diff --git a/core/java/android/net/RouteInfo.java b/core/java/android/net/RouteInfo.java
index e550f85..9876076 100644
--- a/core/java/android/net/RouteInfo.java
+++ b/core/java/android/net/RouteInfo.java
@@ -26,7 +26,6 @@
 import android.os.Build;
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.util.Pair;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -554,15 +553,45 @@
     }
 
     /**
-     * A helper class that contains the destination and the gateway in a {@code RouteInfo},
-     * used by {@link ConnectivityService#updateRoutes} or
+     * A helper class that contains the destination, the gateway and the interface in a
+     * {@code RouteInfo}, used by {@link ConnectivityService#updateRoutes} or
      * {@link LinkProperties#addRoute} to calculate the list to be updated.
+     * {@code RouteInfo} objects with different interfaces are treated as different routes because
+     * *usually* on Android different interfaces use different routing tables, and moving a route
+     * to a new routing table never constitutes an update, but is always a remove and an add.
      *
      * @hide
      */
-    public static class RouteKey extends Pair<IpPrefix, InetAddress> {
-        RouteKey(@NonNull IpPrefix destination, @Nullable InetAddress gateway) {
-            super(destination, gateway);
+    public static class RouteKey {
+        @NonNull private final IpPrefix mDestination;
+        @Nullable private final InetAddress mGateway;
+        @Nullable private final String mInterface;
+
+        RouteKey(@NonNull IpPrefix destination, @Nullable InetAddress gateway,
+                @Nullable String iface) {
+            mDestination = destination;
+            mGateway = gateway;
+            mInterface = iface;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (!(o instanceof RouteKey)) {
+                return false;
+            }
+            RouteKey p = (RouteKey) o;
+            // No need to do anything special for scoped addresses. Inet6Address#equals does not
+            // consider the scope ID, but the netd route IPCs (e.g., INetd#networkAddRouteParcel)
+            // and the kernel ignore scoped addresses both in the prefix and in the nexthop and only
+            // look at RTA_OIF.
+            return Objects.equals(p.mDestination, mDestination)
+                    && Objects.equals(p.mGateway, mGateway)
+                    && Objects.equals(p.mInterface, mInterface);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(mDestination, mGateway, mInterface);
         }
     }
 
@@ -574,7 +603,7 @@
      */
     @NonNull
     public RouteKey getRouteKey() {
-        return new RouteKey(mDestination, mGateway);
+        return new RouteKey(mDestination, mGateway, mInterface);
     }
 
     /**
diff --git a/tests/net/common/java/android/net/LinkPropertiesTest.java b/tests/net/common/java/android/net/LinkPropertiesTest.java
index 0fc9be3..6eba62e 100644
--- a/tests/net/common/java/android/net/LinkPropertiesTest.java
+++ b/tests/net/common/java/android/net/LinkPropertiesTest.java
@@ -16,6 +16,8 @@
 
 package android.net;
 
+import static android.net.RouteInfo.RTN_THROW;
+import static android.net.RouteInfo.RTN_UNICAST;
 import static android.net.RouteInfo.RTN_UNREACHABLE;
 
 import static com.android.testutils.ParcelUtilsKt.assertParcelSane;
@@ -1282,4 +1284,20 @@
         assertTrue(lp.hasIpv6UnreachableDefaultRoute());
         assertFalse(lp.hasIpv4UnreachableDefaultRoute());
     }
+
+    @Test @IgnoreUpTo(Build.VERSION_CODES.Q)
+    public void testRouteAddWithSameKey() throws Exception {
+        LinkProperties lp = new LinkProperties();
+        lp.setInterfaceName("wlan0");
+        final IpPrefix v6 = new IpPrefix("64:ff9b::/96");
+        lp.addRoute(new RouteInfo(v6, address("fe80::1"), "wlan0", RTN_UNICAST, 1280));
+        assertEquals(1, lp.getRoutes().size());
+        lp.addRoute(new RouteInfo(v6, address("fe80::1"), "wlan0", RTN_UNICAST, 1500));
+        assertEquals(1, lp.getRoutes().size());
+        final IpPrefix v4 = new IpPrefix("192.0.2.128/25");
+        lp.addRoute(new RouteInfo(v4, address("192.0.2.1"), "wlan0", RTN_UNICAST, 1460));
+        assertEquals(2, lp.getRoutes().size());
+        lp.addRoute(new RouteInfo(v4, address("192.0.2.1"), "wlan0", RTN_THROW, 1460));
+        assertEquals(2, lp.getRoutes().size());
+    }
 }
diff --git a/tests/net/common/java/android/net/RouteInfoTest.java b/tests/net/common/java/android/net/RouteInfoTest.java
index 8204b49..60cac0b 100644
--- a/tests/net/common/java/android/net/RouteInfoTest.java
+++ b/tests/net/common/java/android/net/RouteInfoTest.java
@@ -25,6 +25,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -56,7 +57,7 @@
     private static final int INVALID_ROUTE_TYPE = -1;
 
