diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/PtToPtIntentVirtualNetworkProviderTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/PtToPtIntentVirtualNetworkProviderTest.java
index 15dcaf8..dd965f8 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/PtToPtIntentVirtualNetworkProviderTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/PtToPtIntentVirtualNetworkProviderTest.java
@@ -220,6 +220,11 @@
         }
 
         @Override
+        public void topologyChanged(Set<Set<ConnectPoint>> clusters) {
+
+        }
+
+        @Override
         public void tunnelUp(NetworkId networkId, ConnectPoint src, ConnectPoint dst, TunnelId tunnelId) {
             // Release one permit on the created semaphore since the tunnelUp method was called.
             created.release();
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java
index ee5a5dd..82c7044 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java
@@ -31,6 +31,7 @@
 import org.onosproject.incubator.net.virtual.VirtualNetwork;
 import org.onosproject.incubator.store.virtual.impl.DistributedVirtualNetworkStore;
 import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DefaultPort;
 import org.onosproject.net.Link;
 import org.onosproject.net.NetTestTools;
 import org.onosproject.net.PortNumber;
@@ -97,7 +98,13 @@
         VirtualDevice dstVirtualDevice =
                 manager.createVirtualDevice(virtualNetwork.id(), DID2);
         ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
+        manager.createVirtualPort(virtualNetwork.id(), src.deviceId(), src.port(),
+                                  new DefaultPort(srcVirtualDevice, src.port(), true));
+
         ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
+        manager.createVirtualPort(virtualNetwork.id(), dst.deviceId(), dst.port(),
+                                  new DefaultPort(dstVirtualDevice, dst.port(), true));
+
         VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), src, dst);
         VirtualLink link2 = manager.createVirtualLink(virtualNetwork.id(), dst, src);
 
@@ -107,12 +114,12 @@
         Iterator<Link> it = linkService.getLinks().iterator();
         assertEquals("The link set size did not match.", 2, Iterators.size(it));
 
-        // test the getActiveLinks() method where all links are ACTIVE
+        // test the getActiveLinks() method where all links are INACTIVE
         Iterator<Link> it2 = linkService.getActiveLinks().iterator();
-        assertEquals("The link set size did not match.", 2, Iterators.size(it2));
+        assertEquals("The link set size did not match.", 0, Iterators.size(it2));
 
         // test the getActiveLinks() method where one link is ACTIVE
-        virtualNetworkManagerStore.updateLink(link1, link1.tunnelId(), Link.State.INACTIVE);
+        virtualNetworkManagerStore.updateLink(link1, link1.tunnelId(), Link.State.ACTIVE);
         Iterator<Link> it3 = linkService.getActiveLinks().iterator();
         assertEquals("The link set size did not match.", 1, Iterators.size(it3));
 
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkManagerTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkManagerTest.java
index 2834881..644ba0c 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkManagerTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkManagerTest.java
@@ -38,12 +38,13 @@
 import org.onosproject.incubator.net.virtual.VirtualNetworkEvent;
 import org.onosproject.incubator.net.virtual.VirtualNetworkIntent;
 import org.onosproject.incubator.net.virtual.VirtualNetworkListener;
-import org.onosproject.incubator.net.virtual.VirtualNetworkService;
+import org.onosproject.incubator.net.virtual.VirtualNetworkProviderService;
 import org.onosproject.incubator.net.virtual.VirtualPort;
 import org.onosproject.incubator.store.virtual.impl.DistributedVirtualNetworkStore;
 import org.onosproject.net.ConnectPoint;
 import org.onosproject.net.DefaultPort;
 import org.onosproject.net.DeviceId;
+import org.onosproject.net.Link;
 import org.onosproject.net.NetTestTools;
 import org.onosproject.net.Port;
 import org.onosproject.net.PortNumber;
@@ -54,8 +55,11 @@
 import org.onosproject.net.intent.Key;
 import org.onosproject.net.intent.MockIdGenerator;
 import org.onosproject.net.intent.TestableIntentService;
+import org.onosproject.net.topology.Topology;
+import org.onosproject.net.topology.TopologyService;
 import org.onosproject.store.service.TestStorageService;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Set;
@@ -72,13 +76,17 @@
     private final String tenantIdValue2 = "TENANT_ID2";
 
     private VirtualNetworkManager manager;
-    private VirtualNetworkService virtualNetworkManagerService;
+    private VirtualNetworkTopologyProvider topologyProvider;
     private DistributedVirtualNetworkStore virtualNetworkManagerStore;
     private CoreService coreService;
     private TestListener listener = new TestListener();
     private TestableIntentService intentService = new FakeIntentManager();
+    private TopologyService topologyService;
     private IdGenerator idGenerator = new MockIdGenerator();
 
