Initial implementation of managing IPs for kubevirt spawned VMIs

Change-Id: I68127e1fe42a142765e7696d8ce80de16d3d94a9
diff --git a/apps/kubevirt-networking/BUILD b/apps/kubevirt-networking/BUILD
index af30386..4dfceee 100644
--- a/apps/kubevirt-networking/BUILD
+++ b/apps/kubevirt-networking/BUILD
@@ -2,6 +2,7 @@
     "//apps/kubevirt-networking/api:onos-apps-kubevirt-networking-api",
     "//apps/kubevirt-networking/app:onos-apps-kubevirt-networking-app",
     "@commons_net//jar",
+    "@ipaddress//jar",
     "@jersey_client//jar",
     "@json//jar",
     "@k8s_client//jar",
diff --git a/apps/kubevirt-networking/api/BUILD b/apps/kubevirt-networking/api/BUILD
index e1e477c..3f1c431 100644
--- a/apps/kubevirt-networking/api/BUILD
+++ b/apps/kubevirt-networking/api/BUILD
@@ -1,6 +1,7 @@
 COMPILE_DEPS = CORE_DEPS + [
     "@k8s_client//jar",
     "@k8s_model//jar",
+    "@ipaddress//jar",
     "@okhttp//jar",
     "@okio//jar",
     "@logging_interceptor//jar",
diff --git a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/Constants.java b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/Constants.java
index 9f8201a..7a5d873 100644
--- a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/Constants.java
+++ b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/Constants.java
@@ -59,6 +59,7 @@
     public static final int CLI_NAME_LENGTH = 30;
     public static final int CLI_IP_ADDRESSES_LENGTH = 50;
     public static final int CLI_IP_ADDRESS_LENGTH = 25;
+    public static final int CLI_IP_ADDRESS_AVAILABILITY = 15;
     public static final int CLI_MAC_ADDRESS_LENGTH = 25;
     public static final int CLI_PORTS_LENGTH = 20;
     public static final int CLI_NAMESPACE_LENGTH = 15;
diff --git a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPort.java b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPort.java
index 049a336..410c098 100644
--- a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPort.java
+++ b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPort.java
@@ -32,6 +32,7 @@
 
     private static final String NOT_NULL_MSG = "Port % cannot be null";
 
+    private final String networkId;
     private final MacAddress macAddress;
     private final IpAddress ipAddress;
     private final DeviceId deviceId;
@@ -40,13 +41,15 @@
     /**
      * Default constructor.
      *
+     * @param networkId         network identifier
      * @param macAddress        MAC address
      * @param ipAddress         IP address
      * @param deviceId          device identifier
      * @param portNumber        port number
      */
-    public DefaultKubevirtPort(MacAddress macAddress, IpAddress ipAddress,
+    public DefaultKubevirtPort(String networkId, MacAddress macAddress, IpAddress ipAddress,
                                DeviceId deviceId, PortNumber portNumber) {
+        this.networkId = networkId;
         this.macAddress = macAddress;
         this.ipAddress = ipAddress;
         this.deviceId = deviceId;
@@ -54,6 +57,11 @@
     }
 
     @Override
+    public String networkId() {
+        return networkId;
+    }
+
+    @Override
     public MacAddress macAddress() {
         return macAddress;
     }
@@ -92,18 +100,20 @@
             return false;
         }
         DefaultKubevirtPort that = (DefaultKubevirtPort) o;
-        return macAddress.equals(that.macAddress) && ipAddress.equals(that.ipAddress) &&
-                deviceId.equals(that.deviceId) && portNumber.equals(that.portNumber);
+        return networkId.equals(that.networkId) && macAddress.equals(that.macAddress) &&
+                ipAddress.equals(that.ipAddress) && deviceId.equals(that.deviceId) &&
+                portNumber.equals(that.portNumber);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(macAddress, ipAddress, deviceId, portNumber);
+        return Objects.hash(networkId, macAddress, ipAddress, deviceId, portNumber);
     }
 
     @Override
     public String toString() {
         return MoreObjects.toStringHelper(this)
+                .add("networkId", networkId)
                 .add("macAddress", macAddress)
                 .add("ipAddress", ipAddress)
                 .add("deviceId", deviceId)
@@ -125,6 +135,7 @@
      */
     public static final class Builder implements KubevirtPort.Builder {
 
+        private String networkId;
         private MacAddress macAddress;
         private IpAddress ipAddress;
         private DeviceId deviceId;
@@ -136,10 +147,18 @@
 
         @Override
         public KubevirtPort build() {
+            checkArgument(networkId != null, NOT_NULL_MSG, "networkId");
             checkArgument(macAddress != null, NOT_NULL_MSG, "macAddress");
             checkArgument(ipAddress != null, NOT_NULL_MSG, "ipAddress");
 
-            return new DefaultKubevirtPort(macAddress, ipAddress, deviceId, portNumber);
+            return new DefaultKubevirtPort(networkId, macAddress, ipAddress,
+                    deviceId, portNumber);
+        }
+
+        @Override
+        public Builder networkId(String networkId) {
+            this.networkId = networkId;
+            return this;
         }
 
         @Override
diff --git a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtIpPool.java b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtIpPool.java
index 64874fd..fb2906e 100644
--- a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtIpPool.java
+++ b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtIpPool.java
@@ -16,9 +16,19 @@
 package org.onosproject.kubevirtnetworking.api;
 
 import com.google.common.base.MoreObjects;
+import com.google.common.collect.ImmutableSet;
+import inet.ipaddr.AddressStringException;
+import inet.ipaddr.IPAddress;
+import inet.ipaddr.IPAddressSeqRange;
+import inet.ipaddr.IPAddressString;
 import org.onlab.packet.IpAddress;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
 import java.util.Objects;
+import java.util.Set;
 