     private InetAddress Address(String addr) {
-        return InetAddress.parseNumericAddress(addr);
+        return InetAddresses.parseNumericAddress(addr);
     }
 
     private IpPrefix Prefix(String prefix) {
@@ -391,4 +392,43 @@
         r = new RouteInfo(Prefix("0.0.0.0/0"), Address("0.0.0.0"), "wlan0");
         assertEquals(0, r.getMtu());
     }
+
+    @Test @IgnoreUpTo(Build.VERSION_CODES.Q)
+    public void testRouteKey() {
+        RouteInfo.RouteKey k1, k2;
+        // Only prefix, null gateway and null interface
+        k1 = new RouteInfo(Prefix("2001:db8::/128"), null).getRouteKey();
+        k2 = new RouteInfo(Prefix("2001:db8::/128"), null).getRouteKey();
+        assertEquals(k1, k2);
+        assertEquals(k1.hashCode(), k2.hashCode());
+
+        // With prefix, gateway and interface. Type and MTU does not affect RouteKey equality
+        k1 = new RouteInfo(Prefix("192.0.2.0/24"), Address("192.0.2.1"), "wlan0",
+                RTN_UNREACHABLE, 1450).getRouteKey();
+        k2 = new RouteInfo(Prefix("192.0.2.0/24"), Address("192.0.2.1"), "wlan0",
+                RouteInfo.RTN_UNICAST, 1400).getRouteKey();
+        assertEquals(k1, k2);
+        assertEquals(k1.hashCode(), k2.hashCode());
+
+        // Different scope IDs are ignored by the kernel, so we consider them equal here too.
+        k1 = new RouteInfo(Prefix("2001:db8::/64"), Address("fe80::1%1"), "wlan0").getRouteKey();
+        k2 = new RouteInfo(Prefix("2001:db8::/64"), Address("fe80::1%2"), "wlan0").getRouteKey();
+        assertEquals(k1, k2);
+        assertEquals(k1.hashCode(), k2.hashCode());
+
+        // Different prefix
+        k1 = new RouteInfo(Prefix("192.0.2.0/24"), null).getRouteKey();
+        k2 = new RouteInfo(Prefix("192.0.3.0/24"), null).getRouteKey();
+        assertNotEquals(k1, k2);
+
+        // Different gateway
+        k1 = new RouteInfo(Prefix("ff02::1/128"), Address("2001:db8::1"), null).getRouteKey();
+        k2 = new RouteInfo(Prefix("ff02::1/128"), Address("2001:db8::2"), null).getRouteKey();
+        assertNotEquals(k1, k2);
+
+        // Different interface
+        k1 = new RouteInfo(Prefix("ff02::1/128"), null, "tun0").getRouteKey();
+        k2 = new RouteInfo(Prefix("ff02::1/128"), null, "tun1").getRouteKey();
+        assertNotEquals(k1, k2);
+    }
 }
diff --git a/tests/net/java/com/android/server/net/NetworkStatsSubscriptionsMonitorTest.java b/tests/net/java/com/android/server/net/NetworkStatsSubscriptionsMonitorTest.java
new file mode 100644
index 0000000..2085053
--- /dev/null
+++ b/tests/net/java/com/android/server/net/NetworkStatsSubscriptionsMonitorTest.java
@@ -0,0 +1,218 @@
+/*
+ * 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 com.android.server.net;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.reset;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.annotation.NonNull;
+import android.content.Context;
+import android.os.Looper;
+import android.telephony.PhoneStateListener;
+import android.telephony.ServiceState;
+import android.telephony.SubscriptionManager;
+import android.telephony.TelephonyManager;
+
+import com.android.internal.util.CollectionUtils;
+import com.android.server.net.NetworkStatsSubscriptionsMonitor.Delegate;
+import com.android.server.net.NetworkStatsSubscriptionsMonitor.RatTypeListener;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+@RunWith(JUnit4.class)
+public final class NetworkStatsSubscriptionsMonitorTest {
+    private static final int TEST_SUBID1 = 3;
+    private static final int TEST_SUBID2 = 5;
+    private static final String TEST_IMSI1 = "466921234567890";
+    private static final String TEST_IMSI2 = "466920987654321";
+    private static final String TEST_IMSI3 = "466929999999999";
+
+    @Mock private Context mContext;
