteger dpnId,
+            String extDeviceNodeId, Long elanTag, Long vni, String macAddress, String displayName,
+            String interfaceName) throws ElanException {
         List<ListenableFuture<Void>> futures = new ArrayList<>();
-        synchronized (macAddress) {
-            Flow flow = buildDmacFlowForExternalRemoteMac(dpnId, extDeviceNodeId, elanTag, vni, macAddress, displayName);
-            futures.add(mdsalMgr.installFlow(dpnId, flow));
+        synchronized (getElanMacKey(elanTag, macAddress)) {
+            Flow flow = buildDmacFlowForExternalRemoteMac(dpnId, extDeviceNodeId, elanTag, vni, macAddress,
+                    displayName);
+            futures.add(mdsalManager.installFlow(dpnId, flow));
 
             Flow dropFlow = buildDmacFlowDropIfPacketComingFromTunnel(dpnId, extDeviceNodeId, elanTag, macAddress);
-            futures.add(mdsalMgr.installFlow(dpnId, dropFlow));
+            futures.add(mdsalManager.installFlow(dpnId, dropFlow));
+            installEtreeDmacFlowsToExternalRemoteMac(dpnId, extDeviceNodeId, elanTag, vni, macAddress, displayName,
+                    interfaceName, futures);
         }
         return futures;
     }
 
+    private void installEtreeDmacFlowsToExternalRemoteMac(BigInteger dpnId, String extDeviceNodeId, Long elanTag,
+            Long vni, String macAddress, String displayName, String interfaceName,
+            List<ListenableFuture<Void>> futures) throws ElanException {
+        EtreeLeafTagName etreeLeafTag = getEtreeLeafTagByElanTag(elanTag);
+        if (etreeLeafTag != null) {
+            buildEtreeDmacFlowDropIfPacketComingFromTunnel(dpnId, extDeviceNodeId, elanTag, macAddress, futures,
+                    etreeLeafTag);
+            buildEtreeDmacFlowForExternalRemoteMac(dpnId, extDeviceNodeId, vni, macAddress, displayName, interfaceName,
+                    futures, etreeLeafTag);
+        }
+    }
+
+    private void buildEtreeDmacFlowForExternalRemoteMac(BigInteger dpnId, String extDeviceNodeId, Long vni,
+            String macAddress, String displayName, String interfaceName, List<ListenableFuture<Void>> futures,
+            EtreeLeafTagName etreeLeafTag) throws ElanException {
+        boolean isRoot = false;
+        if (interfaceName == null) {
+            isRoot = true;
+        } else {
+            EtreeInterface etreeInterface = getEtreeInterfaceByElanInterfaceName(broker, interfaceName);
+            if (etreeInterface != null) {
+                if (etreeInterface.getEtreeInterfaceType() == EtreeInterfaceType.Root) {
+                    isRoot = true;
+                }
+            }
+        }
+        if (isRoot) {
+            Flow flow = buildDmacFlowForExternalRemoteMac(dpnId, extDeviceNodeId,
+                    etreeLeafTag.getEtreeLeafTag().getValue(), vni, macAddress, displayName);
+            futures.add(mdsalManager.installFlow(dpnId, flow));
+        }
+    }
+
+    private void buildEtreeDmacFlowDropIfPacketComingFromTunnel(BigInteger dpnId, String extDeviceNodeId,
+            Long elanTag, String macAddress, List<ListenableFuture<Void>> futures, EtreeLeafTagName etreeLeafTag) {
+        if (etreeLeafTag != null) {
+            Flow dropFlow = buildDmacFlowDropIfPacketComingFromTunnel(dpnId, extDeviceNodeId,
+                    etreeLeafTag.getEtreeLeafTag().getValue(), macAddress);
+            futures.add(mdsalManager.installFlow(dpnId, dropFlow));
+        }
+    }
+
     public static List<MatchInfo> buildMatchesForElanTagShFlagAndDstMac(long elanTag, boolean shFlag, String macAddr) {
         List<MatchInfo> mkMatches = new ArrayList<>();
         mkMatches.add(new MatchInfo(MatchFieldType.metadata, new BigInteger[] {
-                ElanUtils.getElanMetadataLabel(elanTag, shFlag), MetaDataUtil.METADATA_MASK_SERVICE_SH_FLAG }));
+                getElanMetadataLabel(elanTag, shFlag), MetaDataUtil.METADATA_MASK_SERVICE_SH_FLAG }));
         mkMatches.add(new MatchInfo(MatchFieldType.eth_dst, new String[] { macAddr }));
 