 /**
  * Kubevirt IP Pool.
@@ -27,16 +37,25 @@
 
     private final IpAddress start;
     private final IpAddress end;
+    private final Set<IpAddress> allocatedIps;
+    private final Set<IpAddress> availableIps;
 
     /**
      * Default constructor.
      *
-     * @param start     start address of IP pool
-     * @param end       end address of IP pool
+     * @param start             start address of IP pool
+     * @param end               end address of IP pool
      */
     public KubevirtIpPool(IpAddress start, IpAddress end) {
         this.start = start;
         this.end = end;
+        this.allocatedIps = new HashSet<>();
+        this.availableIps = new HashSet<>();
+        try {
+            this.availableIps.addAll(getRangedIps(start.toString(), end.toString()));
+        } catch (AddressStringException e) {
+            e.printStackTrace();
+        }
     }
 
     /**
@@ -57,6 +76,61 @@
         return end;
     }
 
+    /**
+     * Returns the set of IP addresses that have been allocated.
+     *
+     * @return set of IP addresses that have been allocated
+     */
+    public Set<IpAddress> allocatedIps() {
+        return ImmutableSet.copyOf(allocatedIps);
+    }
+
+    /**
+     * Returns the set of IP addresses for allocation.
+     *
+     * @return set of IP addresses for allocation.
+     */
+    public Set<IpAddress> availableIps() {
+        return ImmutableSet.copyOf(availableIps);
+    }
+
+    /**
+     * Allocates a random IP address.
+     *
+     * @return allocated IP address
+     * @throws Exception exception
+     */
+    public synchronized IpAddress allocateIp() throws Exception {
+        if (availableIps.size() <= 0) {
+            throw new Exception("No IP address is available for allocation.");
+        }
+
+        List<IpAddress> sortedList = new ArrayList<>(availableIps);
+        Collections.sort(sortedList);
+
+        IpAddress ip = sortedList.get(0);
+
+        availableIps.remove(ip);
+        allocatedIps.add(ip);
+
+        return ip;
+    }
+
+    /**
+     * Releases the given IP address.
+     *
+     * @param ip IP address to be released
+     * @throws Exception exception
+     */
+    public synchronized void releaseIp(IpAddress ip) throws Exception {
+        if (!allocatedIps.contains(ip)) {
+            throw new Exception("The given IP address is not able to be released.");
+        }
+
+        allocatedIps.remove(ip);
+        availableIps.add(ip);
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) {
@@ -81,4 +155,24 @@
                 .add("end", end)
                 .toString();
     }
+
+    /**
+     * Obtains the IP address list from the given start and end range.
+     *
+     * @param start start range
+     * @param end   end range
+     * @return IP address list from the given start and end range
+     * @throws AddressStringException exception
+     */
+    public Set<IpAddress> getRangedIps(String start, String end) throws AddressStringException {
+        Set<IpAddress> ips = new HashSet<>();
+        IPAddress lower = new IPAddressString(start).toAddress();
+        IPAddress upper = new IPAddressString(end).toAddress();
+        IPAddressSeqRange range = lower.toSequentialRange(upper);
+        for (IPAddress addr : range.getIterable()) {
+            ips.add(IpAddress.valueOf(addr.toString()));
+        }
+
+        return ips;
+    }
 }
diff --git a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtPort.java b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtPort.java
index d7c1ff2..a7ae75e 100644
--- a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtPort.java
+++ b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/KubevirtPort.java
@@ -26,6 +26,13 @@
 public interface KubevirtPort {
 
     /**
+     * Returns the network identifier associated with the port.
+     *
+     * @return network identifier
+     */
+    String networkId();
+
+    /**
      * Returns the MAC address of the port.
      *
      * @return MAC address
@@ -82,6 +89,14 @@
         KubevirtPort build();
 
         /**
+         * Returns port builder with supplied network identifier.
+         *
+         * @param networkId network identifier
+         * @return port builder
+         */
+        Builder networkId(String networkId);
+
+        /**
          * Returns port builder with supplied MAC address.
          *
          * @param macAddress MAC address
diff --git a/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtInstanceTest.java b/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtInstanceTest.java
index c1e59b6..c391eb4 100644
--- a/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtInstanceTest.java
+++ b/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtInstanceTest.java
@@ -36,6 +36,8 @@
     private static final String UID_2 = "2";
     private static final String NAME_1 = "instance-1";
     private static final String NAME_2 = "instance-2";
+    private static final String NETWORK_ID_1 = "net-1";
+    private static final String NETWORK_ID_2 = "net-2";
     private static final MacAddress MAC_1 = MacAddress.valueOf("11:22:33:44:55:66");
     private static final MacAddress MAC_2 = MacAddress.valueOf("66:55:44:33:22:11");
     private static final IpAddress IP_1 = IpAddress.valueOf("10.10.10.10");
@@ -44,8 +46,8 @@
     private static final DeviceId DID_2 = DeviceId.deviceId("did2");
     private static final PortNumber PN_1 = PortNumber.portNumber(1);
     private static final PortNumber PN_2 = PortNumber.portNumber(2);
-    private static final KubevirtPort PORT_1 = createPort(MAC_1, IP_1, DID_1, PN_1);
-    private static final KubevirtPort PORT_2 = createPort(MAC_2, IP_2, DID_2, PN_2);
+    private static final KubevirtPort PORT_1 = createPort(NETWORK_ID_1, MAC_1, IP_1, DID_1, PN_1);
+    private static final KubevirtPort PORT_2 = createPort(NETWORK_ID_2, MAC_2, IP_2, DID_2, PN_2);
 
     private KubevirtInstance instance1;
     private KubevirtInstance sameAsInstance1;
@@ -105,8 +107,10 @@
         assertEquals(ImmutableSet.of(PORT_1), instance1.ports());
     }
 
