Remove unnecessary generic types
[netvirt.git] / vpnservice / dhcpservice / dhcpservice-impl / src / main / java / org / opendaylight / netvirt / dhcpservice / DhcpExternalTunnelManager.java
index c31b54a4ea3950739339d2f20feb8e138a1ddad8..1d4011aeee851d6fa20483f41c8faf35417ee8d5 100644 (file)
@@ -11,6 +11,7 @@ import com.google.common.base.Optional;
 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.Collection;
@@ -22,12 +23,14 @@ import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
+
 import org.apache.commons.lang3.tuple.ImmutablePair;
 import org.apache.commons.lang3.tuple.Pair;
 import org.opendaylight.controller.md.sal.binding.api.DataBroker;
 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.genius.interfacemanager.interfaces.IInterfaceManager;
 import org.opendaylight.genius.mdsalutil.MDSALUtil;
 import org.opendaylight.genius.mdsalutil.NwConstants;
 import org.opendaylight.genius.mdsalutil.interfaces.IMdsalApiManager;
@@ -35,7 +38,7 @@ import org.opendaylight.genius.utils.clustering.ClusteringUtils;
 import org.opendaylight.genius.utils.hwvtep.HwvtepSouthboundConstants;
 import org.opendaylight.genius.utils.hwvtep.HwvtepSouthboundUtils;
 import org.opendaylight.genius.utils.hwvtep.HwvtepUtils;
-import org.opendaylight.netvirt.dhcpservice.api.DHCPMConstants;
+import org.opendaylight.netvirt.dhcpservice.api.DhcpMConstants;
 import org.opendaylight.netvirt.elanmanager.utils.ElanL2GwCacheUtils;
 import org.opendaylight.netvirt.neutronvpn.api.l2gw.L2GatewayDevice;
 import org.opendaylight.netvirt.neutronvpn.api.l2gw.utils.L2GatewayCacheUtils;
@@ -76,27 +79,31 @@ import org.slf4j.LoggerFactory;
 
 public class DhcpExternalTunnelManager {
 
-    private static final Logger logger = LoggerFactory.getLogger(DhcpExternalTunnelManager.class);
+    private static final Logger LOG = LoggerFactory.getLogger(DhcpExternalTunnelManager.class);
     public static final String UNKNOWN_DMAC = "00:00:00:00:00:00";
 
     private final DataBroker broker;
     private final IMdsalApiManager mdsalUtil;
     private final ItmRpcService itmRpcService;
     private final EntityOwnershipService entityOwnershipService;
+    private final IInterfaceManager interfaceManager;
 
-    private ConcurrentMap<BigInteger, Set<Pair<IpAddress, String>>> designatedDpnsToTunnelIpElanNameCache = new ConcurrentHashMap<>();
-    private ConcurrentMap<Pair<IpAddress, String>, Set<String>> tunnelIpElanNameToVmMacCache = new ConcurrentHashMap<>();
-    private ConcurrentMap<Pair<IpAddress, String>, Set<String>> availableVMCache = new ConcurrentHashMap<>();
-    private ConcurrentMap<Pair<BigInteger, String>, Port> vniMacAddressToPortCache = new ConcurrentHashMap<>();
+    private final ConcurrentMap<BigInteger, Set<Pair<IpAddress, String>>> designatedDpnsToTunnelIpElanNameCache =
+            new ConcurrentHashMap<>();
+    private final ConcurrentMap<Pair<IpAddress, String>, Set<String>> tunnelIpElanNameToVmMacCache =
+            new ConcurrentHashMap<>();
+    private final ConcurrentMap<Pair<IpAddress, String>, Set<String>> availableVMCache = new ConcurrentHashMap<>();
+    private final ConcurrentMap<Pair<BigInteger, String>, Port> vniMacAddressToPortCache = new ConcurrentHashMap<>();
 
 
     public DhcpExternalTunnelManager(final DataBroker broker,
             final IMdsalApiManager mdsalUtil, final ItmRpcService itmRpcService,
-            final EntityOwnershipService entityOwnershipService) {
+            final EntityOwnershipService entityOwnershipService, final IInterfaceManager interfaceManager) {
         this.broker = broker;
         this.mdsalUtil = mdsalUtil;
         this.itmRpcService = itmRpcService;
         this.entityOwnershipService = entityOwnershipService;
+        this.interfaceManager = interfaceManager;
     }
 
     public void init() {
@@ -104,28 +111,35 @@ public class DhcpExternalTunnelManager {
     }
 
     private void initilizeCaches() {
-        logger.trace("Loading designatedDpnsToTunnelIpElanNameCache");
-        InstanceIdentifier<DesignatedSwitchesForExternalTunnels> instanceIdentifier = InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class).build();
-        Optional<DesignatedSwitchesForExternalTunnels> designatedSwitchForTunnelOptional = MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, instanceIdentifier);
+        LOG.trace("Loading designatedDpnsToTunnelIpElanNameCache");
+        InstanceIdentifier<DesignatedSwitchesForExternalTunnels> instanceIdentifier =
+                InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class).build();
+        Optional<DesignatedSwitchesForExternalTunnels> designatedSwitchForTunnelOptional =
+                MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, instanceIdentifier);
         if (designatedSwitchForTunnelOptional.isPresent()) {
-            List<DesignatedSwitchForTunnel> list = designatedSwitchForTunnelOptional.get().getDesignatedSwitchForTunnel();
+            List<DesignatedSwitchForTunnel> list =
+                    designatedSwitchForTunnelOptional.get().getDesignatedSwitchForTunnel();
             for (DesignatedSwitchForTunnel designatedSwitchForTunnel : list) {
-                Set<Pair<IpAddress, String>> setOfTunnelIpElanNamePair = designatedDpnsToTunnelIpElanNameCache.get(designatedSwitchForTunnel.getDpId());
+                Set<Pair<IpAddress, String>> setOfTunnelIpElanNamePair =
+                        designatedDpnsToTunnelIpElanNameCache.get(designatedSwitchForTunnel.getDpId());
                 if (setOfTunnelIpElanNamePair == null) {
                     setOfTunnelIpElanNamePair = new CopyOnWriteArraySet<>();
                 }
-                Pair<IpAddress, String> tunnelIpElanNamePair = new ImmutablePair<>(designatedSwitchForTunnel.getTunnelRemoteIpAddress(), designatedSwitchForTunnel.getElanInstanceName());
+                Pair<IpAddress, String> tunnelIpElanNamePair =
+                        new ImmutablePair<>(designatedSwitchForTunnel.getTunnelRemoteIpAddress(),
+                                designatedSwitchForTunnel.getElanInstanceName());
                 setOfTunnelIpElanNamePair.add(tunnelIpElanNamePair);
-                designatedDpnsToTunnelIpElanNameCache.put(BigInteger.valueOf(designatedSwitchForTunnel.getDpId()), setOfTunnelIpElanNamePair);
+                designatedDpnsToTunnelIpElanNameCache.put(BigInteger.valueOf(designatedSwitchForTunnel.getDpId()),
+                        setOfTunnelIpElanNamePair);
             }
         }
-        logger.trace("Loading vniMacAddressToPortCache");
+        LOG.trace("Loading vniMacAddressToPortCache");
         InstanceIdentifier<Ports> inst = InstanceIdentifier.builder(Neutron.class).child(Ports.class).build();
         Optional<Ports> optionalPorts = MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, inst);
         if (optionalPorts.isPresent()) {
             List<Port> list = optionalPorts.get().getPort();
             for (Port port : list) {
-                if(NeutronUtils.isPortVnicTypeNormal(port)) {
+                if (NeutronUtils.isPortVnicTypeNormal(port)) {
                     continue;
                 }
                 String macAddress = port.getMacAddress().getValue();
@@ -137,36 +151,55 @@ public class DhcpExternalTunnelManager {
                 updateVniMacToPortCache(new BigInteger(segmentationId), macAddress, port);
             }
         }
-
     }
 
