diff --git a/src/main/java/org/opencord/cordvtn/impl/AbstractInstanceHandler.java b/src/main/java/org/opencord/cordvtn/impl/AbstractInstanceHandler.java
new file mode 100644
index 0000000..29868b4
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+++ b/src/main/java/org/opencord/cordvtn/impl/AbstractInstanceHandler.java
@@ -0,0 +1,202 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.opencord.cordvtn.impl;
+
+import org.onlab.osgi.DefaultServiceDirectory;
+import org.onlab.osgi.ServiceDirectory;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.net.Host;
+import org.onosproject.net.config.NetworkConfigEvent;
+import org.onosproject.net.config.NetworkConfigListener;
+import org.onosproject.net.config.NetworkConfigRegistry;
+import org.onosproject.net.host.HostEvent;
+import org.onosproject.net.host.HostListener;
+import org.onosproject.net.host.HostService;
+import org.onosproject.xosclient.api.OpenStackAccess;
+import org.onosproject.xosclient.api.VtnPort;
+import org.onosproject.xosclient.api.VtnPortApi;
+import org.onosproject.xosclient.api.VtnPortId;
+import org.onosproject.xosclient.api.VtnService;
+import org.onosproject.xosclient.api.VtnServiceApi;
+import org.onosproject.xosclient.api.VtnServiceApi.ServiceType;
+import org.onosproject.xosclient.api.VtnServiceId;
+import org.onosproject.xosclient.api.XosAccess;
+import org.onosproject.xosclient.api.XosClientService;
+import org.opencord.cordvtn.api.CordVtnConfig;
+import org.opencord.cordvtn.api.CordVtnService;
+import org.opencord.cordvtn.api.Instance;
+import org.opencord.cordvtn.api.InstanceHandler;
+import org.slf4j.Logger;
+
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Provides default virtual network connectivity for service instances.
+ */
+public abstract class AbstractInstanceHandler implements InstanceHandler {
+
+    protected final Logger log = getLogger(getClass());
+
+    protected CoreService coreService;
+    protected MastershipService mastershipService;
+    protected NetworkConfigRegistry configRegistry;
+    protected HostService hostService;
+    protected XosClientService xosClient;
+    protected CordVtnPipeline pipeline;
+    protected CordVtnNodeManager nodeManager;
+
+    protected ApplicationId appId;
+    protected ExecutorService eventExecutor;
+    protected Optional<ServiceType> serviceType = Optional.empty();
+    protected NetworkConfigListener configListener = new InternalConfigListener();
+    protected HostListener hostListener = new InternalHostListener();
+
+    private static final String OPENSTACK_ACCESS_ERROR = "OpenStack access is not configured";
+    private static final String XOS_ACCESS_ERROR = "XOS access is not configured";
+    private XosAccess xosAccess = null;
+    private OpenStackAccess osAccess = null;
+
+    protected void activate() {
+        ServiceDirectory services = new DefaultServiceDirectory();
+        coreService = services.get(CoreService.class);
+        configRegistry = services.get(NetworkConfigRegistry.class);
+        mastershipService = services.get(MastershipService.class);
+        hostService = services.get(HostService.class);
+        xosClient = services.get(XosClientService.class);
+        pipeline = services.get(CordVtnPipeline.class);
+        nodeManager = services.get(CordVtnNodeManager.class);
+
+        appId = coreService.registerApplication(CordVtnService.CORDVTN_APP_ID);
+        hostService.addListener(hostListener);
+        configRegistry.addListener(configListener);
+
+        log.info("Started");
+    }
+
+    protected void deactivate() {
+        hostService.removeListener(hostListener);
+        configRegistry.removeListener(configListener);
+        eventExecutor.shutdown();
+
+        log.info("Stopped");
+    }
+
+    protected VtnService getVtnService(VtnServiceId serviceId) {
+        checkNotNull(osAccess, OPENSTACK_ACCESS_ERROR);
+        checkNotNull(xosAccess, XOS_ACCESS_ERROR);
+
+        // TODO remove openstack access when XOS provides all information
+        VtnServiceApi serviceApi = xosClient.getClient(xosAccess).vtnService();
+        VtnService service = serviceApi.service(serviceId, osAccess);
+        if (service == null) {
+            log.warn("Failed to get VtnService for {}", serviceId);
+        }
+        return service;
+    }
+
+    protected VtnPort getVtnPort(Instance instance) {
+        checkNotNull(osAccess, OPENSTACK_ACCESS_ERROR);
+        checkNotNull(xosAccess, XOS_ACCESS_ERROR);
+
+        VtnPortId vtnPortId = instance.portId();
+        VtnPortApi portApi = xosClient.getClient(xosAccess).vtnPort();
+        VtnPort vtnPort = portApi.vtnPort(vtnPortId, osAccess);
+        if (vtnPort == null) {
+            log.warn("Failed to get port information of {}", instance);
+            return null;
+        }
+        return vtnPort;
+    }
+
+    protected Set<Instance> getInstances(VtnServiceId serviceId) {
+        return StreamSupport.stream(hostService.getHosts().spliterator(), false)
+                .filter(host -> Objects.equals(
+                        serviceId.id(),
+                        host.annotations().value(Instance.SERVICE_ID)))
+                .map(Instance::of)
+                .collect(Collectors.toSet());
+    }
+
+    protected void readConfiguration() {
+        CordVtnConfig config = configRegistry.getConfig(appId, CordVtnConfig.class);
+        if (config == null) {
+            log.debug("No configuration found");
+            return;
+        }
+        osAccess = config.openstackAccess();
+        xosAccess = config.xosAccess();
+    }
+
+    private class InternalHostListener implements HostListener {
+
+        @Override
+        public void event(HostEvent event) {
+            Host host = event.subject();
+            if (!mastershipService.isLocalMaster(host.location().deviceId())) {
+                // do not allow to proceed without mastership
+                return;
+            }
+
+            Instance instance = Instance.of(host);
+            if (serviceType.isPresent() &&
+                    !serviceType.get().equals(instance.serviceType())) {
+                // not my service instance, do nothing
+                return;
+            }
+
+            switch (event.type()) {
+                case HOST_UPDATED:
+                case HOST_ADDED:
+                    eventExecutor.execute(() -> instanceDetected(instance));
+                    break;
+                case HOST_REMOVED:
+                    eventExecutor.execute(() -> instanceRemoved(instance));
+                    break;
+                default:
+                    break;
+            }
+        }
+    }
+
+    private class InternalConfigListener implements NetworkConfigListener {
+
+        @Override
+        public void event(NetworkConfigEvent event) {
+            if (!event.configClass().equals(CordVtnConfig.class)) {
+                return;
+            }
+
+            switch (event.type()) {
+                case CONFIG_ADDED:
+                case CONFIG_UPDATED:
+                    readConfiguration();
+                    break;
+                default:
+                    break;
+            }
+        }
+    }
+}