         return mkMatches;
     }
 
     /**
-     * Builds a Flow to be programmed in a DPN's DMAC table. This method must be used when the MAC is located in an
-     * External Device (TOR).
-     * The flow matches on the specified MAC and
-     *   1) sends the packet over the CSS-TOR tunnel if SHFlag is not set, or
-     *   2) drops it if SHFlag is set (what means the packet came from an external tunnel)
+     * Builds a Flow to be programmed in a DPN's DMAC table. This method must be
+     * used when the MAC is located in an External Device (TOR). The flow
+     * matches on the specified MAC and 1) sends the packet over the CSS-TOR
+     * tunnel if SHFlag is not set, or 2) drops it if SHFlag is set (what means
+     * the packet came from an external tunnel)
      *
-     * @param dpId DPN whose DMAC table is going to be modified
-     * @param extDeviceNodeId Hwvtep node where the mac is attached to
-     * @param elanTag ElanId to which the MAC is being added to
-     * @param vni the vni
-     * @param dstMacAddress The mac address to be programmed
-     * @param displayName the display name
+     * @param dpId
+     *            DPN whose DMAC table is going to be modified
+     * @param extDeviceNodeId
+     *            Hwvtep node where the mac is attached to
+     * @param elanTag
+     *            ElanId to which the MAC is being added to
+     * @param vni
+     *            the vni
+     * @param dstMacAddress
+     *            The mac address to be programmed
+     * @param displayName
+     *            the display name
      * @return the flow
+     * @throws ElanException in case of issues creating the flow objects
      */
-    public static Flow buildDmacFlowForExternalRemoteMac(BigInteger dpId, String extDeviceNodeId, long elanTag,
-            Long vni, String dstMacAddress, String displayName ) {
-        List<MatchInfo> mkMatches = buildMatchesForElanTagShFlagAndDstMac(elanTag, /*shFlag*/ false, dstMacAddress);
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public Flow buildDmacFlowForExternalRemoteMac(BigInteger dpId, String extDeviceNodeId, long elanTag,
+            Long vni, String dstMacAddress, String displayName) throws ElanException {
+        List<MatchInfo> mkMatches = buildMatchesForElanTagShFlagAndDstMac(elanTag, /* shFlag */ false, dstMacAddress);
         List<Instruction> mkInstructions = new ArrayList<>();
         try {
-            List<Action> actions = getExternalItmEgressAction(dpId, new NodeId(extDeviceNodeId), vni);
-            mkInstructions.add( MDSALUtil.buildApplyActionsInstruction(actions) );
+            List<Action> actions = getExternalTunnelItmEgressAction(dpId, new NodeId(extDeviceNodeId), vni);
+            mkInstructions.add(MDSALUtil.buildApplyActionsInstruction(actions));
         } catch (Exception e) {
-            logger.error("Could not get Egress Actions for DpId={}  externalNode={}", dpId, extDeviceNodeId );
+            LOG.error("Could not get Egress Actions for DpId=" + dpId + ", externalNode=" + extDeviceNodeId, e);
         }
 
-        Flow flow = MDSALUtil.buildFlowNew(ElanConstants.ELAN_DMAC_TABLE,
-                getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, dpId, extDeviceNodeId, dstMacAddress, elanTag,
+        Flow flow = MDSALUtil.buildFlowNew(NwConstants.ELAN_DMAC_TABLE,
+                getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpId, extDeviceNodeId, dstMacAddress, elanTag,
                         false),
-                20,  /* prio */
-                displayName, 0,   /* idleTimeout */
-                0,   /* hardTimeout */
+                20, /* prio */
+                displayName, 0, /* idleTimeout */
+                0, /* hardTimeout */
                 ElanConstants.COOKIE_ELAN_KNOWN_DMAC.add(BigInteger.valueOf(elanTag)), mkMatches, mkInstructions);
 