-    static KubevirtPort createPort(MacAddress mac, IpAddress ip, DeviceId did, PortNumber pn) {
+    static KubevirtPort createPort(String networkId, MacAddress mac, IpAddress ip,
+                                   DeviceId did, PortNumber pn) {
         return DefaultKubevirtPort.builder()
+                .networkId(networkId)
                 .macAddress(mac)
                 .ipAddress(ip)
                 .deviceId(did)
diff --git a/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtNetworkTest.java b/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtNetworkTest.java
index 32ca958..1b39db8 100644
--- a/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtNetworkTest.java
+++ b/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtNetworkTest.java
@@ -22,6 +22,7 @@
 import org.onlab.packet.IpAddress;
 
 import static junit.framework.TestCase.assertEquals;
+import static junit.framework.TestCase.assertTrue;
 import static org.onlab.junit.ImmutableClassChecker.assertThatClassIsImmutable;
 import static org.onosproject.kubevirtnetworking.api.KubevirtNetwork.Type.FLAT;
 import static org.onosproject.kubevirtnetworking.api.KubevirtNetwork.Type.VXLAN;
@@ -128,4 +129,31 @@
         assertEquals(CIDR_1, network.cidr());
         assertEquals(new KubevirtIpPool(IP_POOL_START_1, IP_POOL_END_1), network.ipPool());
     }
+
+    /**
+     * Test IP address initialization.
+     */
+    @Test
+    public void testIpInitialization() {
+        KubevirtIpPool ipPool1 = network1.ipPool();
+        assertEquals(101, ipPool1.availableIps().size());
+        assertEquals(0, ipPool1.allocatedIps().size());
+    }
+
+    /**
+     * Test IP address allocation.
+     */
+    @Test
+    public void testIpAllocationAndRelease() throws Exception {
+        KubevirtIpPool ipPool1 = network1.ipPool();
+        IpAddress ip = ipPool1.allocateIp();
+        assertEquals(100, ipPool1.availableIps().size());
+        assertEquals(1, ipPool1.allocatedIps().size());
+        assertEquals(IpAddress.valueOf("10.10.10.100"), ip);
+
+        ipPool1.releaseIp(ip);
+        assertEquals(101, ipPool1.availableIps().size());
+        assertEquals(0, ipPool1.allocatedIps().size());
+        assertTrue(ipPool1.availableIps().contains(ip));
+    }
 }
diff --git a/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPortTest.java b/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPortTest.java
index 00f3cd4..f91ad2e 100644
--- a/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPortTest.java
+++ b/apps/kubevirt-networking/api/src/test/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtPortTest.java
@@ -30,6 +30,8 @@
  * Unit tests for the default kubevirt port class.
  */
 public class DefaultKubevirtPortTest {
+    private static final String NETWORK_ID_1 = "net-1";
+    private static final String NETWORK_ID_2 = "net-2";
     private static final MacAddress MAC_ADDRESS_1 = MacAddress.valueOf("00:11:22:33:44:55");
     private static final MacAddress MAC_ADDRESS_2 = MacAddress.valueOf("11:22:33:44:55:66");
     private static final IpAddress IP_ADDRESS_1 = IpAddress.valueOf("10.10.10.10");
@@ -57,6 +59,7 @@
     @Before
     public void setUp() {
         port1 = DefaultKubevirtPort.builder()
+                .networkId(NETWORK_ID_1)
                 .macAddress(MAC_ADDRESS_1)
                 .ipAddress(IP_ADDRESS_1)
                 .deviceId(DEVICE_ID_1)
@@ -64,6 +67,7 @@
                 .build();
 
         sameAsPort1 = DefaultKubevirtPort.builder()
+                .networkId(NETWORK_ID_1)
                 .macAddress(MAC_ADDRESS_1)
                 .ipAddress(IP_ADDRESS_1)
                 .deviceId(DEVICE_ID_1)
@@ -71,6 +75,7 @@
                 .build();
 
         port2 = DefaultKubevirtPort.builder()
+                .networkId(NETWORK_ID_2)
                 .macAddress(MAC_ADDRESS_2)
                 .ipAddress(IP_ADDRESS_2)
                 .deviceId(DEVICE_ID_2)
@@ -95,6 +100,7 @@
     public void testConstruction() {
         KubevirtPort port = port1;
 