-
-    public BigInteger designateDpnId(IpAddress tunnelIp,
-            String elanInstanceName, List<BigInteger> dpns) {
+    public BigInteger designateDpnId(IpAddress tunnelIp, String elanInstanceName, List<BigInteger> dpns) {
         BigInteger designatedDpnId = readDesignatedSwitchesForExternalTunnel(tunnelIp, elanInstanceName);
-        if (designatedDpnId != null && !designatedDpnId.equals(DHCPMConstants.INVALID_DPID)) {
-            logger.trace("Dpn {} already designated for tunnelIp - elan : {} - {}", designatedDpnId, tunnelIp, elanInstanceName);
+        if (designatedDpnId != null && !designatedDpnId.equals(DhcpMConstants.INVALID_DPID)) {
+            LOG.trace("Dpn {} already designated for tunnelIp - elan : {} - {}", designatedDpnId, tunnelIp,
+                    elanInstanceName);
             return designatedDpnId;
         }
         return chooseDpn(tunnelIp, elanInstanceName, dpns);
     }
 
-    public void installDhcpFlowsForVms(IpAddress tunnelIp, String elanInstanceName, List<BigInteger> dpns,
-            BigInteger designatedDpnId, String vmMacAddress ) {
-        logger.trace("In installDhcpFlowsForVms ipAddress {}, elanInstanceName {}, dpn {}, vmMacAddress {}", tunnelIp, elanInstanceName, designatedDpnId, vmMacAddress);
-        synchronized (getTunnelIpDpnKey(tunnelIp, designatedDpnId)) {
-            installDhcpEntries(designatedDpnId, vmMacAddress, entityOwnershipService);
-            dpns.remove(designatedDpnId);
-            for (BigInteger dpn : dpns) {
-                installDhcpDropAction(dpn, vmMacAddress, entityOwnershipService);
+    public void installDhcpFlowsForVms(final IpAddress tunnelIp, String elanInstanceName, final List<BigInteger> dpns,
+            final BigInteger designatedDpnId, final String vmMacAddress) {
+        LOG.trace("In installDhcpFlowsForVms ipAddress {}, elanInstanceName {}, dpn {}, vmMacAddress {}", tunnelIp,
+                elanInstanceName, designatedDpnId, vmMacAddress);
+        // TODO: Make use a util that directly tells if this is the owner or not rather than making use of callbacks.
+        ListenableFuture<Boolean> checkEntityOwnerFuture = ClusteringUtils.checkNodeEntityOwner(
+                entityOwnershipService, HwvtepSouthboundConstants.ELAN_ENTITY_TYPE,
+                HwvtepSouthboundConstants.ELAN_ENTITY_NAME);
+        Futures.addCallback(checkEntityOwnerFuture, new FutureCallback<Boolean>() {
+            @Override
+            public void onSuccess(Boolean isOwner) {
+                if (isOwner) {
+                    synchronized (getTunnelIpDpnKey(tunnelIp, designatedDpnId)) {
+                        WriteTransaction tx = broker.newWriteOnlyTransaction();
+                        dpns.remove(designatedDpnId);
+                        for (BigInteger dpn : dpns) {
+                            installDhcpDropAction(dpn, vmMacAddress, tx);
+                        }
+                        installDhcpEntries(designatedDpnId, vmMacAddress, tx);
+                        DhcpServiceUtils.submitTransaction(tx);
+                    }
+                } else {
+                    LOG.trace("Exiting installDhcpEntries since this cluster node is not the owner for dpn");
+                }
             }
-            updateLocalCache(tunnelIp, elanInstanceName, vmMacAddress);
-        }
+
+            @Override
+            public void onFailure(Throwable error) {
+                LOG.error("Error while fetching checkNodeEntityOwner", error);
+            }
+        });
+        updateLocalCache(tunnelIp, elanInstanceName, vmMacAddress);
     }
 
-    public void installDhcpFlowsForVms(BigInteger designatedDpnId, Set<String> listVmMacAddress) {
+    public void installDhcpFlowsForVms(BigInteger designatedDpnId, Set<String> listVmMacAddress, WriteTransaction tx) {
         for (String vmMacAddress : listVmMacAddress) {
-            installDhcpEntries(designatedDpnId, vmMacAddress);
+            installDhcpEntries(designatedDpnId, vmMacAddress, tx);
         }
     }
 
@@ -175,41 +208,74 @@ public class DhcpExternalTunnelManager {
         removeFromLocalCache(elanInstanceName, vmMacAddress);
     }
 
+    public void unInstallDhcpFlowsForVms(String elanInstanceName, IpAddress tunnelIp, List<BigInteger> dpns) {
+        Pair<IpAddress, String> tunnelIpElanNamePair = new ImmutablePair<>(tunnelIp, elanInstanceName);
+        Set<String> vmMacs = tunnelIpElanNameToVmMacCache.get(tunnelIpElanNamePair);
+        LOG.trace("In unInstallFlowsForVms elanInstanceName {}, tunnelIp {}, dpns {}, vmMacs {}",
+                elanInstanceName, tunnelIp, dpns, vmMacs);
+        if (vmMacs == null) {
+            return;
+        }
+        for (String vmMacAddress : vmMacs) {
+            unInstallDhcpEntriesOnDpns(dpns, vmMacAddress);
+        }
+        tunnelIpElanNameToVmMacCache.remove(tunnelIpElanNamePair);
+    }
+
     public BigInteger readDesignatedSwitchesForExternalTunnel(IpAddress tunnelIp, String elanInstanceName) {
         if (tunnelIp == null || elanInstanceName == null || elanInstanceName.isEmpty()) {
             return null;
         }
-        InstanceIdentifier<DesignatedSwitchForTunnel> instanceIdentifier = InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class).child(DesignatedSwitchForTunnel.class, new DesignatedSwitchForTunnelKey(elanInstanceName, tunnelIp)).build();
-        Optional<DesignatedSwitchForTunnel> designatedSwitchForTunnelOptional = MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, instanceIdentifier);
+        InstanceIdentifier<DesignatedSwitchForTunnel> instanceIdentifier =
+                InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class)
+                        .child(DesignatedSwitchForTunnel.class,
+                                new DesignatedSwitchForTunnelKey(elanInstanceName, tunnelIp)).build();
+        Optional<DesignatedSwitchForTunnel> designatedSwitchForTunnelOptional =
+                MDSALUtil.read(broker, LogicalDatastoreType.CONFIGURATION, instanceIdentifier);
         if (designatedSwitchForTunnelOptional.isPresent()) {
             return BigInteger.valueOf(designatedSwitchForTunnelOptional.get().getDpId());
         }
         return null;
     }
 
