diff --git a/Tethering/AndroidManifest.xml b/Tethering/AndroidManifest.xml
index 9328611..2b2fe45 100644
--- a/Tethering/AndroidManifest.xml
+++ b/Tethering/AndroidManifest.xml
@@ -34,17 +34,21 @@
     <uses-permission android:name="android.permission.MODIFY_PHONE_STATE" />
     <uses-permission android:name="android.permission.READ_DEVICE_CONFIG" />
     <uses-permission android:name="android.permission.READ_NETWORK_USAGE_HISTORY" />
+    <uses-permission android:name="android.permission.READ_PHONE_STATE"/>
     <uses-permission android:name="android.permission.TETHER_PRIVILEGED" />
     <uses-permission android:name="android.permission.UPDATE_APP_OPS_STATS" />
     <uses-permission android:name="android.permission.UPDATE_DEVICE_STATS" />
     <uses-permission android:name="android.permission.WRITE_SETTINGS" />
 
+    <protected-broadcast android:name="com.android.server.connectivity.tethering.DISABLE_TETHERING" />
+
     <application
         android:process="com.android.networkstack.process"
         android:extractNativeLibs="false"
         android:persistent="true">
-        <service android:name="com.android.server.connectivity.tethering.TetheringService"
-                 android:permission="android.permission.MAINLINE_NETWORK_STACK">
+        <service android:name="com.android.networkstack.tethering.TetheringService"
+                 android:permission="android.permission.MAINLINE_NETWORK_STACK"
+                 android:exported="true">
             <intent-filter>
                 <action android:name="android.net.ITetheringConnector"/>
             </intent-filter>
diff --git a/Tethering/AndroidManifest_InProcess.xml b/Tethering/AndroidManifest_InProcess.xml
index 02ea551..b1f1240 100644
--- a/Tethering/AndroidManifest_InProcess.xml
+++ b/Tethering/AndroidManifest_InProcess.xml
@@ -22,9 +22,10 @@
           android:process="system">
     <uses-sdk android:minSdkVersion="29" android:targetSdkVersion="29" />
     <application>
-        <service android:name="com.android.server.connectivity.tethering.TetheringService"
+        <service android:name="com.android.networkstack.tethering.TetheringService"
                  android:process="system"
-                 android:permission="android.permission.MAINLINE_NETWORK_STACK">
+                 android:permission="android.permission.MAINLINE_NETWORK_STACK"
+                 android:exported="true">
             <intent-filter>
                 <action android:name="android.net.ITetheringConnector.InProcess"/>
             </intent-filter>
diff --git a/Tethering/proguard.flags b/Tethering/proguard.flags
index 1f83a66..051fbd1 100644
--- a/Tethering/proguard.flags
+++ b/Tethering/proguard.flags
@@ -1,5 +1,5 @@
 # Keep class's integer static field for MessageUtils to parsing their name.
--keep class com.android.server.connectivity.tethering.Tethering$TetherMasterSM {
+-keep class com.android.networkstack.tethering.Tethering$TetherMasterSM {
     static final int CMD_*;
     static final int EVENT_*;
 }
diff --git a/Tethering/res/values-mcc204-mnc04/strings.xml b/Tethering/res/values-mcc204-mnc04/strings.xml
deleted file mode 100644
index a996b42..0000000
--- a/Tethering/res/values-mcc204-mnc04/strings.xml
+++ /dev/null
@@ -1,30 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- 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.
--->
-<resources>
-    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_title">Hotspot has no internet</string>
-    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
-    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
-
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_title">Hotspot is on</string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
-    <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_continue_button">Continue</string>
-</resources>
diff --git a/Tethering/res/values-mcc310-mnc004/config.xml b/Tethering/res/values-mcc310-mnc004/config.xml
new file mode 100644
index 0000000..8c627d5
--- /dev/null
+++ b/Tethering/res/values-mcc310-mnc004/config.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+<resources>
+    <!-- Delay(millisecond) to show no upstream notification after there's no Backhaul. Set delay to
+         "0" for disable this feature. -->
+    <integer name="delay_to_show_no_upstream_after_no_backhaul">5000</integer>
+</resources>
\ No newline at end of file
diff --git a/Tethering/res/values-mcc310-mnc004/strings.xml b/Tethering/res/values-mcc310-mnc004/strings.xml
index a996b42..9dadd49 100644
--- a/Tethering/res/values-mcc310-mnc004/strings.xml
+++ b/Tethering/res/values-mcc310-mnc004/strings.xml
@@ -15,16 +15,16 @@
 -->
 <resources>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_title">Hotspot has no internet</string>
+    <string name="no_upstream_notification_title">Tethering has no internet</string>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
-    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
+    <string name="no_upstream_notification_message">Devices can\u2019t connect</string>
+    <!-- String for no upstream notification disable button [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_disable_button">Turn off tethering</string>
 
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_title">Hotspot is on</string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200] -->
+    <string name="upstream_roaming_notification_title">Hotspot or tethering is on</string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500] -->
     <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_continue_button">Continue</string>
 </resources>
diff --git a/Tethering/res/values-mcc311-mnc480/config.xml b/Tethering/res/values-mcc311-mnc480/config.xml
new file mode 100644
index 0000000..8c627d5
--- /dev/null
+++ b/Tethering/res/values-mcc311-mnc480/config.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+<resources>
+    <!-- Delay(millisecond) to show no upstream notification after there's no Backhaul. Set delay to
+         "0" for disable this feature. -->
+    <integer name="delay_to_show_no_upstream_after_no_backhaul">5000</integer>
+</resources>
\ No newline at end of file
diff --git a/Tethering/res/values-mcc311-mnc480/strings.xml b/Tethering/res/values-mcc311-mnc480/strings.xml
index a996b42..9dadd49 100644
--- a/Tethering/res/values-mcc311-mnc480/strings.xml
+++ b/Tethering/res/values-mcc311-mnc480/strings.xml
@@ -15,16 +15,16 @@
 -->
 <resources>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_title">Hotspot has no internet</string>
+    <string name="no_upstream_notification_title">Tethering has no internet</string>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
-    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
+    <string name="no_upstream_notification_message">Devices can\u2019t connect</string>
+    <!-- String for no upstream notification disable button [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_disable_button">Turn off tethering</string>
 
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_title">Hotspot is on</string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200] -->
+    <string name="upstream_roaming_notification_title">Hotspot or tethering is on</string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500] -->
     <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_continue_button">Continue</string>
 </resources>
diff --git a/Tethering/res/values/config.xml b/Tethering/res/values/config.xml
index f825d6b..780a015 100644
--- a/Tethering/res/values/config.xml
+++ b/Tethering/res/values/config.xml
@@ -87,7 +87,7 @@
                         TYPE_MOBILE_HIPRI is appended.
 