         return flow;
     }
 
     /**
-     * Builds the flow that drops the packet if it came through an external tunnel, that is, if the Split-Horizon
-     * flag is set.
+     * Builds the flow that drops the packet if it came through an external
+     * tunnel, that is, if the Split-Horizon flag is set.
      *
-     * @param dpnId DPN whose DMAC table is going to be modified
-     * @param extDeviceNodeId  Hwvtep node where the mac is attached to
-     * @param elanTag ElanId to which the MAC is being added to
-     * @param dstMacAddress The mac address to be programmed
-     * @param displayName
-     * @return
+     * @param dpnId
+     *            DPN whose DMAC table is going to be modified
+     * @param extDeviceNodeId
+     *            Hwvtep node where the mac is attached to
+     * @param elanTag
+     *            ElanId to which the MAC is being added to
+     * @param dstMacAddress
+     *            The mac address to be programmed
      */
     private static Flow buildDmacFlowDropIfPacketComingFromTunnel(BigInteger dpnId, String extDeviceNodeId,
             Long elanTag, String dstMacAddress) {
-        List<MatchInfo> mkMatches = buildMatchesForElanTagShFlagAndDstMac(elanTag, /*shFlag*/ true, dstMacAddress);
+        List<MatchInfo> mkMatches = buildMatchesForElanTagShFlagAndDstMac(elanTag, /* shFlag */ true, dstMacAddress);
         List<Instruction> mkInstructions = MDSALUtil.buildInstructionsDrop();
-        String flowId = getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, dpnId, extDeviceNodeId, dstMacAddress,
+        String flowId = getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpnId, extDeviceNodeId, dstMacAddress,
                 elanTag, true);
-        Flow flow = MDSALUtil.buildFlowNew(ElanConstants.ELAN_DMAC_TABLE, flowId, 20,  /* prio */
-                "Drop", 0,   /* idleTimeout */
-                0,   /* hardTimeout */
+        Flow flow = MDSALUtil.buildFlowNew(NwConstants.ELAN_DMAC_TABLE, flowId, 20, /* prio */
+                "Drop", 0, /* idleTimeout */
+                0, /* hardTimeout */
                 ElanConstants.COOKIE_ELAN_KNOWN_DMAC.add(BigInteger.valueOf(elanTag)), mkMatches, mkInstructions);
 
         return flow;
     }
 
     private static String getDmacDropFlowId(Long elanTag, String dstMacAddress) {
-        return new StringBuilder(ElanConstants.ELAN_DMAC_TABLE).append(elanTag).append(dstMacAddress).append("Drop")
+        return new StringBuilder(NwConstants.ELAN_DMAC_TABLE).append(elanTag).append(dstMacAddress).append("Drop")
                 .toString();
     }
 
     /**
-     * Builds a Flow to be programmed in a remote DPN's DMAC table. This method must be used when the MAC is located
-     * in another CSS.
+     * Builds a Flow to be programmed in a remote DPN's DMAC table. This method
+     * must be used when the MAC is located in another CSS.
      *
-     * This flow consists in:
-     *  Match:
-     *    + elanTag in packet's metadata
-     *    + packet going to a MAC known to be located in another DPN
-     *  Actions:
-     *    + set_tunnel_id(lportTag)
-     *    + output on ITM internal tunnel interface with the other DPN
+     * <p>This flow consists in: Match: + elanTag in packet's metadata + packet
+     * going to a MAC known to be located in another DPN Actions: +
+     * set_tunnel_id(lportTag) + output on ITM internal tunnel interface with
+     * the other DPN
      *
-     * @param localDpId the local dp id
-     * @param remoteDpId the remote dp id
-     * @param lportTag the lport tag
-     * @param elanTag the elan tag
-     * @param macAddress the mac address
-     * @param displayName the display name
+     * @param localDpId
+     *            the local dp id
+     * @param remoteDpId
+     *            the remote dp id
+     * @param lportTag
+     *            the lport tag
+     * @param elanTag
+     *            the elan tag
+     * @param macAddress
+     *            the mac address
+     * @param displayName
+     *            the display name
      * @return the flow
+     * @throws ElanException in case of issues creating the flow objects
      */
-    public static Flow buildDmacFlowForInternalRemoteMac(BigInteger localDpId, BigInteger remoteDpId, long lportTag,
-            long elanTag, String macAddress, String displayName) {
-        List<MatchInfo> mkMatches = buildMatchesForElanTagShFlagAndDstMac(elanTag, /*shFlag*/ false, macAddress);
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public Flow buildDmacFlowForInternalRemoteMac(BigInteger localDpId, BigInteger remoteDpId, int lportTag,
+            long elanTag, String macAddress, String displayName) throws ElanException {
+        List<MatchInfo> mkMatches = buildMatchesForElanTagShFlagAndDstMac(elanTag, /* shFlag */ false, macAddress);
 