-    public void writeDesignatedSwitchForExternalTunnel(BigInteger dpnId, IpAddress tunnelIp, String elanInstanceName) {
-        DesignatedSwitchForTunnelKey designatedSwitchForTunnelKey = new DesignatedSwitchForTunnelKey(elanInstanceName, tunnelIp);
-        InstanceIdentifier<DesignatedSwitchForTunnel> instanceIdentifier = InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class).child(DesignatedSwitchForTunnel.class, designatedSwitchForTunnelKey).build();
-        DesignatedSwitchForTunnel designatedSwitchForTunnel = new DesignatedSwitchForTunnelBuilder().setDpId(dpnId.longValue()).setElanInstanceName(elanInstanceName).setTunnelRemoteIpAddress(tunnelIp).setKey(designatedSwitchForTunnelKey).build();
-        logger.trace("Writing into CONFIG DS tunnelIp {}, elanInstanceName {}, dpnId {}", tunnelIp, elanInstanceName, dpnId);
+    public void writeDesignatedSwitchForExternalTunnel(BigInteger dpnId, IpAddress tunnelIp,
+                                                       String elanInstanceName) {
+        DesignatedSwitchForTunnelKey designatedSwitchForTunnelKey =
+                new DesignatedSwitchForTunnelKey(elanInstanceName, tunnelIp);
+        InstanceIdentifier<DesignatedSwitchForTunnel> instanceIdentifier =
+                InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class)
+                        .child(DesignatedSwitchForTunnel.class, designatedSwitchForTunnelKey).build();
+        DesignatedSwitchForTunnel designatedSwitchForTunnel =
+                new DesignatedSwitchForTunnelBuilder().setDpId(dpnId.longValue())
+                        .setElanInstanceName(elanInstanceName).setTunnelRemoteIpAddress(tunnelIp)
+                        .setKey(designatedSwitchForTunnelKey).build();
+        LOG.trace("Writing into CONFIG DS tunnelIp {}, elanInstanceName {}, dpnId {}", tunnelIp, elanInstanceName,
+                dpnId);
         MDSALUtil.syncUpdate(broker, LogicalDatastoreType.CONFIGURATION, instanceIdentifier, designatedSwitchForTunnel);
         updateLocalCache(dpnId, tunnelIp, elanInstanceName);
     }
 
-    public void removeDesignatedSwitchForExternalTunnel(BigInteger dpnId, IpAddress tunnelIp, String elanInstanceName) {
-        DesignatedSwitchForTunnelKey designatedSwitchForTunnelKey = new DesignatedSwitchForTunnelKey(elanInstanceName, tunnelIp);
-        InstanceIdentifier<DesignatedSwitchForTunnel> instanceIdentifier = InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class).child(DesignatedSwitchForTunnel.class, designatedSwitchForTunnelKey).build();
-        logger.trace("Removing from CONFIG DS tunnelIp {}, elanInstanceName {}, dpnId {}", tunnelIp, elanInstanceName, dpnId);
+    public void removeDesignatedSwitchForExternalTunnel(BigInteger dpnId, IpAddress tunnelIp,
+                                                        String elanInstanceName) {
+        DesignatedSwitchForTunnelKey designatedSwitchForTunnelKey =
+                new DesignatedSwitchForTunnelKey(elanInstanceName, tunnelIp);
+        InstanceIdentifier<DesignatedSwitchForTunnel> instanceIdentifier =
+                InstanceIdentifier.builder(DesignatedSwitchesForExternalTunnels.class)
+                        .child(DesignatedSwitchForTunnel.class, designatedSwitchForTunnelKey).build();
+        LOG.trace("Removing from CONFIG DS tunnelIp {}, elanInstanceName {}, dpnId {}", tunnelIp,
+                elanInstanceName, dpnId);
         MDSALUtil.syncDelete(broker, LogicalDatastoreType.CONFIGURATION, instanceIdentifier);
         removeFromLocalCache(dpnId, tunnelIp, elanInstanceName);
     }
 
     public void installDhcpDropActionOnDpn(BigInteger dpId) {
         List<String> vmMacs = getAllVmMacs();
-        logger.trace("Installing drop actions to this new DPN {} VMs {}", dpId, vmMacs);
+        LOG.trace("Installing drop actions to this new DPN {} VMs {}", dpId, vmMacs);
+        WriteTransaction tx = broker.newWriteOnlyTransaction();
         for (String vmMacAddress : vmMacs) {
-            installDhcpDropAction(dpId, vmMacAddress);
+            installDhcpDropAction(dpId, vmMacAddress, tx);
         }
+        DhcpServiceUtils.submitTransaction(tx);
     }
 
     private List<String> getAllVmMacs() {
@@ -229,7 +295,8 @@ public class DhcpExternalTunnelManager {
             tunnelIpElanNameSet = new CopyOnWriteArraySet<>();
         }
         tunnelIpElanNameSet.add(tunnelIpElanName);
-        logger.trace("Updating designatedDpnsToTunnelIpElanNameCache for designatedDpn {} value {}", designatedDpnId, tunnelIpElanNameSet);
+        LOG.trace("Updating designatedDpnsToTunnelIpElanNameCache for designatedDpn {} value {}", designatedDpnId,
+                tunnelIpElanNameSet);
         designatedDpnsToTunnelIpElanNameCache.put(designatedDpnId, tunnelIpElanNameSet);
     }
 
@@ -241,88 +308,89 @@ public class DhcpExternalTunnelManager {
             setOfExistingVmMacAddress = new CopyOnWriteArraySet<>();
         }
         setOfExistingVmMacAddress.add(vmMacAddress);
-        logger.trace("Updating tunnelIpElanNameToVmMacCache for tunnelIpElanName {} value {}", tunnelIpElanName, setOfExistingVmMacAddress);
+        LOG.trace("Updating tunnelIpElanNameToVmMacCache for tunnelIpElanName {} value {}", tunnelIpElanName,
+                setOfExistingVmMacAddress);
         tunnelIpElanNameToVmMacCache.put(tunnelIpElanName, setOfExistingVmMacAddress);
         updateExistingVMTunnelIPCache(tunnelIp, elanInstanceName, vmMacAddress);
     }
 
     public void updateExistingVMTunnelIPCache(IpAddress tunnelIp, String elanInstanceName, String vmMacAddress) {
-        Pair<IpAddress, String> tunnelIpElanName = new ImmutablePair<IpAddress, String>(tunnelIp, elanInstanceName);
+        Pair<IpAddress, String> tunnelIpElanName = new ImmutablePair<>(tunnelIp, elanInstanceName);
         Set<String> listExistingVmMacAddress;
         listExistingVmMacAddress = availableVMCache.get(tunnelIpElanName);
-        if (null == listExistingVmMacAddress) {
+        if (listExistingVmMacAddress == null) {
             listExistingVmMacAddress = new CopyOnWriteArraySet<>();
         }
         listExistingVmMacAddress.add(vmMacAddress);
-        logger.trace("Updating availableVMCache for tunnelIpElanName {} value {}", tunnelIpElanName,
+        LOG.trace("Updating availableVMCache for tunnelIpElanName {} value {}", tunnelIpElanName,
                 listExistingVmMacAddress);
         availableVMCache.put(tunnelIpElanName, listExistingVmMacAddress);
     }
 