          For other changes applied to this list, now and in the future, see
-         com.android.server.connectivity.tethering.TetheringConfiguration.
+         com.android.networkstack.tethering.TetheringConfiguration.
 
          Note also: the order of this is important. The first upstream type
          for which a satisfying network exists is used.
@@ -200,4 +200,10 @@
     <string name="tethering_notification_title">@string/tethered_notification_title</string>
     <!-- String for tether enable notification message. -->
     <string name="tethering_notification_message">@string/tethered_notification_message</string>
+
+    <!-- No upstream notification is shown when there is a downstream but no upstream that is able
+         to do the tethering. -->
+    <!-- Delay(millisecond) to show no upstream notification after there's no Backhaul. Set delay to
+         "-1" for disable this feature. -->
+    <integer name="delay_to_show_no_upstream_after_no_backhaul">-1</integer>
 </resources>
diff --git a/Tethering/res/values/strings.xml b/Tethering/res/values/strings.xml
index 52a1654..4fa60d4 100644
--- a/Tethering/res/values/strings.xml
+++ b/Tethering/res/values/strings.xml
@@ -40,13 +40,13 @@
     <string name="no_upstream_notification_title"></string>
     <!-- String for no upstream notification message [CHAR LIMIT=200] -->
     <string name="no_upstream_notification_message"></string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
+    <!-- String for no upstream notification disable button [CHAR LIMIT=200] -->
     <string name="no_upstream_notification_disable_button"></string>
 
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_title"></string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500] -->
     <string name="upstream_roaming_notification_message"></string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_continue_button"></string>
 </resources>
diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index 1dac5b7..83727bc 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -122,6 +122,8 @@
     // TODO: have this configurable
     private static final int DHCP_LEASE_TIME_SECS = 3600;
 
+    private static final MacAddress NULL_MAC_ADDRESS = MacAddress.fromString("00:00:00:00:00:00");
+
     private static final String TAG = "IpServer";
     private static final boolean DBG = false;
     private static final boolean VDBG = false;
@@ -902,9 +904,12 @@
             return;
         }
 
+        // When deleting rules, we still need to pass a non-null MAC, even though it's ignored.
+        // Do this here instead of in the Ipv6ForwardingRule constructor to ensure that we never
+        // add rules with a null MAC, only delete them.
+        MacAddress dstMac = e.isValid() ? e.macAddr : NULL_MAC_ADDRESS;
         Ipv6ForwardingRule rule = new Ipv6ForwardingRule(upstreamIfindex,
-                mInterfaceParams.index, (Inet6Address) e.ip, mInterfaceParams.macAddr,
-                e.macAddr);
+                mInterfaceParams.index, (Inet6Address) e.ip, mInterfaceParams.macAddr, dstMac);
         if (e.isValid()) {
             addIpv6ForwardingRule(rule);
         } else {
diff --git a/Tethering/src/com/android/server/connectivity/tethering/ConnectedClientsTracker.java b/Tethering/src/com/android/networkstack/tethering/ConnectedClientsTracker.java
similarity index 98%
rename from Tethering/src/com/android/server/connectivity/tethering/ConnectedClientsTracker.java
rename to Tethering/src/com/android/networkstack/tethering/ConnectedClientsTracker.java
index cdd1a5d..8a96988 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/ConnectedClientsTracker.java
+++ b/Tethering/src/com/android/networkstack/tethering/ConnectedClientsTracker.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.TetheringManager.TETHERING_WIFI;
 
diff --git a/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java b/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
similarity index 86%
rename from Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java
rename to Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
index 639cf65..049a9f6 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java
+++ b/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.TetheringConstants.EXTRA_ADD_TETHER_TYPE;
 import static android.net.TetheringConstants.EXTRA_PROVISION_CALLBACK;
@@ -38,8 +38,6 @@
 import android.net.util.SharedLog;
 import android.os.Bundle;
 import android.os.Handler;
-import android.os.Looper;
-import android.os.Message;
 import android.os.Parcel;
 import android.os.PersistableBundle;
 import android.os.ResultReceiver;
@@ -52,7 +50,6 @@
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.StateMachine;
-import com.android.networkstack.tethering.R;
 
 import java.io.PrintWriter;
 
@@ -71,16 +68,11 @@
     @VisibleForTesting
     protected static final String DISABLE_PROVISIONING_SYSPROP_KEY = "net.tethering.noprovisioning";
     private static final String ACTION_PROVISIONING_ALARM =
-            "com.android.server.connectivity.tethering.PROVISIONING_RECHECK_ALARM";
+            "com.android.networkstack.tethering.PROVISIONING_RECHECK_ALARM";
     private static final String EXTRA_SUBID = "subId";
 
     private final ComponentName mSilentProvisioningService;
     private static final int MS_PER_HOUR = 60 * 60 * 1000;
-    private static final int EVENT_START_PROVISIONING = 0;
-    private static final int EVENT_STOP_PROVISIONING = 1;
-    private static final int EVENT_UPSTREAM_CHANGED = 2;
-    private static final int EVENT_MAYBE_RUN_PROVISIONING = 3;
-    private static final int EVENT_GET_ENTITLEMENT_VALUE = 4;
 
     // The ArraySet contains enabled downstream types, ex:
     // {@link TetheringManager.TETHERING_WIFI}
@@ -91,7 +83,7 @@
     private final int mPermissionChangeMessageCode;
     private final SharedLog mLog;
     private final SparseIntArray mEntitlementCacheValue;
-    private final EntitlementHandler mHandler;
+    private final Handler mHandler;
     private final StateMachine mTetherMasterSM;
     // Key: TetheringManager.TETHERING_*(downstream).
     // Value: TetheringManager.TETHER_ERROR_{NO_ERROR or PROVISION_FAILED}(provisioning result).
@@ -113,10 +105,7 @@
         mEntitlementCacheValue = new SparseIntArray();
         mTetherMasterSM = tetherMasterSM;
         mPermissionChangeMessageCode = permissionChangeMessageCode;
-        final Handler masterHandler = tetherMasterSM.getHandler();
-        // Create entitlement's own handler which is associated with TetherMaster thread
-        // let all entitlement processes run in the same thread.
-        mHandler = new EntitlementHandler(masterHandler.getLooper());
+        mHandler = tetherMasterSM.getHandler();
         mContext.registerReceiver(mReceiver, new IntentFilter(ACTION_PROVISIONING_ALARM),
                 null, mHandler);
         mSilentProvisioningService = ComponentName.unflattenFromString(
@@ -173,14 +162,9 @@
      *        provisioning app UI if there is one.
      */
     public void startProvisioningIfNeeded(int downstreamType, boolean showProvisioningUi) {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_START_PROVISIONING,
-                downstreamType, encodeBool(showProvisioningUi)));
-    }
+        if (!isValidDownstreamType(downstreamType)) return;
 
