diff --git a/apps/t3/app/src/main/java/org/onosproject/t3/api/MastershipNib.java b/apps/t3/app/src/main/java/org/onosproject/t3/api/MastershipNib.java
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+++ b/apps/t3/app/src/main/java/org/onosproject/t3/api/MastershipNib.java
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+/*
+ * Copyright 2020-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.t3.api;
+
+import com.google.common.collect.ImmutableMap;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.net.DeviceId;
+
+import java.util.Map;
+
+/**
+ * Represents Network Information Base (NIB) for mastership
+ * and supports alternative functions to
+ * {@link org.onosproject.mastership.MastershipService} for offline data.
+ */
+public class MastershipNib {
+
+    private Map<DeviceId, NodeId> deviceMasterMap;
+
+    // use the singleton helper to create the instance
+    protected MastershipNib() {
+    }
+
+    /**
+     * Sets a map of device id : master node id.
+     *
+     * @param deviceMasterMap device-master map
+     */
+    public void setDeviceMasterMap(Map<DeviceId, NodeId> deviceMasterMap) {
+        this.deviceMasterMap = deviceMasterMap;
+    }
+
+    /**
+     * Returns the device-master map.
+     *
+     * @return device-master map
+     */
+    public Map<DeviceId, NodeId> getDeviceMasterMap() {
+        return ImmutableMap.copyOf(deviceMasterMap);
+    }
+
+    /**
+     * Returns the current master for a given device.
+     *
+     * @param deviceId the identifier of the device
+     * @return the ID of the master controller for the device
+     */
+    public NodeId getMasterFor(DeviceId deviceId) {
+        return deviceMasterMap.get(deviceId);
+    }
+
+    /**
+     * Returns the singleton instance of mastership NIB.
+     *
+     * @return instance of mastership NIB
+     */
+    public static MastershipNib getInstance() {
+        return MastershipNib.SingletonHelper.INSTANCE;
+    }
+
+    private static class SingletonHelper {
+        private static final MastershipNib INSTANCE = new MastershipNib();
+    }
+
+}