diff --git a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DefaultTopologyDescription.java b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DefaultTopologyDescription.java
new file mode 100644
index 0000000..773762a
--- /dev/null
+++ b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DefaultTopologyDescription.java
@@ -0,0 +1,80 @@
+package org.onlab.onos.net.trivial.impl;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Multimap;
+import org.onlab.graph.Graph;
+import org.onlab.graph.GraphPathSearch;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.topology.ClusterId;
+import org.onlab.onos.net.topology.TopoEdge;
+import org.onlab.onos.net.topology.TopoVertex;
+import org.onlab.onos.net.topology.TopologyCluster;
+import org.onlab.onos.net.topology.TopologyDescription;
+
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Default implementation of an immutable topology data carrier.
+ */
+public class DefaultTopologyDescription implements TopologyDescription {
+
+    private final long nanos;
+    private final Graph<TopoVertex, TopoEdge> graph;
+    private final Map<DeviceId, GraphPathSearch.Result<TopoVertex, TopoEdge>> results;
+    private final Map<ClusterId, TopologyCluster> clusters;
+    private final Multimap<ClusterId, DeviceId> clusterDevices;
+    private final Multimap<ClusterId, Link> clusterLinks;
+    private final Map<DeviceId, TopologyCluster> deviceClusters;
+
+    public DefaultTopologyDescription(long nanos, Graph<TopoVertex, TopoEdge> graph,
+                                      Map<DeviceId, GraphPathSearch.Result<TopoVertex, TopoEdge>> results,
+                                      Map<ClusterId, TopologyCluster> clusters,
+                                      Multimap<ClusterId, DeviceId> clusterDevices,
+                                      Multimap<ClusterId, Link> clusterLinks,
+                                      Map<DeviceId, TopologyCluster> deviceClusters) {
+        this.nanos = nanos;
+        this.graph = graph;
+        this.results = results;
+        this.clusters = clusters;
+        this.clusterDevices = clusterDevices;
+        this.clusterLinks = clusterLinks;
+        this.deviceClusters = deviceClusters;
+    }
+
+    @Override
+    public long timestamp() {
+        return nanos;
+    }
+
+    @Override
+    public Graph<TopoVertex, TopoEdge> graph() {
+        return graph;
+    }
+
+    @Override
+    public GraphPathSearch.Result<TopoVertex, TopoEdge> pathResults(DeviceId srcDeviceId) {
+        return results.get(srcDeviceId);
+    }
+
+    @Override
+    public Set<TopologyCluster> clusters() {
+        return ImmutableSet.copyOf(clusters.values());
+    }
+
+    @Override
+    public Set<DeviceId> clusterDevices(TopologyCluster cluster) {
+        return null; // clusterDevices.get(cluster.id());
+    }
+
+    @Override
+    public Set<Link> clusterLinks(TopologyCluster cluster) {
+        return null; // clusterLinks.get(cluster.id());
+    }
+
+    @Override
+    public TopologyCluster clusterFor(DeviceId deviceId) {
+        return deviceClusters.get(deviceId);
+    }
+}
diff --git a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
index 29c119d..87a548e 100644
--- a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
+++ b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
@@ -150,7 +150,7 @@
     private class InternalDeviceProviderService extends AbstractProviderService<DeviceProvider>
             implements DeviceProviderService {
 
-        public InternalDeviceProviderService(DeviceProvider provider) {
+        InternalDeviceProviderService(DeviceProvider provider) {
             super(provider);
         }
 
diff --git a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java
index c9aa71b..17849b1 100644
--- a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java
+++ b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java
@@ -59,7 +59,7 @@
     private class InternalHostProviderService extends AbstractProviderService<HostProvider>
             implements HostProviderService {
 
-        public InternalHostProviderService(HostProvider provider) {
+        InternalHostProviderService(HostProvider provider) {
             super(provider);
         }
 
diff --git a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java
index 6e7c567..c7b56c0 100644
--- a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java
+++ b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java
@@ -148,7 +148,7 @@
     private class InternalLinkProviderService extends AbstractProviderService<LinkProvider>
             implements LinkProviderService {
 