-    private void handleStartProvisioningIfNeeded(int type, boolean showProvisioningUi) {
-        if (!isValidDownstreamType(type)) return;
-
-        if (!mCurrentTethers.contains(type)) mCurrentTethers.add(type);
+        if (!mCurrentTethers.contains(downstreamType)) mCurrentTethers.add(downstreamType);
 
         final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
         if (isTetherProvisioningRequired(config)) {
@@ -193,9 +177,9 @@
             // till upstream change to cellular.
             if (mUsingCellularAsUpstream) {
                 if (showProvisioningUi) {
-                    runUiTetherProvisioning(type, config.activeDataSubId);
+                    runUiTetherProvisioning(downstreamType, config.activeDataSubId);
                 } else {
-                    runSilentTetherProvisioning(type, config.activeDataSubId);
+                    runSilentTetherProvisioning(downstreamType, config.activeDataSubId);
                 }
                 mNeedReRunProvisioningUi = false;
             } else {
@@ -212,10 +196,6 @@
      * @param type tethering type from TetheringManager.TETHERING_{@code *}
      */
     public void stopProvisioningIfNeeded(int type) {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_STOP_PROVISIONING, type, 0));
-    }
-
-    private void handleStopProvisioningIfNeeded(int type) {
         if (!isValidDownstreamType(type)) return;
 
         mCurrentTethers.remove(type);
@@ -231,11 +211,6 @@
      * @param isCellular whether tethering upstream is cellular.
      */
     public void notifyUpstream(boolean isCellular) {
-        mHandler.sendMessage(mHandler.obtainMessage(
-                EVENT_UPSTREAM_CHANGED, encodeBool(isCellular), 0));
-    }
-
-    private void handleNotifyUpstream(boolean isCellular) {
         if (DBG) {
             mLog.i("notifyUpstream: " + isCellular
                     + ", mCellularUpstreamPermitted: " + mCellularUpstreamPermitted
@@ -245,16 +220,17 @@
 
         if (mUsingCellularAsUpstream) {
             final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
-            handleMaybeRunProvisioning(config);
+            maybeRunProvisioning(config);
         }
     }
 
     /** Run provisioning if needed */
     public void maybeRunProvisioning() {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_MAYBE_RUN_PROVISIONING));
+        final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
+        maybeRunProvisioning(config);
     }
 
-    private void handleMaybeRunProvisioning(final TetheringConfiguration config) {
+    private void maybeRunProvisioning(final TetheringConfiguration config) {
         if (mCurrentTethers.size() == 0 || !isTetherProvisioningRequired(config)) {
             return;
         }
@@ -320,7 +296,7 @@
         }
 
         if (mUsingCellularAsUpstream) {
-            handleMaybeRunProvisioning(config);
+            maybeRunProvisioning(config);
         }
     }
 
@@ -495,46 +471,6 @@
         }
     };
 
-    private class EntitlementHandler extends Handler {
-        EntitlementHandler(Looper looper) {
-            super(looper);
-        }
-
-        @Override
-        public void handleMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_START_PROVISIONING:
-                    handleStartProvisioningIfNeeded(msg.arg1, toBool(msg.arg2));
-                    break;
-                case EVENT_STOP_PROVISIONING:
-                    handleStopProvisioningIfNeeded(msg.arg1);
-                    break;
-                case EVENT_UPSTREAM_CHANGED:
-                    handleNotifyUpstream(toBool(msg.arg1));
-                    break;
-                case EVENT_MAYBE_RUN_PROVISIONING:
-                    final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
-                    handleMaybeRunProvisioning(config);
-                    break;
-                case EVENT_GET_ENTITLEMENT_VALUE:
-                    handleRequestLatestTetheringEntitlementValue(msg.arg1,
-                            (ResultReceiver) msg.obj, toBool(msg.arg2));
-                    break;
-                default:
-                    mLog.log("Unknown event: " + msg.what);
-                    break;
-            }
-        }
-    }
-
-    private static boolean toBool(int encodedBoolean) {
-        return encodedBoolean != 0;
-    }
-
-    private static int encodeBool(boolean b) {
-        return b ? 1 : 0;
-    }
-
     private static boolean isValidDownstreamType(int type) {
         switch (type) {
             case TETHERING_BLUETOOTH:
@@ -645,13 +581,6 @@
     /** Get the last value of the tethering entitlement check. */
     public void requestLatestTetheringEntitlementResult(int downstream, ResultReceiver receiver,
             boolean showEntitlementUi) {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_GET_ENTITLEMENT_VALUE,
-                downstream, encodeBool(showEntitlementUi), receiver));
-
-    }
-
-    private void handleRequestLatestTetheringEntitlementValue(int downstream,
-            ResultReceiver receiver, boolean showEntitlementUi) {
         if (!isValidDownstreamType(downstream)) {
             receiver.send(TETHER_ERROR_ENTITLEMENT_UNKNOWN, null);
             return;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinator.java b/Tethering/src/com/android/networkstack/tethering/IPv6TetheringCoordinator.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinator.java
rename to Tethering/src/com/android/networkstack/tethering/IPv6TetheringCoordinator.java
index 66b9ade..d450c46 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinator.java
+++ b/Tethering/src/com/android/networkstack/tethering/IPv6TetheringCoordinator.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.net.IpPrefix;
 import android.net.LinkAddress;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java b/Tethering/src/com/android/networkstack/tethering/OffloadController.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/OffloadController.java
rename to Tethering/src/com/android/networkstack/tethering/OffloadController.java
index 15cdb6a..c007c17 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java
+++ b/Tethering/src/com/android/networkstack/tethering/OffloadController.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
 import static android.net.NetworkStats.METERED_NO;
@@ -50,7 +50,7 @@
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.IndentingPrintWriter;
-import com.android.server.connectivity.tethering.OffloadHardwareInterface.ForwardedStats;
+import com.android.networkstack.tethering.OffloadHardwareInterface.ForwardedStats;
 
 import java.net.Inet4Address;
 import java.net.Inet6Address;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/OffloadHardwareInterface.java b/Tethering/src/com/android/networkstack/tethering/OffloadHardwareInterface.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/OffloadHardwareInterface.java
rename to Tethering/src/com/android/networkstack/tethering/OffloadHardwareInterface.java
index b545717..85a23fb 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/OffloadHardwareInterface.java
+++ b/Tethering/src/com/android/networkstack/tethering/OffloadHardwareInterface.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.util.TetheringUtils.uint16;
 
diff --git a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
similarity index 98%
rename from Tethering/src/com/android/server/connectivity/tethering/Tethering.java
rename to Tethering/src/com/android/networkstack/tethering/Tethering.java
index 343ed4b..14d2886 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.Manifest.permission.NETWORK_SETTINGS;
 import static android.Manifest.permission.NETWORK_STACK;
@@ -60,7 +60,7 @@
 import static android.telephony.CarrierConfigManager.ACTION_CARRIER_CONFIG_CHANGED;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
-import static com.android.server.connectivity.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
+import static com.android.networkstack.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
 
 import android.app.usage.NetworkStatsManager;
 import android.bluetooth.BluetoothAdapter;
@@ -257,7 +257,7 @@
         mContext = mDeps.getContext();
         mNetd = mDeps.getINetd(mContext);
         mLooper = mDeps.getTetheringLooper();
-        mNotificationUpdater = mDeps.getNotificationUpdater(mContext);
+        mNotificationUpdater = mDeps.getNotificationUpdater(mContext, mLooper);
 
         mPublicSync = new Object();
 