+    private ConnectPoint cp6;
+    private ConnectPoint cp7;
+
     @Before
     public void setUp() throws Exception {
         virtualNetworkManagerStore = new DistributedVirtualNetworkStore();
@@ -96,7 +104,6 @@
         manager.intentService = intentService;
         NetTestTools.injectEventDispatcher(manager, new TestEventDispatcher());
         manager.activate();
-        virtualNetworkManagerService = manager;
     }
 
     @After
@@ -313,7 +320,13 @@
         VirtualDevice dstVirtualDevice =
                 manager.createVirtualDevice(virtualNetwork1.id(), DID2);
         ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
+        manager.createVirtualPort(virtualNetwork1.id(), src.deviceId(), src.port(),
+                                  new DefaultPort(srcVirtualDevice, src.port(), true));
+
         ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
+        manager.createVirtualPort(virtualNetwork1.id(), dst.deviceId(), dst.port(),
+                                  new DefaultPort(dstVirtualDevice, dst.port(), true));
+
         manager.createVirtualLink(virtualNetwork1.id(), src, dst);
         manager.createVirtualLink(virtualNetwork1.id(), dst, src);
 
@@ -348,7 +361,13 @@
         VirtualDevice dstVirtualDevice =
                 manager.createVirtualDevice(virtualNetwork1.id(), DID2);
         ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
+        manager.createVirtualPort(virtualNetwork1.id(), src.deviceId(), src.port(),
+                                  new DefaultPort(srcVirtualDevice, src.port(), true));
+
         ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
+        manager.createVirtualPort(virtualNetwork1.id(), dst.deviceId(), dst.port(),
+                                  new DefaultPort(dstVirtualDevice, dst.port(), true));
+
         manager.createVirtualLink(virtualNetwork1.id(), src, dst);
         manager.createVirtualLink(virtualNetwork1.id(), src, dst);
     }
@@ -479,6 +498,126 @@
         assertTrue("The tunnels should be empty.", manager.store.getTunnelIds(virtualIntent).isEmpty());
     }
 
