openstack/net-virt-providers/src/main/java/org/opendaylight/ovsdb/openstack/netvirt/providers/openflow13/services/arp/GatewayMacResolverService.java

   1 /*
   2  * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.ovsdb.openstack.netvirt.providers.openflow13.services.arp;
   9
  10 import static com.google.common.base.Preconditions.checkNotNull;
  11
  12 import java.math.BigInteger;
  13 import java.util.Map.Entry;
  14 import java.util.concurrent.Callable;
  15 import java.util.concurrent.ConcurrentHashMap;
  16 import java.util.concurrent.ConcurrentMap;
  17 import java.util.concurrent.Executors;
  18 import java.util.concurrent.Future;
  19 import java.util.concurrent.ScheduledExecutorService;
  20 import java.util.concurrent.TimeUnit;
  21 import java.util.concurrent.atomic.AtomicBoolean;
  22 import java.util.concurrent.atomic.AtomicLong;
  23
  24 import javax.annotation.Nullable;
  25
  26 import org.opendaylight.controller.sal.binding.api.BindingAwareBroker.ProviderContext;
  27 import org.opendaylight.openflowplugin.api.OFConstants;
  28 import org.opendaylight.ovsdb.openstack.netvirt.api.GatewayMacResolver;
  29 import org.opendaylight.ovsdb.openstack.netvirt.providers.ConfigInterface;
  30 import org.opendaylight.ovsdb.openstack.netvirt.providers.NetvirtProvidersProvider;
  31 import org.opendaylight.ovsdb.openstack.netvirt.providers.openflow13.AbstractServiceInstance;
  32 import org.opendaylight.ovsdb.openstack.netvirt.providers.openflow13.Service;
  33 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev100924.IpAddress;
  34 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev100924.Ipv4Address;
  35 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.yang.types.rev100924.MacAddress;
  36 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.FlowCapableNode;
  37 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.FlowId;
  38 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.Table;
  39 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.TableKey;
  40 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.table.Flow;
  41 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.table.FlowBuilder;
  42 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.table.FlowKey;
  43 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.service.rev130819.AddFlowInputBuilder;
  44 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.service.rev130819.AddFlowOutput;
  45 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.service.rev130819.RemoveFlowInputBuilder;
  46 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.service.rev130819.SalFlowService;
  47 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.FlowCookie;
  48 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.FlowModFlags;
  49 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.FlowRef;
  50 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.flow.InstructionsBuilder;
  51 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.flow.Match;
  52 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.flow.MatchBuilder;
  53 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.instruction.instruction.ApplyActionsCaseBuilder;
  54 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.instruction.instruction.apply.actions._case.ApplyActions;
  55 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.instruction.instruction.apply.actions._case.ApplyActionsBuilder;
  56 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.instruction.list.Instruction;
  57 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.types.rev131026.instruction.list.InstructionBuilder;
  58 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.NodeRef;
  59 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.Nodes;
  60 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.node.NodeConnector;
  61 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.node.NodeConnectorKey;
  62 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.Node;
  63 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.NodeKey;
  64 import org.opendaylight.yang.gen.v1.urn.opendaylight.model.match.types.rev131026.match.EthernetMatch;
  65 import org.opendaylight.yang.gen.v1.urn.opendaylight.model.match.types.rev131026.match.layer._3.match.ArpMatch;
  66 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.service.rev130709.PacketProcessingListener;
  67 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.service.rev130709.PacketProcessingService;
  68 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.service.rev130709.PacketReceived;
  69 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
  70 import org.opendaylight.yangtools.yang.binding.KeyedInstanceIdentifier;
  71 import org.opendaylight.yangtools.yang.common.RpcResult;
  72 import org.osgi.framework.BundleContext;
  73 import org.osgi.framework.ServiceReference;
  74 import org.slf4j.Logger;
  75 import org.slf4j.LoggerFactory;
  76
  77 import com.google.common.base.Preconditions;
  78 import com.google.common.collect.ImmutableList;
  79 import com.google.common.util.concurrent.FutureCallback;
  80 import com.google.common.util.concurrent.Futures;
  81 import com.google.common.util.concurrent.JdkFutureAdapters;
  82 import com.google.common.util.concurrent.ListenableFuture;
  83 import com.google.common.util.concurrent.ListeningExecutorService;
  84 import com.google.common.util.concurrent.MoreExecutors;
  85
  86 /**
  87  *
  88  * @author Anil Vishnoi (avishnoi@Brocade.com)