@@ -337,6 +337,11 @@
         filter.addAction(ACTION_RESTRICT_BACKGROUND_CHANGED);
         mContext.registerReceiver(mStateReceiver, filter, null, mHandler);
 
+        final IntentFilter noUpstreamFilter = new IntentFilter();
+        noUpstreamFilter.addAction(TetheringNotificationUpdater.ACTION_DISABLE_TETHERING);
+        mContext.registerReceiver(
+                mStateReceiver, noUpstreamFilter, PERMISSION_MAINLINE_NETWORK_STACK, mHandler);
+
         final WifiManager wifiManager = getWifiManager();
         if (wifiManager != null) {
             wifiManager.registerSoftApCallback(mExecutor, new TetheringSoftApCallback());
@@ -855,6 +860,8 @@
             } else if (action.equals(ACTION_RESTRICT_BACKGROUND_CHANGED)) {
                 mLog.log("OBSERVED data saver changed");
                 handleDataSaverChanged();
+            } else if (action.equals(TetheringNotificationUpdater.ACTION_DISABLE_TETHERING)) {
+                untetherAll();
             }
         }
 
@@ -922,8 +929,10 @@
                     case WifiManager.WIFI_AP_STATE_ENABLED:
                         enableWifiIpServingLocked(ifname, ipmode);
                         break;
-                    case WifiManager.WIFI_AP_STATE_DISABLED:
                     case WifiManager.WIFI_AP_STATE_DISABLING:
+                        // We can see this state on the way to disabled.
+                        break;
+                    case WifiManager.WIFI_AP_STATE_DISABLED:
                     case WifiManager.WIFI_AP_STATE_FAILED:
                     default:
                         disableWifiIpServingLocked(ifname, curState);
@@ -1944,10 +1953,12 @@
     /** Get the latest value of the tethering entitlement check. */
     void requestLatestTetheringEntitlementResult(int type, ResultReceiver receiver,
             boolean showEntitlementUi) {
-        if (receiver != null) {
+        if (receiver == null) return;
+
+        mHandler.post(() -> {
             mEntitlementMgr.requestLatestTetheringEntitlementResult(type, receiver,
                     showEntitlementUi);
-        }
+        });
     }
 
     /** Register tethering event callback */
@@ -2011,6 +2022,7 @@
         } finally {
             mTetheringEventCallbacks.finishBroadcast();
         }
+        mNotificationUpdater.onUpstreamNetworkChanged(network);
     }
 
     private void reportConfigurationChanged(TetheringConfigurationParcel config) {
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringConfiguration.java b/Tethering/src/com/android/networkstack/tethering/TetheringConfiguration.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringConfiguration.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringConfiguration.java
index 7e9e26f..aeac437 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringConfiguration.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringConfiguration.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.content.Context.TELEPHONY_SERVICE;
 import static android.net.ConnectivityManager.TYPE_ETHERNET;
@@ -33,7 +33,6 @@
 import android.text.TextUtils;
 
 import com.android.internal.annotations.VisibleForTesting;
-import com.android.networkstack.tethering.R;
 
 import java.io.PrintWriter;
 import java.util.ArrayList;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringDependencies.java b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
similarity index 95%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringDependencies.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
index 0330dad..9b54b5f 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringDependencies.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
@@ -106,8 +106,9 @@
     /**
      * Get a reference to the TetheringNotificationUpdater to be used by tethering.
      */
-    public TetheringNotificationUpdater getNotificationUpdater(@NonNull final Context ctx) {
-        return new TetheringNotificationUpdater(ctx);
+    public TetheringNotificationUpdater getNotificationUpdater(@NonNull final Context ctx,
+            @NonNull final Looper looper) {
+        return new TetheringNotificationUpdater(ctx, looper);
     }
 
