[GEANT] Unit tests for  SDX-L3 ARP handler.

Change-Id: I5d2a4f5cdde72cf089413a2299681a6c56fb2868
diff --git a/sdx-l3/src/test/java/org/onosproject/sdxl3/SdxL3ArpHandlerTest.java b/sdx-l3/src/test/java/org/onosproject/sdxl3/SdxL3ArpHandlerTest.java
new file mode 100644
index 0000000..2c50246
--- /dev/null
+++ b/sdx-l3/src/test/java/org/onosproject/sdxl3/SdxL3ArpHandlerTest.java
@@ -0,0 +1,1246 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.sdxl3;
+
+import com.google.common.collect.Sets;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.packet.ARP;
+import org.onlab.packet.Ethernet;
+import org.onlab.packet.ICMP6;
+import org.onlab.packet.IPacket;
+import org.onlab.packet.IPv6;
+import org.onlab.packet.Ip4Address;
+import org.onlab.packet.Ip4Prefix;
+import org.onlab.packet.Ip6Address;
+import org.onlab.packet.Ip6Prefix;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.IpPrefix;
+import org.onlab.packet.MacAddress;
+import org.onlab.packet.VlanId;
+import org.onlab.packet.ndp.NeighborAdvertisement;
+import org.onlab.packet.ndp.NeighborDiscoveryOptions;
+import org.onlab.packet.ndp.NeighborSolicitation;
+import org.onosproject.incubator.net.intf.Interface;
+import org.onosproject.incubator.net.intf.InterfaceService;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DefaultHost;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Host;
+import org.onosproject.net.HostId;
+import org.onosproject.net.HostLocation;
+import org.onosproject.net.Link;
+import org.onosproject.net.Port;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.device.DeviceListener;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.edge.EdgePortService;
+import org.onosproject.net.flow.instructions.Instruction;
+import org.onosproject.net.flow.instructions.Instructions.OutputInstruction;
+import org.onosproject.net.host.HostService;
+import org.onosproject.net.host.InterfaceIpAddress;
+import org.onosproject.net.link.LinkListener;
+import org.onosproject.net.link.LinkService;
+import org.onosproject.net.packet.DefaultInboundPacket;
+import org.onosproject.net.packet.InboundPacket;
+import org.onosproject.net.packet.OutboundPacket;
+import org.onosproject.net.packet.PacketServiceAdapter;
+import org.onosproject.net.provider.ProviderId;
+import org.onosproject.routing.config.BgpConfig;
+
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+
+import static org.easymock.EasyMock.anyObject;
+import static org.easymock.EasyMock.createMock;
+import static org.easymock.EasyMock.expect;
+import static org.easymock.EasyMock.replay;
+import static org.easymock.EasyMock.reset;
+import static org.hamcrest.Matchers.anyOf;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Tests for the {@link SdxL3ArpHandler} class. It is based on tests for basic
+ * proxy ARP handling. Additional test cases for traffic between BGP peers are
+ * also included.
+ */
+public class SdxL3ArpHandlerTest {
+
+    private static final int NUM_DEVICES = 10;
+    private static final int NUM_PORTS_PER_DEVICE = 3;
+    private static final int LAST_CONF_DEVICE_INTF_VLAN_IP = 3;
+    private static final int LAST_CONF_DEVICE_INTF_VLAN = 6;
+
+    private static final Ip4Address IP1 = Ip4Address.valueOf("192.168.1.1");
+    private static final Ip4Address IP2 = Ip4Address.valueOf("192.168.1.2");
+    private static final Ip6Address IP3 = Ip6Address.valueOf("1000:ffff::1");
+    private static final Ip6Address IP4 = Ip6Address.valueOf("1000:ffff::2");
+
+    private static final ProviderId PID = new ProviderId("of", "foo");
+
+    private static final VlanId VLAN1 = VlanId.vlanId((short) 1);
+    private static final VlanId VLAN2 = VlanId.vlanId((short) 2);
+    private static final VlanId VLAN10 = VlanId.vlanId((short) 10);
+
+    private static final MacAddress MAC1 = MacAddress.valueOf("00:00:00:00:00:01");
+    private static final MacAddress MAC2 = MacAddress.valueOf("00:00:00:00:00:02");
+    private static final MacAddress MAC3 = MacAddress.valueOf("00:00:00:00:00:03");
+    private static final MacAddress MAC4 = MacAddress.valueOf("00:00:00:00:00:04");
+    private static final MacAddress MAC10 = MacAddress.valueOf("00:00:00:00:00:0A");
+
+    private static final MacAddress SOLICITED_MAC3 = MacAddress.valueOf("33:33:FF:00:00:01");
+
+    private static final HostId HID1 = HostId.hostId(MAC1, VLAN1);
+    private static final HostId HID2 = HostId.hostId(MAC2, VLAN1);
+    private static final HostId HID3 = HostId.hostId(MAC3, VLAN1);
+    private static final HostId HID4 = HostId.hostId(MAC4, VLAN1);
+    private static final HostId HID10 = HostId.hostId(MAC10, VLAN10);
+
+    private static final DeviceId DID1 = getDeviceId(1);
+    private static final DeviceId DID2 = getDeviceId(2);
+
+    private static final PortNumber P1 = PortNumber.portNumber(1);
+
+    private static final ConnectPoint CP1 = new ConnectPoint(DID1, P1);
+    private static final ConnectPoint CP2 = new ConnectPoint(DID2, P1);
+
+    private static final HostLocation LOC1 = new HostLocation(DID1, P1, 123L);
+
+    private static final String PEER1_IP = "10.0.1.201";
+    private static final String PEER2_IP = "10.0.1.101";
+    private static final String PEER1_IP6 = "1000::1";
+    private static final String PEER2_IP6 = "1000::100";
+
+    private final byte[] zeroMacAddress = MacAddress.ZERO.toBytes();
+
+    // The first three devices in the topology have interfaces configured
+    // with VLANs and IPs
+    private final List<ConnectPoint> configIpCPoints = new ArrayList<>();
+
+    // Other three devices in the topology (from 4 to 6) have interfaces
+    // configured only with VLANs
+    private final List<ConnectPoint> configVlanCPoints = new ArrayList<>();
+
+    // Remaining devices in the network (id > 6) don't have any interface
+    // configured.