  89  *
  90  */
  91 public class GatewayMacResolverService extends AbstractServiceInstance
  92                                         implements ConfigInterface, GatewayMacResolver,PacketProcessingListener {
  93
  94     private static final Logger LOG = LoggerFactory.getLogger(GatewayMacResolverService.class);
  95     private static final short TABEL_FOR_ARP_FLOW = 0;
  96     private static final String ARP_REPLY_TO_CONTROLLER_FLOW_NAME = "GatewayArpReplyRouter";
  97     private static final int ARP_REPLY_TO_CONTROLLER_FLOW_PRIORITY = 10000;
  98     private static final Instruction SEND_TO_CONTROLLER_INSTRUCTION;
  99     private ArpSender arpSender;
 100     private SalFlowService flowService;
 101     private final AtomicLong flowCookie = new AtomicLong();
 102     private final ConcurrentMap<Ipv4Address, ArpResolverMetadata> gatewayToArpMetadataMap =
 103             new ConcurrentHashMap<Ipv4Address, ArpResolverMetadata>();
 104     private final int ARP_WATCH_BROTHERS = 10;
 105     private final int WAIT_CYCLES = 3;
 106     private final int PER_CYCLE_WAIT_DURATION = 1000;
 107     private final int REFRESH_INTERVAL = 10;
 108     private final ListeningExecutorService arpWatcherWall = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(ARP_WATCH_BROTHERS));
 109     private final ScheduledExecutorService gatewayMacRefresherPool = Executors.newScheduledThreadPool(1);
 110     private final ScheduledExecutorService refreshRequester = Executors.newSingleThreadScheduledExecutor();
 111     private AtomicBoolean initializationDone = new AtomicBoolean(false);
 112
 113     static {
 114         ApplyActions applyActions = new ApplyActionsBuilder().setAction(
 115                 ImmutableList.of(ArpFlowFactory.createSendToControllerAction(0))).build();
 116         SEND_TO_CONTROLLER_INSTRUCTION = new InstructionBuilder().setOrder(0)
 117             .setInstruction(new ApplyActionsCaseBuilder().setApplyActions(applyActions).build())
 118             .build();
 119     }
 120
 121     public GatewayMacResolverService(){
 122         super(Service.GATEWAY_RESOLVER);
 123     }
 124
 125     public GatewayMacResolverService(Service service){
 126         super(service);
 127     }
 128
 129     private void init(){
 130         if(!initializationDone.get()){
 131             initializationDone.set(true);
 132             ProviderContext providerContext = NetvirtProvidersProvider.getProviderContext();
 133             checkNotNull(providerContext);
 134             PacketProcessingService packetProcessingService = providerContext.getRpcService(PacketProcessingService.class);
 135             if (packetProcessingService != null) {
 136                 LOG.debug("{} was found.", PacketProcessingService.class.getSimpleName());
 137                 this.arpSender = new ArpSender(packetProcessingService);
 138             } else {
 139                 LOG.error("Missing service {}", PacketProcessingService.class.getSimpleName());
 140                 this.arpSender = null;
 141             }
 142             flowService = providerContext.getRpcService(SalFlowService.class);
 143             refreshRequester.scheduleWithFixedDelay(new Runnable(){
 144
 145                 @Override
 146                 public void run() {
 147                     if (!gatewayToArpMetadataMap.isEmpty()){
 148                         for(final Entry<Ipv4Address, ArpResolverMetadata> gatewayToArpMetadataEntry : gatewayToArpMetadataMap.entrySet()){
 149                             final Ipv4Address gatewayIp = gatewayToArpMetadataEntry.getKey();
 150                             final ArpResolverMetadata gatewayMetaData = gatewayToArpMetadataEntry.getValue();
 151                             gatewayMacRefresherPool.schedule(new Runnable(){
 152
 153                                 @Override
 154                                 public void run() {
 155
 156                                     final Node externalNetworkBridge = getExternalBridge(gatewayMetaData.getExternalNetworkBridgeDpid());
 157                                     if(externalNetworkBridge == null){
 158                                         LOG.error("MAC address for gateway {} can not be resolved, because external bridge {} "
 159                                                 + "is not connected to controller.",gatewayIp.getValue(),gatewayMetaData.getExternalNetworkBridgeDpid() );
 160                                     }
 161
 162                                     LOG.debug("Refresh Gateway Mac for gateway {} using source ip {} and mac {} for ARP request",
 163                                             gatewayIp.getValue(),gatewayMetaData.getArpRequestSourceIp().getValue(),gatewayMetaData.getArpRequestMacAddress().getValue());
 164
 165                                     sendGatewayArpRequest(externalNetworkBridge,gatewayIp,gatewayMetaData.getArpRequestSourceIp(), gatewayMetaData.getArpRequestMacAddress());
 166                                 }
 167                             }, 1, TimeUnit.SECONDS);
 168                         }
 169                     }
 170                 }
 171             }, REFRESH_INTERVAL, REFRESH_INTERVAL, TimeUnit.SECONDS);
 172         }
 173     }
 174     /**
 175      * Method do following actions:
 176      * 1. Install flow to direct ARP response packet to controller
 177      * 2. Send ARP request packet out on all port of the given External network bridge.