     public void handleDesignatedDpnDown(BigInteger dpnId, List<BigInteger> listOfDpns) {
-        logger.trace("In handleDesignatedDpnDown dpnId {}, listOfDpns {}", dpnId, listOfDpns);
+        LOG.trace("In handleDesignatedDpnDown dpnId {}, listOfDpns {}", dpnId, listOfDpns);
         try {
             Set<Pair<IpAddress, String>> setOfTunnelIpElanNamePairs = designatedDpnsToTunnelIpElanNameCache.get(dpnId);
-            if (!dpnId.equals(DHCPMConstants.INVALID_DPID)) {
+            WriteTransaction tx = broker.newWriteOnlyTransaction();
+            if (!dpnId.equals(DhcpMConstants.INVALID_DPID)) {
                 List<String> listOfVms = getAllVmMacs();
                 for (String vmMacAddress : listOfVms) {
-                    unInstallDhcpEntries(dpnId, vmMacAddress);
+                    unInstallDhcpEntries(dpnId, vmMacAddress, tx);
                 }
             }
             if (setOfTunnelIpElanNamePairs == null || setOfTunnelIpElanNamePairs.isEmpty()) {
-                logger.trace("No tunnelIpElanName to handle for dpn {}. Returning", dpnId);
+                LOG.trace("No tunnelIpElanName to handle for dpn {}. Returning", dpnId);
                 return;
             }
             for (Pair<IpAddress, String> pair : setOfTunnelIpElanNamePairs) {
-                updateCacheAndInstallNewFlows(dpnId, listOfDpns, pair);
+                updateCacheAndInstallNewFlows(dpnId, listOfDpns, pair, tx);
             }
-        } catch (Exception e) {
-            logger.error("Error in handleDesignatedDpnDown {}", e);
+            DhcpServiceUtils.submitTransaction(tx);
+        } catch (ExecutionException e) {
+            LOG.error("Error in handleDesignatedDpnDown {}", e);
         }
     }
 
     public void updateCacheAndInstallNewFlows(BigInteger dpnId,
-            List<BigInteger> listOfDpns, Pair<IpAddress, String> pair)
+            List<BigInteger> listOfDpns, Pair<IpAddress, String> pair, WriteTransaction tx)
             throws ExecutionException {
         BigInteger newDesignatedDpn = chooseDpn(pair.getLeft(), pair.getRight(), listOfDpns);
-        if (newDesignatedDpn.equals(DHCPMConstants.INVALID_DPID)) {
+        if (newDesignatedDpn.equals(DhcpMConstants.INVALID_DPID)) {
             return;
         }
         Set<String> setOfVmMacs = tunnelIpElanNameToVmMacCache.get(pair);
         if (setOfVmMacs != null && !setOfVmMacs.isEmpty()) {
-            logger.trace("Updating DHCP flows for VMs {} with new designated DPN {}", setOfVmMacs, newDesignatedDpn);
-            installDhcpFlowsForVms(newDesignatedDpn, setOfVmMacs);
+            LOG.trace("Updating DHCP flows for VMs {} with new designated DPN {}", setOfVmMacs, newDesignatedDpn);
+            installDhcpFlowsForVms(newDesignatedDpn, setOfVmMacs, tx);
         }
     }
 
-    private void changeExistingFlowToDrop(Pair<IpAddress, String> tunnelIpElanNamePair, BigInteger dpnId) {
-        try {
-            Set<String> setOfVmMacAddress = tunnelIpElanNameToVmMacCache.get(tunnelIpElanNamePair);
-            if (setOfVmMacAddress == null || setOfVmMacAddress.isEmpty()) {
-                return;
-            }
-            for (String vmMacAddress : setOfVmMacAddress) {
-                installDhcpDropAction(dpnId, vmMacAddress);
-            }
-        } catch (Exception e) {
-            logger.error("Error in uninstallExistingFlows {}", e);
+    private void changeExistingFlowToDrop(Pair<IpAddress, String> tunnelIpElanNamePair, BigInteger dpnId,
+                                          WriteTransaction tx) {
+        Set<String> setOfVmMacAddress = tunnelIpElanNameToVmMacCache.get(tunnelIpElanNamePair);
+        if (setOfVmMacAddress == null || setOfVmMacAddress.isEmpty()) {
+            return;
+        }
+        for (String vmMacAddress : setOfVmMacAddress) {
+            installDhcpDropAction(dpnId, vmMacAddress, tx);
         }
     }
 
     /**
      * Choose a dpn among the list of elanDpns such that it has lowest count of being the designated dpn.
-     * @param tunnelIp
-     * @param elanInstanceName
-     * @param dpns
-     * @return
+     * @param tunnelIp The tunnel Ip address
+     * @param elanInstanceName The elan instance name
+     * @param dpns The data path nodes
+     * @return The designated dpn
      */
     private BigInteger chooseDpn(IpAddress tunnelIp, String elanInstanceName,
             List<BigInteger> dpns) {
-        BigInteger designatedDpnId = DHCPMConstants.INVALID_DPID;
+        BigInteger designatedDpnId = DhcpMConstants.INVALID_DPID;
         if (dpns != null && dpns.size() != 0) {
             List<BigInteger> candidateDpns = DhcpServiceUtils.getDpnsForElan(elanInstanceName, broker);
             candidateDpns.retainAll(dpns);
-            logger.trace("Choosing new dpn for tunnelIp {}, elanInstanceName {}, among elanDpns {}", tunnelIp, elanInstanceName, candidateDpns);
+            LOG.trace("Choosing new dpn for tunnelIp {}, elanInstanceName {}, among elanDpns {}",
+                    tunnelIp, elanInstanceName, candidateDpns);
             boolean elanDpnAvailableFlag = true;
             if (candidateDpns == null || candidateDpns.isEmpty()) {
                 candidateDpns = dpns;
@@ -331,7 +399,8 @@ public class DhcpExternalTunnelManager {
             int size = 0;
             L2GatewayDevice device = getDeviceFromTunnelIp(elanInstanceName, tunnelIp);
             if (device == null) {
-                logger.trace("Could not find any device for elanInstanceName {} and tunnelIp {}", elanInstanceName, tunnelIp);
+                LOG.trace("Could not find any device for elanInstanceName {} and tunnelIp {}",
+                        elanInstanceName, tunnelIp);
                 handleUnableToDesignateDpn(tunnelIp, elanInstanceName);
                 return designatedDpnId;
             }
@@ -339,11 +408,11 @@ public class DhcpExternalTunnelManager {
                 String hwvtepNodeId = device.getHwvtepNodeId();
                 if (!elanDpnAvailableFlag) {
                     if (!isTunnelConfigured(dpn, hwvtepNodeId)) {
-                        logger.trace("Tunnel is not configured on dpn {} to TOR {}", dpn, hwvtepNodeId);
+                        LOG.trace("Tunnel is not configured on dpn {} to TOR {}", dpn, hwvtepNodeId);
                         continue;
                     }
                 } else if (!isTunnelUp(hwvtepNodeId, dpn)) {
-                    logger.trace("Tunnel is not up between dpn {} and TOR {}", dpn, hwvtepNodeId);
+                    LOG.trace("Tunnel is not up between dpn {} and TOR {}", dpn, hwvtepNodeId);
                     continue;
                 }
                 Set<Pair<IpAddress, String>> tunnelIpElanNameSet = designatedDpnsToTunnelIpElanNameCache.get(dpn);
@@ -364,121 +433,63 @@ public class DhcpExternalTunnelManager {
     }
 
     private void handleUnableToDesignateDpn(IpAddress tunnelIp, String elanInstanceName) {
-        writeDesignatedSwitchForExternalTunnel(DHCPMConstants.INVALID_DPID, tunnelIp, elanInstanceName);
+        writeDesignatedSwitchForExternalTunnel(DhcpMConstants.INVALID_DPID, tunnelIp, elanInstanceName);
     }
 
