diff --git a/core/api/src/main/java/org/onlab/onos/store/Timestamp.java b/core/api/src/main/java/org/onlab/onos/store/Timestamp.java
new file mode 100644
index 0000000..b9d3648
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/store/Timestamp.java
@@ -0,0 +1,8 @@
+package org.onlab.onos.store;
+
+/**
+ * Opaque version structure.
+ */
+public interface Timestamp extends Comparable<Timestamp> {
+
+}
diff --git a/core/store/src/main/java/org/onlab/onos/store/impl/OnosTimestamp.java b/core/store/src/main/java/org/onlab/onos/store/impl/OnosTimestamp.java
new file mode 100644
index 0000000..f994e02
--- /dev/null
+++ b/core/store/src/main/java/org/onlab/onos/store/impl/OnosTimestamp.java
@@ -0,0 +1,105 @@
+package org.onlab.onos.store.impl;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkArgument;
+
+import java.util.Objects;
+
+import org.onlab.onos.net.ElementId;
+import org.onlab.onos.store.Timestamp;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.collect.ComparisonChain;
+
+// If it is store specific, implement serializable interfaces?
+/**
+ * Default implementation of Timestamp.
+ */
+public final class OnosTimestamp implements Timestamp {
+
+    private final ElementId id;
+    private final int termNumber;
+    private final int sequenceNumber;
+
+    /**
+     * Default version tuple.
+     *
+     * @param id identifier of the element
+     * @param termNumber the mastership termNumber
+     * @param sequenceNumber  the sequenceNumber number within the termNumber
+     */
+    public OnosTimestamp(ElementId id, int termNumber, int sequenceNumber) {
+        this.id = checkNotNull(id);
+        this.termNumber = termNumber;
+        this.sequenceNumber = sequenceNumber;
+    }
+
+    @Override
+    public int compareTo(Timestamp o) {
+        checkArgument(o instanceof OnosTimestamp, "Must be OnosTimestamp", o);
+        OnosTimestamp that = (OnosTimestamp) o;
+        checkArgument(this.id.equals(that.id),
+                "Cannot compare version for different element this:%s, that:%s",
+                    this, that);
+
+        return ComparisonChain.start()
+                .compare(this.termNumber, that.termNumber)
+                .compare(this.sequenceNumber, that.sequenceNumber)
+                .result();
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, termNumber, sequenceNumber);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof OnosTimestamp)) {
+            return false;
+        }
+        OnosTimestamp that = (OnosTimestamp) obj;
+        return Objects.equals(this.id, that.id) &&
+                Objects.equals(this.termNumber, that.termNumber) &&
+                Objects.equals(this.sequenceNumber, that.sequenceNumber);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                    .add("id", id)
+                    .add("termNumber", termNumber)
+                    .add("sequenceNumber", sequenceNumber)
+                    .toString();
+    }
+
+    /**
+     * Returns the element.
+     *
+     * @return element identifier
+     */
+    public ElementId id() {
+        return id;
+    }
+
+    /**
+     * Returns the termNumber.
+     *
+     * @return termNumber
+     */
+    public int termNumber() {
+        return termNumber;
+    }
+
+    /**
+     * Returns the sequenceNumber number.
+     *
+     * @return sequenceNumber
+     */
+    public int sequenceNumber() {
+        return sequenceNumber;
+    }
+}
diff --git a/core/store/src/main/java/org/onlab/onos/store/impl/StoreManager.java b/core/store/src/main/java/org/onlab/onos/store/impl/StoreManager.java
index abd8ade..c22d915 100644
--- a/core/store/src/main/java/org/onlab/onos/store/impl/StoreManager.java
+++ b/core/store/src/main/java/org/onlab/onos/store/impl/StoreManager.java
@@ -4,7 +4,9 @@
 import com.hazelcast.config.FileSystemXmlConfig;
 import com.hazelcast.core.Hazelcast;
 import com.hazelcast.core.HazelcastInstance;
+
 import de.javakaffee.kryoserializers.URISerializer;
+
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
@@ -26,6 +28,7 @@
 import org.onlab.onos.store.serializers.DeviceIdSerializer;
 import org.onlab.onos.store.serializers.IpPrefixSerializer;
 import org.onlab.onos.store.serializers.NodeIdSerializer;
+import org.onlab.onos.store.serializers.OnosTimestampSerializer;
 import org.onlab.onos.store.serializers.PortNumberSerializer;
 import org.onlab.onos.store.serializers.ProviderIdSerializer;
 import org.onlab.packet.IpPrefix;
@@ -90,6 +93,7 @@
                 .register(DeviceId.class, new DeviceIdSerializer())
                 .register(PortNumber.class, new PortNumberSerializer())
                 .register(DefaultPort.class, new DefaultPortSerializer())
+                .register(OnosTimestamp.class, new OnosTimestampSerializer())
                 .build()
                 .populate(10);
     }
diff --git a/core/store/src/main/java/org/onlab/onos/store/serializers/DefaultPortSerializer.java b/core/store/src/main/java/org/onlab/onos/store/serializers/DefaultPortSerializer.java
index 836adea..8455e80 100644
--- a/core/store/src/main/java/org/onlab/onos/store/serializers/DefaultPortSerializer.java
+++ b/core/store/src/main/java/org/onlab/onos/store/serializers/DefaultPortSerializer.java
@@ -9,7 +9,6 @@
 import com.esotericsoftware.kryo.io.Input;
 import com.esotericsoftware.kryo.io.Output;
 
