diff --git a/Tethering/tests/privileged/src/android/net/ip/RouterAdvertisementDaemonTest.java b/Tethering/tests/privileged/src/android/net/ip/RouterAdvertisementDaemonTest.java
new file mode 100644
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+++ b/Tethering/tests/privileged/src/android/net/ip/RouterAdvertisementDaemonTest.java
@@ -0,0 +1,305 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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 android.net.ip;
+
+import static com.android.net.module.util.NetworkStackConstants.ETHER_HEADER_LEN;
+import static com.android.net.module.util.NetworkStackConstants.ETHER_TYPE_IPV6;
+import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ND_OPTION_MTU;
+import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ND_OPTION_PIO;
+import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ND_OPTION_RDNSS;
+import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ND_OPTION_SLLA;
+import static com.android.net.module.util.NetworkStackConstants.ICMPV6_RA_HEADER_LEN;
+import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ROUTER_ADVERTISEMENT;
+import static com.android.net.module.util.NetworkStackConstants.IPV6_ADDR_ALL_NODES_MULTICAST;
+import static com.android.net.module.util.NetworkStackConstants.IPV6_ADDR_LEN;
+import static com.android.net.module.util.NetworkStackConstants.IPV6_HEADER_LEN;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import android.app.Instrumentation;
+import android.content.Context;
+import android.net.INetd;
+import android.net.IpPrefix;
+import android.net.MacAddress;
+import android.net.ip.RouterAdvertisementDaemon.RaParams;
+import android.net.util.InterfaceParams;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.IBinder;
+import android.os.Looper;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.net.module.util.Ipv6Utils;
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.structs.EthernetHeader;
+import com.android.net.module.util.structs.Icmpv6Header;
+import com.android.net.module.util.structs.Ipv6Header;
+import com.android.net.module.util.structs.LlaOption;
+import com.android.net.module.util.structs.MtuOption;
+import com.android.net.module.util.structs.PrefixInformationOption;
+import com.android.net.module.util.structs.RaHeader;
+import com.android.net.module.util.structs.RdnssOption;
+import com.android.testutils.TapPacketReader;
+import com.android.testutils.TapPacketReaderRule;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.MockitoAnnotations;
+
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.nio.ByteBuffer;
+import java.util.HashSet;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public final class RouterAdvertisementDaemonTest {
+    private static final String TAG = RouterAdvertisementDaemonTest.class.getSimpleName();
+    private static final int DATA_BUFFER_LEN = 4096;
+    private static final int PACKET_TIMEOUT_MS = 5_000;
+
+    @Rule
+    public final TapPacketReaderRule mTetheredReader = new TapPacketReaderRule(
+            DATA_BUFFER_LEN, false /* autoStart */);
+
+    private InterfaceParams mTetheredParams;
+    private HandlerThread mHandlerThread;
+    private Handler mHandler;
+    private TapPacketReader mTetheredPacketReader;
+    private RouterAdvertisementDaemon mRaDaemon;
+
+    private static INetd sNetd;
+
+    @BeforeClass
+    public static void setupOnce() {
+        System.loadLibrary("tetherutilsjni");
+
+        final Instrumentation inst = InstrumentationRegistry.getInstrumentation();
+        final IBinder netdIBinder =
+                (IBinder) inst.getContext().getSystemService(Context.NETD_SERVICE);
+        sNetd = INetd.Stub.asInterface(netdIBinder);
+    }
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+
+        mHandlerThread = new HandlerThread(getClass().getSimpleName());
+        mHandlerThread.start();
+        mHandler = new Handler(mHandlerThread.getLooper());
+
+        setupTapInterfaces();
+
+        // Looper must be prepared here since AndroidJUnitRunner runs tests on separate threads.
+        if (Looper.myLooper() == null) Looper.prepare();
+
+        mRaDaemon = new RouterAdvertisementDaemon(mTetheredParams);
+        sNetd.networkAddInterface(INetd.LOCAL_NET_ID, mTetheredParams.name);
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        mTetheredReader.stop();
+        if (mHandlerThread != null) {
+            mHandlerThread.quitSafely();
+            mHandlerThread.join(PACKET_TIMEOUT_MS);
+        }
+
+        if (mTetheredParams != null) {
+            sNetd.networkRemoveInterface(INetd.LOCAL_NET_ID, mTetheredParams.name);
+        }
+    }
+
+    private void setupTapInterfaces() {
+        // Create tethered test iface.