+
+    /**
+     * Method to create the virtual network for further testing.
+     **/
+    private VirtualNetwork setupVirtualNetworkTopology() {
+        manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
+        VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
+
+        VirtualDevice virtualDevice1 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice virtualDevice2 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID2);
+        VirtualDevice virtualDevice3 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID3);
+        VirtualDevice virtualDevice4 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID4);
+        VirtualDevice virtualDevice5 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID5);
+
+        ConnectPoint cp1 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(1));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice1.id(),
+                                  PortNumber.portNumber(1),
+                                  new DefaultPort(virtualDevice1, PortNumber.portNumber(1), true));
+
+        ConnectPoint cp2 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(2));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice1.id(),
+                                  PortNumber.portNumber(2),
+                                  new DefaultPort(virtualDevice1, PortNumber.portNumber(2), true));
+
+        ConnectPoint cp3 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(3));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice2.id(),
+                                  PortNumber.portNumber(3),
+                                  new DefaultPort(virtualDevice2, PortNumber.portNumber(3), true));
+
+        ConnectPoint cp4 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(4));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice2.id(),
+                                  PortNumber.portNumber(4),
+                                  new DefaultPort(virtualDevice2, PortNumber.portNumber(4), true));
+
+        ConnectPoint cp5 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(5));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice3.id(),
+                                  PortNumber.portNumber(5),
+                                  new DefaultPort(virtualDevice3, PortNumber.portNumber(5), true));
+
+        cp6 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(6));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice3.id(),
+                                  PortNumber.portNumber(6),
+                                  new DefaultPort(virtualDevice3, PortNumber.portNumber(6), true));
+
+        cp7 = new ConnectPoint(virtualDevice4.id(), PortNumber.portNumber(7));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice4.id(),
+                                  PortNumber.portNumber(7),
+                                  new DefaultPort(virtualDevice4, PortNumber.portNumber(7), true));
+
+        ConnectPoint cp8 = new ConnectPoint(virtualDevice4.id(), PortNumber.portNumber(8));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice4.id(),
+                                  PortNumber.portNumber(8),
+                                  new DefaultPort(virtualDevice4, PortNumber.portNumber(8), true));
+
+        ConnectPoint cp9 = new ConnectPoint(virtualDevice5.id(), PortNumber.portNumber(9));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice5.id(),
+                                  PortNumber.portNumber(9),
+                                  new DefaultPort(virtualDevice5, PortNumber.portNumber(9), true));
+
+        VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), cp1, cp3);
+        virtualNetworkManagerStore.updateLink(link1, link1.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link2 = manager.createVirtualLink(virtualNetwork.id(), cp3, cp1);
+        virtualNetworkManagerStore.updateLink(link2, link2.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link3 = manager.createVirtualLink(virtualNetwork.id(), cp4, cp5);
+        virtualNetworkManagerStore.updateLink(link3, link3.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link4 = manager.createVirtualLink(virtualNetwork.id(), cp5, cp4);
+        virtualNetworkManagerStore.updateLink(link4, link4.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link5 = manager.createVirtualLink(virtualNetwork.id(), cp8, cp9);
+        virtualNetworkManagerStore.updateLink(link5, link5.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link6 = manager.createVirtualLink(virtualNetwork.id(), cp9, cp8);
+        virtualNetworkManagerStore.updateLink(link6, link6.tunnelId(), Link.State.ACTIVE);
+
+        topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        topologyProvider = new VirtualNetworkTopologyProvider();
+        topologyProvider.topologyService = topologyService;
+
+        return virtualNetwork;
+    }
+
+    /**
+     * Test the topologyChanged() method.
+     */
+    @Test
+    public void testTopologyChanged() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+        VirtualNetworkProviderService providerService = manager.createProviderService(topologyProvider);
+
+        // Initial setup is two clusters of devices/links.
+        assertEquals("The cluster count did not match.", 2, topologyService.currentTopology().clusterCount());
+
+        // Adding this link will join the two clusters together.
+        List<Event> reasons = new ArrayList<>();
+        VirtualLink link = manager.createVirtualLink(virtualNetwork.id(), cp6, cp7);
+        virtualNetworkManagerStore.updateLink(link, link.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link2 = manager.createVirtualLink(virtualNetwork.id(), cp7, cp6);
+        virtualNetworkManagerStore.updateLink(link2, link2.tunnelId(), Link.State.ACTIVE);
+
+        Topology topology = topologyService.currentTopology();
+        providerService.topologyChanged(topologyProvider.getConnectPoints(topology));
+
+        // Validate that all links are still active.
+        manager.getVirtualLinks(virtualNetwork.id()).forEach(virtualLink -> {
