diff --git a/core/api/src/main/java/org/onlab/onos/cluster/ClusterEvent.java b/core/api/src/main/java/org/onlab/onos/cluster/ClusterEvent.java
index 300a143..a47c43f 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/ClusterEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/ClusterEvent.java
@@ -5,7 +5,7 @@
 /**
  * Describes cluster-related event.
  */
-public class ClusterEvent extends AbstractEvent<ClusterEvent.Type, ControllerInstance> {
+public class ClusterEvent extends AbstractEvent<ClusterEvent.Type, ControllerNode> {
 
     /**
      * Type of cluster-related events.
@@ -39,7 +39,7 @@
      * @param type     cluster event type
      * @param instance cluster device subject
      */
-    public ClusterEvent(Type type, ControllerInstance instance) {
+    public ClusterEvent(Type type, ControllerNode instance) {
         super(type, instance);
     }
 
@@ -50,7 +50,7 @@
      * @param instance event device subject
      * @param time     occurrence time
      */
-    public ClusterEvent(Type type, ControllerInstance instance, long time) {
+    public ClusterEvent(Type type, ControllerNode instance, long time) {
         super(type, instance, time);
     }
 
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/ClusterService.java b/core/api/src/main/java/org/onlab/onos/cluster/ClusterService.java
index 017ccd2..9c0af8f 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/ClusterService.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/ClusterService.java
@@ -3,24 +3,40 @@
 import java.util.Set;
 
 /**
- * Service for obtaining information about the individual instances within
+ * Service for obtaining information about the individual nodes within
  * the controller cluster.
  */
 public interface ClusterService {
 
     /**
+     * Returns the local controller node.
+     *
+     * @return local controller node
+     */
+    ControllerNode getLocalNode();
+
+    /**
      * Returns the set of current cluster members.
      *
      * @return set of cluster members
      */
-    Set<ControllerInstance> getInstances();
+    Set<ControllerNode> getNodes();
 
     /**
-     * Returns the availability state of the specified controller instance.
+     * Returns the specified controller node.
      *
+     * @param nodeId controller node identifier
+     * @return controller node
+     */
+    ControllerNode getNode(NodeId nodeId);
+
+    /**
+     * Returns the availability state of the specified controller node.
+     *
+     * @param nodeId controller node identifier
      * @return availability state
      */
-    ControllerInstance.State getState(ControllerInstance instance);
+    ControllerNode.State getState(NodeId nodeId);
 
     /**
      * Adds the specified cluster event listener.
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/ClusterStore.java b/core/api/src/main/java/org/onlab/onos/cluster/ClusterStore.java
new file mode 100644
index 0000000..7d4b71f
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/cluster/ClusterStore.java
@@ -0,0 +1,40 @@
+package org.onlab.onos.cluster;
+
+import java.util.Set;
+
+/**
+ * Manages inventory of controller cluster nodes; not intended for direct use.
+ */
+public interface ClusterStore {
+
+    /**
+     * Returns the local controller instance.
+     *
+     * @return local controller instance
+     */
+    ControllerNode getLocalNode();
+
+    /**
+     * Returns the set of current cluster members.
+     *
+     * @return set of cluster members
+     */
+    Set<ControllerNode> getNodes();
+
+    /**
+     * Returns the specified controller instance.
+     *
+     * @param nodeId controller instance identifier
+     * @return controller instance
+     */
+    ControllerNode getNode(NodeId nodeId);
+
+    /**
+     * Returns the availability state of the specified controller instance.
+     *
+     * @param nodeId controller instance identifier
+     * @return availability state
+     */
+    ControllerNode.State getState(NodeId nodeId);
+
+}
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/ControllerInstance.java b/core/api/src/main/java/org/onlab/onos/cluster/ControllerNode.java
similarity index 92%
rename from core/api/src/main/java/org/onlab/onos/cluster/ControllerInstance.java
rename to core/api/src/main/java/org/onlab/onos/cluster/ControllerNode.java
index 9255175..c6f0cb3 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/ControllerInstance.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/ControllerNode.java
@@ -5,7 +5,7 @@
 /**
  * Represents a controller instance as a member in a cluster.
  */
-public interface ControllerInstance {
+public interface ControllerNode {
 
     /** Represents the operational state of the instance. */
     public enum State {
@@ -26,7 +26,7 @@
      *
      * @return instance identifier
      */
-    InstanceId id();
+    NodeId id();
 