         List<Instruction> mkInstructions = new ArrayList<>();
 
         try {
-            //List of Action for the provided Source and Destination DPIDs
-            List<Action> actions = getInternalItmEgressAction(localDpId, remoteDpId, lportTag);
-            mkInstructions.add( MDSALUtil.buildApplyActionsInstruction(actions) );
+            // List of Action for the provided Source and Destination DPIDs
+            List<Action> actions = getInternalTunnelItmEgressAction(localDpId, remoteDpId, lportTag);
+            mkInstructions.add(MDSALUtil.buildApplyActionsInstruction(actions));
         } catch (Exception e) {
-            logger.error("Could not get Egress Actions for localDpId={}  remoteDpId={}   lportTag={}",
-                         localDpId, remoteDpId, lportTag);
+            LOG.error("Could not get Egress Actions for localDpId=" + localDpId + ", remoteDpId="
+                    + remoteDpId + ", lportTag=" + lportTag, e);
         }
 
-        Flow flow = MDSALUtil.buildFlowNew(ElanConstants.ELAN_DMAC_TABLE,
-                getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, localDpId, remoteDpId, macAddress, elanTag),
-                20,  /* prio */
-                displayName, 0,   /* idleTimeout */
-                0,   /* hardTimeout */
+        Flow flow = MDSALUtil.buildFlowNew(NwConstants.ELAN_DMAC_TABLE,
+                getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, localDpId, remoteDpId, macAddress, elanTag),
+                20, /* prio */
+                displayName, 0, /* idleTimeout */
+                0, /* hardTimeout */
                 ElanConstants.COOKIE_ELAN_KNOWN_DMAC.add(BigInteger.valueOf(elanTag)), mkMatches, mkInstructions);
 
         return flow;
@@ -1468,14 +1821,19 @@ public class ElanUtils {
      *            the elan instance name
      * @param addOrRemove
      *            Indicates if flows must be installed or removed.
+     * @param interfaceName
+     *            the interface name
+     * @throws ElanException in case of issues creating the flow objects
      * @see org.opendaylight.genius.mdsalutil.MDSALUtil.MdsalOp
      */
-    public static void setupDmacFlowsToExternalRemoteMac(BigInteger dpId, String extNodeId, Long elanTag, Long vni,
-            String macAddress, String elanInstanceName, MdsalOp addOrRemove) {
-        if ( addOrRemove == MdsalOp.CREATION_OP ) {
-            ElanUtils.installDmacFlowsToExternalRemoteMac(dpId, extNodeId, elanTag, vni, macAddress, elanInstanceName);
-        } else if ( addOrRemove == MdsalOp.REMOVAL_OP ) {
-            ElanUtils.deleteDmacFlowsToExternalMac(elanTag, dpId, extNodeId, macAddress );
+    public void setupDmacFlowsToExternalRemoteMac(BigInteger dpId, String extNodeId, Long elanTag, Long vni,
+            String macAddress, String elanInstanceName, MdsalOp addOrRemove, String interfaceName)
+            throws ElanException {
+        if (addOrRemove == MdsalOp.CREATION_OP) {
+            installDmacFlowsToExternalRemoteMac(dpId, extNodeId, elanTag, vni, macAddress, elanInstanceName,
+                    interfaceName);
+        } else if (addOrRemove == MdsalOp.REMOVAL_OP) {
+            deleteDmacFlowsToExternalMac(elanTag, dpId, extNodeId, macAddress);
         }
     }
 