+    private final List<ConnectPoint> noConfigCPoints = new ArrayList<>();
+
+    private SdxL3ArpHandler proxyArp;
+
+    private BgpConfig bgpConfig;
+    private TestPacketService packetService;
+    private DeviceService deviceService;
+    private EdgePortService edgePortService;
+    private LinkService linkService;
+    private HostService hostService;
+    private InterfaceService interfaceService;
+
+    @Before
+    public void setUp() throws Exception {
+
+        bgpConfig = createMock(BgpConfig.class);
+        packetService = new TestPacketService();
+        hostService = createMock(HostService.class);
+        edgePortService = createMock(EdgePortService.class);
+        interfaceService = createMock(InterfaceService.class);
+
+        // Create the topology
+        createTopology();
+
+        setupNoConfigCPoints();
+        setupconfigIpCPoints();
+        setupconfigVlanCPoints();
+
+        proxyArp = new SdxL3ArpHandler(bgpConfig,
+                                       edgePortService,
+                                       hostService,
+                                       packetService,
+                                       interfaceService);
+    }
+
+    /**
+     * Creates a fake topology to feed into the ARP module.
+     * <p>
+     * The default topology is a unidirectional ring topology. Each switch has
+     * 3 ports. Ports 2 and 3 have the links to neighbor switches, and port 1
+     * is free (edge port).
+     * The first half of the switches have IP addresses configured on their
+     * free ports (port 1). The second half of the switches have no IP
+     * addresses configured.
+     */
+    private void createTopology() {
+        deviceService = createMock(DeviceService.class);
+        linkService = createMock(LinkService.class);
+
+        deviceService.addListener(anyObject(DeviceListener.class));
+        linkService.addListener(anyObject(LinkListener.class));
+
+        createDevices(NUM_DEVICES, NUM_PORTS_PER_DEVICE);
+        createLinks(NUM_DEVICES);
+        addIntfConfig();
+        addEmptyBgpConfig();
+        popluateEdgePortService();
+    }
+
+    /**
+     * Creates the devices for the fake topology.
+     */
+    private void createDevices(int numDevices, int numPorts) {
+        List<Device> devices = new ArrayList<>();
+
+        for (int i = 1; i <= numDevices; i++) {
+            DeviceId devId = getDeviceId(i);
+            Device device = createMock(Device.class);
+            expect(device.id()).andReturn(devId).anyTimes();
+            replay(device);
+
+            devices.add(device);
+
+            List<Port> ports = new ArrayList<>();
+            for (int j = 1; j <= numPorts; j++) {
+                Port port = createMock(Port.class);
+                expect(port.number()).andReturn(PortNumber.portNumber(j)).anyTimes();
+                replay(port);
+                ports.add(port);
+            }
+
+            expect(deviceService.getPorts(devId)).andReturn(ports).anyTimes();
+            expect(deviceService.getDevice(devId)).andReturn(device).anyTimes();
+        }
+
+        expect(deviceService.getDevices()).andReturn(devices).anyTimes();
+        replay(deviceService);
+    }
+
+    /**
+     * Creates the links for the fake topology.
+     * NB: Only unidirectional links are created, as for this purpose all we
+     * need is to occupy the ports with some link.
+     */
+    private void createLinks(int numDevices) {
+        List<Link> links = new ArrayList<>();
+
+        for (int i = 1; i <= numDevices; i++) {
+            ConnectPoint src = new ConnectPoint(
+                    getDeviceId(i),
+                    PortNumber.portNumber(2));
+            ConnectPoint dst = new ConnectPoint(
+                    getDeviceId((i + 1 > numDevices) ? 1 : i + 1),
+                    PortNumber.portNumber(3));
+
+            Link link = createMock(Link.class);
+            expect(link.src()).andReturn(src).anyTimes();
+            expect(link.dst()).andReturn(dst).anyTimes();
+            replay(link);
+
+            links.add(link);
+        }
+
+        expect(linkService.getLinks()).andReturn(links).anyTimes();
+        replay(linkService);
+    }
+
+    /**
+     * On the first three devices two config interfaces are binded on port 1.
+     * The first one with VLAN1, the second one with VLAN equals to none.
+     * Both interfaces have an IP.
+     * On devices 4, 5 and 6 it's binded a config interface on port 1.
+     * The interface is configured with VLAN 1 and no IP.