     /**
      * Returns the IP address of the controller instance.
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/DefaultControllerNode.java b/core/api/src/main/java/org/onlab/onos/cluster/DefaultControllerNode.java
new file mode 100644
index 0000000..9735fdb
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/cluster/DefaultControllerNode.java
@@ -0,0 +1,60 @@
+package org.onlab.onos.cluster;
+
+import org.onlab.packet.IpPrefix;
+
+import java.util.Objects;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+
+/**
+ * Default implementation of a controller instance descriptor.
+ */
+public class DefaultControllerNode implements ControllerNode {
+
+    private final NodeId id;
+    private final IpPrefix ip;
+
+    /**
+     * Creates a new instance with the specified id and IP address.
+     *
+     * @param id instance identifier
+     * @param ip instance IP address
+     */
+    public DefaultControllerNode(NodeId id, IpPrefix ip) {
+        this.id = id;
+        this.ip = ip;
+    }
+
+    @Override
+    public NodeId id() {
+        return id;
+    }
+
+    @Override
+    public IpPrefix ip() {
+        return ip;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o instanceof DefaultControllerNode) {
+            DefaultControllerNode that = (DefaultControllerNode) o;
+            return Objects.equals(this.id, that.id);
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this).add("id", id).add("ip", ip).toString();
+    }
+
+}
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/MastershipAdminService.java b/core/api/src/main/java/org/onlab/onos/cluster/MastershipAdminService.java
index 6c58020..907b3f8 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/MastershipAdminService.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/MastershipAdminService.java
@@ -15,6 +15,6 @@
      * @param deviceId device identifier
      * @param role     requested role
      */
-    void setRole(InstanceId instance, DeviceId deviceId, MastershipRole role);
+    void setRole(NodeId instance, DeviceId deviceId, MastershipRole role);
 
 }
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java b/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java
index a835449..2a5e62e 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/MastershipEvent.java
@@ -8,7 +8,7 @@
  */
 public class MastershipEvent extends AbstractEvent<MastershipEvent.Type, DeviceId> {
 
-    InstanceId master;
+    NodeId master;
 
     /**
      * Type of mastership events.
@@ -28,7 +28,7 @@
      * @param device event device subject
      * @param master master ID subject
      */
-    protected MastershipEvent(Type type, DeviceId device, InstanceId master) {
+    protected MastershipEvent(Type type, DeviceId device, NodeId master) {
         super(type, device);
         this.master = master;
     }
@@ -42,7 +42,7 @@
      * @param master master ID subject
      * @param time   occurrence time
      */
-    protected MastershipEvent(Type type, DeviceId device, InstanceId master, long time) {
+    protected MastershipEvent(Type type, DeviceId device, NodeId master, long time) {
         super(type, device, time);
         this.master = master;
     }
@@ -52,7 +52,7 @@
      *
      * @return master ID subject
      */
-    public InstanceId master() {
+    public NodeId master() {
         return master;
     }
 }
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/MastershipService.java b/core/api/src/main/java/org/onlab/onos/cluster/MastershipService.java
index bc5f19c..6a9b60e 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/MastershipService.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/MastershipService.java
@@ -19,15 +19,15 @@
      * @param deviceId the identifier of the device
      * @return the ID of the master controller for the device
      */
-    InstanceId getMasterFor(DeviceId deviceId);
+    NodeId getMasterFor(DeviceId deviceId);
 
     /**
      * Returns the devices for which a controller is master.
      *
-     * @param instanceId the ID of the controller
+     * @param nodeId the ID of the controller
      * @return a set of device IDs
      */
-    Set<DeviceId> getDevicesOf(InstanceId instanceId);
+    Set<DeviceId> getDevicesOf(NodeId nodeId);
 
     /**
      * Returns the mastership status of this controller for a given device.
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/MastershipStore.java b/core/api/src/main/java/org/onlab/onos/cluster/MastershipStore.java
index 67eeff5..728e77d 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/MastershipStore.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/MastershipStore.java
@@ -6,11 +6,12 @@
 import org.onlab.onos.net.MastershipRole;
 
 /**
- * Manages inventory of mastership roles for devices, across controller instances.
+ * Manages inventory of mastership roles for devices, across controller
+ * instances; not intended for direct use.
  */
 public interface MastershipStore {
 
-    // three things to map: InstanceId, DeviceId, MastershipRole
+    // three things to map: NodeId, DeviceId, MastershipRole
 
     /**
      * Sets a device's role for a specified controller instance.
@@ -20,7 +21,7 @@
      * @param role     new role
      * @return a mastership event
      */
-    MastershipEvent setRole(InstanceId instance, DeviceId deviceId,
+    MastershipEvent setRole(NodeId instance, DeviceId deviceId,
                             MastershipRole role);
 
     /**
@@ -31,7 +32,7 @@
      * @param role     new role
      * @return a mastership event
      */
-    MastershipEvent addOrUpdateDevice(InstanceId instance, DeviceId deviceId,
+    MastershipEvent addOrUpdateDevice(NodeId instance, DeviceId deviceId,
                                       MastershipRole role);
 
     /**
@@ -40,22 +41,22 @@
      * @param deviceId the device identifier
      * @return the instance identifier of the master
      */
-    InstanceId getMaster(DeviceId deviceId);
+    NodeId getMaster(DeviceId deviceId);
 
     /**
      * Returns the devices that a controller instance is master of.
      *
-     * @param instanceId the instance identifier
+     * @param nodeId the instance identifier
      * @return a set of device identifiers
      */
-    Set<DeviceId> getDevices(InstanceId instanceId);
+    Set<DeviceId> getDevices(NodeId nodeId);
 