 178      * 3. Cache the flow that need to be removed once ARP resolution is done.
 179      * 4. Return listenable future so that user can add callback to get the MacAddress
 180      * @param externalNetworkBridgeDpid Broadcast ARP request packet on this bridge
 181      * @param gatewayIp IP address for which MAC need to be resolved
 182      * @param sourceIpAddress Source Ip address for the ARP request packet
 183      * @param sourceMacAddress Source Mac address for the ARP request packet
 184      * @param periodicRefresh Enable/Disable periodic refresh of the Gateway Mac address
 185      * NOTE:Periodic refresh is not supported yet.
 186      * @param gatewayIp  Resolve MAC address of this Gateway Ip
 187      * @return Future object
 188      */
 189     @Override
 190     public ListenableFuture<MacAddress> resolveMacAddress( final Long externalNetworkBridgeDpid, final Ipv4Address gatewayIp,
 191             final Ipv4Address sourceIpAddress, final MacAddress sourceMacAddress, final Boolean periodicRefresh){
 192         Preconditions.checkNotNull(sourceIpAddress);
 193         Preconditions.checkNotNull(sourceMacAddress);
 194         Preconditions.checkNotNull(gatewayIp);
 195
 196         LOG.info("Trigger Mac resolution for gateway {}, using source ip {} and mac {}",
 197                 gatewayIp.getValue(),sourceIpAddress.getValue(),sourceMacAddress.getValue());
 198
 199         init();
 200         if(gatewayToArpMetadataMap.containsKey(gatewayIp)){
 201             if(gatewayToArpMetadataMap.get(gatewayIp).getGatewayMacAddress() != null){
 202                 return arpWatcherWall.submit(new Callable<MacAddress>(){
 203
 204                     @Override
 205                     public MacAddress call() throws Exception {
 206                         return gatewayToArpMetadataMap.get(gatewayIp).getGatewayMacAddress();
 207                     }
 208                 });
 209             }
 210         }else{
 211             gatewayToArpMetadataMap.put(gatewayIp,new ArpResolverMetadata(
 212                     externalNetworkBridgeDpid, gatewayIp,sourceIpAddress,sourceMacAddress,periodicRefresh));
 213         }
 214
 215
 216         final Node externalNetworkBridge = getExternalBridge(externalNetworkBridgeDpid);
 217         if(externalNetworkBridge == null){
 218             LOG.error("MAC address for gateway {} can not be resolved, because external bridge {} "
 219                     + "is not connected to controller.",gatewayIp.getValue(),externalNetworkBridgeDpid );
 220             return null;
 221         }
 222
 223         sendGatewayArpRequest(externalNetworkBridge,gatewayIp,sourceIpAddress, sourceMacAddress);
 224
 225         //Wait for MacAddress population in cache
 226         return waitForMacAddress(gatewayIp);
 227     }
 228
 229     private Node getExternalBridge(final Long externalNetworkBridgeDpid){
 230         final String nodeName = OPENFLOW + externalNetworkBridgeDpid;
 231
 232         return getOpenFlowNode(nodeName);
 233     }
 234
 235     private void sendGatewayArpRequest(final Node externalNetworkBridge,final Ipv4Address gatewayIp,
 236             final Ipv4Address sourceIpAddress, final MacAddress sourceMacAddress){
 237         final ArpMessageAddress senderAddress = new ArpMessageAddress(sourceMacAddress,sourceIpAddress);
 238
 239         //Build arp reply router flow
 240         final Flow arpReplyToControllerFlow = createArpReplyToControllerFlow(senderAddress, gatewayIp);
 241
 242         final InstanceIdentifier<Node> nodeIid = InstanceIdentifier.builder(Nodes.class)
 243                 .child(Node.class, externalNetworkBridge.getKey())
 244                 .build();
 245         final InstanceIdentifier<Flow> flowIid = createFlowIid(arpReplyToControllerFlow, nodeIid);
 246         final NodeRef nodeRef = new NodeRef(nodeIid);
 247
 248         //Install flow
 249         Future<RpcResult<AddFlowOutput>> addFlowResult = flowService.addFlow(new AddFlowInputBuilder(
 250                 arpReplyToControllerFlow).setFlowRef(new FlowRef(flowIid)).setNode(nodeRef).build());