+     */
+    private void addIntfConfig() {
+        Set<Interface> interfaces = Sets.newHashSet();
+
+        Set<Interface> vlanOneSet = new HashSet<>();
+
+        for (int i = 1; i <= LAST_CONF_DEVICE_INTF_VLAN_IP; i++) {
+            ConnectPoint cp = new ConnectPoint(getDeviceId(i), P1);
+
+            // Interface addresses for IPv4
+            Ip4Prefix prefix1 = Ip4Prefix.valueOf("10.0." + (2 * i - 1) + ".0/24");
+            Ip4Address addr1 = Ip4Address.valueOf("10.0." + (2 * i - 1) + ".1");
+            Ip4Prefix prefix2 = Ip4Prefix.valueOf("10.0." + (2 * i) + ".0/24");
+            Ip4Address addr2 = Ip4Address.valueOf("10.0." + (2 * i) + ".1");
+            InterfaceIpAddress ia1 = new InterfaceIpAddress(addr1, prefix1);
+            InterfaceIpAddress ia2 = new InterfaceIpAddress(addr2, prefix2);
+
+            // Interface addresses for IPv6
+            Ip6Prefix prefix3 = Ip6Prefix.valueOf((2 * i - 1) + "000::0/64");
+            Ip6Address addr3 = Ip6Address.valueOf((2 * i - 1) + "000::1");
+            Ip6Prefix prefix4 = Ip6Prefix.valueOf((2 * i) + "000::0/64");
+            Ip6Address addr4 = Ip6Address.valueOf((2 * i) + "000::2");
+            InterfaceIpAddress ia3 = new InterfaceIpAddress(addr3, prefix3);
+            InterfaceIpAddress ia4 = new InterfaceIpAddress(addr4, prefix4);
+
+            // Setting up interfaces
+            Interface intf1 = new Interface(cp, Sets.newHashSet(ia1, ia3),
+                                            MacAddress.valueOf(2 * i - 1),
+                                            VlanId.vlanId((short) 1));
+            Interface intf2 = new Interface(cp, Sets.newHashSet(ia2, ia4),
+                                            MacAddress.valueOf(2 * i),
+                                            VlanId.NONE);
+
+            interfaces.add(intf1);
+            interfaces.add(intf2);
+
+            vlanOneSet.add(intf1);
+
+            expect(interfaceService.getInterfacesByPort(cp))
+                    .andReturn(Sets.newHashSet(intf1, intf2)).anyTimes();
+        }
+        for (int i = LAST_CONF_DEVICE_INTF_VLAN_IP + 1; i <= LAST_CONF_DEVICE_INTF_VLAN; i++) {
+            ConnectPoint cp = new ConnectPoint(getDeviceId(i), P1);
+            Interface intf1 = new Interface(cp, null,
+                                            MacAddress.NONE,
+                                            VlanId.vlanId((short) 1));
+
+            interfaces.add(intf1);
+            vlanOneSet.add(intf1);
+
+            expect(interfaceService.getInterfacesByPort(cp))
+                    .andReturn(Sets.newHashSet(intf1)).anyTimes();
+        }
+        expect(interfaceService.getInterfacesByVlan(VLAN1))
+                .andReturn(vlanOneSet).anyTimes();
+        expect(interfaceService.getInterfacesByVlan(VLAN10))
+                .andReturn(Collections.emptySet()).anyTimes();
+        expect(interfaceService.getInterfaces()).andReturn(interfaces).anyTimes();
+
+        for (int i = LAST_CONF_DEVICE_INTF_VLAN + 1; i <= NUM_DEVICES; i++) {
+            ConnectPoint cp = new ConnectPoint(getDeviceId(i),
+                                               P1);
+            expect(interfaceService.getInterfacesByPort(cp))
+                    .andReturn(Collections.emptySet()).anyTimes();
+        }
+    }
+
+    /**
+     * Adds an empty BGP configuration for the purposes of basic ARP handling.
+     */
+    private void addEmptyBgpConfig() {
+        Set<BgpConfig.BgpSpeakerConfig> speakers = Sets.newHashSet();
+
+        expect(bgpConfig.bgpSpeakers()).andReturn(speakers).anyTimes();
+        replay(bgpConfig);
+    }
+
+    /**
+     * Populates edge ports in the EdgePortService to return all port 1
+     * as edge ports.
+     */
+    private void popluateEdgePortService() {
+        Set<ConnectPoint> edgeConnectPoints = new HashSet<>();
+
+        for (int i = 1; i <= NUM_DEVICES; i++) {
+            for (int j = 1; j <= NUM_PORTS_PER_DEVICE; j++) {
+                ConnectPoint edgeConnectPoint = new ConnectPoint(
+                        getDeviceId(i),
+                        PortNumber.portNumber(1));
+                ConnectPoint noEdgeConnectPointOne = new ConnectPoint(
+                        getDeviceId(i),
+                        PortNumber.portNumber(2));
+                ConnectPoint noEdgeConnectPointTwo = new ConnectPoint(
+                        getDeviceId(i),
+                        PortNumber.portNumber(3));
+
+                edgeConnectPoints.add(edgeConnectPoint);
+
+                expect(edgePortService.isEdgePoint(edgeConnectPoint))
+                        .andReturn(true).anyTimes();
+                expect(edgePortService.isEdgePoint(noEdgeConnectPointOne))
+                        .andReturn(false).anyTimes();
+                expect(edgePortService.isEdgePoint(noEdgeConnectPointTwo))
+                        .andReturn(false).anyTimes();
+            }
+        }
+        expect(edgePortService.getEdgePoints())
+                .andReturn(edgeConnectPoints).anyTimes();
+
+        replay(edgePortService);
+    }
+
+    /**
+     * Creates a list of connect points used to verify floodling on ports
+     * with no interfaces configured (all ports without interface config).
+     */
+    private void setupNoConfigCPoints() {
+        for (int i = NUM_DEVICES / 2 + 2; i <= NUM_DEVICES; i++) {
+            ConnectPoint connectPoint = new ConnectPoint(
+                    getDeviceId(i),
+                    PortNumber.portNumber(1));
+            noConfigCPoints.add(connectPoint);
+        }
+    }
+
+    /**
+     * Creates a list of connect points used to verify floodling on ports
+     * with interfaces configured (both VLAN and IP).
+     */
+    private void setupconfigIpCPoints() {
+        for (int i = 1; i <= 3; i++) {
+            ConnectPoint connectPoint = new ConnectPoint(
+                    getDeviceId(i),
+                    PortNumber.portNumber(1));
+            configIpCPoints.add(connectPoint);
+        }
+    }
+
+    /**
+     * Creates a list of connect points used to verify floodling on ports
+     * with interfaces configured (both VLAN and IP).