+        assertEquals(NETWORK_ID_1, port.networkId());
         assertEquals(MAC_ADDRESS_1, port.macAddress());
         assertEquals(IP_ADDRESS_1, port.ipAddress());
         assertEquals(DEVICE_ID_1, port.deviceId());
diff --git a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/cli/KubevirtListIpAddressCommand.java b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/cli/KubevirtListIpAddressCommand.java
new file mode 100644
index 0000000..343997b
--- /dev/null
+++ b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/cli/KubevirtListIpAddressCommand.java
@@ -0,0 +1,81 @@
+/*
+ * 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.onosproject.kubevirtnetworking.cli;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.karaf.shell.api.action.Argument;
+import org.apache.karaf.shell.api.action.Command;
+import org.apache.karaf.shell.api.action.Completion;
+import org.apache.karaf.shell.api.action.lifecycle.Service;
+import org.onlab.packet.IpAddress;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.kubevirtnetworking.api.KubevirtIpPool;
+import org.onosproject.kubevirtnetworking.api.KubevirtNetwork;
+import org.onosproject.kubevirtnetworking.api.KubevirtNetworkService;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import static org.onosproject.kubevirtnetworking.api.Constants.CLI_IP_ADDRESS_AVAILABILITY;
+import static org.onosproject.kubevirtnetworking.api.Constants.CLI_IP_ADDRESS_LENGTH;
+import static org.onosproject.kubevirtnetworking.util.KubevirtNetworkingUtil.genFormatString;
+
+/**
+ * Lists all IP addresses.
+ */
+@Service
+@Command(scope = "onos", name = "kubevirt-ips",
+        description = "Lists all IP addresses")
+public class KubevirtListIpAddressCommand extends AbstractShellCommand {
+
+    @Argument(name = "networkId", description = "Network ID")
+    @Completion(KubevirtNetworkIdCompleter.class)
+    private String networkId = null;
+
+    @Override
+    protected void doExecute() throws Exception {
+        KubevirtNetworkService service = get(KubevirtNetworkService.class);
+        KubevirtNetwork network = service.network(networkId);
+
+        if (network == null) {
+            print("No network was found with the given network ID");
+            return;
+        }
+
+        KubevirtIpPool pool = network.ipPool();
+        if (pool == null) {
+            print("No IP pool was found with the given network ID");
+            return;
+        }
+
+        String format = genFormatString(ImmutableList.of(
+                CLI_IP_ADDRESS_LENGTH, CLI_IP_ADDRESS_AVAILABILITY));
+        print(format, "IP Address", "Availability");
+
+        List<IpAddress> sortedAllocatedIps = new ArrayList<>(pool.allocatedIps());
+        Collections.sort(sortedAllocatedIps);
+        for (IpAddress ip : sortedAllocatedIps) {
+            print(format, ip.toString(), "[ X ]");
+        }
+
+        List<IpAddress> sortedAvailableIps = new ArrayList<>(pool.availableIps());
+        Collections.sort(sortedAvailableIps);
+        for (IpAddress ip : sortedAvailableIps) {
+            print(format, ip.toString(), "[ O ]");
+        }
+    }
+}
diff --git a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/cli/KubevirtNetworkIdCompleter.java b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/cli/KubevirtNetworkIdCompleter.java
new file mode 100644
index 0000000..91b011b
--- /dev/null
+++ b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/cli/KubevirtNetworkIdCompleter.java
@@ -0,0 +1,51 @@
+/*
+ * 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.onosproject.kubevirtnetworking.cli;
+
+import org.apache.karaf.shell.api.action.lifecycle.Service;
+import org.apache.karaf.shell.api.console.CommandLine;
+import org.apache.karaf.shell.api.console.Completer;
+import org.apache.karaf.shell.api.console.Session;
+import org.apache.karaf.shell.support.completers.StringsCompleter;
+import org.onosproject.kubevirtnetworking.api.KubevirtNetwork;
+import org.onosproject.kubevirtnetworking.api.KubevirtNetworkService;
+
+import java.util.List;
+import java.util.Set;
+import java.util.SortedSet;
+import java.util.stream.Collectors;
+
+import static org.onosproject.cli.AbstractShellCommand.get;
+
+/**
+ * Kubevirt network ID completer.
+ */
+@Service
+public class KubevirtNetworkIdCompleter implements Completer {
+    @Override
+    public int complete(Session session, CommandLine commandLine, List<String> candidates) {
+        StringsCompleter delegate = new StringsCompleter();
+        KubevirtNetworkService networkService = get(KubevirtNetworkService.class);
+
+        Set<String> netIds = networkService.networks().stream().map(KubevirtNetwork::networkId)
+                .collect(Collectors.toSet());
+        SortedSet<String> strings = delegate.getStrings();
+
+        strings.addAll(netIds);
+
+        return delegate.complete(session, commandLine, candidates);
+    }
+}
diff --git a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/codec/KubevirtNetworkCodec.java b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/codec/KubevirtNetworkCodec.java
index 3416ba2..c8cc377 100644
--- a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/codec/KubevirtNetworkCodec.java
+++ b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/codec/KubevirtNetworkCodec.java
@@ -115,6 +115,13 @@
                 .gatewayIp(IpAddress.valueOf(gatewayIp))
                 .cidr(cidr);
 