@@ -1490,28 +1848,49 @@ public class ElanUtils {
      *            the ext device node id
      * @param macToRemove
      *            the mac to remove
+     * @return dmac flow
      */
-    public static List<ListenableFuture<Void>> deleteDmacFlowsToExternalMac(long elanTag, BigInteger dpId,
-            String extDeviceNodeId, String macToRemove ) {
+    public List<ListenableFuture<Void>> deleteDmacFlowsToExternalMac(long elanTag, BigInteger dpId,
+            String extDeviceNodeId, String macToRemove) {
         List<ListenableFuture<Void>> futures = new ArrayList<>();
-        synchronized (macToRemove) {
+        synchronized (getElanMacKey(elanTag, macToRemove)) {
             // Removing the flows that sends the packet on an external tunnel
-            String flowId = getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, dpId, extDeviceNodeId,
-                    macToRemove, elanTag, false);
-            Flow flowToRemove = new FlowBuilder().setId(new FlowId(flowId)).setTableId(ElanConstants.ELAN_DMAC_TABLE)
-                    .build();
-            futures.add(mdsalMgr.removeFlow(dpId, flowToRemove));
+            removeFlowThatSendsThePacketOnAnExternalTunnel(elanTag, dpId, extDeviceNodeId, macToRemove, futures);
 
             // And now removing the drop flow
-            flowId = getKnownDynamicmacFlowRef(ElanConstants.ELAN_DMAC_TABLE, dpId, extDeviceNodeId, macToRemove,
-                    elanTag, true);
-            flowToRemove = new FlowBuilder().setId(new FlowId(flowId)).setTableId(ElanConstants.ELAN_DMAC_TABLE)
-                    .build();
-            futures.add(mdsalMgr.removeFlow(dpId, flowToRemove));
+            removeTheDropFlow(elanTag, dpId, extDeviceNodeId, macToRemove, futures);
+
+            deleteEtreeDmacFlowsToExternalMac(elanTag, dpId, extDeviceNodeId, macToRemove, futures);
         }
         return futures;
     }
 
+    private void deleteEtreeDmacFlowsToExternalMac(long elanTag, BigInteger dpId, String extDeviceNodeId,
+            String macToRemove, List<ListenableFuture<Void>> futures) {
+        EtreeLeafTagName etreeLeafTag = getEtreeLeafTagByElanTag(elanTag);
+        if (etreeLeafTag != null) {
+            removeFlowThatSendsThePacketOnAnExternalTunnel(etreeLeafTag.getEtreeLeafTag().getValue(), dpId,
+                    extDeviceNodeId, macToRemove, futures);
+            removeTheDropFlow(etreeLeafTag.getEtreeLeafTag().getValue(), dpId, extDeviceNodeId, macToRemove, futures);
+        }
+    }
+
+    private void removeTheDropFlow(long elanTag, BigInteger dpId, String extDeviceNodeId, String macToRemove,
+            List<ListenableFuture<Void>> futures) {
+        String flowId = getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpId, extDeviceNodeId, macToRemove,
+                elanTag, true);
+        Flow flowToRemove = new FlowBuilder().setId(new FlowId(flowId)).setTableId(NwConstants.ELAN_DMAC_TABLE).build();
+        futures.add(mdsalManager.removeFlow(dpId, flowToRemove));
+    }
+
+    private void removeFlowThatSendsThePacketOnAnExternalTunnel(long elanTag, BigInteger dpId,
+            String extDeviceNodeId, String macToRemove, List<ListenableFuture<Void>> futures) {
+        String flowId = getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpId, extDeviceNodeId, macToRemove,
+                elanTag, false);
+        Flow flowToRemove = new FlowBuilder().setId(new FlowId(flowId)).setTableId(NwConstants.ELAN_DMAC_TABLE).build();
+        futures.add(mdsalManager.removeFlow(dpId, flowToRemove));
+    }
+
     /**
      * Gets the dpid from interface.
      *
@@ -1519,9 +1898,9 @@ public class ElanUtils {
      *            the interface name
      * @return the dpid from interface
      */
-    public static BigInteger getDpidFromInterface(String interfaceName) {
+    public BigInteger getDpidFromInterface(String interfaceName) {
         BigInteger dpId = null;
-        Future<RpcResult<GetDpidFromInterfaceOutput>> output = interfaceMgrRpcService
+        Future<RpcResult<GetDpidFromInterfaceOutput>> output = interfaceManagerRpcService
                 .getDpidFromInterface(new GetDpidFromInterfaceInputBuilder().setIntfName(interfaceName).build());
         try {
             RpcResult<GetDpidFromInterfaceOutput> rpcResult = output.get();
@@ -1529,7 +1908,7 @@ public class ElanUtils {
                 dpId = rpcResult.getResult().getDpid();
             }
         } catch (NullPointerException | InterruptedException | ExecutionException e) {
-            logger.error("Failed to get the DPN ID: {} for interface {}: {} ", dpId, interfaceName, e);
+            LOG.error("Failed to get the DPN ID: {} for interface {}: {} ", dpId, interfaceName, e);
         }
         return dpId;
     }
@@ -1551,7 +1930,7 @@ public class ElanUtils {
         if (ifState == null) {
             return false;
         }
-        return ((ifState.getOperStatus() == OperStatus.Up) && (ifState.getAdminStatus() == AdminStatus.Up));
+        return ifState.getOperStatus() == OperStatus.Up && ifState.getAdminStatus() == AdminStatus.Up;
     }
 