+     */
+    private void setupconfigVlanCPoints() {
+        for (int i = LAST_CONF_DEVICE_INTF_VLAN_IP + 1; i <= LAST_CONF_DEVICE_INTF_VLAN; i++) {
+            ConnectPoint connectPoint = new ConnectPoint(
+                    getDeviceId(i),
+                    PortNumber.portNumber(1));
+            configVlanCPoints.add(connectPoint);
+        }
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * destination host is known.
+     * Two host using the same VLAN are registered on the host service on devices 5 and 6.
+     * Host on port 6 asks for the MAC of the device on port 5.
+     * Since the destination mac address is known, the request is not flooded to anywhere
+     * and ONOS directly builds an ARP reply, sended back to the requester on device 6.
+     * It's verified that a proper ARP reply is received on port 1 of device 6.
+     */
+    @Test
+    public void testReplyKnown() {
+        Host requestor = new DefaultHost(PID, HID1, MAC1, VLAN1, getLocation(NUM_DEVICES),
+                                         Collections.singleton(IP1));
+
+        Host replyer = new DefaultHost(PID, HID2, MAC2, VLAN1, getLocation(NUM_DEVICES - 1),
+                                       Collections.singleton(IP2));
+
+        expect(hostService.getHostsByIp(IP2))
+                .andReturn(Collections.singleton(replyer));
+        expect(hostService.getHost(HID1)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, IP1, IP2);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(NUM_DEVICES), P1),
+                                         arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+        Ethernet arpReply = buildArp(ARP.OP_REPLY, VLAN1, MAC2, MAC1, IP2, IP1);
+        verifyPacketOut(arpReply, getLocation(NUM_DEVICES), packetService.packets.get(0));
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * destination host is known.
+     * Verifies the correct NDP reply is sent out the correct port.
+     */
+    @Test
+    public void testReplyKnownIpv6() {
+        Host replyer = new DefaultHost(PID, HID3, MAC3, VLAN1, getLocation(4),
+                                       Collections.singleton(IP3));
+
+        Host requestor = new DefaultHost(PID, HID4, MAC4, VLAN1, getLocation(5),
+                                         Collections.singleton(IP4));
+
+        expect(hostService.getHostsByIp(IP3))
+                .andReturn(Collections.singleton(replyer));
+        expect(hostService.getHost(HID4)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                                       MAC4, SOLICITED_MAC3,
+                                       IP4, IP3);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(5), P1),
+                                         ndpRequest,
+                                         ByteBuffer.wrap(ndpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+        Ethernet ndpReply = buildNdp(ICMP6.NEIGHBOR_ADVERTISEMENT,
+                                     MAC3, MAC4, IP3, IP4);
+        verifyPacketOut(ndpReply, getLocation(5), packetService.packets.get(0));
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * destination host is not known.
+     * Only a requestor is present (on device 6, port 1). The device has a VLAN configured
+     * which is not configured anywhere in the system.
+     * Since the destination is not known, and since the ARP request can't be sent out of
+     * interfaces configured, the ARP request is flooded out of ports 4 and 5.
+     * Verifies the ARP request is flooded out the correct edge ports.
+     */
+    @Test
+    public void testReplyUnknown() {
+        Host requestor = new DefaultHost(PID, HID10, MAC10, VLAN10, getLocation(NUM_DEVICES),
+                                         Collections.singleton(IP1));
+
+        expect(hostService.getHostsByIp(IP2))
+                .andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(IP1))
+                .andReturn(Collections.emptySet());
+        expect(hostService.getHost(HID10)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN10, MAC10, null, IP1, IP2);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(NUM_DEVICES), P1),
+                                         arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        verifyFlood(arpRequest, noConfigCPoints);
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * destination host is not known.
+     * Verifies the NDP request is flooded out the correct edge ports.
+     */
+    @Test
+    public void testReplyUnknownIpv6() {
+        Host requestor = new DefaultHost(PID, HID4, MAC4, VLAN1, getLocation(NUM_DEVICES),
+                                         Collections.singleton(IP4));
+
+        expect(hostService.getHostsByIp(IP3))
+                .andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(IP4))
+                .andReturn(Collections.emptySet());
+        expect(hostService.getHost(HID4)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                                       MAC4, SOLICITED_MAC3,
+                                       IP4, IP3);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(NUM_DEVICES), P1),
+                                         ndpRequest,
+                                         ByteBuffer.wrap(ndpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        verifyFlood(ndpRequest, noConfigCPoints);
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * destination host is known for that IP address, but is not on the same
+     * VLAN as the source host.
+     * An host is connected on device 6, port 1 where no interfaces are defined. It sends
+     * ARP requests from VLAN10, not configured anywhere in the network. Another host with
+     * the IP address requested lives on device 5, port 1 in the network. Anyway, since the
+     * host uses another VLAN it's not found and the ARP packet is flooded out of port
+     * 4 and 5.
+     *
+     * Verifies the ARP request is flooded out the correct edge ports.
+     */
+    @Test
+    public void testReplyDifferentVlan() {
+        Host requestor = new DefaultHost(PID, HID10, MAC10, VLAN10, getLocation(NUM_DEVICES),
+                                         Collections.singleton(IP1));
+
+        Host replyer = new DefaultHost(PID, HID2, MAC2, VLAN2, getLocation(NUM_DEVICES - 1),
+                                       Collections.singleton(IP2));
+
+        expect(hostService.getHostsByIp(IP2))
+                .andReturn(Collections.singleton(replyer));
+        expect(interfaceService.getInterfacesByIp(IP1))
+                .andReturn(Collections.emptySet());
+        expect(hostService.getHost(HID10)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN10, MAC10, null, IP1, IP2);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(NUM_DEVICES), P1),
+                                         arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        verifyFlood(arpRequest, noConfigCPoints);
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * a vlan packet comes in from a port without interfaces configured. The destination
+     * host is unknown for that IP address and there are some interfaces configured on
+     * the same vlan.