-    public void installDhcpEntries(BigInteger dpnId, String vmMacAddress) {
-        DhcpServiceUtils.setupDhcpFlowEntry(dpnId, NwConstants.DHCP_TABLE_EXTERNAL_TUNNEL, vmMacAddress, NwConstants.ADD_FLOW, mdsalUtil);
+    private void installDhcpEntries(BigInteger dpnId, String vmMacAddress, WriteTransaction tx) {
+        DhcpServiceUtils.setupDhcpFlowEntry(dpnId, NwConstants.DHCP_TABLE_EXTERNAL_TUNNEL,
+                vmMacAddress, NwConstants.ADD_FLOW, mdsalUtil, tx);
     }
 
-    public void installDhcpEntries(final BigInteger dpnId, final String vmMacAddress, EntityOwnershipService eos) {
-        final String nodeId = DhcpServiceUtils.getNodeIdFromDpnId(dpnId);
-        ListenableFuture<Boolean> checkEntityOwnerFuture = ClusteringUtils.checkNodeEntityOwner(
-                eos, HwvtepSouthboundConstants.ELAN_ENTITY_TYPE,
-                HwvtepSouthboundConstants.ELAN_ENTITY_NAME);
-        Futures.addCallback(checkEntityOwnerFuture, new FutureCallback<Boolean>() {
-            @Override
-            public void onSuccess(Boolean isOwner) {
-                if (isOwner) {
-                    installDhcpEntries(dpnId, vmMacAddress);
-                } else {
-                    logger.trace("Exiting installDhcpEntries since this cluster node is not the owner for dpn {}", nodeId);
-                }
-            }
-
-            @Override
-            public void onFailure(Throwable error) {
-                logger.error("Error while fetching checkNodeEntityOwner", error);
-            }
-        });
+    public void unInstallDhcpEntries(BigInteger dpnId, String vmMacAddress, WriteTransaction tx) {
+        DhcpServiceUtils.setupDhcpFlowEntry(dpnId, NwConstants.DHCP_TABLE_EXTERNAL_TUNNEL,
+                vmMacAddress, NwConstants.DEL_FLOW, mdsalUtil, tx);
     }
 
-    public void unInstallDhcpEntries(BigInteger dpnId, String vmMacAddress) {
-        DhcpServiceUtils.setupDhcpFlowEntry(dpnId, NwConstants.DHCP_TABLE_EXTERNAL_TUNNEL, vmMacAddress, NwConstants.DEL_FLOW, mdsalUtil);
+    private void installDhcpDropAction(BigInteger dpn, String vmMacAddress, WriteTransaction tx) {
+        DhcpServiceUtils.setupDhcpDropAction(dpn, NwConstants.DHCP_TABLE_EXTERNAL_TUNNEL,
+                vmMacAddress, NwConstants.ADD_FLOW, mdsalUtil, tx);
     }
 
-    public void unInstallDhcpEntries(final BigInteger dpnId, final String vmMacAddress, EntityOwnershipService eos) {
-        final String nodeId = DhcpServiceUtils.getNodeIdFromDpnId(dpnId);
-        // TODO: Make use a util that directly tells if this is the owner or not rather than making use of callbacks.
-        ListenableFuture<Boolean> checkEntityOwnerFuture = ClusteringUtils.checkNodeEntityOwner(
-                eos, HwvtepSouthboundConstants.ELAN_ENTITY_TYPE,
-                HwvtepSouthboundConstants.ELAN_ENTITY_NAME);
-        Futures.addCallback(checkEntityOwnerFuture, new FutureCallback<Boolean>() {
-            @Override
-            public void onSuccess(Boolean isOwner) {
-                if (isOwner) {
-                    unInstallDhcpEntries(dpnId, vmMacAddress);
-                } else {
-                    logger.trace("Exiting unInstallDhcpEntries since this cluster node is not the owner for dpn {}", nodeId);
-                }
-            }
-
-            @Override
-            public void onFailure(Throwable error) {
-                logger.error("Error while fetching checkNodeEntityOwner", error);
-            }
-        });
-    }
-
-    public void installDhcpDropAction(BigInteger dpn, String vmMacAddress) {
-        DhcpServiceUtils.setupDhcpDropAction(dpn, NwConstants.DHCP_TABLE_EXTERNAL_TUNNEL, vmMacAddress, NwConstants.ADD_FLOW, mdsalUtil);
-    }
-
-    public void installDhcpDropAction(final BigInteger dpnId, final String vmMacAddress, EntityOwnershipService eos) {
-        final String nodeId = DhcpServiceUtils.getNodeIdFromDpnId(dpnId);
-        ListenableFuture<Boolean> checkEntityOwnerFuture = ClusteringUtils.checkNodeEntityOwner(
-                eos, HwvtepSouthboundConstants.ELAN_ENTITY_TYPE,
-                HwvtepSouthboundConstants.ELAN_ENTITY_NAME);
-        Futures.addCallback(checkEntityOwnerFuture, new FutureCallback<Boolean>() {
-            @Override
-            public void onSuccess(Boolean isOwner) {
-                if (isOwner) {
-                    installDhcpDropAction(dpnId, vmMacAddress);
-                } else {
-                    logger.trace("Exiting installDhcpDropAction since this cluster node is not the owner for dpn {}", nodeId);
-                }
-            }
-
-            @Override
-            public void onFailure(Throwable error) {
-                logger.error("Error while fetching checkNodeEntityOwner", error);
-            }
-        });
-    }
-
-    public void handleTunnelStateDown(IpAddress tunnelIp, BigInteger interfaceDpn) {
-        logger.trace("In handleTunnelStateDown tunnelIp {}, interfaceDpn {}", tunnelIp, interfaceDpn);
+    public void handleTunnelStateDown(IpAddress tunnelIp, BigInteger interfaceDpn,
+                                      List<ListenableFuture<Void>> futures) {
+        LOG.trace("In handleTunnelStateDown tunnelIp {}, interfaceDpn {}", tunnelIp, interfaceDpn);
         if (interfaceDpn == null) {
             return;
         }
         try {
             synchronized (getTunnelIpDpnKey(tunnelIp, interfaceDpn)) {
-                Set<Pair<IpAddress, String>> tunnelElanPairSet = designatedDpnsToTunnelIpElanNameCache.get(interfaceDpn);
+                Set<Pair<IpAddress, String>> tunnelElanPairSet =
+                        designatedDpnsToTunnelIpElanNameCache.get(interfaceDpn);
                 if (tunnelElanPairSet == null || tunnelElanPairSet.isEmpty()) {
                     return;
                 }
+                WriteTransaction tx = broker.newWriteOnlyTransaction();
                 for (Pair<IpAddress, String> tunnelElanPair : tunnelElanPairSet) {
                     IpAddress tunnelIpInDpn = tunnelElanPair.getLeft();
                     if (tunnelIpInDpn.equals(tunnelIp)) {
                         if (!checkL2GatewayConnection(tunnelElanPair)) {
-                            logger.trace("Couldn't find device for given tunnelIpElanPair {} in L2GwConnCache", tunnelElanPair);
+                            LOG.trace("Couldn't find device for given tunnelIpElanPair {} in L2GwConnCache",
+                                    tunnelElanPair);
                             return;
                         }
                         List<BigInteger> dpns = DhcpServiceUtils.getListOfDpns(broker);
                         dpns.remove(interfaceDpn);
-                        changeExistingFlowToDrop(tunnelElanPair, interfaceDpn);
-                        updateCacheAndInstallNewFlows(interfaceDpn, dpns, tunnelElanPair);
+                        changeExistingFlowToDrop(tunnelElanPair, interfaceDpn, tx);
+                        updateCacheAndInstallNewFlows(interfaceDpn, dpns, tunnelElanPair, tx);
                     }
                 }
+                futures.add(tx.submit());
             }
-        } catch (Exception e) {
-            logger.error("Error in handleTunnelStateDown {}", e.getMessage());
-            logger.trace("Exception details {}", e);
+        } catch (ExecutionException e) {
+            LOG.error("Error in handleTunnelStateDown {}", e.getMessage());
+            LOG.trace("Exception details {}", e);
         }
     }
 