+        if (!type.equals(KubevirtNetwork.Type.FLAT.name())) {
+            JsonNode segmentIdJson = json.get(SEGMENT_ID);
+            if (segmentIdJson != null) {
+                networkBuilder.segmentId(segmentIdJson.asText());
+            }
+        }
+
         JsonNode ipPoolJson = json.get(IP_POOL);
         if (ipPoolJson != null) {
             final JsonCodec<KubevirtIpPool>
diff --git a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/KubevirtDhcpHandler.java b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/KubevirtDhcpHandler.java
new file mode 100644
index 0000000..74b7c8a
--- /dev/null
+++ b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/KubevirtDhcpHandler.java
@@ -0,0 +1,622 @@
+/*
+ * 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.onosproject.kubevirtnetworking.impl;
+
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+import org.onlab.packet.DHCP;
+import org.onlab.packet.Ethernet;
+import org.onlab.packet.IPv4;
+import org.onlab.packet.Ip4Address;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.IpPrefix;
+import org.onlab.packet.MacAddress;
+import org.onlab.packet.UDP;
+import org.onlab.packet.dhcp.DhcpOption;
+import org.onlab.util.Tools;
+import org.onosproject.cfg.ComponentConfigService;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.cluster.LeadershipService;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.kubevirtnetworking.api.KubevirtFlowRuleService;
+import org.onosproject.kubevirtnetworking.api.KubevirtHostRoute;
+import org.onosproject.kubevirtnetworking.api.KubevirtNetwork;
+import org.onosproject.kubevirtnetworking.api.KubevirtNetworkService;
+import org.onosproject.kubevirtnetworking.api.KubevirtPort;
+import org.onosproject.kubevirtnetworking.api.KubevirtPortService;
+import org.onosproject.kubevirtnode.api.KubevirtNodeEvent;
+import org.onosproject.kubevirtnode.api.KubevirtNodeListener;
+import org.onosproject.kubevirtnode.api.KubevirtNodeService;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.flow.DefaultTrafficTreatment;
+import org.onosproject.net.flow.TrafficTreatment;
+import org.onosproject.net.packet.DefaultOutboundPacket;
+import org.onosproject.net.packet.PacketContext;
+import org.onosproject.net.packet.PacketProcessor;
+import org.onosproject.net.packet.PacketService;
+import org.osgi.service.component.ComponentContext;
+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.Modified;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.component.annotations.ReferenceCardinality;
+import org.slf4j.Logger;
+
+import java.nio.ByteBuffer;
+import java.util.Dictionary;
+import java.util.List;
+import java.util.Objects;
+import java.util.concurrent.ExecutorService;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_BroadcastAddress;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_Classless_Static_Route;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_DHCPServerIp;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_DomainServer;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_END;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_LeaseTime;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_MessageType;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_RouterAddress;
+import static org.onlab.packet.DHCP.DHCPOptionCode.OptionCode_SubnetMask;
+import static org.onlab.packet.DHCP.MsgType.DHCPACK;
+import static org.onlab.packet.DHCP.MsgType.DHCPOFFER;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.onosproject.kubevirtnetworking.api.Constants.KUBEVIRT_NETWORKING_APP_ID;
+import static org.onosproject.kubevirtnetworking.impl.OsgiPropertyConstants.DHCP_SERVER_MAC;
+import static org.onosproject.kubevirtnetworking.impl.OsgiPropertyConstants.DHCP_SERVER_MAC_DEFAULT;
+import static org.onosproject.kubevirtnetworking.util.KubevirtNetworkingUtil.getBroadcastAddr;
+import static org.onosproject.kubevirtnode.api.KubevirtNode.Type.WORKER;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Handles DHCP requests for the virtual instances.
+ */
+@Component(
+        immediate = true,
+        property = {
+                DHCP_SERVER_MAC + "=" + DHCP_SERVER_MAC_DEFAULT
+        }
+)
+public class KubevirtDhcpHandler {
+    protected final Logger log = getLogger(getClass());
+
+    private static final Ip4Address DEFAULT_PRIMARY_DNS = Ip4Address.valueOf("8.8.8.8");
+    private static final Ip4Address DEFAULT_SECONDARY_DNS = Ip4Address.valueOf("8.8.4.4");
+    private static final byte PACKET_TTL = (byte) 127;
+
+    // TODO add MTU, static route option codes to ONOS DHCP and remove here
+    private static final byte DHCP_OPTION_MTU = (byte) 26;
+    private static final byte[] DHCP_DATA_LEASE_INFINITE =
+            ByteBuffer.allocate(4).putInt(-1).array();
+
+    private static final int OCTET_BIT_LENGTH = 8;
+    private static final int V4_BYTE_SIZE = 4;
+    private static final int V4_CIDR_LOWER_BOUND = -1;
+    private static final int V4_CIDR_UPPER_BOUND = 33;
+    private static final int PADDING_SIZE = 4;
+
+    private static final byte HARDWARE_ADDR_LENGTH = (byte) 6;
+    private static final byte DHCP_OPTION_DATA_LENGTH = (byte) 4;
+    private static final int DHCP_OPTION_DNS_LENGTH = 8;
+    private static final int DHCP_OPTION_MTU_LENGTH = 2;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected ComponentConfigService configService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected PacketService packetService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected LeadershipService leadershipService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected KubevirtNodeService nodeService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected KubevirtPortService portService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected KubevirtNetworkService networkService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected KubevirtFlowRuleService flowService;
+
+    /** Fake MAC address for virtual network subnet gateway. */
+    private String dhcpServerMac = DHCP_SERVER_MAC_DEFAULT;
+
+    private final PacketProcessor packetProcessor = new InternalPacketProcessor();
+    private final KubevirtNodeListener nodeListener = new InternalNodeEventListener();
+
+    private final ExecutorService eventExecutor = newSingleThreadExecutor(
+            groupedThreads(this.getClass().getSimpleName(), "event-handler"));
+
+    private ApplicationId appId;
+    private NodeId localNodeId;
+
+    @Activate
+    protected void activate() {
+        appId = coreService.registerApplication(KUBEVIRT_NETWORKING_APP_ID);