     /**
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringInterfaceUtils.java b/Tethering/src/com/android/networkstack/tethering/TetheringInterfaceUtils.java
similarity index 98%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringInterfaceUtils.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringInterfaceUtils.java
index 4dd6830..ff38f71 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringInterfaceUtils.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringInterfaceUtils.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.annotation.Nullable;
 import android.net.LinkProperties;
diff --git a/Tethering/src/com/android/networkstack/tethering/TetheringNotificationUpdater.java b/Tethering/src/com/android/networkstack/tethering/TetheringNotificationUpdater.java
new file mode 100644
index 0000000..ff83fd1
--- /dev/null
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringNotificationUpdater.java
@@ -0,0 +1,392 @@
+/*
+ * 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.networkstack.tethering;
+
+import static android.net.TetheringManager.TETHERING_BLUETOOTH;
+import static android.net.TetheringManager.TETHERING_USB;
+import static android.net.TetheringManager.TETHERING_WIFI;
+import static android.text.TextUtils.isEmpty;
+
+import android.app.Notification;
+import android.app.Notification.Action;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.content.Intent;
+import android.content.res.Configuration;
+import android.content.res.Resources;
+import android.net.Network;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.telephony.SubscriptionManager;
+import android.telephony.TelephonyManager;
+import android.util.Log;
+import android.util.SparseArray;
+
+import androidx.annotation.ArrayRes;
+import androidx.annotation.DrawableRes;
+import androidx.annotation.IntDef;
+import androidx.annotation.IntRange;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * A class to display tethering-related notifications.
+ *
+ * <p>This class is not thread safe, it is intended to be used only from the tethering handler
+ * thread. However the constructor is an exception, as it is called on another thread ;
+ * therefore for thread safety all members of this class MUST either be final or initialized
+ * to their default value (0, false or null).
+ *
+ * @hide
+ */
+public class TetheringNotificationUpdater {
+    private static final String TAG = TetheringNotificationUpdater.class.getSimpleName();
+    private static final String CHANNEL_ID = "TETHERING_STATUS";
+    private static final String WIFI_DOWNSTREAM = "WIFI";
+    private static final String USB_DOWNSTREAM = "USB";
+    private static final String BLUETOOTH_DOWNSTREAM = "BT";
+    @VisibleForTesting
+    static final String ACTION_DISABLE_TETHERING =
+            "com.android.server.connectivity.tethering.DISABLE_TETHERING";
+    private static final boolean NOTIFY_DONE = true;
+    private static final boolean NO_NOTIFY = false;
+    @VisibleForTesting
+    static final int EVENT_SHOW_NO_UPSTREAM = 1;
+    // Id to update and cancel enable notification. Must be unique within the tethering app.
+    @VisibleForTesting
+    static final int ENABLE_NOTIFICATION_ID = 1000;
+    // Id to update and cancel restricted notification. Must be unique within the tethering app.
+    @VisibleForTesting
+    static final int RESTRICTED_NOTIFICATION_ID = 1001;
+    // Id to update and cancel no upstream notification. Must be unique within the tethering app.
+    @VisibleForTesting
+    static final int NO_UPSTREAM_NOTIFICATION_ID = 1002;
+    @VisibleForTesting
+    static final int NO_ICON_ID = 0;
+    @VisibleForTesting
+    static final int DOWNSTREAM_NONE = 0;
+    private final Context mContext;
+    private final NotificationManager mNotificationManager;
+    private final NotificationChannel mChannel;
+    private final Handler mHandler;
+
+    // WARNING : the constructor is called on a different thread. Thread safety therefore
+    // relies on these values being initialized to 0 or false, and not any other value. If you need
+    // to change this, you will need to change the thread where the constructor is invoked,
+    // or to introduce synchronization.
+    // Downstream type is one of ConnectivityManager.TETHERING_* constants, 0 1 or 2.
+    // This value has to be made 1 2 and 4, and OR'd with the others.
+    private int mDownstreamTypesMask = DOWNSTREAM_NONE;
+    private boolean mNoUpstream = false;
+
+    // WARNING : this value is not able to being initialized to 0 and must have volatile because
+    // telephony service is not guaranteed that is up before tethering service starts. If telephony
+    // is up later than tethering, TetheringNotificationUpdater will use incorrect and valid
+    // subscription id(0) to query resources. Therefore, initialized subscription id must be
+    // INVALID_SUBSCRIPTION_ID.
+    private volatile int mActiveDataSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
+
+    @IntDef({ENABLE_NOTIFICATION_ID, RESTRICTED_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID})
+    @interface NotificationId {}
+
+    private static final class MccMncOverrideInfo {
+        public final List<String> visitedMccMncs;
+        public final int homeMcc;
+        public final int homeMnc;
+        MccMncOverrideInfo(List<String> visitedMccMncs, int mcc, int mnc) {
+            this.visitedMccMncs = visitedMccMncs;
+            this.homeMcc = mcc;
+            this.homeMnc = mnc;
+        }
+    }
+
+    private static final SparseArray<MccMncOverrideInfo> sCarrierIdToMccMnc = new SparseArray<>();
+
+    static {
+        // VZW
+        sCarrierIdToMccMnc.put(
+                1839, new MccMncOverrideInfo(Arrays.asList(new String[] {"20404"}), 311, 480));
+    }
+
+    public TetheringNotificationUpdater(@NonNull final Context context,
+            @NonNull final Looper looper) {
+        mContext = context;
+        mNotificationManager = (NotificationManager) context.createContextAsUser(UserHandle.ALL, 0)
+                .getSystemService(Context.NOTIFICATION_SERVICE);
+        mChannel = new NotificationChannel(
+                CHANNEL_ID,
+                context.getResources().getString(R.string.notification_channel_tethering_status),
+                NotificationManager.IMPORTANCE_LOW);
+        mNotificationManager.createNotificationChannel(mChannel);
+        mHandler = new NotificationHandler(looper);
+    }
+
+    private class NotificationHandler extends Handler {
+        NotificationHandler(Looper looper) {
+            super(looper);
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            switch(msg.what) {
+                case EVENT_SHOW_NO_UPSTREAM:
+                    notifyTetheringNoUpstream();
+                    break;
+            }
+        }
+    }
+
+    /** Called when downstream has changed */
+    public void onDownstreamChanged(@IntRange(from = 0, to = 7) final int downstreamTypesMask) {
+        if (mDownstreamTypesMask == downstreamTypesMask) return;
+        mDownstreamTypesMask = downstreamTypesMask;
+        updateEnableNotification();
+        updateNoUpstreamNotification();
+    }
+
+    /** Called when active data subscription id changed */
+    public void onActiveDataSubscriptionIdChanged(final int subId) {
+        if (mActiveDataSubId == subId) return;
+        mActiveDataSubId = subId;
+        updateEnableNotification();
+        updateNoUpstreamNotification();
+    }
+
+    /** Called when upstream network changed */
+    public void onUpstreamNetworkChanged(@Nullable final Network network) {
+        final boolean isNoUpstream = (network == null);
+        if (mNoUpstream == isNoUpstream) return;
+        mNoUpstream = isNoUpstream;
+        updateNoUpstreamNotification();
+    }
+
+    @NonNull
+    @VisibleForTesting
+    final Handler getHandler() {
+        return mHandler;
+    }
+
+    @NonNull
+    @VisibleForTesting
+    Resources getResourcesForSubId(@NonNull final Context context, final int subId) {
+        final Resources res = SubscriptionManager.getResourcesForSubId(context, subId);
+        final TelephonyManager tm =
+                ((TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE))
+                        .createForSubscriptionId(mActiveDataSubId);
+        final int carrierId = tm.getSimCarrierId();
+        final String mccmnc = tm.getSimOperator();
+        final MccMncOverrideInfo overrideInfo = sCarrierIdToMccMnc.get(carrierId);
+        if (overrideInfo != null && overrideInfo.visitedMccMncs.contains(mccmnc)) {
+            // Re-configure MCC/MNC value to specific carrier to get right resources.
+            final Configuration config = res.getConfiguration();
+            config.mcc = overrideInfo.homeMcc;
+            config.mnc = overrideInfo.homeMnc;
+            return context.createConfigurationContext(config).getResources();
+        }
+        return res;
+    }
+
+    private void updateEnableNotification() {
+        final boolean tetheringInactive = mDownstreamTypesMask == DOWNSTREAM_NONE;
+
+        if (tetheringInactive || setupNotification() == NO_NOTIFY) {
+            clearNotification(ENABLE_NOTIFICATION_ID);
+        }
+    }
+
+    private void updateNoUpstreamNotification() {
+        final boolean tetheringInactive = mDownstreamTypesMask == DOWNSTREAM_NONE;
+
+        if (tetheringInactive
+                || !mNoUpstream
+                || setupNoUpstreamNotification() == NO_NOTIFY) {
+            clearNotification(NO_UPSTREAM_NOTIFICATION_ID);
+            mHandler.removeMessages(EVENT_SHOW_NO_UPSTREAM);
+        }
+    }
+
+    @VisibleForTesting
+    void tetheringRestrictionLifted() {
+        clearNotification(RESTRICTED_NOTIFICATION_ID);
+    }
+
+    private void clearNotification(@NotificationId final int id) {
+        mNotificationManager.cancel(null /* tag */, id);
+    }
+
+    @VisibleForTesting
+    void notifyTetheringDisabledByRestriction() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final String title = res.getString(R.string.disable_tether_notification_title);
+        final String message = res.getString(R.string.disable_tether_notification_message);
+        if (isEmpty(title) || isEmpty(message)) return;
+
+        final PendingIntent pi = PendingIntent.getActivity(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                new Intent(Settings.ACTION_TETHER_SETTINGS),
+                Intent.FLAG_ACTIVITY_NEW_TASK,
+                null /* options */);
+
+        showNotification(R.drawable.stat_sys_tether_general, title, message,
+                RESTRICTED_NOTIFICATION_ID, pi, new Action[0]);
+    }
+
+    private void notifyTetheringNoUpstream() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final String title = res.getString(R.string.no_upstream_notification_title);
+        final String message = res.getString(R.string.no_upstream_notification_message);
+        final String disableButton =
+                res.getString(R.string.no_upstream_notification_disable_button);
+        if (isEmpty(title) || isEmpty(message) || isEmpty(disableButton)) return;
+
+        final Intent intent = new Intent(ACTION_DISABLE_TETHERING);
+        intent.setPackage(mContext.getPackageName());
+        final PendingIntent pi = PendingIntent.getBroadcast(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                intent,
+                0 /* flags */);
+        final Action action = new Action.Builder(NO_ICON_ID, disableButton, pi).build();
+
+        showNotification(R.drawable.stat_sys_tether_general, title, message,
+                NO_UPSTREAM_NOTIFICATION_ID, null /* pendingIntent */, action);
+    }
+
+    /**
+     * Returns the downstream types mask which convert from given string.
+     *
+     * @param types This string has to be made by "WIFI", "USB", "BT", and OR'd with the others.
+     *
+     * @return downstream types mask value.
+     */
+    @VisibleForTesting
+    @IntRange(from = 0, to = 7)
+    int getDownstreamTypesMask(@NonNull final String types) {
+        int downstreamTypesMask = DOWNSTREAM_NONE;
+        final String[] downstreams = types.split("\\|");
+        for (String downstream : downstreams) {
+            if (USB_DOWNSTREAM.equals(downstream.trim())) {
+                downstreamTypesMask |= (1 << TETHERING_USB);
+            } else if (WIFI_DOWNSTREAM.equals(downstream.trim())) {
+                downstreamTypesMask |= (1 << TETHERING_WIFI);
+            } else if (BLUETOOTH_DOWNSTREAM.equals(downstream.trim())) {
+                downstreamTypesMask |= (1 << TETHERING_BLUETOOTH);
+            }
+        }
+        return downstreamTypesMask;
+    }
+
+    /**
+     * Returns the icons {@link android.util.SparseArray} which get from given string-array resource
+     * id.
+     *
+     * @param id String-array resource id
+     *
+     * @return {@link android.util.SparseArray} with downstream types and icon id info.
+     */
+    @NonNull
+    @VisibleForTesting
+    SparseArray<Integer> getIcons(@ArrayRes int id, @NonNull Resources res) {
+        final String[] array = res.getStringArray(id);
+        final SparseArray<Integer> icons = new SparseArray<>();
+        for (String config : array) {
+            if (isEmpty(config)) continue;
+
+            final String[] elements = config.split(";");
+            if (elements.length != 2) {
+                Log.wtf(TAG,
+                        "Unexpected format in Tethering notification configuration : " + config);
+                continue;
+            }
+
+            final String[] types = elements[0].split(",");
+            for (String type : types) {
+                int mask = getDownstreamTypesMask(type);
+                if (mask == DOWNSTREAM_NONE) continue;
+                icons.put(mask, res.getIdentifier(
+                        elements[1].trim(), null /* defType */, null /* defPackage */));
+            }
+        }
+        return icons;
+    }
+
+    private boolean setupNoUpstreamNotification() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final int delayToShowUpstreamNotification =
+                res.getInteger(R.integer.delay_to_show_no_upstream_after_no_backhaul);
+
+        if (delayToShowUpstreamNotification < 0) return NO_NOTIFY;