+     * It's expected to see the ARP request going out through ports with no interfaces
+     * configured, devices 4 and 5, port 1.
+     *
+     * Verifies the ARP request is flooded out the correct edge ports.
+     */
+    @Test
+    public void testConfiguredVlan() {
+        Host requestor = new DefaultHost(PID, HID1, MAC1, VLAN1, getLocation(NUM_DEVICES),
+                                         Collections.singleton(IP1));
+
+        expect(hostService.getHostsByIp(IP2))
+                .andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(IP1))
+                .andReturn(Collections.emptySet());
+        expect(hostService.getHost(HID1)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, IP1, IP2);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(NUM_DEVICES), P1),
+                                         arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        verifyFlood(arpRequest, noConfigCPoints);
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * a vlan packet comes in from a port without interfaces configured. The destination
+     * host is not known for that IP address and there are some interfaces configured on
+     * the same vlan.
+     * It's expected to see the ARP request going out through ports with no interfaces
+     * configured, devices 4 and 5, port 1.
+     *
+     * Verifies the ARP request is flooded out the correct edge ports.
+     */
+    @Test
+    public void testConfiguredVlanOnInterfaces() {
+        Host requestor = new DefaultHost(PID, HID1, MAC1, VLAN1, getLocation(6),
+                                         Collections.singleton(IP1));
+
+        expect(hostService.getHostsByIp(IP2))
+                .andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(IP1))
+                .andReturn(Collections.emptySet());
+        expect(hostService.getHost(HID1)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, IP1, IP2);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(6), P1),
+                                         arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        verifyFlood(arpRequest, configVlanCPoints);
+    }
+
+    /**
+     * Tests {@link SdxL3ArpHandler#processPacketIn(InboundPacket)} in the case where the
+     * destination host is known for that IP address, but is not on the same
+     * VLAN as the source host.
+     * Verifies the NDP request is flooded out the correct edge ports.
+     */
+    @Test
+    public void testReplyDifferentVlanIpv6() {
+        Host requestor = new DefaultHost(PID, HID4, MAC4, VLAN1, getLocation(NUM_DEVICES),
+                                         Collections.singleton(IP4));
+
+        Host replyer = new DefaultHost(PID, HID3, MAC3, VLAN2, getLocation(NUM_DEVICES - 1),
+                                       Collections.singleton(IP3));
+
+        expect(hostService.getHostsByIp(IP3))
+                .andReturn(Collections.singleton(replyer));
+        expect(interfaceService.getInterfacesByIp(IP4))
+                .andReturn(Collections.emptySet());
+        expect(hostService.getHost(HID4)).andReturn(requestor);
+
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                                       MAC4, SOLICITED_MAC3,
+                                       IP4, IP3);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(NUM_DEVICES), P1),
+                                         ndpRequest,
+                                         ByteBuffer.wrap(ndpRequest.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        verifyFlood(ndpRequest, noConfigCPoints);
+    }
+
+    /**
+     * Test ARP request from external network to an internal host.
+     */
+    @Test
+    public void testReplyToRequestForUs() {
+        Ip4Address theirIp = Ip4Address.valueOf("10.0.1.254");
+        Ip4Address ourFirstIp = Ip4Address.valueOf("10.0.1.1");
+        Ip4Address ourSecondIp = Ip4Address.valueOf("10.0.2.1");
+        MacAddress firstMac = MacAddress.valueOf(1L);
+        MacAddress secondMac = MacAddress.valueOf(2L);
+
+        Host requestor = new DefaultHost(PID, HID1, MAC1, VLAN1, LOC1,
+                                         Collections.singleton(theirIp));
+
+        expect(hostService.getHost(HID1)).andReturn(requestor);
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, theirIp, ourFirstIp);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(CP1, arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+        Ethernet arpReply = buildArp(ARP.OP_REPLY, VLAN1, firstMac, MAC1, ourFirstIp, theirIp);
+        verifyPacketOut(arpReply, CP1, packetService.packets.get(0));
+
+        // Test a request for the second address on that port
+        packetService.packets.clear();
+        arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, theirIp, ourSecondIp);
+
+        pkt = new DefaultInboundPacket(CP1, arpRequest,
+                                       ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+        arpReply = buildArp(ARP.OP_REPLY, VLAN1, secondMac, MAC1, ourSecondIp, theirIp);
+        verifyPacketOut(arpReply, CP1, packetService.packets.get(0));
+    }
+
+    /**
+     * Test NDP request from external network to an internal host.