+        localNodeId = clusterService.getLocalNode().id();
+        nodeService.addListener(nodeListener);
+        configService.registerProperties(getClass());
+        packetService.addProcessor(packetProcessor, PacketProcessor.director(0));
+        leadershipService.runForLeadership(appId.name());
+
+        log.info("Started");
+    }
+
+    @Deactivate
+    protected void deactivate() {
+        packetService.removeProcessor(packetProcessor);
+        nodeService.removeListener(nodeListener);
+        configService.unregisterProperties(getClass(), false);
+        leadershipService.withdraw(appId.name());
+        eventExecutor.shutdown();
+
+        log.info("Stopped");
+    }
+
+    @Modified
+    protected void modified(ComponentContext context) {
+        Dictionary<?, ?> properties = context.getProperties();
+        String updatedMac;
+
+        updatedMac = Tools.get(properties, DHCP_SERVER_MAC);
+
+        if (!Strings.isNullOrEmpty(updatedMac) && !updatedMac.equals(dhcpServerMac)) {
+            dhcpServerMac = updatedMac;
+        }
+
+        log.info("Modified");
+    }
+
+    private class InternalPacketProcessor implements PacketProcessor {
+
+        @Override
+        public void process(PacketContext context) {
+            if (context.isHandled()) {
+                return;
+            }
+
+            Ethernet ethPacket = context.inPacket().parsed();
+            if (ethPacket == null || ethPacket.getEtherType() != Ethernet.TYPE_IPV4) {
+                return;
+            }
+            IPv4 ipv4Packet = (IPv4) ethPacket.getPayload();
+            if (ipv4Packet.getProtocol() != IPv4.PROTOCOL_UDP) {
+                return;
+            }
+            UDP udpPacket = (UDP) ipv4Packet.getPayload();
+            if (udpPacket.getDestinationPort() != UDP.DHCP_SERVER_PORT ||
+                    udpPacket.getSourcePort() != UDP.DHCP_CLIENT_PORT) {
+                return;
+            }
+
+            DHCP dhcpPacket = (DHCP) udpPacket.getPayload();
+
+            eventExecutor.execute(() -> processDhcp(context, dhcpPacket));
+        }
+
+        private void processDhcp(PacketContext context, DHCP dhcpPacket) {
+            if (dhcpPacket == null) {
+                log.trace("DHCP packet without payload received, do nothing");
+                return;
+            }
+
+            DHCP.MsgType inPacketType = getPacketType(dhcpPacket);
+            if (inPacketType == null || dhcpPacket.getClientHardwareAddress() == null) {
+                log.trace("Malformed DHCP packet received, ignore it");
+                return;
+            }
+
+            MacAddress clientMac = MacAddress.valueOf(dhcpPacket.getClientHardwareAddress());
+
+            KubevirtPort port = portService.ports().stream()
+                    .filter(p -> p.macAddress().equals(clientMac))
+                    .findAny().orElse(null);
+
+            if (port == null) {
+                log.debug("Ignore DHCP request, since it comes from unmanaged VM {}", clientMac);
+                return;
+            }
+
+            IpAddress fixedIp = port.ipAddress();
+
+            if (fixedIp == null) {
+                log.warn("There is no IP addresses are assigned with the port {}", port.macAddress());
+                return;
+            }
+
+            Ethernet ethPacket = context.inPacket().parsed();
+            switch (inPacketType) {
+                case DHCPDISCOVER:
+                    processDhcpDiscover(context, clientMac, port, ethPacket);
+                    break;
+                case DHCPREQUEST:
+                    processDhcpRequest(context, clientMac, port, ethPacket);
+                    break;
+                case DHCPRELEASE:
+                    log.trace("DHCP RELEASE received from {}", clientMac);
+                    // do nothing
+                    break;
+                default:
+                    break;
+            }
+        }
+
+        private void processDhcpDiscover(PacketContext context, MacAddress clientMac,
+                                         KubevirtPort port, Ethernet ethPacket) {
+            log.trace("DHCP DISCOVER received from {}", clientMac);
+            Ethernet discoverReply = buildReply(ethPacket,
+                    (byte) DHCPOFFER.getValue(),
+                    port);
+            sendReply(context, discoverReply);
+            log.trace("DHCP OFFER({}) is sent for {}", port.ipAddress().toString(), clientMac);
+        }
+
+        private void processDhcpRequest(PacketContext context, MacAddress clientMac,
+                                        KubevirtPort port, Ethernet ethPacket) {
+            log.trace("DHCP REQUEST received from {}", clientMac);
+            Ethernet requestReply = buildReply(ethPacket,
+                    (byte) DHCPACK.getValue(),
+                    port);
+            sendReply(context, requestReply);
+            log.trace("DHCP ACK({}) is sent for {}", port.ipAddress(), clientMac);
+        }
+
+        private DHCP.MsgType getPacketType(DHCP dhcpPacket) {
+            DhcpOption optType = dhcpPacket.getOption(OptionCode_MessageType);
+            if (optType == null) {
+                log.trace("DHCP packet with no message type, ignore it");
+                return null;
+            }
+
+            DHCP.MsgType inPacketType = DHCP.MsgType.getType(optType.getData()[0]);
+            if (inPacketType == null) {
+                log.trace("DHCP packet with no packet type, ignore it");
+            }
+            return inPacketType;
+        }
+
+        private Ethernet buildReply(Ethernet ethRequest, byte packetType,
+                                    KubevirtPort port) {
+            log.trace("Build for DHCP reply msg for openstack port {}", port.toString());
+
+            // pick one IP address to make a reply
+            // since we check the validity of fixed IP address at parent method,
+            // so no need to double check the fixed IP existence here
+            IpAddress fixedIp = port.ipAddress();
+
+            KubevirtNetwork network = networkService.network(port.networkId());
+
+            Ethernet ethReply = new Ethernet();
+            ethReply.setSourceMACAddress(dhcpServerMac);
+            ethReply.setDestinationMACAddress(ethRequest.getSourceMAC());
+            ethReply.setEtherType(Ethernet.TYPE_IPV4);
+
+            IPv4 ipv4Request = (IPv4) ethRequest.getPayload();
+            IPv4 ipv4Reply = new IPv4();
+
+            ipv4Reply.setSourceAddress(
+                    clusterService.getLocalNode().ip().getIp4Address().toString());