     /**
@@ -1563,16 +1942,13 @@ public class ElanUtils {
      *            the data broker
      * @return the interface state from oper ds
      */
-    public static org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface getInterfaceStateFromOperDS(
+    public static org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang
+        .ietf.interfaces.rev140508.interfaces.state.Interface getInterfaceStateFromOperDS(
             String interfaceName, DataBroker dataBroker) {
-        InstanceIdentifier<org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface> ifStateId = createInterfaceStateInstanceIdentifier(
+        InstanceIdentifier<org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang
+            .ietf.interfaces.rev140508.interfaces.state.Interface> ifStateId = createInterfaceStateInstanceIdentifier(
                 interfaceName);
-        Optional<org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface> ifStateOptional = MDSALUtil
-                .read(dataBroker, LogicalDatastoreType.OPERATIONAL, ifStateId);
-        if (ifStateOptional.isPresent()) {
-            return ifStateOptional.get();
-        }
-        return null;
+        return MDSALUtil.read(dataBroker, LogicalDatastoreType.OPERATIONAL, ifStateId).orNull();
     }
 
     /**
@@ -1582,15 +1958,166 @@ public class ElanUtils {
      *            the interface name
      * @return the instance identifier
      */
-    public static InstanceIdentifier<org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface> createInterfaceStateInstanceIdentifier(
+    public static InstanceIdentifier<org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang
+        .ietf.interfaces.rev140508.interfaces.state.Interface> createInterfaceStateInstanceIdentifier(
             String interfaceName) {
-        InstanceIdentifierBuilder<org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface> idBuilder = InstanceIdentifier
+        InstanceIdentifierBuilder<org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang
+            .ietf.interfaces.rev140508.interfaces.state.Interface> idBuilder = InstanceIdentifier
                 .builder(InterfacesState.class)
-                .child(org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface.class,
-                        new org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.InterfaceKey(
+                .child(org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang
+                        .ietf.interfaces.rev140508.interfaces.state.Interface.class,
+                        new org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang
+                            .ietf.interfaces.rev140508.interfaces.state.InterfaceKey(
                                 interfaceName));
         return idBuilder.build();
     }
 
