diff --git a/core/api/src/main/java/org/onosproject/store/cluster/messaging/ClusterCommunicationService.java b/core/api/src/main/java/org/onosproject/store/cluster/messaging/ClusterCommunicationService.java
index 4a46885..dfc558d 100644
--- a/core/api/src/main/java/org/onosproject/store/cluster/messaging/ClusterCommunicationService.java
+++ b/core/api/src/main/java/org/onosproject/store/cluster/messaging/ClusterCommunicationService.java
@@ -15,152 +15,15 @@
  */
 package org.onosproject.store.cluster.messaging;
 
-import java.util.Set;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.Executor;
-import java.util.concurrent.ExecutorService;
-import java.util.function.Consumer;
-import java.util.function.Function;
-
-import org.onosproject.cluster.NodeId;
-
 /**
  * Service for assisting communications between controller cluster nodes.
+ * <p>
+ * Communication via this service is isolated to nodes running a single version of the software. During upgrades, when
+ * nodes may be running multiple versions simultaneously, this service prevents nodes running different versions of
+ * the software from communicating with each other, thus avoiding compatibility issues. For an equivalent cross-version
+ * compatible service, see {@link UnifiedClusterCommunicationService}.
+ *
+ * @see UnifiedClusterCommunicationService
  */
-public interface ClusterCommunicationService {
-
-    /**
-     * Adds a new subscriber for the specified message subject.
-     *
-     * @param subject    message subject
-     * @param subscriber message subscriber
-     * @param executor executor to use for running handler.
-     * @deprecated in Cardinal Release
-     */
-    @Deprecated
-    void addSubscriber(MessageSubject subject, ClusterMessageHandler subscriber, ExecutorService executor);
-
-    /**
-     * Broadcasts a message to all controller nodes.
-     *
-     * @param message message to send
-     * @param subject message subject
-     * @param encoder function for encoding message to byte[]
-     * @param <M> message type
-     */
-    <M> void broadcast(M message,
-                       MessageSubject subject,
-                       Function<M, byte[]> encoder);
-
-    /**
-     * Broadcasts a message to all controller nodes including self.
-     *
-     * @param message message to send
-     * @param subject message subject
-     * @param encoder function for encoding message to byte[]
-     * @param <M> message type
-     */
-    <M> void broadcastIncludeSelf(M message,
-                                  MessageSubject subject,
-                                  Function<M, byte[]> encoder);
-
-    /**
-     * Sends a message to the specified controller node.
-     *
-     * @param message message to send
-     * @param subject message subject
-     * @param encoder function for encoding message to byte[]
-     * @param toNodeId destination node identifier
-     * @param <M> message type
-     * @return future that is completed when the message is sent
-     */
-    <M> CompletableFuture<Void> unicast(M message,
-                        MessageSubject subject,
-                        Function<M, byte[]> encoder,
-                        NodeId toNodeId);
-
-    /**
-     * Multicasts a message to a set of controller nodes.
-     *
-     * @param message message to send
-     * @param subject message subject
-     * @param encoder function for encoding message to byte[]
-     * @param nodeIds  recipient node identifiers
-     * @param <M> message type
-     */
-    <M> void multicast(M message,
-                       MessageSubject subject,
-                       Function<M, byte[]> encoder,
-                       Set<NodeId> nodeIds);
-
-    /**
-     * Sends a message and expects a reply.
-     *
-     * @param message message to send
-     * @param subject message subject
-     * @param encoder function for encoding request to byte[]
-     * @param decoder function for decoding response from byte[]
-     * @param toNodeId recipient node identifier
-     * @param <M> request type
-     * @param <R> reply type
-     * @return reply future
-     */
-    <M, R> CompletableFuture<R> sendAndReceive(M message,
-                                               MessageSubject subject,
-                                               Function<M, byte[]> encoder,
-                                               Function<byte[], R> decoder,
-                                               NodeId toNodeId);
-
-    /**
-     * Adds a new subscriber for the specified message subject.
-     *
-     * @param subject message subject
-     * @param decoder decoder for resurrecting incoming message
-     * @param handler handler function that processes the incoming message and produces a reply
-     * @param encoder encoder for serializing reply
-     * @param executor executor to run this handler on
-     * @param <M> incoming message type
-     * @param <R> reply message type
-     */
-    <M, R> void addSubscriber(MessageSubject subject,
-                              Function<byte[], M> decoder,
-                              Function<M, R> handler,
-                              Function<R, byte[]> encoder,
-                              Executor executor);
-
-    /**
-     * Adds a new subscriber for the specified message subject.
-     *
-     * @param subject message subject
-     * @param decoder decoder for resurrecting incoming message
-     * @param handler handler function that processes the incoming message and produces a reply
-     * @param encoder encoder for serializing reply
-     * @param <M> incoming message type
-     * @param <R> reply message type
-     */
-    <M, R> void addSubscriber(MessageSubject subject,
-                              Function<byte[], M> decoder,
-                              Function<M, CompletableFuture<R>> handler,
-                              Function<R, byte[]> encoder);
-
-    /**
-     * Adds a new subscriber for the specified message subject.
-     *
-     * @param subject message subject
-     * @param decoder decoder to resurrecting incoming message
-     * @param handler handler for handling message
-     * @param executor executor to run this handler on
-     * @param <M> incoming message type
-     */
-    <M> void addSubscriber(MessageSubject subject,
-                           Function<byte[], M> decoder,
-                           Consumer<M> handler,
-                           Executor executor);
-
-    /**
-     * Removes a subscriber for the specified message subject.