 251         //wait for flow installation
 252         Futures.addCallback(JdkFutureAdapters.listenInPoolThread(addFlowResult),
 253                 new FutureCallback<RpcResult<AddFlowOutput>>() {
 254
 255             @Override
 256             public void onSuccess(RpcResult<AddFlowOutput> result) {
 257                 if (!result.isSuccessful()) {
 258                     LOG.warn("Flow to route ARP Reply to Controller is not installed successfully : {} \nErrors: {}", flowIid,result.getErrors());
 259                     return;
 260                 }
 261                 LOG.debug("Flow to route ARP Reply to Controller installed successfully : {}", flowIid);
 262
 263                 //cache metadata
 264                 gatewayToArpMetadataMap.get(gatewayIp).setFlowToRemove(
 265                         new RemoveFlowInputBuilder(arpReplyToControllerFlow).setNode(nodeRef).build());
 266
 267                 //Broadcast ARP request packets
 268                 for (NodeConnector egressNc : externalNetworkBridge.getNodeConnector()) {
 269                     KeyedInstanceIdentifier<NodeConnector, NodeConnectorKey> egressNcIid = nodeIid.child(
 270                             NodeConnector.class, new NodeConnectorKey(egressNc.getId()));
 271                     ListenableFuture<RpcResult<Void>> futureSendArpResult = arpSender.sendArp(
 272                             senderAddress, gatewayIp, egressNcIid);
 273                     Futures.addCallback(futureSendArpResult, logResult(gatewayIp, egressNcIid));
 274                 }
 275             }
 276
 277             @Override
 278             public void onFailure(Throwable t) {
 279                 LOG.warn("ARP Reply to Controller flow was not created: {}", flowIid, t);
 280             }
 281             }
 282         );
 283     }
 284
 285     private ListenableFuture<MacAddress> waitForMacAddress(final Ipv4Address gatewayIp){
 286
 287         return arpWatcherWall.submit(new Callable<MacAddress>(){
 288
 289             @Override
 290             public MacAddress call() throws Exception {
 291                 for(int cycle = 0;cycle < WAIT_CYCLES;cycle++){
 292                     //Sleep before checking mac address, so meanwhile ARP request packets
 293                     // will be broadcasted on the bridge.
 294                     Thread.sleep(PER_CYCLE_WAIT_DURATION);
 295                     ArpResolverMetadata arpResolverMetadata = gatewayToArpMetadataMap.get(gatewayIp);
 296                     if(arpResolverMetadata != null && arpResolverMetadata.getGatewayMacAddress() != null){
 297                         if(!arpResolverMetadata.isPeriodicRefresh()){
 298                             return gatewayToArpMetadataMap.remove(gatewayIp).getGatewayMacAddress();
 299                         }
 300                         return arpResolverMetadata.getGatewayMacAddress();
 301                     }
 302                 }
 303                 return null;
 304             }
 305         });
 306     }
 307
 308     private static @Nullable Ipv4Address getIPv4Addresses(IpAddress ipAddress) {
 309         if (ipAddress.getIpv4Address() == null) {
 310             return null;
 311         }
 312         return ipAddress.getIpv4Address();
 313     }
 314
 315     private Flow createArpReplyToControllerFlow(final ArpMessageAddress senderAddress, final Ipv4Address ipForRequestedMac) {
 316         checkNotNull(senderAddress);
 317         checkNotNull(ipForRequestedMac);
 318         FlowBuilder arpFlow = new FlowBuilder().setTableId(TABEL_FOR_ARP_FLOW)
 319             .setFlowName(ARP_REPLY_TO_CONTROLLER_FLOW_NAME)
 320             .setPriority(ARP_REPLY_TO_CONTROLLER_FLOW_PRIORITY)
 321             .setBufferId(OFConstants.OFP_NO_BUFFER)
 322             .setIdleTimeout(0)
 323             .setHardTimeout(0)
 324             .setCookie(new FlowCookie(BigInteger.valueOf(flowCookie.incrementAndGet())))
 325             .setFlags(new FlowModFlags(false, false, false, false, false));