+            assertTrue("The virtual link should be active.", virtualLink.state().equals(Link.State.ACTIVE));
+        });
+
+        virtualNetworkManagerStore.updateLink(link, link.tunnelId(), Link.State.INACTIVE);
+        virtualNetworkManagerStore.updateLink(link2, link2.tunnelId(), Link.State.INACTIVE);
+        providerService.topologyChanged(topologyProvider.getConnectPoints(topology));
+
+        // Validate that all links are active again.
+        manager.getVirtualLinks(virtualNetwork.id()).forEach(virtualLink -> {
+            assertTrue("The virtual link should be active.", virtualLink.state().equals(Link.State.ACTIVE));
+        });
+    }
+
     /**
      * Method to validate that the actual versus expected virtual network events were
      * received correctly.
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyProviderTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyProviderTest.java
new file mode 100644
index 0000000..6f53387
--- /dev/null
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyProviderTest.java
@@ -0,0 +1,388 @@
+/*
+ * 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.onosproject.incubator.net.virtual.impl;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.junit.TestUtils;
+import org.onosproject.common.event.impl.TestEventDispatcher;
+import org.onosproject.core.CoreService;
+import org.onosproject.core.CoreServiceAdapter;
+import org.onosproject.core.IdGenerator;
+import org.onosproject.event.Event;
+import org.onosproject.incubator.net.tunnel.TunnelId;
+import org.onosproject.incubator.net.virtual.NetworkId;
+import org.onosproject.incubator.net.virtual.TenantId;
+import org.onosproject.incubator.net.virtual.VirtualDevice;
+import org.onosproject.incubator.net.virtual.VirtualLink;
+import org.onosproject.incubator.net.virtual.VirtualNetwork;
+import org.onosproject.incubator.net.virtual.VirtualNetworkProvider;
+import org.onosproject.incubator.net.virtual.VirtualNetworkProviderRegistry;
+import org.onosproject.incubator.net.virtual.VirtualNetworkProviderService;
+import org.onosproject.incubator.store.virtual.impl.DistributedVirtualNetworkStore;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DefaultPort;
+import org.onosproject.net.Link;
+import org.onosproject.net.NetTestTools;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.TestDeviceParams;
+import org.onosproject.net.intent.FakeIntentManager;
+import org.onosproject.net.intent.TestableIntentService;
+import org.onosproject.net.link.LinkEvent;
+import org.onosproject.net.provider.AbstractProviderService;
+import org.onosproject.net.provider.ProviderId;
+import org.onosproject.net.topology.TopologyEvent;
+import org.onosproject.net.topology.TopologyService;
+import org.onosproject.store.service.TestStorageService;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static org.junit.Assert.*;
+
+/**
+ * Junit tests for VirtualNetworkTopologyProvider.
+ */
+public class VirtualNetworkTopologyProviderTest extends TestDeviceParams {
+
+    private final String tenantIdValue1 = "TENANT_ID1";
+
+    private VirtualNetwork virtualNetwork;
+    private VirtualDevice virtualDevice1;
+    private VirtualDevice virtualDevice2;
+    private VirtualDevice virtualDevice3;
+    private VirtualDevice virtualDevice4;
+    private VirtualDevice virtualDevice5;
+    private ConnectPoint cp1;
+    private ConnectPoint cp2;
+    private ConnectPoint cp3;
+    private ConnectPoint cp4;
+    private ConnectPoint cp5;
+    private ConnectPoint cp6;
+    private ConnectPoint cp7;
+    private ConnectPoint cp8;
+    private ConnectPoint cp9;
+
+    private VirtualNetworkManager manager;
+    private DistributedVirtualNetworkStore virtualNetworkManagerStore;
+    private CoreService coreService;
+    private VirtualNetworkTopologyProvider topologyProvider;
+    private TopologyService topologyService;
+    private TestableIntentService intentService = new FakeIntentManager();
+    private final VirtualNetworkRegistryAdapter virtualNetworkRegistry = new VirtualNetworkRegistryAdapter();
+
+    private static final int MAX_WAIT_TIME = 5;
+    private static final int MAX_PERMITS = 1;
+    private static Semaphore changed;
+
+    private Set<Set<ConnectPoint>> clusters;
+
+    @Before
+    public void setUp() throws Exception {
+
+        virtualNetworkManagerStore = new DistributedVirtualNetworkStore();
+
+        coreService = new VirtualNetworkTopologyProviderTest.TestCoreService();
+
+        virtualNetworkManagerStore.setCoreService(coreService);
+        TestUtils.setField(coreService, "coreService", new VirtualNetworkTopologyProviderTest.TestCoreService());
+        TestUtils.setField(virtualNetworkManagerStore, "storageService", new TestStorageService());
+        virtualNetworkManagerStore.activate();
+
+        manager = new VirtualNetworkManager();
+        manager.store = virtualNetworkManagerStore;
+        manager.intentService = intentService;
+        NetTestTools.injectEventDispatcher(manager, new TestEventDispatcher());
+        manager.activate();
+
+        manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
+        virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
+
+        topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        topologyProvider = new VirtualNetworkTopologyProvider();
+        topologyProvider.topologyService = topologyService;
+        topologyProvider.providerRegistry = virtualNetworkRegistry;
+        topologyProvider.activate();
+
+        setupVirtualNetworkTopology();
+        changed = new Semaphore(0, true);
+    }
+
+    @After
+    public void tearDown() {
+        topologyProvider.deactivate();
+        virtualNetworkManagerStore.deactivate();
+        manager.deactivate();
+        NetTestTools.injectEventDispatcher(manager, null);
+    }
+
+    /**
+     * Method to create the virtual network for further testing.
+     **/
+    private void setupVirtualNetworkTopology() {
+        virtualDevice1 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        virtualDevice2 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID2);