+            ipv4Reply.setDestinationAddress(fixedIp.toString());
+            ipv4Reply.setTtl(PACKET_TTL);
+
+            UDP udpRequest = (UDP) ipv4Request.getPayload();
+            UDP udpReply = new UDP();
+            udpReply.setSourcePort((byte) UDP.DHCP_SERVER_PORT);
+            udpReply.setDestinationPort((byte) UDP.DHCP_CLIENT_PORT);
+
+            DHCP dhcpRequest = (DHCP) udpRequest.getPayload();
+            DHCP dhcpReply = buildDhcpReply(
+                    dhcpRequest,
+                    packetType,
+                    Ip4Address.valueOf(fixedIp.toString()), port, network);
+
+            udpReply.setPayload(dhcpReply);
+            ipv4Reply.setPayload(udpReply);
+            ethReply.setPayload(ipv4Reply);
+
+            return ethReply;
+        }
+
+        private void sendReply(PacketContext context, Ethernet ethReply) {
+            if (ethReply == null) {
+                return;
+            }
+            ConnectPoint srcPoint = context.inPacket().receivedFrom();
+            TrafficTreatment treatment = DefaultTrafficTreatment
+                    .builder()
+                    .setOutput(srcPoint.port())
+                    .build();
+
+            packetService.emit(new DefaultOutboundPacket(
+                    srcPoint.deviceId(),
+                    treatment,
+                    ByteBuffer.wrap(ethReply.serialize())));
+            context.block();
+        }
+
+        private DHCP buildDhcpReply(DHCP request, byte msgType, Ip4Address yourIp,
+                                    KubevirtPort port, KubevirtNetwork network) {
+            Ip4Address gatewayIp = clusterService.getLocalNode().ip().getIp4Address();
+            int subnetPrefixLen = IpPrefix.valueOf(network.cidr()).prefixLength();
+
+            DHCP dhcpReply = new DHCP();
+            dhcpReply.setOpCode(DHCP.OPCODE_REPLY);
+            dhcpReply.setHardwareType(DHCP.HWTYPE_ETHERNET);
+            dhcpReply.setHardwareAddressLength(HARDWARE_ADDR_LENGTH);
+            dhcpReply.setTransactionId(request.getTransactionId());
+            dhcpReply.setFlags(request.getFlags());
+            dhcpReply.setYourIPAddress(yourIp.toInt());
+            dhcpReply.setServerIPAddress(gatewayIp.toInt());
+            dhcpReply.setClientHardwareAddress(request.getClientHardwareAddress());
+
+            List<DhcpOption> options = Lists.newArrayList();
+
+            // message type
+            options.add(doMsgType(msgType));
+
+            // server identifier
+            options.add(doServerId(gatewayIp));
+
+            // lease time
+            options.add(doLeaseTime());
+
+            // subnet mask
+            options.add(doSubnetMask(subnetPrefixLen));
+
+            // broadcast address
+            options.add(doBroadcastAddr(yourIp, subnetPrefixLen));
+
+            // domain server
+            options.add(doDomainServer(network));
+
+            // mtu
+            options.add(doMtu(network));
+
+            // classless static route
+            if (!network.hostRoutes().isEmpty()) {
+                options.add(doClasslessSr(network));
+            }
+
+            // Sets the default router address up.
+            // Performs only if the gateway is set in subnet.
+            if (network.gatewayIp() != null) {
+                options.add(doRouterAddr(network));
+            }
+
+            // end option
+            options.add(doEnd());
+
+            dhcpReply.setOptions(options);
+            return dhcpReply;
+        }
+
+
+        private DhcpOption doMsgType(byte msgType) {
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_MessageType.getValue());
+            option.setLength((byte) 1);
+            byte[] optionData = {msgType};
+            option.setData(optionData);
+            return option;
+        }
+
+        private DhcpOption doServerId(IpAddress gatewayIp) {
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_DHCPServerIp.getValue());
+            option.setLength(DHCP_OPTION_DATA_LENGTH);
+            option.setData(gatewayIp.toOctets());
+            return option;
+        }
+
+        private DhcpOption doLeaseTime() {
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_LeaseTime.getValue());
+            option.setLength(DHCP_OPTION_DATA_LENGTH);
+            option.setData(DHCP_DATA_LEASE_INFINITE);
+            return option;
+        }
+
+        private DhcpOption doSubnetMask(int subnetPrefixLen) {
+            Ip4Address subnetMask = Ip4Address.makeMaskPrefix(subnetPrefixLen);
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_SubnetMask.getValue());
+            option.setLength(DHCP_OPTION_DATA_LENGTH);
+            option.setData(subnetMask.toOctets());
+            return option;
+        }
+
+        private DhcpOption doBroadcastAddr(Ip4Address yourIp, int subnetPrefixLen) {
+            String broadcast = getBroadcastAddr(yourIp.toString(), subnetPrefixLen);
+
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_BroadcastAddress.getValue());
+            option.setLength(DHCP_OPTION_DATA_LENGTH);
+            option.setData(IpAddress.valueOf(broadcast).toOctets());
+
+            return option;
+        }
+
+        private DhcpOption doDomainServer(KubevirtNetwork network) {
+            DhcpOption option = new DhcpOption();
+
+            option.setCode(OptionCode_DomainServer.getValue());
+
+            option.setLength((byte) DHCP_OPTION_DNS_LENGTH);
+            ByteBuffer dnsByteBuf = ByteBuffer.allocate(DHCP_OPTION_DNS_LENGTH);
+            dnsByteBuf.put(DEFAULT_PRIMARY_DNS.toOctets());
+            dnsByteBuf.put(DEFAULT_SECONDARY_DNS.toOctets());
+
+            option.setData(dnsByteBuf.array());
+
+            // TODO: need to customize the DNS server list
+//            if (dnsServers.isEmpty()) {
+//
+//            } else {
+//                int dnsLength = 4 * dnsServers.size();
+//
+//                option.setLength((byte) dnsLength);
+//
+//                ByteBuffer dnsByteBuf = ByteBuffer.allocate(DHCP_OPTION_DNS_LENGTH);
+//
+//                for (String dnsServer : dnsServers) {
+//                    dnsByteBuf.put(IpAddress.valueOf(dnsServer).toOctets());
+//                }
+//                option.setData(dnsByteBuf.array());
+//            }
+
+            return option;
+        }
+
+        private DhcpOption doMtu(KubevirtNetwork network) {
+            DhcpOption option = new DhcpOption();
+            option.setCode(DHCP_OPTION_MTU);
+            option.setLength((byte) DHCP_OPTION_MTU_LENGTH);
+            checkNotNull(network);