+
+        mHandler.sendMessageDelayed(mHandler.obtainMessage(EVENT_SHOW_NO_UPSTREAM),
+                delayToShowUpstreamNotification);
+        return NOTIFY_DONE;
+    }
+
+    private boolean setupNotification() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final SparseArray<Integer> downstreamIcons =
+                getIcons(R.array.tethering_notification_icons, res);
+
+        final int iconId = downstreamIcons.get(mDownstreamTypesMask, NO_ICON_ID);
+        if (iconId == NO_ICON_ID) return NO_NOTIFY;
+
+        final String title = res.getString(R.string.tethering_notification_title);
+        final String message = res.getString(R.string.tethering_notification_message);
+        if (isEmpty(title) || isEmpty(message)) return NO_NOTIFY;
+
+        final PendingIntent pi = PendingIntent.getActivity(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                new Intent(Settings.ACTION_TETHER_SETTINGS),
+                Intent.FLAG_ACTIVITY_NEW_TASK,
+                null /* options */);
+
+        showNotification(iconId, title, message, ENABLE_NOTIFICATION_ID, pi, new Action[0]);
+        return NOTIFY_DONE;
+    }
+
+    private void showNotification(@DrawableRes final int iconId, @NonNull final String title,
+            @NonNull final String message, @NotificationId final int id, @Nullable PendingIntent pi,
+            @NonNull final Action... actions) {
+        final Notification notification =
+                new Notification.Builder(mContext, mChannel.getId())
+                        .setSmallIcon(iconId)
+                        .setContentTitle(title)
+                        .setContentText(message)
+                        .setOngoing(true)
+                        .setColor(mContext.getColor(
+                                android.R.color.system_notification_accent_color))
+                        .setVisibility(Notification.VISIBILITY_PUBLIC)
+                        .setCategory(Notification.CATEGORY_STATUS)
+                        .setContentIntent(pi)
+                        .setActions(actions)
+                        .build();
+
+        mNotificationManager.notify(null /* tag */, id, notification);
+    }
+}
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java b/Tethering/src/com/android/networkstack/tethering/TetheringService.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringService.java
index c30be25..3ed2115 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringService.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ACCESS_TETHERING_PERMISSION;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java
rename to Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
index 45bb4ab..25ddce4 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java
+++ b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.ConnectivityManager.TYPE_BLUETOOTH;
 import static android.net.ConnectivityManager.TYPE_ETHERNET;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkState.java b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkState.java
similarity index 96%
rename from Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkState.java
rename to Tethering/src/com/android/networkstack/tethering/UpstreamNetworkState.java
index 68bb837..bab9f84 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkState.java
+++ b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkState.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.net.LinkProperties;
 import android.net.Network;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java b/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java
deleted file mode 100644
index 992cdd8..0000000
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java
+++ /dev/null
@@ -1,244 +0,0 @@
-/*
- * 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.connectivity.tethering;
-
-import static android.net.TetheringManager.TETHERING_BLUETOOTH;
-import static android.net.TetheringManager.TETHERING_USB;
-import static android.net.TetheringManager.TETHERING_WIFI;
-
-import android.app.Notification;
-import android.app.NotificationChannel;
-import android.app.NotificationManager;
-import android.app.PendingIntent;
-import android.content.Context;
-import android.content.Intent;
-import android.content.res.Resources;
-import android.os.UserHandle;
-import android.provider.Settings;
-import android.telephony.SubscriptionManager;
-import android.text.TextUtils;
-import android.util.Log;
-import android.util.SparseArray;
-
-import androidx.annotation.ArrayRes;
-import androidx.annotation.DrawableRes;
-import androidx.annotation.IntDef;
-import androidx.annotation.IntRange;
-import androidx.annotation.NonNull;
-
-import com.android.internal.annotations.VisibleForTesting;
-import com.android.networkstack.tethering.R;
-
-/**
- * A class to display tethering-related notifications.
- *
- * <p>This class is not thread safe, it is intended to be used only from the tethering handler
- * thread. However the constructor is an exception, as it is called on another thread ;
- * therefore for thread safety all members of this class MUST either be final or initialized
- * to their default value (0, false or null).
- *
- * @hide
- */
-public class TetheringNotificationUpdater {
-    private static final String TAG = TetheringNotificationUpdater.class.getSimpleName();
-    private static final String CHANNEL_ID = "TETHERING_STATUS";
-    private static final String WIFI_DOWNSTREAM = "WIFI";
-    private static final String USB_DOWNSTREAM = "USB";
-    private static final String BLUETOOTH_DOWNSTREAM = "BT";
-    private static final boolean NOTIFY_DONE = true;
-    private static final boolean NO_NOTIFY = false;
-    // Id to update and cancel tethering notification. Must be unique within the tethering app.
-    private static final int ENABLE_NOTIFICATION_ID = 1000;
-    // Id to update and cancel restricted notification. Must be unique within the tethering app.
-    private static final int RESTRICTED_NOTIFICATION_ID = 1001;
-    @VisibleForTesting
-    static final int NO_ICON_ID = 0;
-    @VisibleForTesting
-    static final int DOWNSTREAM_NONE = 0;
-    private final Context mContext;
-    private final NotificationManager mNotificationManager;
-    private final NotificationChannel mChannel;
-
-    // WARNING : the constructor is called on a different thread. Thread safety therefore
-    // relies on this value being initialized to 0, and not any other value. If you need
-    // to change this, you will need to change the thread where the constructor is invoked,
-    // or to introduce synchronization.
-    // Downstream type is one of ConnectivityManager.TETHERING_* constants, 0 1 or 2.
-    // This value has to be made 1 2 and 4, and OR'd with the others.
-    private int mDownstreamTypesMask = DOWNSTREAM_NONE;
-
-    // WARNING : this value is not able to being initialized to 0 and must have volatile because
-    // telephony service is not guaranteed that is up before tethering service starts. If telephony
-    // is up later than tethering, TetheringNotificationUpdater will use incorrect and valid
-    // subscription id(0) to query resources. Therefore, initialized subscription id must be
-    // INVALID_SUBSCRIPTION_ID.
-    private volatile int mActiveDataSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
-
-    @IntDef({ENABLE_NOTIFICATION_ID, RESTRICTED_NOTIFICATION_ID})
-    @interface NotificationId {}
-
-    public TetheringNotificationUpdater(@NonNull final Context context) {
-        mContext = context;
-        mNotificationManager = (NotificationManager) context.createContextAsUser(UserHandle.ALL, 0)
-                .getSystemService(Context.NOTIFICATION_SERVICE);
-        mChannel = new NotificationChannel(
-                CHANNEL_ID,
-                context.getResources().getString(R.string.notification_channel_tethering_status),
-                NotificationManager.IMPORTANCE_LOW);
-        mNotificationManager.createNotificationChannel(mChannel);
-    }
-
-    /** Called when downstream has changed */
-    public void onDownstreamChanged(@IntRange(from = 0, to = 7) final int downstreamTypesMask) {
-        if (mDownstreamTypesMask == downstreamTypesMask) return;
-        mDownstreamTypesMask = downstreamTypesMask;
-        updateEnableNotification();
-    }
-
-    /** Called when active data subscription id changed */
-    public void onActiveDataSubscriptionIdChanged(final int subId) {
-        if (mActiveDataSubId == subId) return;
-        mActiveDataSubId = subId;
-        updateEnableNotification();
-    }
-
-    @VisibleForTesting
-    Resources getResourcesForSubId(@NonNull final Context c, final int subId) {
-        return SubscriptionManager.getResourcesForSubId(c, subId);
-    }
-
-    private void updateEnableNotification() {
-        final boolean tetheringInactive = mDownstreamTypesMask <= DOWNSTREAM_NONE;
-
-        if (tetheringInactive || setupNotification() == NO_NOTIFY) {
-            clearNotification(ENABLE_NOTIFICATION_ID);
-        }
-    }
-
-    @VisibleForTesting
-    void tetheringRestrictionLifted() {
-        clearNotification(RESTRICTED_NOTIFICATION_ID);
-    }
-
-    private void clearNotification(@NotificationId final int id) {
-        mNotificationManager.cancel(null /* tag */, id);
-    }
-
-    @VisibleForTesting
-    void notifyTetheringDisabledByRestriction() {
-        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
-        final String title = res.getString(R.string.disable_tether_notification_title);
-        final String message = res.getString(R.string.disable_tether_notification_message);
-
-        showNotification(R.drawable.stat_sys_tether_general, title, message,
-                RESTRICTED_NOTIFICATION_ID);
-    }
-
-    /**
-     * Returns the downstream types mask which convert from given string.
-     *
-     * @param types This string has to be made by "WIFI", "USB", "BT", and OR'd with the others.
-     *
-     * @return downstream types mask value.
-     */
-    @VisibleForTesting
-    @IntRange(from = 0, to = 7)
-    int getDownstreamTypesMask(@NonNull final String types) {
-        int downstreamTypesMask = DOWNSTREAM_NONE;
-        final String[] downstreams = types.split("\\|");
-        for (String downstream : downstreams) {
-            if (USB_DOWNSTREAM.equals(downstream.trim())) {
-                downstreamTypesMask |= (1 << TETHERING_USB);
-            } else if (WIFI_DOWNSTREAM.equals(downstream.trim())) {
-                downstreamTypesMask |= (1 << TETHERING_WIFI);
-            } else if (BLUETOOTH_DOWNSTREAM.equals(downstream.trim())) {
-                downstreamTypesMask |= (1 << TETHERING_BLUETOOTH);
-            }
-        }
-        return downstreamTypesMask;
-    }
-
-    /**
-     * Returns the icons {@link android.util.SparseArray} which get from given string-array resource
-     * id.
-     *
-     * @param id String-array resource id
-     *
-     * @return {@link android.util.SparseArray} with downstream types and icon id info.
-     */
-    @VisibleForTesting
-    SparseArray<Integer> getIcons(@ArrayRes int id, @NonNull Resources res) {
-        final String[] array = res.getStringArray(id);
-        final SparseArray<Integer> icons = new SparseArray<>();
-        for (String config : array) {
-            if (TextUtils.isEmpty(config)) continue;
-
-            final String[] elements = config.split(";");
-            if (elements.length != 2) {
-                Log.wtf(TAG,
-                        "Unexpected format in Tethering notification configuration : " + config);
-                continue;
-            }
-
-            final String[] types = elements[0].split(",");
-            for (String type : types) {
-                int mask = getDownstreamTypesMask(type);
-                if (mask == DOWNSTREAM_NONE) continue;
-                icons.put(mask, res.getIdentifier(
-                        elements[1].trim(), null /* defType */, null /* defPackage */));
-            }
-        }
-        return icons;
-    }
-
-    private boolean setupNotification() {
-        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
-        final SparseArray<Integer> downstreamIcons =
-                getIcons(R.array.tethering_notification_icons, res);
-
-        final int iconId = downstreamIcons.get(mDownstreamTypesMask, NO_ICON_ID);
-        if (iconId == NO_ICON_ID) return NO_NOTIFY;
-
-        final String title = res.getString(R.string.tethering_notification_title);
-        final String message = res.getString(R.string.tethering_notification_message);
-
-        showNotification(iconId, title, message, ENABLE_NOTIFICATION_ID);
-        return NOTIFY_DONE;
-    }
-
-    private void showNotification(@DrawableRes final int iconId, @NonNull final String title,
-            @NonNull final String message, @NotificationId final int id) {
-        final Intent intent = new Intent(Settings.ACTION_TETHER_SETTINGS);
-        final PendingIntent pi = PendingIntent.getActivity(
-                mContext.createContextAsUser(UserHandle.CURRENT, 0),
-                0 /* requestCode */, intent, 0 /* flags */, null /* options */);
-        final Notification notification =
-                new Notification.Builder(mContext, mChannel.getId())
-                        .setSmallIcon(iconId)
-                        .setContentTitle(title)
-                        .setContentText(message)
-                        .setOngoing(true)
-                        .setColor(mContext.getColor(
-                                android.R.color.system_notification_accent_color))
-                        .setVisibility(Notification.VISIBILITY_PUBLIC)
-                        .setCategory(Notification.CATEGORY_STATUS)
-                        .setContentIntent(pi)
-                        .build();
-
-        mNotificationManager.notify(null /* tag */, id, notification);
-    }
-}
diff --git a/Tethering/tests/unit/AndroidManifest.xml b/Tethering/tests/unit/AndroidManifest.xml
index 4ff1d37..31eaabf 100644
--- a/Tethering/tests/unit/AndroidManifest.xml
+++ b/Tethering/tests/unit/AndroidManifest.xml
@@ -16,16 +16,17 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           package="com.android.networkstack.tethering.tests.unit">
 