+        virtualDevice3 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID3);
+        virtualDevice4 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID4);
+        virtualDevice5 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID5);
+
+        cp1 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(1));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice1.id(),
+                                  PortNumber.portNumber(1),
+                                  new DefaultPort(virtualDevice1, PortNumber.portNumber(1), true));
+
+        cp2 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(2));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice1.id(),
+                                  PortNumber.portNumber(2),
+                                  new DefaultPort(virtualDevice1, PortNumber.portNumber(2), true));
+
+        cp3 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(3));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice2.id(),
+                                  PortNumber.portNumber(3),
+                                  new DefaultPort(virtualDevice2, PortNumber.portNumber(3), true));
+
+        cp4 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(4));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice2.id(),
+                                  PortNumber.portNumber(4),
+                                  new DefaultPort(virtualDevice2, PortNumber.portNumber(4), true));
+
+        cp5 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(5));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice3.id(),
+                                  PortNumber.portNumber(5),
+                                  new DefaultPort(virtualDevice3, PortNumber.portNumber(5), true));
+
+        cp6 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(6));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice3.id(),
+                                  PortNumber.portNumber(6),
+                                  new DefaultPort(virtualDevice3, PortNumber.portNumber(6), true));
+
+        cp7 = new ConnectPoint(virtualDevice4.id(), PortNumber.portNumber(7));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice4.id(),
+                                  PortNumber.portNumber(7),
+                                  new DefaultPort(virtualDevice4, PortNumber.portNumber(7), true));
+
+        cp8 = new ConnectPoint(virtualDevice4.id(), PortNumber.portNumber(8));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice4.id(),
+                                  PortNumber.portNumber(8),
+                                  new DefaultPort(virtualDevice4, PortNumber.portNumber(8), true));
+
+        cp9 = new ConnectPoint(virtualDevice5.id(), PortNumber.portNumber(9));
+        manager.createVirtualPort(virtualNetwork.id(), virtualDevice5.id(),
+                                  PortNumber.portNumber(9),
+                                  new DefaultPort(virtualDevice5, PortNumber.portNumber(9), true));
+
+        VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), cp1, cp3);
+        virtualNetworkManagerStore.updateLink(link1, link1.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link2 = manager.createVirtualLink(virtualNetwork.id(), cp3, cp1);
+        virtualNetworkManagerStore.updateLink(link2, link2.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link3 = manager.createVirtualLink(virtualNetwork.id(), cp4, cp5);
+        virtualNetworkManagerStore.updateLink(link3, link3.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link4 = manager.createVirtualLink(virtualNetwork.id(), cp5, cp4);
+        virtualNetworkManagerStore.updateLink(link4, link4.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link5 = manager.createVirtualLink(virtualNetwork.id(), cp8, cp9);
+        virtualNetworkManagerStore.updateLink(link5, link5.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link6 = manager.createVirtualLink(virtualNetwork.id(), cp9, cp8);
+        virtualNetworkManagerStore.updateLink(link6, link6.tunnelId(), Link.State.ACTIVE);
+
+        clusters = null;
+    }
+
+    /**
+     * Test isTraversable() method using a null source connect point.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testIsTraversableNullSrc() {
+        // test the isTraversable() method with a null source connect point.
+        topologyProvider.isTraversable(null, cp3);
+    }
+
+    /**
+     * Test isTraversable() method using a null destination connect point.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testIsTraversableNullDst() {
+        // test the isTraversable() method with a null destination connect point.
+        topologyProvider.isTraversable(cp1, null);
+    }
+
+    /**
+     * Test isTraversable() method.
+     */
+    @Test
+    public void testIsTraversable() {
+        // test the isTraversable() method.
+        assertTrue("These two connect points should be traversable.",
+                   topologyProvider.isTraversable(new ConnectPoint(cp1.elementId(), cp1.port()),
+                                                  new ConnectPoint(cp3.elementId(), cp3.port())));
+        assertTrue("These two connect points should be traversable.",
+                   topologyProvider.isTraversable(new ConnectPoint(cp1.elementId(), cp1.port()),
+                                                  new ConnectPoint(cp5.elementId(), cp5.port())));
+        assertFalse("These two connect points should not be traversable.",
+                    topologyProvider.isTraversable(new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(1)),
+                                                   new ConnectPoint(virtualDevice4.id(), PortNumber.portNumber(6))));
+    }
+
+    /**
+     * Test the topologyChanged() method.
+     */
+    @Test
+    public void testTopologyChanged() {
+        // Initial setup is two clusters of devices/links.
+        assertEquals("The cluster count did not match.", 2, topologyService.currentTopology().clusterCount());