+        mTetheredReader.start(mHandler);
+        mTetheredParams = InterfaceParams.getByName(mTetheredReader.iface.getInterfaceName());
+        assertNotNull(mTetheredParams);
+        mTetheredPacketReader = mTetheredReader.getReader();
+        mHandler.post(mTetheredPacketReader::start);
+    }
+
+    private class TestRaPacket {
+        final RaParams mNewParams, mOldParams;
+
+        TestRaPacket(final RaParams oldParams, final RaParams newParams) {
+            mOldParams = oldParams;
+            mNewParams = newParams;
+        }
+
+        public boolean isPacketMatched(final byte[] pkt) throws Exception {
+            if (pkt.length < (ETHER_HEADER_LEN + IPV6_HEADER_LEN + ICMPV6_RA_HEADER_LEN)) {
+                return false;
+            }
+            final ByteBuffer buf = ByteBuffer.wrap(pkt);
+
+            // Parse Ethernet header
+            final EthernetHeader ethHdr = Struct.parse(EthernetHeader.class, buf);
+            if (ethHdr.etherType != ETHER_TYPE_IPV6) return false;
+
+            // Parse IPv6 header
+            final Ipv6Header ipv6Hdr = Struct.parse(Ipv6Header.class, buf);
+            assertEquals((ipv6Hdr.vtf >> 28), 6 /* ip version*/);
+
+            final int payLoadLength = pkt.length - ETHER_HEADER_LEN - IPV6_HEADER_LEN;
+            assertEquals(payLoadLength, ipv6Hdr.payloadLength);
+
+            // Parse ICMPv6 header
+            final Icmpv6Header icmpv6Hdr = Struct.parse(Icmpv6Header.class, buf);
+            if (icmpv6Hdr.type != (short) ICMPV6_ROUTER_ADVERTISEMENT) return false;
+
+            // Parse RA header
+            final RaHeader raHdr = Struct.parse(RaHeader.class, buf);
+            assertEquals(mNewParams.hopLimit, raHdr.hopLimit);
+
+            while (buf.position() < pkt.length) {
+                final int currentPos = buf.position();
+                final int type = Byte.toUnsignedInt(buf.get());
+                final int length = Byte.toUnsignedInt(buf.get());
+                switch (type) {
+                    case ICMPV6_ND_OPTION_PIO:
+                        assertEquals(4, length);
+
+                        final ByteBuffer pioBuf = ByteBuffer.wrap(buf.array(), currentPos,
+                                Struct.getSize(PrefixInformationOption.class));
+                        final PrefixInformationOption pio =
+                                Struct.parse(PrefixInformationOption.class, pioBuf);
+                        assertEquals((byte) 0xc0, pio.flags); // L & A set
+
+                        final InetAddress address = InetAddress.getByAddress(pio.prefix);
+                        final IpPrefix prefix = new IpPrefix(address, pio.prefixLen);
+                        if (mNewParams.prefixes.contains(prefix)) {
+                            assertTrue(pio.validLifetime > 0);
+                            assertTrue(pio.preferredLifetime > 0);
+                        } else if (mOldParams != null && mOldParams.prefixes.contains(prefix)) {
+                            assertEquals(0, pio.validLifetime);
+                            assertEquals(0, pio.preferredLifetime);
+                        } else {
+                            fail("Unepxected prefix: " + prefix);
+                        }
+
+                        // Move ByteBuffer position to the next option.
+                        buf.position(currentPos + Struct.getSize(PrefixInformationOption.class));
+                        break;
+                    case ICMPV6_ND_OPTION_MTU:
+                        assertEquals(1, length);
+
+                        final ByteBuffer mtuBuf = ByteBuffer.wrap(buf.array(), currentPos,
+                                Struct.getSize(MtuOption.class));
+                        final MtuOption mtu = Struct.parse(MtuOption.class, mtuBuf);
+                        assertEquals(mNewParams.mtu, mtu.mtu);
+
+                        // Move ByteBuffer position to the next option.