-}
+    public static CheckedFuture<Void, TransactionCommitFailedException> waitForTransactionToComplete(
+            WriteTransaction tx) {
+        CheckedFuture<Void, TransactionCommitFailedException> futures = tx.submit();
+        try {
+            futures.get();
+        } catch (InterruptedException | ExecutionException e) {
+            LOG.error("Error writing to datastore {}", e);
+        }
+        return futures;
+    }
+
+    public static boolean isVxlan(ElanInstance elanInstance) {
+        return elanInstance != null && elanInstance.getSegmentType() != null
+                && elanInstance.getSegmentType().isAssignableFrom(SegmentTypeVxlan.class)
+                && elanInstance.getSegmentationId() != null && elanInstance.getSegmentationId().longValue() != 0;
+    }
+
+    public static boolean isVlan(ElanInstance elanInstance) {
+        return elanInstance != null && elanInstance.getSegmentType() != null
+                && elanInstance.getSegmentType().isAssignableFrom(SegmentTypeVlan.class)
+                && elanInstance.getSegmentationId() != null && elanInstance.getSegmentationId().longValue() != 0;
+    }
+
+    public static boolean isFlat(ElanInstance elanInstance) {
+        return elanInstance != null && elanInstance.getSegmentType() != null
+                && elanInstance.getSegmentType().isAssignableFrom(SegmentTypeFlat.class);
+    }
+
+    public static boolean isEtreeRootInterfaceByInterfaceName(DataBroker broker, String interfaceName) {
+        EtreeInterface etreeInterface = getEtreeInterfaceByElanInterfaceName(broker, interfaceName);
+        if (etreeInterface != null && etreeInterface.getEtreeInterfaceType() == EtreeInterfaceType.Root) {
+            return true;
+        }
+        return false;
+    }
+
+    public void handleDmacRedirectToDispatcherFlows(Long elanTag, String displayName,
+            String macAddress, int addOrRemove, List<BigInteger> dpnIds) {
+        for (BigInteger dpId : dpnIds) {
+            if (addOrRemove == NwConstants.ADD_FLOW) {
+                WriteTransaction writeTx = broker.newWriteOnlyTransaction();
+                mdsalManager.addFlowToTx(buildDmacRedirectToDispatcherFlow(dpId, macAddress, displayName, elanTag),
+                        writeTx);
+                writeTx.submit();
+            } else {
+                String flowId = getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpId, macAddress, elanTag);
+                mdsalManager.removeFlow(dpId, MDSALUtil.buildFlow(NwConstants.ELAN_DMAC_TABLE, flowId));
+            }
+        }
+    }
 