 326
 327         EthernetMatch ethernetMatch = ArpFlowFactory.createEthernetMatch(senderAddress.getHardwareAddress());
 328         ArpMatch arpMatch = ArpFlowFactory.createArpMatch(senderAddress, ipForRequestedMac);
 329         Match match = new MatchBuilder().setEthernetMatch(ethernetMatch).setLayer3Match(arpMatch).build();
 330         arpFlow.setMatch(match);
 331         arpFlow.setInstructions(new InstructionsBuilder().setInstruction(
 332                 ImmutableList.of(SEND_TO_CONTROLLER_INSTRUCTION)).build());
 333         arpFlow.setId(createFlowId(senderAddress, ipForRequestedMac));
 334         return arpFlow.build();
 335     }
 336
 337     private FlowId createFlowId(ArpMessageAddress senderAddress, Ipv4Address ipForRequestedMac) {
 338         String flowId = ARP_REPLY_TO_CONTROLLER_FLOW_NAME + "|" + ipForRequestedMac.getValue();
 339         return new FlowId(flowId);
 340     }
 341
 342     private static InstanceIdentifier<Flow> createFlowIid(Flow flow, InstanceIdentifier<Node> nodeIid) {
 343         return nodeIid.builder()
 344             .augmentation(FlowCapableNode.class)
 345             .child(Table.class, new TableKey(flow.getTableId()))
 346             .child(Flow.class, new FlowKey(flow.getId()))
 347             .build();
 348     }
 349
 350     private FutureCallback<RpcResult<Void>> logResult(final Ipv4Address tpa,
 351             final KeyedInstanceIdentifier<NodeConnector, NodeConnectorKey> egressNcIid) {
 352         return new FutureCallback<RpcResult<Void>>() {
 353
 354             @Override
 355             public void onSuccess(RpcResult<Void> result) {
 356                 LOG.debug("ARP Request for IP {} was sent from {}.", tpa.getValue(), egressNcIid);
 357             }
 358
 359             @Override
 360             public void onFailure(Throwable t) {
 361                 LOG.warn("ARP Request for IP {} was NOT sent from {}.", tpa.getValue(), egressNcIid);
 362             }
 363         };
 364     }
 365
 366     @Override
 367     public void onPacketReceived(PacketReceived potentialArp) {
 368         Arp arp = ArpResolverUtils.getArpFrom(potentialArp);
 369         if(arp != null){
 370             if (arp.getOperation() != ArpOperation.REPLY.intValue()) {
 371                 LOG.trace("Packet is not ARP REPLY packet.");
 372                 return;
 373             }
 374             if (LOG.isTraceEnabled()) {
 375                 LOG.trace("ARP REPLY received - {}", ArpUtils.getArpToStringFormat(arp));
 376             }
 377             NodeKey nodeKey = potentialArp.getIngress().getValue().firstKeyOf(Node.class, NodeKey.class);
 378             if (nodeKey == null) {
 379                 LOG.info("Unknown source node of ARP packet: {}", potentialArp);
 380                 return;
 381             }
 382             Ipv4Address gatewayIpAddress = ArpUtils.bytesToIp(arp.getSenderProtocolAddress());
 383             MacAddress gatewayMacAddress = ArpUtils.bytesToMac(arp.getSenderHardwareAddress());
 384             ArpResolverMetadata candidateGatewayIp = gatewayToArpMetadataMap.get(gatewayIpAddress);
 385             if(candidateGatewayIp != null){
 386                 LOG.debug("Resolved MAC for Gateway Ip {} is {}",gatewayIpAddress.getValue(),gatewayMacAddress.getValue());
 387                 candidateGatewayIp.setGatewayMacAddress(gatewayMacAddress);
 388                 flowService.removeFlow(candidateGatewayIp.getFlowToRemove());
 389             }
 390         }
 391     }
 392
 393     @Override
 394     public void setDependencies(BundleContext bundleContext,
 395             ServiceReference serviceReference) {
 396         super.setDependencies(bundleContext.getServiceReference(GatewayMacResolver.class.getName()), this);
 397
 398     }
 399
 400     @Override
 401     public void setDependencies(Object impl) {}
 402
 403     @Override
 404     public void stopPeriodicRefresh(Ipv4Address gatewayIp) {
 405         init();
 406         gatewayToArpMetadataMap.remove(gatewayIp);
 407     }
 408
 409 }