+    <uses-permission android:name="android.permission.READ_PHONE_STATE"/>
     <uses-permission android:name="android.permission.TETHER_PRIVILEGED"/>
 
     <application android:debuggable="true">
         <uses-library android:name="android.test.runner" />
         <service
-            android:name="com.android.server.connectivity.tethering.MockTetheringService"
+            android:name="com.android.networkstack.tethering.MockTetheringService"
             android:permission="android.permission.TETHER_PRIVILEGED"
             android:exported="true">
             <intent-filter>
-                <action android:name="com.android.server.connectivity.tethering.TetheringService"/>
+                <action android:name="com.android.networkstack.tethering.TetheringService"/>
             </intent-filter>
         </service>
     </application>
diff --git a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
index fdfdae8..f9be7b9 100644
--- a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
+++ b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
@@ -587,6 +587,7 @@
         final InetAddress neighB = InetAddresses.parseNumericAddress("2001:db8::2");
         final InetAddress neighLL = InetAddresses.parseNumericAddress("fe80::1");
         final InetAddress neighMC = InetAddresses.parseNumericAddress("ff02::1234");
+        final MacAddress macNull = MacAddress.fromString("00:00:00:00:00:00");
         final MacAddress macA = MacAddress.fromString("00:00:00:00:00:0a");
         final MacAddress macB = MacAddress.fromString("11:22:33:00:00:0b");
 