     private boolean checkL2GatewayConnection(Pair<IpAddress, String> tunnelElanPair) {
-        ConcurrentMap<String, L2GatewayDevice> l2GwDevices = ElanL2GwCacheUtils.getInvolvedL2GwDevices(tunnelElanPair.getRight());
+        ConcurrentMap<String, L2GatewayDevice> l2GwDevices =
+                ElanL2GwCacheUtils.getInvolvedL2GwDevices(tunnelElanPair.getRight());
         for (L2GatewayDevice device : l2GwDevices.values()) {
             if (device.getTunnelIp().equals(tunnelElanPair.getLeft())) {
                 return true;
@@ -488,7 +499,7 @@ public class DhcpExternalTunnelManager {
     }
 
     private String getTunnelIpDpnKey(IpAddress tunnelIp, BigInteger interfaceDpn) {
-        return new StringBuffer().append(tunnelIp.toString()).append(interfaceDpn).toString().intern();
+        return tunnelIp.toString() + interfaceDpn;
     }
 
     private void removeFromLocalCache(String elanInstanceName, String vmMacAddress) {
@@ -500,7 +511,8 @@ public class DhcpExternalTunnelManager {
                 if (setOfExistingVmMacAddress == null || setOfExistingVmMacAddress.isEmpty()) {
                     continue;
                 }
-                logger.trace("Removing vmMacAddress {} from listOfMacs {} for elanInstanceName {}", vmMacAddress, setOfExistingVmMacAddress, elanInstanceName);
+                LOG.trace("Removing vmMacAddress {} from listOfMacs {} for elanInstanceName {}", vmMacAddress,
+                        setOfExistingVmMacAddress, elanInstanceName);
                 setOfExistingVmMacAddress.remove(vmMacAddress);
                 if (setOfExistingVmMacAddress.size() > 0) {
                     tunnelIpElanNameToVmMacCache.put(pair, setOfExistingVmMacAddress);
@@ -516,7 +528,9 @@ public class DhcpExternalTunnelManager {
         Set<Pair<IpAddress, String>> tunnelIpElanNameSet;
         tunnelIpElanNameSet = designatedDpnsToTunnelIpElanNameCache.get(designatedDpnId);
         if (tunnelIpElanNameSet != null) {
-            logger.trace("Removing tunnelIpElan {} from designatedDpnsToTunnelIpElanNameCache. Existing list {} for designatedDpnId {}", tunnelIpElanName, tunnelIpElanNameSet, designatedDpnId);
+            LOG.trace("Removing tunnelIpElan {} from designatedDpnsToTunnelIpElanNameCache. Existing list {} for "
+                            + "designatedDpnId {}",
+                    tunnelIpElanName, tunnelIpElanNameSet, designatedDpnId);
             tunnelIpElanNameSet.remove(tunnelIpElanName);
             if (tunnelIpElanNameSet.size() != 0) {
                 designatedDpnsToTunnelIpElanNameCache.put(designatedDpnId, tunnelIpElanNameSet);
@@ -531,7 +545,8 @@ public class DhcpExternalTunnelManager {
             return;
         }
         Pair<BigInteger, String> vniMacAddressPair = new ImmutablePair<>(vni, macAddress.toUpperCase());
-        logger.trace("Updating vniMacAddressToPortCache with vni {} , mac {} , pair {} and port {}", vni, macAddress.toUpperCase(), vniMacAddressPair, port);
+        LOG.trace("Updating vniMacAddressToPortCache with vni {} , mac {} , pair {} and port {}", vni,
+                macAddress.toUpperCase(), vniMacAddressPair, port);
         vniMacAddressToPortCache.put(vniMacAddressPair, port);
     }
 
@@ -548,7 +563,8 @@ public class DhcpExternalTunnelManager {
             return null;
         }
         Pair<BigInteger, String> vniMacAddressPair = new ImmutablePair<>(vni, macAddress.toUpperCase());
-        logger.trace("Reading vniMacAddressToPortCache with vni {} , mac {} , pair {} and port {}", vni, macAddress.toUpperCase(), vniMacAddressPair, vniMacAddressToPortCache.get(vniMacAddressPair));
+        LOG.trace("Reading vniMacAddressToPortCache with vni {} , mac {} , pair {} and port {}",
+                vni, macAddress.toUpperCase(), vniMacAddressPair, vniMacAddressToPortCache.get(vniMacAddressPair));
         return vniMacAddressToPortCache.get(vniMacAddressPair);
     }
 
@@ -563,13 +579,12 @@ public class DhcpExternalTunnelManager {
             RpcResult<GetExternalTunnelInterfaceNameOutput> rpcResult = output.get();
             if (rpcResult.isSuccessful()) {
                 tunnelInterfaceName = rpcResult.getResult().getInterfaceName();
-                logger.debug("Tunnel interface name: {}", tunnelInterfaceName);
+                LOG.trace("Tunnel interface name: {}", tunnelInterfaceName);
             } else {
-                logger.warn("RPC call to ITM.GetExternalTunnelInterfaceName failed with error: {}",
-                        rpcResult.getErrors());
+                LOG.warn("RPC call to ITM.GetExternalTunnelInterfaceName failed with error: {}", rpcResult.getErrors());
             }
         } catch (NullPointerException | InterruptedException | ExecutionException e) {
-            logger.error("Failed to get external tunnel interface name for sourceNode: {} and dstNode: {}: {} ",
+            LOG.error("Failed to get external tunnel interface name for sourceNode: {} and dstNode: {}: {} ",
                     sourceNode, dstNode, e);
         }
         return tunnelInterfaceName;
@@ -578,8 +593,7 @@ public class DhcpExternalTunnelManager {
     public static Optional<Node> getNode(DataBroker dataBroker, String physicalSwitchNodeId) {
         InstanceIdentifier<Node> psNodeId = HwvtepSouthboundUtils
                 .createInstanceIdentifier(new NodeId(physicalSwitchNodeId));
-        Optional<Node> physicalSwitchOptional = MDSALUtil.read(LogicalDatastoreType.CONFIGURATION, psNodeId, dataBroker);
-        return physicalSwitchOptional;
+        return MDSALUtil.read(LogicalDatastoreType.CONFIGURATION, psNodeId, dataBroker);
     }
 
     public RemoteMcastMacs createRemoteMcastMac(Node dstDevice, String logicalSwitchName, IpAddress internalTunnelIp) {
@@ -601,11 +615,12 @@ public class DhcpExternalTunnelManager {
         return remoteUcastMacs;
     }
 