+     */
+    @Test
+    public void testReplyToRequestForUsIpv6() {
+        Ip6Address theirIp = Ip6Address.valueOf("1000::ffff");
+        Ip6Address ourFirstIp = Ip6Address.valueOf("1000::1");
+        Ip6Address ourSecondIp = Ip6Address.valueOf("2000::2");
+        MacAddress firstMac = MacAddress.valueOf(1L);
+        MacAddress secondMac = MacAddress.valueOf(2L);
+
+        Host requestor = new DefaultHost(PID, HID2, MAC2, VLAN1, LOC1,
+                                         Collections.singleton(theirIp));
+
+        expect(hostService.getHost(HID2)).andReturn(requestor);
+        expect(hostService.getHostsByIp(ourFirstIp))
+                .andReturn(Collections.singleton(requestor));
+        replay(hostService);
+        replay(interfaceService);
+
+        Ethernet ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                                       MAC2,
+                                       MacAddress.valueOf("33:33:ff:00:00:01"),
+                                       theirIp,
+                                       ourFirstIp);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(CP1, ndpRequest,
+                                         ByteBuffer.wrap(ndpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+
+        Ethernet ndpReply = buildNdp(ICMP6.NEIGHBOR_ADVERTISEMENT,
+                                     firstMac,
+                                     MAC2,
+                                     ourFirstIp,
+                                     theirIp);
+        verifyPacketOut(ndpReply, CP1, packetService.packets.get(0));
+
+        // Test a request for the second address on that port
+        packetService.packets.clear();
+        ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                              MAC2,
+                              MacAddress.valueOf("33:33:ff:00:00:01"),
+                              theirIp,
+                              ourSecondIp);
+
+        pkt = new DefaultInboundPacket(CP1, ndpRequest,
+                                       ByteBuffer.wrap(ndpReply.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+
+        ndpReply = buildNdp(ICMP6.NEIGHBOR_ADVERTISEMENT,
+                            secondMac,
+                            MAC2,
+                            ourSecondIp,
+                            theirIp);
+        verifyPacketOut(ndpReply, CP1, packetService.packets.get(0));
+    }
+
+    /**
+     * Request for a valid external IPv4 address but coming in the wrong port.
+     */
+    @Test
+    public void testReplyExternalPortBadRequest() {
+        replay(hostService); // no further host service expectations
+        replay(interfaceService);
+
+        Ip4Address theirIp = Ip4Address.valueOf("10.0.1.254");
+
+        // Request for a valid external IP address but coming in the wrong port
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, theirIp,
+                                       Ip4Address.valueOf("10.0.3.1"));
+        InboundPacket pkt =
+                new DefaultInboundPacket(CP1, arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(0, packetService.packets.size());
+
+        // Request for a valid internal IP address but coming in an external port
+        packetService.packets.clear();
+        arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, theirIp, IP1);
+        pkt = new DefaultInboundPacket(CP1, arpRequest,
+                                       ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+        assertEquals(0, packetService.packets.size());
+    }
+
+    /**
+     * Request for a valid external IPv6 address but coming in the wrong port.
+     */
+    @Test
+    public void testReplyExternalPortBadRequestIpv6() {
+        replay(hostService); // no further host service expectations
+        replay(interfaceService);
+
+        Ip6Address theirIp = Ip6Address.valueOf("1000::ffff");
+
+        Ethernet ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                                       MAC1,
+                                       MacAddress.valueOf("33:33:ff:00:00:01"),
+                                       theirIp,
+                                       Ip6Address.valueOf("3000::1"));
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(CP1, ndpRequest,
+                                         ByteBuffer.wrap(ndpRequest.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(0, packetService.packets.size());
+
+        // Request for a valid internal IP address but coming in an external port
+        packetService.packets.clear();
+        ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                              MAC1,
+                              MacAddress.valueOf("33:33:ff:00:00:01"),
+                              theirIp,
+                              IP3);
+
+        pkt = new DefaultInboundPacket(CP1, ndpRequest,
+                                       ByteBuffer.wrap(ndpRequest.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(0, packetService.packets.size());
+    }
+
+    /**
+     * Test ARP request from internal network to an external host.
+     */
+    @Test
+    public void testReplyToRequestFromUs() {
+        Ip4Address ourIp = Ip4Address.valueOf("10.0.1.1");
+        MacAddress ourMac = MacAddress.valueOf(1L);
+        Ip4Address theirIp = Ip4Address.valueOf("10.0.1.100");
+
+        expect(hostService.getHostsByIp(theirIp)).andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(ourIp)).andReturn(
+                        Collections.singleton(new Interface(getLocation(1),
+                        Collections.singleton(new InterfaceIpAddress(ourIp, IpPrefix.valueOf("10.0.1.1/24"))),
+                        ourMac, VLAN1)));
+        expect(hostService.getHost(HostId.hostId(ourMac, VLAN1))).andReturn(null);
+        replay(hostService);
+        replay(interfaceService);
+
+        // This is a request from something inside our network (like a BGP
+        // daemon) to an external host.
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, ourMac, null, ourIp, theirIp);
+        //Ensure the packet is allowed through (it is not to an internal port)
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(5), P1),
+                                         arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+
+        verifyPacketOut(arpRequest, getLocation(1), packetService.packets.get(0));
+
+        // The same request from a random external port should fail
+        packetService.packets.clear();
+        pkt = new DefaultInboundPacket(new ConnectPoint(getDeviceId(2), P1),
+                                       arpRequest,
+                                       ByteBuffer.wrap(arpRequest.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(0, packetService.packets.size());
+    }
+
+    /**
+     * Test NDP request from internal network to an external host.
+     */
+    @Test
+    public void testReplyToRequestFromUsIpv6() {
+        Ip6Address ourIp = Ip6Address.valueOf("1000::1");
+        MacAddress ourMac = MacAddress.valueOf(1L);
+        Ip6Address theirIp = Ip6Address.valueOf("1000::100");
+
+        expect(hostService.getHostsByIp(theirIp)).andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(ourIp))
+                .andReturn(Collections.singleton(new Interface(getLocation(1),
+                                                               Collections.singleton(new InterfaceIpAddress(
+                                                                       ourIp,
+                                                                       IpPrefix.valueOf("1000::1/64"))),
+                                                               ourMac,
+                                                               VLAN1)));
+        expect(hostService.getHost(HostId.hostId(ourMac, VLAN1))).andReturn(null);
+        replay(hostService);
+        replay(interfaceService);
+
+        // This is a request from something inside our network (like a BGP
+        // daemon) to an external host.