+            checkNotNull(network.mtu());
+
+            option.setData(ByteBuffer.allocate(DHCP_OPTION_MTU_LENGTH)
+                    .putShort(network.mtu().shortValue()).array());
+
+            return option;
+        }
+
+        private DhcpOption doClasslessSr(KubevirtNetwork network) {
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_Classless_Static_Route.getValue());
+
+            int hostRoutesSize = hostRoutesSize(ImmutableList.copyOf(network.hostRoutes()));
+            if (hostRoutesSize == 0) {
+                throw new IllegalArgumentException("Illegal CIDR hostRoutesSize value!");
+            }
+
+            log.trace("hostRouteSize: {}", hostRoutesSize);
+
+            option.setLength((byte) hostRoutesSize);
+            ByteBuffer hostRouteByteBuf = ByteBuffer.allocate(hostRoutesSize);
+
+            network.hostRoutes().forEach(h -> {
+                log.debug("processing host route information: {}", h.toString());
+
+                IpPrefix ipPrefix = h.destination();
+
+                hostRouteByteBuf.put(Objects.requireNonNull(bytesDestinationDescriptor(ipPrefix)));
+                hostRouteByteBuf.put(h.nexthop().toOctets());
+            });
+
+            option.setData(hostRouteByteBuf.array());
+            return option;
+        }
+
+        private DhcpOption doRouterAddr(KubevirtNetwork network) {
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_RouterAddress.getValue());
+            option.setLength(DHCP_OPTION_DATA_LENGTH);
+            option.setData(Ip4Address.valueOf(network.gatewayIp().toString()).toOctets());
+            return option;
+        }
+
+        private DhcpOption doEnd() {
+            DhcpOption option = new DhcpOption();
+            option.setCode(OptionCode_END.getValue());
+            option.setLength((byte) 1);
+            return option;
+        }
+
+        private int hostRoutesSize(List<KubevirtHostRoute> hostRoutes) {
+            int size = 0;
+            int preFixLen;
+
+            for (KubevirtHostRoute h : hostRoutes) {
+                preFixLen = h.destination().prefixLength();
+                if (Math.max(V4_CIDR_LOWER_BOUND, preFixLen) == V4_CIDR_LOWER_BOUND ||
+                        Math.min(preFixLen, V4_CIDR_UPPER_BOUND) == V4_CIDR_UPPER_BOUND) {
+                    throw new IllegalArgumentException("Illegal CIDR length value!");
+                }
+
+                for (int i = 0; i <= V4_BYTE_SIZE; i++) {
+                    if (preFixLen == Math.min(preFixLen, i * OCTET_BIT_LENGTH)) {
+                        size = size + i + 1 + PADDING_SIZE;
+                        break;
+                    }
+                }
+            }
+            return size;
+        }
+
+        private byte[] bytesDestinationDescriptor(IpPrefix ipPrefix) {
+            ByteBuffer byteBuffer;
+            int prefixLen = ipPrefix.prefixLength();
+
+            // retrieve ipPrefix to the destination descriptor format
+            // ex) 10.1.1.0/24 -> [10,1,1,0]
+            String[] ipPrefixString = ipPrefix.getIp4Prefix().toString()
+                    .split("/")[0]
+                    .split("\\.");
+
+            // retrieve destination descriptor and put this to byte buffer
+            // according to RFC 3442
+            // ex) 0.0.0.0/0 -> 0
+            // ex) 10.0.0.0/8 -> 8.10
+            // ex) 10.17.0.0/16 -> 16.10.17
+            // ex) 10.27.129.0/24 -> 24.10.27.129
+            // ex) 10.229.0.128/25 -> 25.10.229.0.128
+            for (int i = 0; i <= V4_BYTE_SIZE; i++) {
+                if (prefixLen == Math.min(prefixLen, i * OCTET_BIT_LENGTH)) {
+                    byteBuffer = ByteBuffer.allocate(i + 1);
+                    byteBuffer.put((byte) prefixLen);
+
+                    for (int j = 0; j < i; j++) {
+                        byteBuffer.put((byte) Integer.parseInt(ipPrefixString[j]));
+                    }
+                    return byteBuffer.array();
+                }
+            }
+
+            return null;
+        }
+    }
+
+    private class InternalNodeEventListener implements KubevirtNodeListener {
+
+        @Override
+        public boolean isRelevant(KubevirtNodeEvent event) {
+            return event.subject().type() == WORKER;
+        }
+
+        private boolean isRelevantHelper() {
+            return Objects.equals(localNodeId, leadershipService.getLeader(appId.name()));
+        }
+
+        @Override
+        public void event(KubevirtNodeEvent event) {
+
+        }
+    }
+}
diff --git a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/util/KubevirtNetworkingUtil.java b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/util/KubevirtNetworkingUtil.java
index e00eb52..c7051bb 100644
--- a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/util/KubevirtNetworkingUtil.java
+++ b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/util/KubevirtNetworkingUtil.java
@@ -17,14 +17,19 @@
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.apache.commons.lang.StringUtils;
+import org.apache.commons.net.util.SubnetUtils;
+import org.onlab.packet.IpAddress;
 import org.onosproject.cfg.ConfigProperty;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  * An utility that used in KubeVirt networking app.
@@ -105,4 +110,39 @@
         }
         return null;
     }
+
+    /**
+     * Obtains valid IP addresses of the given subnet.
+     *
+     * @param cidr CIDR
+     * @return set of IP addresses
+     */
+    public static Set<IpAddress> getSubnetIps(String cidr) {
+        SubnetUtils utils = new SubnetUtils(cidr);
+        utils.setInclusiveHostCount(false);
+        SubnetUtils.SubnetInfo info = utils.getInfo();
+        Set<String> allAddresses =
+                new HashSet<>(Arrays.asList(info.getAllAddresses()));
+
+        if (allAddresses.size() > 2) {
+            allAddresses.remove(info.getLowAddress());
+            allAddresses.remove(info.getHighAddress());
+        }
+
+        return allAddresses.stream()
+                .map(IpAddress::valueOf).collect(Collectors.toSet());
+    }
+
+    /**
+     * Calculate the broadcast address from given IP address and subnet prefix length.
+     *
+     * @param ipAddr        IP address
+     * @param prefixLength  subnet prefix length
+     * @return broadcast address
+     */
+    public static String getBroadcastAddr(String ipAddr, int prefixLength) {
+        String subnet = ipAddr + "/" + prefixLength;
+        SubnetUtils utils = new SubnetUtils(subnet);
+        return utils.getInfo().getBroadcastAddress();
+    }
 }