diff --git a/impl/src/main/java/org/opencord/olt/impl/OltDeviceServiceInterface.java b/impl/src/main/java/org/opencord/olt/impl/OltDeviceServiceInterface.java
new file mode 100644
index 0000000..e8fcccb
--- /dev/null
+++ b/impl/src/main/java/org/opencord/olt/impl/OltDeviceServiceInterface.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2021-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.opencord.olt.impl;
+
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Port;
+import org.onosproject.net.PortNumber;
+
+import java.util.Optional;
+
+/**
+ * Service for olt device handling.
+ */
+public interface OltDeviceServiceInterface {
+    /**
+     * Returns true if the device is a known OLT to sadis/config.
+     * @param device the device
+     * @return true if a configured olt
+     */
+    boolean isOlt(Device device);
+
+    /**
+     * Returns true if the port is an NNI port of the OLT device.
+     * @param device the device
+     * @param port the port
+     * @return true if an NNI port of that OLT
+     */
+    boolean isNniPort(Device device, PortNumber port);
+
+    /**
+     * Returns the NNi port fo the OLT device if present.
+     * @param device the device
+     * @return the nni Port, if present
+     */
+    Optional<Port> getNniPort(Device device);
+
+    /**
+     * Returns true if the instance is leader for the OLT device.
+     * @param deviceId the device
+     * @return true if master, false otherwise.
+     */
+    boolean isLocalLeader(DeviceId deviceId);
+}