+                        buf.position(currentPos + Struct.getSize(MtuOption.class));
+                        break;
+                    case ICMPV6_ND_OPTION_RDNSS:
+                        final int rdnssHeaderLen = Struct.getSize(RdnssOption.class);
+                        final ByteBuffer RdnssBuf = ByteBuffer.wrap(buf.array(), currentPos,
+                                rdnssHeaderLen);
+                        final RdnssOption rdnss = Struct.parse(RdnssOption.class, RdnssBuf);
+                        final String msg =
+                                rdnss.lifetime > 0 ? "Unknown dns" : "Unknown deprecated dns";
+                        final HashSet<Inet6Address> dnses =
+                                rdnss.lifetime > 0 ? mNewParams.dnses : mOldParams.dnses;
+                        assertNotNull(msg, dnses);
+
+                        // Check DNS servers included in this option.
+                        buf.position(currentPos + rdnssHeaderLen); // skip the rdnss option header
+                        final int numOfDnses = (length - 1) / 2;
+                        for (int i = 0; i < numOfDnses; i++) {
+                            byte[] rawAddress = new byte[IPV6_ADDR_LEN];
+                            buf.get(rawAddress);
+                            final Inet6Address dns =
+                                    (Inet6Address) InetAddress.getByAddress(rawAddress);
+                            if (!dnses.contains(dns)) fail("Unexpected dns: " + dns);
+                        }
+                        // Unnecessary to move ByteBuffer position here, since the position has been
+                        // moved forward correctly after reading DNS servers from ByteBuffer.
+                        break;
+                    case ICMPV6_ND_OPTION_SLLA:
+                        // Do nothing, just move ByteBuffer position to the next option.
+                        buf.position(currentPos + Struct.getSize(LlaOption.class));
+                        break;
+                    default:
+                        fail("Unknown RA option type " + type);
+                }
+            }
+            return true;
+        }
+    }
+
+    private RaParams createRaParams(final String ipv6Address) throws Exception {
+        final RaParams params = new RaParams();
+        final Inet6Address address = (Inet6Address) InetAddress.getByName(ipv6Address);
+        params.dnses.add(address);
+        params.prefixes.add(new IpPrefix(address, 64));
+
+        return params;
+    }
+
+    private boolean assertRaPacket(final TestRaPacket testRa)
+            throws Exception {
+        byte[] packet;
+        while ((packet = mTetheredPacketReader.poll(PACKET_TIMEOUT_MS)) != null) {
+            if (testRa.isPacketMatched(packet)) return true;
+        }
+        return false;
+    }
+
+    private ByteBuffer createRsPacket(final String srcIp) throws Exception {
+        final MacAddress dstMac = MacAddress.fromString("33:33:03:04:05:06");
+        final MacAddress srcMac = mTetheredParams.macAddr;
+        final ByteBuffer slla = LlaOption.build((byte) ICMPV6_ND_OPTION_SLLA, srcMac);
+
+        return Ipv6Utils.buildRsPacket(srcMac, dstMac, (Inet6Address) InetAddress.getByName(srcIp),
+                IPV6_ADDR_ALL_NODES_MULTICAST, slla);
+    }
+
+    @Test
+    public void testUnSolicitRouterAdvertisement() throws Exception {
+        assertTrue(mRaDaemon.start());
+        final RaParams params1 = createRaParams("2001:1122:3344::5566");
+        mRaDaemon.buildNewRa(null, params1);
+        assertRaPacket(new TestRaPacket(null, params1));
+
+        final RaParams params2 = createRaParams("2006:3344:5566::7788");
+        mRaDaemon.buildNewRa(params1, params2);
+        assertRaPacket(new TestRaPacket(params1, params2));
+    }
+
+    @Test
+    public void testSolicitRouterAdvertisement() throws Exception {
+        assertTrue(mRaDaemon.start());
+        final RaParams params1 = createRaParams("2001:1122:3344::5566");
+        mRaDaemon.buildNewRa(null, params1);
+        assertRaPacket(new TestRaPacket(null, params1));
+
+        final ByteBuffer rs = createRsPacket("fe80::1122:3344:5566:7788");
+        mTetheredPacketReader.sendResponse(rs);
+        assertRaPacket(new TestRaPacket(null, params1));
+    }
+}