+        Ethernet ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                                       ourMac,
+                                       MacAddress.valueOf("33:33:ff:00:00:01"),
+                                       ourIp,
+                                       theirIp);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(new ConnectPoint(getDeviceId(5), P1),
+                                         ndpRequest,
+                                         ByteBuffer.wrap(ndpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+
+        verifyPacketOut(ndpRequest, getLocation(1), packetService.packets.get(0));
+
+        // The same request from a random external port should fail
+        packetService.packets.clear();
+
+        pkt = new DefaultInboundPacket(new ConnectPoint(getDeviceId(2), P1),
+                                       ndpRequest,
+                                       ByteBuffer.wrap(ndpRequest.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(0, packetService.packets.size());
+    }
+
+
+    /**
+     * Request for a valid IPv4 address for BGP peer and coming from a
+     * BGP peer.
+     */
+    @Test
+    public void testReplyExternalPortForPeer() {
+        Ip4Address peer1 = Ip4Address.valueOf(PEER1_IP);
+        MacAddress ourMac = MacAddress.valueOf(1L);
+        Ip4Address peer2 = Ip4Address.valueOf(PEER2_IP);
+
+        expect(hostService.getHostsByIp(peer2)).andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(peer1)).andReturn(
+                Collections.singleton(
+                        new Interface(getLocation(1),
+                                      Collections.singleton(
+                                              new InterfaceIpAddress(
+                                                      peer1,
+                                                      IpPrefix.valueOf("10.0.1.1/24"))),
+                                      ourMac, VLAN1)));
+        expect(hostService.getHost(HostId.hostId(ourMac, VLAN1))).andReturn(null);
+        replay(hostService);
+        replay(interfaceService);
+
+        addPeersToBgpConfig();
+
+        // Request for a valid external IP address belonging to BGP peer
+        Ethernet arpRequest = buildArp(ARP.OP_REQUEST, VLAN1, MAC1, null, peer1,
+                                       peer2);
+        InboundPacket pkt =
+                new DefaultInboundPacket(CP1, arpRequest,
+                                         ByteBuffer.wrap(arpRequest.serialize()));
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+    }
+
+    /**
+     * Request for a valid IPv6 address for BGP peer and coming from a
+     * BGP peer.
+     */
+    @Test
+    public void testReplyExternalPortForPeerIpv6() {
+        Ip6Address peer1 = Ip6Address.valueOf(PEER1_IP6);
+        MacAddress peer1Mac = MacAddress.valueOf(1L);
+        Ip6Address peer2 = Ip6Address.valueOf(PEER2_IP6);
+
+        expect(hostService.getHostsByIp(peer2)).andReturn(Collections.emptySet());
+        expect(interfaceService.getInterfacesByIp(peer1))
+                .andReturn(Collections.singleton(new Interface(getLocation(1),
+                                                               Collections.singleton(new InterfaceIpAddress(
+                                                                       peer1,
+                                                                       IpPrefix.valueOf("1000::1/64"))),
+                                                               peer1Mac,
+                                                               VLAN1)));
+        expect(hostService.getHost(HostId.hostId(peer1Mac, VLAN1))).andReturn(null);
+        replay(hostService);
+        replay(interfaceService);
+
+        addPeersToBgpConfig();
+
+        Ethernet ndpRequest = buildNdp(ICMP6.NEIGHBOR_SOLICITATION,
+                                       MAC1,
+                                       MacAddress.valueOf("33:33:ff:00:00:01"),
+                                       peer1,
+                                       peer2);
+
+        InboundPacket pkt =
+                new DefaultInboundPacket(CP1, ndpRequest,
+                                         ByteBuffer.wrap(ndpRequest.serialize()));
+
+        proxyArp.processPacketIn(pkt);
+
+        assertEquals(1, packetService.packets.size());
+    }
+
+    private void addPeersToBgpConfig() {
+        reset(bgpConfig);
+
+        Set<BgpConfig.BgpSpeakerConfig> speakers = new HashSet<>();
+
+        Optional<String> speakerName = Optional.empty();
+        ConnectPoint connectPoint = CP2;
+        Set<IpAddress> connectedPeers =
+                new HashSet<>(Arrays.asList(IpAddress.valueOf(PEER1_IP),
+                                            IpAddress.valueOf(PEER2_IP),
+                                            IpAddress.valueOf(PEER1_IP6),
+                                            IpAddress.valueOf(PEER2_IP6)));
+
+        speakers.add(new BgpConfig.BgpSpeakerConfig(speakerName,
+                                                    connectPoint,
+                                                    connectedPeers));
+
+        expect(bgpConfig.bgpSpeakers()).andReturn(speakers).anyTimes();
+        replay(bgpConfig);
+    }
+
+    /**
+     * Verifies that the given packet was flooded out all available edge ports,
+     * except for the input port.
+     *
+     * @param packet the packet that was expected to be flooded
+     * @param connectPoints the connectPoints where the outpacket should be
+     *                      observed
+     */
+    private void verifyFlood(Ethernet packet, List<ConnectPoint> connectPoints) {
+
+        // There should be 1 less than NUM_FLOOD_PORTS; the inPort should be excluded.
+        assertEquals(connectPoints.size() - 1, packetService.packets.size());
+
+        Collections.sort(packetService.packets,
+                         (o1, o2) -> o1.sendThrough().uri().compareTo(o2.sendThrough().uri()));
+
+        for (int i = 0; i < connectPoints.size() - 1; i++) {
+            OutboundPacket outboundPacket = packetService.packets.get(i);
+            verifyPacketOut(packet, connectPoints.get(i), outboundPacket);
+        }
+    }
+
+    /**
+     * Verifies the given packet was sent out the given port.