+
+        // Adding this link will join the two clusters together.
+        List<Event> reasons = new ArrayList<>();
+        VirtualLink link = manager.createVirtualLink(virtualNetwork.id(), cp6, cp7);
+        virtualNetworkManagerStore.updateLink(link, link.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link2 = manager.createVirtualLink(virtualNetwork.id(), cp7, cp6);
+        virtualNetworkManagerStore.updateLink(link2, link2.tunnelId(), Link.State.ACTIVE);
+
+        reasons.add(new LinkEvent(LinkEvent.Type.LINK_ADDED, link));
+        reasons.add(new LinkEvent(LinkEvent.Type.LINK_ADDED, link2));
+        TopologyEvent event = new TopologyEvent(
+                TopologyEvent.Type.TOPOLOGY_CHANGED,
+                topologyService.currentTopology(),
+                reasons);
+
+        topologyProvider.topologyListener.event(event);
+
+        // Wait for the topology changed event, and that the topologyChanged method was called.
+        try {
+            if (!changed.tryAcquire(MAX_PERMITS, MAX_WAIT_TIME, TimeUnit.SECONDS)) {
+                fail("Failed to wait for topology changed event.");
+            }
+        } catch (InterruptedException e) {
+            fail("Semaphore exception." + e.getMessage());
+        }
+
+        // Validate that the topology changed method received a single cluster of connect points.
+        // This means that the two previous clusters have now joined into a single cluster.
+        assertEquals("The cluster count did not match.", 1, this.clusters.size());
+        assertEquals("The cluster count did not match.", 1, topologyService.currentTopology().clusterCount());
+
+        // Now remove the virtual link to split it back into two clusters.
+        manager.removeVirtualLink(virtualNetwork.id(), link.src(), link.dst());
+        manager.removeVirtualLink(virtualNetwork.id(), link2.src(), link2.dst());
+        assertEquals("The cluster count did not match.", 2, topologyService.currentTopology().clusterCount());
+
+        reasons = new ArrayList<>();
+        reasons.add(new LinkEvent(LinkEvent.Type.LINK_REMOVED, link));
+        reasons.add(new LinkEvent(LinkEvent.Type.LINK_REMOVED, link2));
+        event = new TopologyEvent(
+                TopologyEvent.Type.TOPOLOGY_CHANGED,
+                topologyService.currentTopology(),
+                reasons);
+
+        topologyProvider.topologyListener.event(event);
+
+        // Wait for the topology changed event, and that the topologyChanged method was called.
+        try {
+            if (!changed.tryAcquire(MAX_PERMITS, MAX_WAIT_TIME, TimeUnit.SECONDS)) {
+                fail("Failed to wait for topology changed event.");
+            }
+        } catch (InterruptedException e) {
+            fail("Semaphore exception." + e.getMessage());
+        }
+
+        // Validate that the topology changed method received two clusters of connect points.
+        // This means that the single previous clusters has now split into two clusters.
+        assertEquals("The cluster count did not match.", 2, this.clusters.size());
+    }
+
+    /**
+     * Virtual network registry implementation for this test class.
+     */
+    private class VirtualNetworkRegistryAdapter implements VirtualNetworkProviderRegistry {
+        private VirtualNetworkProvider provider;
+
+        @Override
+        public VirtualNetworkProviderService register(VirtualNetworkProvider theProvider) {
+            this.provider = theProvider;
+            return new TestVirtualNetworkProviderService(theProvider);
+        }
+
+        @Override
+        public void unregister(VirtualNetworkProvider theProvider) {
+            this.provider = null;
+        }
+
+        @Override
+        public Set<ProviderId> getProviders() {
+            return null;
+        }
+    }
+
+
+    /**
+     * Virtual network provider service implementation for this test class.
+     */
+    private class TestVirtualNetworkProviderService
+            extends AbstractProviderService<VirtualNetworkProvider>
+            implements VirtualNetworkProviderService {
+
+        /**
+         * Constructor.
+         *
+         * @param provider virtual network test provider
+         */
+        protected TestVirtualNetworkProviderService(VirtualNetworkProvider provider) {
+            super(provider);
+        }
+
+        @Override
+        public void topologyChanged(Set<Set<ConnectPoint>> theClusters) {
+            clusters = theClusters;
+            changed.release();
+        }
+
+        @Override
+        public void tunnelUp(NetworkId networkId, ConnectPoint src, ConnectPoint dst, TunnelId tunnelId) {
+        }
+
+        @Override
+        public void tunnelDown(NetworkId networkId, ConnectPoint src, ConnectPoint dst, TunnelId tunnelId) {
+        }
+    }
+
+    /**
+     * Core service test class.
+     */
+    private class TestCoreService extends CoreServiceAdapter {
+
+        @Override
+        public IdGenerator getIdGenerator(String topic) {
+            return new IdGenerator() {
+                private AtomicLong counter = new AtomicLong(0);
+
+                @Override
+                public long getNewId() {
+                    return counter.getAndIncrement();
+                }
+            };
+        }
+    }
+}
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyServiceTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyServiceTest.java
index 802bc0f..267e012 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyServiceTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyServiceTest.java
@@ -31,6 +31,7 @@
 import org.onosproject.incubator.net.virtual.VirtualNetwork;
 import org.onosproject.incubator.store.virtual.impl.DistributedVirtualNetworkStore;
 import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DefaultPort;
 import org.onosproject.net.DeviceId;
 import org.onosproject.net.DisjointPath;
 import org.onosproject.net.Link;
@@ -108,11 +109,29 @@
                 manager.createVirtualDevice(virtualNetwork.id(), DID4);
 