+    @Mock private PhoneStateListener mPhoneStateListener;
+    @Mock private SubscriptionManager mSubscriptionManager;
+    @Mock private TelephonyManager mTelephonyManager;
+    @Mock private Delegate mDelegate;
+    private final List<Integer> mTestSubList = new ArrayList<>();
+
+    private final Executor mExecutor = Executors.newSingleThreadExecutor();
+    private NetworkStatsSubscriptionsMonitor mMonitor;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+
+        if (Looper.myLooper() == null) {
+            Looper.prepare();
+        }
+
+        when(mTelephonyManager.createForSubscriptionId(anyInt())).thenReturn(mTelephonyManager);
+
+        when(mContext.getSystemService(eq(Context.TELEPHONY_SUBSCRIPTION_SERVICE)))
+                .thenReturn(mSubscriptionManager);
+        when(mContext.getSystemService(eq(Context.TELEPHONY_SERVICE)))
+                .thenReturn(mTelephonyManager);
+
+        mMonitor = new NetworkStatsSubscriptionsMonitor(mContext, mExecutor, mDelegate);
+    }
+
+    @Test
+    public void testStartStop() {
+        // Verify that addOnSubscriptionsChangedListener() is never called before start().
+        verify(mSubscriptionManager, never())
+                .addOnSubscriptionsChangedListener(mExecutor, mMonitor);
+        mMonitor.start();
+        verify(mSubscriptionManager).addOnSubscriptionsChangedListener(mExecutor, mMonitor);
+
+        // Verify that removeOnSubscriptionsChangedListener() is never called before stop()
+        verify(mSubscriptionManager, never()).removeOnSubscriptionsChangedListener(mMonitor);
+        mMonitor.stop();
+        verify(mSubscriptionManager).removeOnSubscriptionsChangedListener(mMonitor);
+    }
+
+    @NonNull
+    private static int[] convertArrayListToIntArray(@NonNull List<Integer> arrayList) {
+        final int[] list = new int[arrayList.size()];
+        for (int i = 0; i < arrayList.size(); i++) {
+            list[i] = arrayList.get(i);
+        }
+        return list;
+    }
+
+    private void setRatTypeForSub(List<RatTypeListener> listeners,
+            int subId, int type) {
+        final ServiceState serviceState = mock(ServiceState.class);
+        when(serviceState.getDataNetworkType()).thenReturn(type);
+        final RatTypeListener match = CollectionUtils
+                .find(listeners, it -> it.getSubId() == subId);
+        if (match != null) {
+            match.onServiceStateChanged(serviceState);
+        }
+    }
+
+    private void addTestSub(int subId, String subscriberId) {
+        // add SubId to TestSubList.
+        if (!mTestSubList.contains(subId)) {
+            mTestSubList.add(subId);
+        }
+        final int[] subList = convertArrayListToIntArray(mTestSubList);
+        when(mSubscriptionManager.getActiveAndHiddenSubscriptionIdList()).thenReturn(subList);
+        when(mTelephonyManager.getSubscriberId(subId)).thenReturn(subscriberId);
+        mMonitor.onSubscriptionsChanged();
+    }
+
+    private void removeTestSub(int subId) {
+        // Remove subId from TestSubList.
+        mTestSubList.removeIf(it -> it == subId);
+        final int[] subList = convertArrayListToIntArray(mTestSubList);
+        when(mSubscriptionManager.getActiveAndHiddenSubscriptionIdList()).thenReturn(subList);
+        mMonitor.onSubscriptionsChanged();
+    }
+
+    private void assertRatTypeChangedForSub(String subscriberId, int ratType) {
+        assertEquals(mMonitor.getRatTypeForSubscriberId(subscriberId), ratType);
+        final ArgumentCaptor<Integer> typeCaptor = ArgumentCaptor.forClass(Integer.class);
+        // Verify callback with the subscriberId and the RAT type should be as expected.
+        // It will fail if get a callback with an unexpected RAT type.
+        verify(mDelegate).onCollapsedRatTypeChanged(eq(subscriberId), typeCaptor.capture());