+    public static FlowEntity buildDmacRedirectToDispatcherFlow(BigInteger dpId, String dstMacAddress,
+            String displayName, long elanTag) {
+        List<MatchInfo> matches = new ArrayList<MatchInfo>();
+        matches.add(new MatchInfo(MatchFieldType.metadata,
+                new BigInteger[] { getElanMetadataLabel(elanTag), MetaDataUtil.METADATA_MASK_SERVICE }));
+        matches.add(new MatchInfo(MatchFieldType.eth_dst, new String[] { dstMacAddress }));
+        List<InstructionInfo> instructions = new ArrayList<InstructionInfo>();
+        List<ActionInfo> actions = new ArrayList<ActionInfo>();
+        actions.add(new ActionInfo(ActionType.nx_resubmit,
+                new String[] { String.valueOf(NwConstants.LPORT_DISPATCHER_TABLE) }));
+
+        instructions.add(new InstructionInfo(InstructionType.apply_actions, actions));
+        String flowId = getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpId, dstMacAddress, elanTag);
+        FlowEntity flow  = MDSALUtil.buildFlowEntity(dpId, NwConstants.ELAN_DMAC_TABLE, flowId, 20, displayName, 0, 0,
+                ElanConstants.COOKIE_ELAN_KNOWN_DMAC.add(BigInteger.valueOf(elanTag)),
+                matches, instructions);
+        return flow;
+    }
+
+    public static FlowEntity buildDmacRedirectToDispatcherFlowMacNoActions(BigInteger dpId, String dstMacAddress,
+            String displayName, long elanTag) {
+        List<MatchInfo> matches = new ArrayList<MatchInfo>();
+        matches.add(new MatchInfo(MatchFieldType.metadata,
+                new BigInteger[] { getElanMetadataLabel(elanTag), MetaDataUtil.METADATA_MASK_SERVICE }));
+        matches.add(new MatchInfo(MatchFieldType.eth_dst, new String[] { dstMacAddress }));
+
+        String flowId = getKnownDynamicmacFlowRef(NwConstants.ELAN_DMAC_TABLE, dpId, dstMacAddress, elanTag);
+        FlowEntity flow  = MDSALUtil.buildFlowEntity(dpId, NwConstants.ELAN_DMAC_TABLE, flowId, 20, displayName, 0, 0,
+                ElanConstants.COOKIE_ELAN_KNOWN_DMAC.add(BigInteger.valueOf(elanTag)),
+                matches, new ArrayList<InstructionInfo>());
+        return flow;
+    }
+
+    /**
+     * Add Mac Address to ElanInterfaceForwardingEntries and ElanForwardingTables
+     * Install SMAC and DMAC flows.
+     */
+    public void addMacEntryToDsAndSetupFlows(IInterfaceManager interfaceManager, String interfaceName,
+            String macAddress, String elanName, WriteTransaction tx, WriteTransaction flowWritetx, int macTimeOut)
+            throws ElanException {
+        LOG.trace("Adding mac address {} and interface name {} to ElanInterfaceForwardingEntries and "
+            + "ElanForwardingTables DS", macAddress, interfaceName);
+        BigInteger timeStamp = new BigInteger(String.valueOf(System.currentTimeMillis()));
+        PhysAddress physAddress = new PhysAddress(macAddress);
+        MacEntry macEntry = new MacEntryBuilder().setInterface(interfaceName).setMacAddress(physAddress)
+                .setKey(new MacEntryKey(physAddress)).setControllerLearnedForwardingEntryTimestamp(timeStamp)
+                .setIsStaticAddress(false).build();
+        InstanceIdentifier<MacEntry> macEntryId = ElanUtils
+                .getInterfaceMacEntriesIdentifierOperationalDataPath(interfaceName, physAddress);
+        tx.put(LogicalDatastoreType.OPERATIONAL, macEntryId, macEntry);
+        InstanceIdentifier<MacEntry> elanMacEntryId = ElanUtils.getMacEntryOperationalDataPath(elanName, physAddress);
+        tx.put(LogicalDatastoreType.OPERATIONAL, elanMacEntryId, macEntry);
+        ElanInstance elanInstance = ElanUtils.getElanInstanceByName(broker, elanName);
+        setupMacFlows(elanInstance, interfaceManager.getInterfaceInfo(interfaceName), macTimeOut, macAddress, true,
+                flowWritetx);
+    }
+
+    /**
+     * Remove Mac Address from ElanInterfaceForwardingEntries and ElanForwardingTables
+     * Remove SMAC and DMAC flows.
+     */
+    public void deleteMacEntryFromDsAndRemoveFlows(IInterfaceManager interfaceManager, String interfaceName,
+            String macAddress, String elanName, WriteTransaction tx, WriteTransaction deleteFlowTx) {
+        LOG.trace("Deleting mac address {} and interface name {} from ElanInterfaceForwardingEntries "
+                + "and ElanForwardingTables DS", macAddress, interfaceName);
+        PhysAddress physAddress = new PhysAddress(macAddress);
+        MacEntry macEntry = getInterfaceMacEntriesOperationalDataPath(interfaceName, physAddress);
+        InterfaceInfo interfaceInfo = interfaceManager.getInterfaceInfo(interfaceName);
+        if (macEntry != null && interfaceInfo != null) {
+            deleteMacFlows(ElanUtils.getElanInstanceByName(broker, elanName), interfaceInfo, macEntry, deleteFlowTx);
+        }
+        tx.delete(LogicalDatastoreType.OPERATIONAL,
+                ElanUtils.getInterfaceMacEntriesIdentifierOperationalDataPath(interfaceName, physAddress));
+        tx.delete(LogicalDatastoreType.OPERATIONAL,
+                ElanUtils.getMacEntryOperationalDataPath(elanName, physAddress));
+    }
+
+    public String getExternalElanInterface(String elanInstanceName, BigInteger dpnId) {
+        DpnInterfaces dpnInterfaces = getElanInterfaceInfoByElanDpn(elanInstanceName, dpnId);
+        if (dpnInterfaces == null || dpnInterfaces.getInterfaces() == null) {
+            LOG.trace("Elan {} does not have interfaces in DPN {}", elanInstanceName, dpnId);
+            return null;
+        }
+
+        for (String dpnInterface : dpnInterfaces.getInterfaces()) {
+            if (interfaceManager.isExternalInterface(dpnInterface)) {
+                return dpnInterface;
+            }
+        }
+
+        LOG.trace("Elan {} does not have any external interace attached to DPN {}", elanInstanceName, dpnId);
+        return null;
+    }
+
+    public static String getElanMacKey(long elanTag, String macAddress) {
+        return ("MAC-" + macAddress + " ELAN_TAG-" + elanTag).intern();
+    }
+}