     /**
      * Returns the role of a device for a specific controller instance.
      *
-     * @param instanceId the instance identifier
+     * @param nodeId the instance identifier
      * @param deviceId   the device identifiers
      * @return the role
      */
-    MastershipRole getRole(InstanceId instanceId, DeviceId deviceId);
+    MastershipRole getRole(NodeId nodeId, DeviceId deviceId);
 }
diff --git a/core/api/src/main/java/org/onlab/onos/cluster/InstanceId.java b/core/api/src/main/java/org/onlab/onos/cluster/NodeId.java
similarity index 62%
rename from core/api/src/main/java/org/onlab/onos/cluster/InstanceId.java
rename to core/api/src/main/java/org/onlab/onos/cluster/NodeId.java
index 14f1eda..2430d52 100644
--- a/core/api/src/main/java/org/onlab/onos/cluster/InstanceId.java
+++ b/core/api/src/main/java/org/onlab/onos/cluster/NodeId.java
@@ -2,26 +2,24 @@
 
 import java.util.Objects;
 
-import static com.google.common.base.MoreObjects.toStringHelper;
-
 /**
  * Controller cluster identity.
  */
-public class InstanceId {
+public class NodeId {
 
     private final String id;
 
     // Default constructor for serialization
-    protected InstanceId() {
+    protected NodeId() {
         id = null;
     }
 
     /**
-     * Creates a new cluster instance identifier from the specified string.
+     * Creates a new cluster node identifier from the specified string.
      *
      * @param id string identifier
      */
-    public InstanceId(String id) {
+    public NodeId(String id) {
         this.id = id;
     }
 
@@ -35,8 +33,8 @@
         if (this == obj) {
             return true;
         }
-        if (obj instanceof InstanceId) {
-            final InstanceId other = (InstanceId) obj;
+        if (obj instanceof NodeId) {
+            final NodeId other = (NodeId) obj;
             return Objects.equals(this.id, other.id);
         }
         return false;
@@ -44,7 +42,7 @@
 
     @Override
     public String toString() {
-        return toStringHelper(this).add("id", id).toString();
+        return id;
     }
 
 }
diff --git a/core/api/src/main/java/org/onlab/onos/net/device/DeviceStore.java b/core/api/src/main/java/org/onlab/onos/net/device/DeviceStore.java
index 851fbc1..3ed477b 100644
--- a/core/api/src/main/java/org/onlab/onos/net/device/DeviceStore.java
+++ b/core/api/src/main/java/org/onlab/onos/net/device/DeviceStore.java
@@ -10,7 +10,7 @@
 import java.util.List;
 
 /**
- * Manages inventory of infrastructure devices.
+ * Manages inventory of infrastructure devices; not intended for direct use.
  */
 public interface DeviceStore {
 
diff --git a/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleStore.java b/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleStore.java
index 0698721..f00b595 100644
--- a/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleStore.java
+++ b/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleStore.java
@@ -3,7 +3,7 @@
 import org.onlab.onos.net.DeviceId;
 
 /**
- * Manages inventory of flow rules.
+ * Manages inventory of flow rules; not intended for direct use.
  */
 public interface FlowRuleStore {
 
diff --git a/core/api/src/main/java/org/onlab/onos/net/host/HostStore.java b/core/api/src/main/java/org/onlab/onos/net/host/HostStore.java
index 94c4585..ea316b2 100644
--- a/core/api/src/main/java/org/onlab/onos/net/host/HostStore.java
+++ b/core/api/src/main/java/org/onlab/onos/net/host/HostStore.java
@@ -12,8 +12,7 @@
 import java.util.Set;
 
 /**
- * Manages inventory of end-station hosts. It may do so using whatever
- * means are appropriate.
+ * Manages inventory of end-station hosts; not intended for direct use.
  */
 public interface HostStore {
 
diff --git a/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java b/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java
index 4391471..dbe4877 100644
--- a/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java
+++ b/core/api/src/main/java/org/onlab/onos/net/link/LinkStore.java
@@ -8,8 +8,7 @@
 import java.util.Set;
 
 /**
- * Manages inventory of infrastructure links. It may do so using whatever
- * means are appropriate.
+ * Manages inventory of infrastructure links; not intended for direct use.
  */
 public interface LinkStore {
 
diff --git a/core/api/src/main/java/org/onlab/onos/net/topology/TopologyStore.java b/core/api/src/main/java/org/onlab/onos/net/topology/TopologyStore.java
index 5e8b19d..adc6145 100644
--- a/core/api/src/main/java/org/onlab/onos/net/topology/TopologyStore.java
+++ b/core/api/src/main/java/org/onlab/onos/net/topology/TopologyStore.java
@@ -11,8 +11,7 @@
 import java.util.Set;
 
 /**
- * Manages inventory of topology snapshots. It may do so using whatever
- * means appropriate.
+ * Manages inventory of topology snapshots; not intended for direct use.
  */
 public interface TopologyStore {