+        final int type = typeCaptor.getValue();
+        assertEquals(ratType, type);
+    }
+
+    private void assertRatTypeNotChangedForSub(String subscriberId, int ratType) {
+        assertEquals(mMonitor.getRatTypeForSubscriberId(subscriberId), ratType);
+        // Should never get callback with any RAT type.
+        verify(mDelegate, never()).onCollapsedRatTypeChanged(eq(subscriberId), anyInt());
+    }
+
+    @Test
+    public void testSubChangedAndRatTypeChanged() {
+        final ArgumentCaptor<RatTypeListener> ratTypeListenerCaptor =
+                ArgumentCaptor.forClass(RatTypeListener.class);
+
+        mMonitor.start();
+        // Insert sim1, verify RAT type is NETWORK_TYPE_UNKNOWN, and never get any callback
+        // before changing RAT type.
+        addTestSub(TEST_SUBID1, TEST_IMSI1);
+        assertRatTypeNotChangedForSub(TEST_IMSI1, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+
+        // Insert sim2.
+        addTestSub(TEST_SUBID2, TEST_IMSI2);
+        assertRatTypeNotChangedForSub(TEST_IMSI1, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        verify(mTelephonyManager, times(2)).listen(ratTypeListenerCaptor.capture(),
+                eq(PhoneStateListener.LISTEN_SERVICE_STATE));
+        reset(mDelegate);
+
+        // Set RAT type of sim1 to UMTS.
+        // Verify RAT type of sim1 after subscription gets onCollapsedRatTypeChanged() callback
+        // and others remain untouched.
+        setRatTypeForSub(ratTypeListenerCaptor.getAllValues(), TEST_SUBID1,
+                TelephonyManager.NETWORK_TYPE_UMTS);
+        assertRatTypeChangedForSub(TEST_IMSI1, TelephonyManager.NETWORK_TYPE_UMTS);
+        assertRatTypeNotChangedForSub(TEST_IMSI2, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        assertRatTypeNotChangedForSub(TEST_IMSI3, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        reset(mDelegate);
+
+        // Set RAT type of sim2 to LTE.
+        // Verify RAT type of sim2 after subscription gets onCollapsedRatTypeChanged() callback
+        // and others remain untouched.
+        setRatTypeForSub(ratTypeListenerCaptor.getAllValues(), TEST_SUBID2,
+                TelephonyManager.NETWORK_TYPE_LTE);
+        assertRatTypeNotChangedForSub(TEST_IMSI1, TelephonyManager.NETWORK_TYPE_UMTS);
+        assertRatTypeChangedForSub(TEST_IMSI2, TelephonyManager.NETWORK_TYPE_LTE);
+        assertRatTypeNotChangedForSub(TEST_IMSI3, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        reset(mDelegate);
+
+        // Remove sim2 and verify that callbacks are fired and RAT type is correct for sim2.
+        // while the other two remain untouched.
+        removeTestSub(TEST_SUBID2);
+        verify(mTelephonyManager).listen(any(), eq(PhoneStateListener.LISTEN_NONE));
+        assertRatTypeNotChangedForSub(TEST_IMSI1, TelephonyManager.NETWORK_TYPE_UMTS);
+        assertRatTypeChangedForSub(TEST_IMSI2, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        assertRatTypeNotChangedForSub(TEST_IMSI3, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        reset(mDelegate);
+
+        // Set RAT type of sim1 to UNKNOWN. Then stop monitoring subscription changes
+        // and verify that the listener for sim1 is removed.
+        setRatTypeForSub(ratTypeListenerCaptor.getAllValues(), TEST_SUBID1,
+                TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        assertRatTypeChangedForSub(TEST_IMSI1, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        reset(mDelegate);
+
+        mMonitor.stop();
+        verify(mTelephonyManager, times(2)).listen(any(), eq(PhoneStateListener.LISTEN_NONE));
+        assertRatTypeChangedForSub(TEST_IMSI1, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+    }
+}