         ConnectPoint cp1 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(1));
+        manager.createVirtualPort(virtualNetwork.id(), cp1.deviceId(), cp1.port(),
+                                  new DefaultPort(virtualDevice1, cp1.port(), true));
+
         ConnectPoint cp2 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(2));
+        manager.createVirtualPort(virtualNetwork.id(), cp2.deviceId(), cp2.port(),
+                                  new DefaultPort(virtualDevice1, cp2.port(), true));
+
         ConnectPoint cp3 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(3));
+        manager.createVirtualPort(virtualNetwork.id(), cp3.deviceId(), cp3.port(),
+                                  new DefaultPort(virtualDevice2, cp3.port(), true));
+
         ConnectPoint cp4 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(4));
+        manager.createVirtualPort(virtualNetwork.id(), cp4.deviceId(), cp4.port(),
+                                  new DefaultPort(virtualDevice2, cp4.port(), true));
+
         ConnectPoint cp5 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(5));
+        manager.createVirtualPort(virtualNetwork.id(), cp5.deviceId(), cp5.port(),
+                                  new DefaultPort(virtualDevice3, cp5.port(), true));
+
         ConnectPoint cp6 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(6));
+        manager.createVirtualPort(virtualNetwork.id(), cp6.deviceId(), cp6.port(),
+                                  new DefaultPort(virtualDevice3, cp6.port(), true));
+
         VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), cp1, cp3);
         virtualNetworkManagerStore.updateLink(link1, link1.tunnelId(), Link.State.ACTIVE);
         VirtualLink link2 = manager.createVirtualLink(virtualNetwork.id(), cp3, cp1);
@@ -177,7 +196,12 @@
 
         topology = topologyService.currentTopology();
         ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
+        manager.createVirtualPort(virtualNetwork.id(), src.deviceId(), src.port(),
+                                  new DefaultPort(srcVirtualDevice, src.port(), true));
+
         ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
+        manager.createVirtualPort(virtualNetwork.id(), dst.deviceId(), dst.port(),
+                                  new DefaultPort(dstVirtualDevice, dst.port(), true));
         VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), src, dst);
 
         // test the isLatest() method where a new link has been added to the current topology.