diff --git a/impl/src/main/java/org/opencord/olt/impl/OltDeviceService.java b/impl/src/main/java/org/opencord/olt/impl/OltDeviceService.java
new file mode 100644
index 0000000..b336c28
--- /dev/null
+++ b/impl/src/main/java/org/opencord/olt/impl/OltDeviceService.java
@@ -0,0 +1,156 @@
+/*
+ * 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.cluster.ClusterService;
+import org.onosproject.cluster.LeadershipService;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Port;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.device.DeviceService;
+import org.opencord.sadis.BaseInformationService;
+import org.opencord.sadis.SadisService;
+import org.opencord.sadis.SubscriberAndDeviceInformation;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.component.annotations.ReferenceCardinality;
+import org.osgi.service.component.annotations.ReferencePolicy;
+import org.slf4j.Logger;
+
+import java.util.List;
+import java.util.Optional;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * The implementation of the OltDeviceService.
+ */
+@Component(immediate = true)
+public class OltDeviceService implements OltDeviceServiceInterface {
+
+    protected BaseInformationService<SubscriberAndDeviceInformation> subsService;
+    private final Logger log = getLogger(getClass());
+
+    @Reference(cardinality = ReferenceCardinality.OPTIONAL,
+            bind = "bindSadisService",
+            unbind = "unbindSadisService",
+            policy = ReferencePolicy.DYNAMIC)
+    protected volatile SadisService sadisService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected DeviceService deviceService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected MastershipService mastershipService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected LeadershipService leadershipService;
+
+    @Activate
+    public void activate() {
+        log.info("Activated");
+    }
+
+    /**
+     * Returns true if the device is an OLT.
+     *
+     * @param device the Device to be checked
+     * @return boolean
+     */
+    public boolean isOlt(Device device) {
+        return getOltInfo(device) != null;
+    }
+
+    private SubscriberAndDeviceInformation getOltInfo(Device dev) {
+        if (subsService == null) {
+            return null;
+        }
+        String devSerialNo = dev.serialNumber();
+        return subsService.get(devSerialNo);
+    }
+
+
+    /**
+     * Returns true if the port is an NNI Port on the OLT.
+     * NOTE: We can check if a port is a NNI based on the SADIS config, specifically the uplinkPort section
+     *
+     * @param dev  the Device this port belongs to
+     * @param portNumber the PortNumber to be checked
+     * @return boolean
+     */
+    @Override
+    public boolean isNniPort(Device dev, PortNumber portNumber) {
+        SubscriberAndDeviceInformation deviceInfo = getOltInfo(dev);
+        return deviceInfo != null && portNumber.toLong() == deviceInfo.uplinkPort();
+    }
+
+    @Override
+    public Optional<Port> getNniPort(Device device) {
+        SubscriberAndDeviceInformation deviceInfo = getOltInfo(device);
+        if (deviceInfo == null) {
+            return Optional.empty();
+        }
+        List<Port> ports = deviceService.getPorts(device.id());
+        if (log.isTraceEnabled()) {
+            log.trace("Get NNI Port looks for NNI in: {}", ports);
+        }
+        return ports.stream()
+                .filter(p -> p.number().toLong() == deviceInfo.uplinkPort())
+                .findFirst();
+    }
+
+    protected void bindSadisService(SadisService service) {
+        this.subsService = service.getSubscriberInfoService();
+        log.info("Sadis service is loaded");
+    }
+
+    protected void unbindSadisService(SadisService service) {
+        this.subsService = null;
+        log.info("Sadis service is unloaded");
+    }
+
+    /**
+     * Checks for mastership or falls back to leadership on deviceId.
+     * If the device is available use mastership,
+     * otherwise fallback on leadership.
+     * Leadership on the device topic is needed because the master can be NONE
+     * in case the device went away, we still need to handle events
+     * consistently
+     *
+     * @param deviceId The device ID to check.
+     * @return boolean (true if the current instance is managing the device)
+     */
+    @Override
+    public boolean isLocalLeader(DeviceId deviceId) {
+        if (deviceService.isAvailable(deviceId)) {
+            return mastershipService.isLocalMaster(deviceId);
+        } else {
+            // Fallback with Leadership service - device id is used as topic
+            NodeId leader = leadershipService.runForLeadership(
+                    deviceId.toString()).leaderNodeId();
+            // Verify if this node is the leader
+            return clusterService.getLocalNode().id().equals(leader);
+        }
+    }
+}