-        public InternalLinkProviderService(LinkProvider provider) {
+        InternalLinkProviderService(LinkProvider provider) {
             super(provider);
         }
 
diff --git a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyManager.java b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyManager.java
new file mode 100644
index 0000000..1ea0638
--- /dev/null
+++ b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyManager.java
@@ -0,0 +1,153 @@
+package org.onlab.onos.net.trivial.impl;
+
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.apache.felix.scr.annotations.Service;
+import org.onlab.graph.Graph;
+import org.onlab.onos.event.AbstractListenerRegistry;
+import org.onlab.onos.event.Event;
+import org.onlab.onos.event.EventDeliveryService;
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.provider.AbstractProviderRegistry;
+import org.onlab.onos.net.provider.AbstractProviderService;
+import org.onlab.onos.net.topology.LinkWeight;
+import org.onlab.onos.net.topology.TopoEdge;
+import org.onlab.onos.net.topology.TopoVertex;
+import org.onlab.onos.net.topology.Topology;
+import org.onlab.onos.net.topology.TopologyCluster;
+import org.onlab.onos.net.topology.TopologyDescription;
+import org.onlab.onos.net.topology.TopologyEvent;
+import org.onlab.onos.net.topology.TopologyListener;
+import org.onlab.onos.net.topology.TopologyProvider;
+import org.onlab.onos.net.topology.TopologyProviderRegistry;
+import org.onlab.onos.net.topology.TopologyProviderService;
+import org.onlab.onos.net.topology.TopologyService;
+import org.slf4j.Logger;
+
+import java.util.List;
+import java.util.Set;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Provides basic implementation of the topology SB &amp; NB APIs.
+ */
+@Component(immediate = true)
+@Service
+public class SimpleTopologyManager
+        extends AbstractProviderRegistry<TopologyProvider, TopologyProviderService>
+        implements TopologyService, TopologyProviderRegistry {
+
+    public static final String TOPOLOGY_NULL = "Topology cannot be null";
+    private static final String DEVICE_ID_NULL = "Device ID cannot be null";
+    public static final String CONNECTION_POINT_NULL = "Connection point cannot be null";
+
+    private final Logger log = getLogger(getClass());
+
+    private final AbstractListenerRegistry<TopologyEvent, TopologyListener>
+            listenerRegistry = new AbstractListenerRegistry<>();
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private EventDeliveryService eventDispatcher;
+
+
+    @Activate
+    public void activate() {
+        eventDispatcher.addSink(TopologyEvent.class, listenerRegistry);
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        eventDispatcher.removeSink(TopologyEvent.class);
+        log.info("Stopped");
+    }
+
+    @Override
+    protected TopologyProviderService createProviderService(TopologyProvider provider) {
+        return new InternalTopologyProviderService(provider);
+    }
+
+    @Override
+    public Topology currentTopology() {
+        return null;
+    }
+
+    @Override
+    public Set<TopologyCluster> getClusters(Topology topology) {
+        checkNotNull(topology, TOPOLOGY_NULL);
+        return null;
+    }
+
+    @Override
+    public Graph<TopoVertex, TopoEdge> getGraph(Topology topology) {
+        checkNotNull(topology, TOPOLOGY_NULL);
+        return null;
+    }
+
+    @Override
+    public Set<Path> getPaths(Topology topology, DeviceId src, DeviceId dst) {
+        checkNotNull(topology, TOPOLOGY_NULL);
+        checkNotNull(src, DEVICE_ID_NULL);
+        checkNotNull(dst, DEVICE_ID_NULL);
+        return null;
+    }
+
+    @Override
+    public Set<Path> getPaths(Topology topology, DeviceId src, DeviceId dst, LinkWeight weight) {
+        checkNotNull(topology, TOPOLOGY_NULL);
+        checkNotNull(src, DEVICE_ID_NULL);
+        checkNotNull(dst, DEVICE_ID_NULL);
+        checkNotNull(weight, "Link weight cannot be null");
+        return null;
+    }
+
+    @Override
+    public boolean isInfrastructure(Topology topology, ConnectPoint connectPoint) {
+        checkNotNull(topology, TOPOLOGY_NULL);
+        checkNotNull(connectPoint, CONNECTION_POINT_NULL);
+        return false;
+    }
+
+    @Override
+    public boolean isInBroadcastTree(Topology topology, ConnectPoint connectPoint) {
+        checkNotNull(topology, TOPOLOGY_NULL);
+        checkNotNull(connectPoint, CONNECTION_POINT_NULL);
+        return false;
+    }
+
+    @Override
+    public void addListener(TopologyListener listener) {
+        listenerRegistry.addListener(listener);
+    }
+
+    @Override
+    public void removeListener(TopologyListener listener) {
+        listenerRegistry.removeListener(listener);
+    }
+
+    // Personalized host provider service issued to the supplied provider.
+    private class InternalTopologyProviderService
+            extends AbstractProviderService<TopologyProvider>
+            implements TopologyProviderService {
+
+        InternalTopologyProviderService(TopologyProvider provider) {
+            super(provider);
+        }
+
+        @Override
+        public void topologyChanged(TopologyDescription topoDescription,
+                                    List<Event> reasons) {
+            checkNotNull(topoDescription, "Topology description cannot be null");
+            log.info("Topology changed due to: {}",
+                     reasons == null ? "initial compute" : reasons);
+        }
+    }
+
+}