-     *
-     * @param subject message subject
-     */
-    void removeSubscriber(MessageSubject subject);
+public interface ClusterCommunicationService extends ClusterCommunicator {
 }
diff --git a/core/api/src/main/java/org/onosproject/store/cluster/messaging/ClusterCommunicator.java b/core/api/src/main/java/org/onosproject/store/cluster/messaging/ClusterCommunicator.java
new file mode 100644
index 0000000..7d2480e
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/cluster/messaging/ClusterCommunicator.java
@@ -0,0 +1,166 @@
+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * 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.store.cluster.messaging;
+
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+import org.onosproject.cluster.NodeId;
+
+/**
+ * Service for assisting communications between controller cluster nodes.
+ */
+public interface ClusterCommunicator {
+
+    /**
+     * Adds a new subscriber for the specified message subject.
+     *
+     * @param subject    message subject
+     * @param subscriber message subscriber
+     * @param executor executor to use for running handler.
+     * @deprecated in Cardinal Release
+     */
+    @Deprecated
+    void addSubscriber(MessageSubject subject, ClusterMessageHandler subscriber, ExecutorService executor);
+
+    /**
+     * Broadcasts a message to all controller nodes.
+     *
+     * @param message message to send
+     * @param subject message subject
+     * @param encoder function for encoding message to byte[]
+     * @param <M> message type
+     */
+    <M> void broadcast(M message,
+            MessageSubject subject,
+            Function<M, byte[]> encoder);
+
+    /**
+     * Broadcasts a message to all controller nodes including self.
+     *
+     * @param message message to send
+     * @param subject message subject
+     * @param encoder function for encoding message to byte[]
+     * @param <M> message type
+     */
+    <M> void broadcastIncludeSelf(M message,
+            MessageSubject subject,
+            Function<M, byte[]> encoder);
+
+    /**
+     * Sends a message to the specified controller node.
+     *
+     * @param message message to send
+     * @param subject message subject
+     * @param encoder function for encoding message to byte[]
+     * @param toNodeId destination node identifier
+     * @param <M> message type
+     * @return future that is completed when the message is sent
+     */
+    <M> CompletableFuture<Void> unicast(M message,
+            MessageSubject subject,
+            Function<M, byte[]> encoder,
+            NodeId toNodeId);
+
+    /**
+     * Multicasts a message to a set of controller nodes.
+     *
+     * @param message message to send
+     * @param subject message subject
+     * @param encoder function for encoding message to byte[]
+     * @param nodeIds  recipient node identifiers
+     * @param <M> message type
+     */
+    <M> void multicast(M message,
+            MessageSubject subject,
+            Function<M, byte[]> encoder,
+            Set<NodeId> nodeIds);
+
+    /**
+     * Sends a message and expects a reply.
+     *
+     * @param message message to send
+     * @param subject message subject
+     * @param encoder function for encoding request to byte[]
+     * @param decoder function for decoding response from byte[]
+     * @param toNodeId recipient node identifier
+     * @param <M> request type
+     * @param <R> reply type
+     * @return reply future
+     */
+    <M, R> CompletableFuture<R> sendAndReceive(M message,
+            MessageSubject subject,
+            Function<M, byte[]> encoder,
+            Function<byte[], R> decoder,
+            NodeId toNodeId);
+
+    /**
+     * Adds a new subscriber for the specified message subject.
+     *
+     * @param subject message subject
+     * @param decoder decoder for resurrecting incoming message
+     * @param handler handler function that processes the incoming message and produces a reply
+     * @param encoder encoder for serializing reply
+     * @param executor executor to run this handler on
+     * @param <M> incoming message type
+     * @param <R> reply message type
+     */
+    <M, R> void addSubscriber(MessageSubject subject,
+            Function<byte[], M> decoder,
+            Function<M, R> handler,
+            Function<R, byte[]> encoder,
+            Executor executor);
+
+    /**
+     * Adds a new subscriber for the specified message subject.
+     *
+     * @param subject message subject
+     * @param decoder decoder for resurrecting incoming message
+     * @param handler handler function that processes the incoming message and produces a reply
+     * @param encoder encoder for serializing reply
+     * @param <M> incoming message type
+     * @param <R> reply message type
+     */
+    <M, R> void addSubscriber(MessageSubject subject,
+            Function<byte[], M> decoder,
+            Function<M, CompletableFuture<R>> handler,
+            Function<R, byte[]> encoder);
+
+    /**
+     * Adds a new subscriber for the specified message subject.
+     *
+     * @param subject message subject
+     * @param decoder decoder to resurrecting incoming message
+     * @param handler handler for handling message
+     * @param executor executor to run this handler on
+     * @param <M> incoming message type
+     */
+    <M> void addSubscriber(MessageSubject subject,
+            Function<byte[], M> decoder,
+            Consumer<M> handler,
+            Executor executor);
+
+    /**
+     * Removes a subscriber for the specified message subject.
+     *
+     * @param subject message subject
+     */
+    void removeSubscriber(MessageSubject subject);
+}
diff --git a/core/api/src/main/java/org/onosproject/store/cluster/messaging/UnifiedClusterCommunicationService.java b/core/api/src/main/java/org/onosproject/store/cluster/messaging/UnifiedClusterCommunicationService.java
new file mode 100644
index 0000000..042c803
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/cluster/messaging/UnifiedClusterCommunicationService.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * 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.store.cluster.messaging;
+
+import com.google.common.annotations.Beta;
+
+/**
+ * Service for unified communication across controller nodes running multiple software versions.
+ * <p>
+ * This service supports communicating across nodes running different versions of the software simultaneously. During
+ * upgrades, when nodes may be running a mixture of versions, this service can be used to coordinate across those
+ * versions. But users of this service must be extremely careful to preserve backward/forward compatibility for
+ * messages sent across versions. Encoders and decoders used for messages sent/received on this service should
+ * support evolving schemas.
+ */
+@Beta
+public interface UnifiedClusterCommunicationService extends ClusterCommunicator {
+}