-    private WriteTransaction putRemoteMcastMac(WriteTransaction transaction, String elanName, L2GatewayDevice device, IpAddress internalTunnelIp) {
+    private WriteTransaction putRemoteMcastMac(WriteTransaction transaction, String elanName,
+                                               L2GatewayDevice device, IpAddress internalTunnelIp) {
         Optional<Node> optionalNode = getNode(broker, device.getHwvtepNodeId());
         Node dstNode = optionalNode.get();
         if (dstNode == null) {
-            logger.debug("could not get device node {} ", device.getHwvtepNodeId());
+            LOG.trace("could not get device node {} ", device.getHwvtepNodeId());
             return null;
         }
         RemoteMcastMacs macs = createRemoteMcastMac(dstNode, elanName, internalTunnelIp);
@@ -613,23 +628,27 @@ public class DhcpExternalTunnelManager {
         return transaction;
     }
 
-    public void installRemoteMcastMac(final BigInteger designatedDpnId, final IpAddress tunnelIp, final String elanInstanceName) {
-        if (designatedDpnId.equals(DHCPMConstants.INVALID_DPID)) {
+    public void installRemoteMcastMac(final BigInteger designatedDpnId, final IpAddress tunnelIp,
+                                      final String elanInstanceName) {
+        if (designatedDpnId.equals(DhcpMConstants.INVALID_DPID)) {
             return;
         }
-        ListenableFuture<Boolean> checkEntityOwnerFuture = ClusteringUtils.checkNodeEntityOwner(entityOwnershipService, HwvtepSouthboundConstants.ELAN_ENTITY_TYPE, HwvtepSouthboundConstants.ELAN_ENTITY_NAME);
+        ListenableFuture<Boolean> checkEntityOwnerFuture = ClusteringUtils.checkNodeEntityOwner(entityOwnershipService,
+                HwvtepSouthboundConstants.ELAN_ENTITY_TYPE, HwvtepSouthboundConstants.ELAN_ENTITY_NAME);
         Futures.addCallback(checkEntityOwnerFuture, new FutureCallback<Boolean>() {
             @Override
             public void onSuccess(Boolean isOwner) {
                 if (isOwner) {
-                    logger.info("Installing remote McastMac");
+                    LOG.info("Installing remote McastMac");
                     L2GatewayDevice device = getDeviceFromTunnelIp(elanInstanceName, tunnelIp);
-                    String tunnelInterfaceName = getExternalTunnelInterfaceName(String.valueOf(designatedDpnId), device.getHwvtepNodeId());
+                    String tunnelInterfaceName = getExternalTunnelInterfaceName(String.valueOf(designatedDpnId),
+                            device.getHwvtepNodeId());
                     IpAddress internalTunnelIp = null;
                     if (tunnelInterfaceName != null) {
-                        Interface tunnelInterface = DhcpServiceUtils.getInterfaceFromConfigDS(tunnelInterfaceName, broker);
+                        Interface tunnelInterface =
+                                interfaceManager.getInterfaceInfoFromConfigDataStore(tunnelInterfaceName);
                         if (tunnelInterface == null) {
-                            logger.trace("Tunnel Interface is not present {}", tunnelInterfaceName);
+                            LOG.trace("Tunnel Interface is not present {}", tunnelInterfaceName);
                             return;
                         }
                         internalTunnelIp = tunnelInterface.getAugmentation(IfTunnel.class).getTunnelSource();
@@ -640,20 +659,20 @@ public class DhcpExternalTunnelManager {
                         }
                     }
                 } else {
-                      logger.info("Installing remote McastMac is not executed for this node.");
+                    LOG.info("Installing remote McastMac is not executed for this node.");
                 }
             }
 
             @Override
             public void onFailure(Throwable error) {
-                logger.error("Failed to install remote McastMac", error);
+                LOG.error("Failed to install remote McastMac", error);
             }
         });
     }
 
     private L2GatewayDevice getDeviceFromTunnelIp(String elanInstanceName, IpAddress tunnelIp) {
         ConcurrentMap<String, L2GatewayDevice> devices = L2GatewayCacheUtils.getCache();
-        logger.trace("In getDeviceFromTunnelIp devices {}", devices);
+        LOG.trace("In getDeviceFromTunnelIp devices {}", devices);
         for (L2GatewayDevice device : devices.values()) {
             if (tunnelIp.equals(device.getTunnelIp())) {
                 return device;
@@ -663,47 +682,46 @@ public class DhcpExternalTunnelManager {
     }
 
     private boolean isTunnelUp(String nodeName, BigInteger dpn) {
-        boolean isTunnelUp = false;
         String tunnelInterfaceName = getExternalTunnelInterfaceName(String.valueOf(dpn), nodeName);
         if (tunnelInterfaceName == null) {
-            logger.debug("Tunnel Interface is not present {}", tunnelInterfaceName);
-            return isTunnelUp;
+            LOG.trace("Tunnel Interface is not present on node {} with dpn {}", nodeName, dpn);
+            return false;
         }
-        org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface tunnelInterface = DhcpServiceUtils.getInterfaceFromOperationalDS(tunnelInterfaceName, broker);
+        org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state
+                .Interface tunnelInterface =
+                DhcpServiceUtils.getInterfaceFromOperationalDS(tunnelInterfaceName, broker);
         if (tunnelInterface == null) {
-            logger.debug("Interface {} is not present in interface state", tunnelInterfaceName);
-            return isTunnelUp;
+            LOG.trace("Interface {} is not present in interface state", tunnelInterfaceName);
+            return false;
         }
-        isTunnelUp = (tunnelInterface.getOperStatus() == OperStatus.Up);
-        return isTunnelUp;
+        return tunnelInterface.getOperStatus() == OperStatus.Up;
     }
 