-// TODO move to util, etc.
 /**
  * Kryo Serializer for {@link DefaultPort}.
  */
diff --git a/core/store/src/main/java/org/onlab/onos/store/serializers/DeviceIdSerializer.java b/core/store/src/main/java/org/onlab/onos/store/serializers/DeviceIdSerializer.java
index 709dce0..c63b676 100644
--- a/core/store/src/main/java/org/onlab/onos/store/serializers/DeviceIdSerializer.java
+++ b/core/store/src/main/java/org/onlab/onos/store/serializers/DeviceIdSerializer.java
@@ -9,7 +9,6 @@
 import com.esotericsoftware.kryo.io.Input;
 import com.esotericsoftware.kryo.io.Output;
 
-//TODO move to util, etc.
 /**
 * Kryo Serializer for {@link DeviceId}.
 */
diff --git a/core/store/src/main/java/org/onlab/onos/store/serializers/IpPrefixSerializer.java b/core/store/src/main/java/org/onlab/onos/store/serializers/IpPrefixSerializer.java
index 8ac6679..2dbec57 100644
--- a/core/store/src/main/java/org/onlab/onos/store/serializers/IpPrefixSerializer.java
+++ b/core/store/src/main/java/org/onlab/onos/store/serializers/IpPrefixSerializer.java
@@ -7,7 +7,6 @@
 import com.esotericsoftware.kryo.io.Input;
 import com.esotericsoftware.kryo.io.Output;
 
-// TODO move to util, etc.
 /**
  * Kryo Serializer for {@link IpPrefix}.
  */
diff --git a/core/store/src/main/java/org/onlab/onos/store/serializers/OnosTimestampSerializer.java b/core/store/src/main/java/org/onlab/onos/store/serializers/OnosTimestampSerializer.java
new file mode 100644
index 0000000..812bc9d
--- /dev/null
+++ b/core/store/src/main/java/org/onlab/onos/store/serializers/OnosTimestampSerializer.java
@@ -0,0 +1,37 @@
+package org.onlab.onos.store.serializers;
+
+import org.onlab.onos.net.ElementId;
+import org.onlab.onos.store.impl.OnosTimestamp;
+
+import com.esotericsoftware.kryo.Kryo;
+import com.esotericsoftware.kryo.Serializer;
+import com.esotericsoftware.kryo.io.Input;
+import com.esotericsoftware.kryo.io.Output;
+
+/**
+ * Kryo Serializer for {@link OnosTimestamp}.
+ */
+public class OnosTimestampSerializer extends Serializer<OnosTimestamp> {
+
+    /**
+     * Default constructor.
+     */
+    public OnosTimestampSerializer() {
+        // non-null, immutable
+        super(false, true);
+    }
+    @Override
+    public void write(Kryo kryo, Output output, OnosTimestamp object) {
+        kryo.writeClassAndObject(output, object.id());
+        output.writeInt(object.termNumber());
+        output.writeInt(object.sequenceNumber());
+    }
+
+    @Override
+    public OnosTimestamp read(Kryo kryo, Input input, Class<OnosTimestamp> type) {
+        ElementId id = (ElementId) kryo.readClassAndObject(input);
+        final int term = input.readInt();
+        final int sequence = input.readInt();
+        return new OnosTimestamp(id, term, sequence);
+    }
+}
diff --git a/core/store/src/main/java/org/onlab/onos/store/serializers/PortNumberSerializer.java b/core/store/src/main/java/org/onlab/onos/store/serializers/PortNumberSerializer.java
index e89c379..02805bb 100644
--- a/core/store/src/main/java/org/onlab/onos/store/serializers/PortNumberSerializer.java
+++ b/core/store/src/main/java/org/onlab/onos/store/serializers/PortNumberSerializer.java
@@ -7,7 +7,6 @@
 import com.esotericsoftware.kryo.io.Input;
 import com.esotericsoftware.kryo.io.Output;
 
-// TODO move to util, etc.
 /**
  * Serializer for {@link PortNumber}.
  */
diff --git a/core/store/src/main/java/org/onlab/onos/store/serializers/ProviderIdSerializer.java b/core/store/src/main/java/org/onlab/onos/store/serializers/ProviderIdSerializer.java
index 3abb784..1a1c6f6 100644
--- a/core/store/src/main/java/org/onlab/onos/store/serializers/ProviderIdSerializer.java
+++ b/core/store/src/main/java/org/onlab/onos/store/serializers/ProviderIdSerializer.java
@@ -7,7 +7,6 @@
 import com.esotericsoftware.kryo.io.Input;
 import com.esotericsoftware.kryo.io.Output;
 
-//TODO move to util, etc.
 /**
  * Serializer for {@link ProviderId}.
  */