diff --git a/apps/k8s-node/app/src/main/java/org/onosproject/k8snode/impl/ExternalNetworkManager.java b/apps/k8s-node/app/src/main/java/org/onosproject/k8snode/impl/ExternalNetworkManager.java
new file mode 100644
index 0000000..184998a
--- /dev/null
+++ b/apps/k8s-node/app/src/main/java/org/onosproject/k8snode/impl/ExternalNetworkManager.java
@@ -0,0 +1,160 @@
+/*
+ * 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.k8snode.impl;
+
+import org.apache.commons.net.util.SubnetUtils;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.IpPrefix;
+import org.onlab.util.KryoNamespace;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.k8snode.api.ExternalNetworkService;
+import org.onosproject.store.serializers.KryoNamespaces;
+import org.onosproject.store.service.ConsistentMap;
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.StorageService;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Deactivate;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.component.annotations.ReferenceCardinality;
+import org.slf4j.Logger;
+
+import java.util.Arrays;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.stream.Collectors;
+
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.onosproject.k8snode.api.K8sNodeService.APP_ID;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * External network service implementation.
+ */
+@Component(
+        immediate = true,
+        service = { ExternalNetworkService.class }
+)
+public class ExternalNetworkManager implements ExternalNetworkService {
+
+    private final Logger log = getLogger(getClass());
+
+    private static final KryoNamespace
+            SERIALIZER_EXTERNAL_NETWORK = KryoNamespace.newBuilder()
+            .register(KryoNamespaces.API)
+            .build();
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected StorageService storageService;
+
+    private final ExecutorService eventExecutor = newSingleThreadExecutor(
+            groupedThreads(this.getClass().getSimpleName(), "event-handler", log));
+
+    private ConsistentMap<String, Set<String>> networkIpPool;
+
+    @Activate
+    protected void activate() {
+        ApplicationId appId = coreService.registerApplication(APP_ID);
+        networkIpPool = storageService.<String, Set<String>>consistentMapBuilder()
+                .withSerializer(Serializer.using(SERIALIZER_EXTERNAL_NETWORK))
+                .withName("external-network-ip-pool")
+                .withApplicationId(appId)
+                .build();
+        log.info("Started");
+    }
+
+    @Deactivate
+    protected void deactivate() {
+        eventExecutor.shutdown();
+        log.info("Stopped");
+    }
+
+    @Override
+    public void registerNetwork(IpPrefix cidr) {
+        if (!networkIpPool.containsKey(cidr.toString())) {
+            SubnetUtils utils = new SubnetUtils(cidr.toString());
+            utils.setInclusiveHostCount(false);
+            SubnetUtils.SubnetInfo info = utils.getInfo();
+
+            Set<String> all = Arrays.stream(info.getAllAddresses())
+                    .collect(Collectors.toSet());
+            all.remove(info.getNetworkAddress());
+            all.remove(info.getHighAddress());
+            all.remove(info.getLowAddress());
+            all.remove(info.getBroadcastAddress());
+
+            networkIpPool.put(cidr.toString(), all);
+        }
+    }
+
+    @Override
+    public void unregisterNetwork(IpPrefix cidr) {
+        if (!networkIpPool.containsKey(cidr.toString())) {
+            log.warn("The given network {} is not found!", cidr.toString());
+        } else {
+            networkIpPool.remove(cidr.toString());
+        }
+    }
+
+    @Override
+    public IpAddress getGatewayIp(IpPrefix cidr) {
+        SubnetUtils utils = new SubnetUtils(cidr.toString());
+        utils.setInclusiveHostCount(false);
+        SubnetUtils.SubnetInfo info = utils.getInfo();
+
+        return IpAddress.valueOf(info.getLowAddress());
+    }
+
+    @Override
+    public IpAddress allocateIp(IpPrefix cidr) {
+        if (!networkIpPool.containsKey(cidr.toString())) {
+            log.error("The given network {} is not found", cidr.toString());
+            return null;
+        } else {
+            Set<String> pool = networkIpPool.get(cidr.toString()).value();
+            String ipStr = pool.stream().findFirst().orElse(null);
+            if (ipStr == null) {
+                log.error("No IPs are found in the given network {}", cidr.toString());
+                return null;
+            }
+
+            pool.remove(ipStr);
+            networkIpPool.put(cidr.toString(), pool);
+            return IpAddress.valueOf(ipStr);
+        }
+    }
+
+    @Override
+    public void releaseIp(IpPrefix cidr, IpAddress ip) {
+        if (!networkIpPool.containsKey(cidr.toString())) {
+            log.error("The given network {} is not found", cidr.toString());
+        } else {
+            Set<String> pool = networkIpPool.get(cidr.toString()).value();
+            pool.add(ip.toString());
+            networkIpPool.put(cidr.toString(), pool);
+        }
+    }
+
+    @Override
+    public Set<String> getAllIps(IpPrefix cidr) {
+        return networkIpPool.get(cidr.toString()).value();
+    }
+}