-    public void handleTunnelStateUp(IpAddress tunnelIp, BigInteger interfaceDpn) {
-        logger.trace("In handleTunnelStateUp tunnelIp {}, interfaceDpn {}", tunnelIp, interfaceDpn);
-        try {
-            synchronized (getTunnelIpDpnKey(tunnelIp, interfaceDpn)) {
-                Set<Pair<IpAddress, String>> tunnelIpElanPair = designatedDpnsToTunnelIpElanNameCache.get(DHCPMConstants.INVALID_DPID);
-                List<BigInteger> dpns = DhcpServiceUtils.getListOfDpns(broker);
-                if (tunnelIpElanPair == null || tunnelIpElanPair.isEmpty()) {
-                    logger.trace("There are no undesignated DPNs");
-                    return;
-                }
-                for (Pair<IpAddress, String> pair : tunnelIpElanPair) {
-                    if (tunnelIp.equals(pair.getLeft())) {
-                        BigInteger newDesignatedDpn = designateDpnId(tunnelIp, pair.getRight(), dpns);
-                        if (newDesignatedDpn != null && !newDesignatedDpn.equals(DHCPMConstants.INVALID_DPID)) {
-                            Set<String> vmMacAddress = tunnelIpElanNameToVmMacCache.get(pair);
-                            if (vmMacAddress != null && !vmMacAddress.isEmpty()) {
-                                logger.trace("Updating DHCP flow for macAddress {} with newDpn {}", vmMacAddress, newDesignatedDpn);
-                                installDhcpFlowsForVms(newDesignatedDpn, vmMacAddress);
-                            }
+    public void handleTunnelStateUp(IpAddress tunnelIp, BigInteger interfaceDpn, List<ListenableFuture<Void>> futures) {
+        LOG.trace("In handleTunnelStateUp tunnelIp {}, interfaceDpn {}", tunnelIp, interfaceDpn);
+        synchronized (getTunnelIpDpnKey(tunnelIp, interfaceDpn)) {
+            Set<Pair<IpAddress, String>> tunnelIpElanPair =
+                    designatedDpnsToTunnelIpElanNameCache.get(DhcpMConstants.INVALID_DPID);
+            List<BigInteger> dpns = DhcpServiceUtils.getListOfDpns(broker);
+            if (tunnelIpElanPair == null || tunnelIpElanPair.isEmpty()) {
+                LOG.trace("There are no undesignated DPNs");
+                return;
+            }
+            WriteTransaction tx = broker.newWriteOnlyTransaction();
+            for (Pair<IpAddress, String> pair : tunnelIpElanPair) {
+                if (tunnelIp.equals(pair.getLeft())) {
+                    BigInteger newDesignatedDpn = designateDpnId(tunnelIp, pair.getRight(), dpns);
+                    if (newDesignatedDpn != null && !newDesignatedDpn.equals(DhcpMConstants.INVALID_DPID)) {
+                        Set<String> vmMacAddress = tunnelIpElanNameToVmMacCache.get(pair);
+                        if (vmMacAddress != null && !vmMacAddress.isEmpty()) {
+                            LOG.trace("Updating DHCP flow for macAddress {} with newDpn {}",
+                                    vmMacAddress, newDesignatedDpn);
+                            installDhcpFlowsForVms(newDesignatedDpn, vmMacAddress, tx);
                         }
                     }
                 }
             }
-        } catch (Exception e) {
-            logger.error("Error in handleTunnelStateUp {}", e.getMessage());
-            logger.trace("Exception details {}", e);
+            futures.add(tx.submit());
         }
     }
 
@@ -712,62 +730,62 @@ public class DhcpExternalTunnelManager {
         if (tunnelInterfaceName == null) {
             return false;
         }
-        Interface tunnelInterface = DhcpServiceUtils.getInterfaceFromConfigDS(tunnelInterfaceName, broker);
+        Interface tunnelInterface = interfaceManager.getInterfaceInfoFromConfigDataStore(tunnelInterfaceName);
         if (tunnelInterface == null) {
-            logger.debug("Tunnel Interface is not present {}", tunnelInterfaceName);
+            LOG.trace("Tunnel Interface is not present {}", tunnelInterfaceName);
             return false;
         }
         return true;
     }
 
-    public void unInstallDhcpFlowsForVms(String elanInstanceName, IpAddress tunnelIp, List<BigInteger> dpns) {
-        Pair<IpAddress, String> tunnelIpElanNamePair = new ImmutablePair<>(tunnelIp, elanInstanceName);
-        Set<String> vmMacs = tunnelIpElanNameToVmMacCache.get(tunnelIpElanNamePair);
-        logger.trace("In unInstallFlowsForVms elanInstanceName {}, tunnelIp {}, dpns {}, vmMacs {}",
-                elanInstanceName, tunnelIp, dpns, vmMacs);
-        if (vmMacs == null) {
-            return;
-        }
-        for (String vmMacAddress : vmMacs) {
-            unInstallDhcpEntriesOnDpns(dpns, vmMacAddress);
-        }
-        tunnelIpElanNameToVmMacCache.remove(tunnelIpElanNamePair);
-    }
-
     public void removeFromAvailableCache(Pair<IpAddress, String> tunnelIpElanName) {
         availableVMCache.remove(tunnelIpElanName);
     }
 
-    private void unInstallDhcpEntriesOnDpns(List<BigInteger> dpns, String vmMacAddress) {
-        for (BigInteger dpn : dpns) {
-            unInstallDhcpEntries(dpn, vmMacAddress, entityOwnershipService);
-        }
+    private void unInstallDhcpEntriesOnDpns(final List<BigInteger> dpns, final String vmMacAddress) {
+        // TODO: Make use a util that directly tells if this is the owner or not rather than making use of callbacks.
+        ListenableFuture<Boolean> checkEntityOwnerFuture = ClusteringUtils.checkNodeEntityOwner(
+                entityOwnershipService, HwvtepSouthboundConstants.ELAN_ENTITY_TYPE,
+                HwvtepSouthboundConstants.ELAN_ENTITY_NAME);
+        Futures.addCallback(checkEntityOwnerFuture, new FutureCallback<Boolean>() {
+            @Override
+            public void onSuccess(Boolean isOwner) {
+                if (isOwner) {
+                    WriteTransaction tx = broker.newWriteOnlyTransaction();
+                    for (final BigInteger dpn : dpns) {
+                        unInstallDhcpEntries(dpn, vmMacAddress, tx);
+                    }
+                    DhcpServiceUtils.submitTransaction(tx);
+                } else {
+                    LOG.trace("Exiting unInstallDhcpEntries since this cluster node is not the owner for dpn");
+                }
+            }
+
+            @Override
+            public void onFailure(Throwable error) {
+                LOG.error("Error while fetching checkNodeEntityOwner", error);
+            }
+        });
     }
 
     public IpAddress getTunnelIpBasedOnElan(String elanInstanceName, String vmMacAddress) {
-        if (logger.isTraceEnabled()) {
-            logger.trace("DhcpExternalTunnelManager getTunnelIpBasedOnElan elanInstanceName " + elanInstanceName);
-        }
+        LOG.trace("DhcpExternalTunnelManager getTunnelIpBasedOnElan elanInstanceName {}", elanInstanceName);
         IpAddress tunnelIp = null;
         Set<Pair<IpAddress, String>> tunnelElanKeySet = availableVMCache.keySet();
         Set<String> listExistingVmMacAddress;
         for (Pair<IpAddress, String> pair : tunnelElanKeySet) {
-            if (logger.isTraceEnabled()) {
-                logger.trace("DhcpExternalTunnelManager getTunnelIpBasedOnElan left  " + pair.getLeft() + " right:" +
-                        pair.getRight());
-            }
+            LOG.trace("DhcpExternalTunnelManager getTunnelIpBasedOnElan left {} right {}", pair.getLeft(),
+                    pair.getRight());
             if (pair.getRight().trim().equalsIgnoreCase(elanInstanceName.trim())) {
                 listExistingVmMacAddress = availableVMCache.get(pair);
-                if (listExistingVmMacAddress != null && !listExistingVmMacAddress.isEmpty() &&
-                        listExistingVmMacAddress.contains(vmMacAddress)) {
+                if (listExistingVmMacAddress != null && !listExistingVmMacAddress.isEmpty()
+                        && listExistingVmMacAddress.contains(vmMacAddress)) {
                     tunnelIp = pair.getLeft();
                     break;
                 }
             }
         }
-        if (logger.isTraceEnabled()) {
-            logger.trace("DhcpExternalTunnelManager getTunnelIpBasedOnElan returned tunnelIP " + tunnelIp);
-        }
+        LOG.trace("DhcpExternalTunnelManager getTunnelIpBasedOnElan returned tunnelIP {}", tunnelIp);
         return tunnelIp;
     }
 }