+     *
+     * @param expected the packet that was expected to be sent
+     * @param outPort  the port the packet was expected to be sent out
+     * @param actual   the actual OutboundPacket to verify
+     */
+    private void verifyPacketOut(Ethernet expected, ConnectPoint outPort,
+                                 OutboundPacket actual) {
+        assertArrayEquals(expected.serialize(), actual.data().array());
+        assertEquals(1, actual.treatment().immediate().size());
+        assertEquals(outPort.deviceId(), actual.sendThrough());
+        Instruction instruction = actual.treatment().immediate().get(0);
+        assertTrue(instruction instanceof OutputInstruction);
+        assertEquals(outPort.port(), ((OutputInstruction) instruction).port());
+    }
+
+    /**
+     * Returns the device ID of the ith device.
+     *
+     * @param i device to get the ID of
+     * @return the device ID
+     */
+    private static DeviceId getDeviceId(int i) {
+        return DeviceId.deviceId("" + i);
+    }
+
+    private static HostLocation getLocation(int i) {
+        return new HostLocation(new ConnectPoint(getDeviceId(i), P1), 123L);
+    }
+
+    /**
+     * Builds an ARP packet with the given parameters.
+     *
+     * @param opcode opcode of the ARP packet
+     * @param srcMac source MAC address
+     * @param dstMac destination MAC address, or null if this is a request
+     * @param srcIp  source IP address
+     * @param dstIp  destination IP address
+     * @return the ARP packet
+     */
+    private Ethernet buildArp(short opcode, VlanId vlanId, MacAddress srcMac,
+                              MacAddress dstMac, Ip4Address srcIp, Ip4Address dstIp) {
+        Ethernet eth = new Ethernet();
+
+        if (dstMac == null) {
+            eth.setDestinationMACAddress(MacAddress.BROADCAST);
+        } else {
+            eth.setDestinationMACAddress(dstMac);
+        }
+
+        eth.setSourceMACAddress(srcMac);
+        eth.setEtherType(Ethernet.TYPE_ARP);
+        eth.setVlanID(vlanId.toShort());
+
+        ARP arp = new ARP();
+        arp.setOpCode(opcode);
+        arp.setProtocolType(ARP.PROTO_TYPE_IP);
+        arp.setHardwareType(ARP.HW_TYPE_ETHERNET);
+
+        arp.setProtocolAddressLength((byte) Ip4Address.BYTE_LENGTH);
+        arp.setHardwareAddressLength((byte) Ethernet.DATALAYER_ADDRESS_LENGTH);
+        arp.setSenderHardwareAddress(srcMac.toBytes());
+
+        if (dstMac == null) {
+            arp.setTargetHardwareAddress(zeroMacAddress);
+        } else {
+            arp.setTargetHardwareAddress(dstMac.toBytes());
+        }
+
+        arp.setSenderProtocolAddress(srcIp.toOctets());
+        arp.setTargetProtocolAddress(dstIp.toOctets());
+
+        eth.setPayload(arp);
+        return eth;
+    }
+
+    /**
+     * Builds an NDP packet with the given parameters.
+     *
+     * @param type NeighborSolicitation or NeighborAdvertisement
+     * @param srcMac source MAC address
+     * @param dstMac destination MAC address, or null if this is a request
+     * @param srcIp  source IP address
+     * @param dstIp  destination IP address
+     * @return the NDP packet
+     */
+    private Ethernet buildNdp(byte type, MacAddress srcMac, MacAddress dstMac,
+                              Ip6Address srcIp, Ip6Address dstIp) {
+        assertThat(type, anyOf(
+                is(ICMP6.NEIGHBOR_SOLICITATION),
+                is(ICMP6.NEIGHBOR_ADVERTISEMENT)
+        ));
+        assertNotNull(srcMac);
+        assertNotNull(dstMac);
+        assertNotNull(srcIp);
+        assertNotNull(dstIp);
+
+        IPacket ndp;
+        if (type == ICMP6.NEIGHBOR_SOLICITATION) {
+            ndp = new NeighborSolicitation().setTargetAddress(dstIp.toOctets());
+        } else {
+            ndp = new NeighborAdvertisement()
+                    .setSolicitedFlag((byte) 1)
+                    .setOverrideFlag((byte) 1)
+                    .setTargetAddress(srcIp.toOctets())
+                    .addOption(NeighborDiscoveryOptions.TYPE_TARGET_LL_ADDRESS,
+                               srcMac.toBytes());
+        }
+
+        ICMP6 icmp6 = new ICMP6();
+        icmp6.setIcmpType(type);
+        icmp6.setIcmpCode((byte) 0);
+        icmp6.setPayload(ndp);
+
+        IPv6 ipv6 = new IPv6();
+        ipv6.setDestinationAddress(dstIp.toOctets());
+        ipv6.setSourceAddress(srcIp.toOctets());
+        ipv6.setNextHeader(IPv6.PROTOCOL_ICMP6);
+        ipv6.setHopLimit((byte) 255);
+        ipv6.setPayload(icmp6);
+
+        Ethernet eth = new Ethernet();
+        eth.setDestinationMACAddress(dstMac);
+        eth.setSourceMACAddress(srcMac);
+        eth.setEtherType(Ethernet.TYPE_IPV6);
+        eth.setVlanID(VLAN1.toShort());
+        eth.setPayload(ipv6);
+
+        return eth;
+    }
+
+    /**
+     * Test PacketService implementation that simply stores OutboundPackets
+     * passed to {@link #emit(OutboundPacket)} for later verification.
+     */
+    class TestPacketService extends PacketServiceAdapter {
+
+        List<OutboundPacket> packets = new ArrayList<>();
+
+        @Override
+        public void emit(OutboundPacket packet) {
+            packets.add(packet);
+        }
+    }
+}
+