@@ -612,13 +613,14 @@
         verifyNoMoreInteractions(mNetd);
 
         // A neighbor that is no longer valid causes the rule to be removed.
-        recvNewNeigh(myIfindex, neighA, NUD_FAILED, macA);
-        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighA, macA));
+        // NUD_FAILED events do not have a MAC address.
+        recvNewNeigh(myIfindex, neighA, NUD_FAILED, null);
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighA, macNull));
         reset(mNetd);
 
         // A neighbor that is deleted causes the rule to be removed.
         recvDelNeigh(myIfindex, neighB, NUD_STALE, macB);
-        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macB));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macNull));
         reset(mNetd);
 
         // Upstream changes result in deleting and re-adding the rules.
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/ConnectedClientsTrackerTest.kt b/Tethering/tests/unit/src/com/android/networkstack/tethering/ConnectedClientsTrackerTest.kt
similarity index 98%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/ConnectedClientsTrackerTest.kt
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/ConnectedClientsTrackerTest.kt
index 1cdc3bb..d915354 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/ConnectedClientsTrackerTest.kt
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/ConnectedClientsTrackerTest.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering
+package com.android.networkstack.tethering
 
 import android.net.LinkAddress
 import android.net.MacAddress
@@ -159,4 +159,4 @@
             return time
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
similarity index 99%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
index 6695eed..8bd0edc 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.TetheringManager.TETHERING_BLUETOOTH;
 import static android.net.TetheringManager.TETHERING_ETHERNET;
@@ -59,7 +59,6 @@
 import com.android.internal.util.State;
 import com.android.internal.util.StateMachine;
 import com.android.internal.util.test.BroadcastInterceptingContext;
-import com.android.networkstack.tethering.R;
 
 import org.junit.After;
 import org.junit.Before;
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinatorTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/IPv6TetheringCoordinatorTest.java
similarity index 98%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinatorTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/IPv6TetheringCoordinatorTest.java
index 9121243..820f255 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinatorTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/IPv6TetheringCoordinatorTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
 import static android.net.RouteInfo.RTN_UNICAST;
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/MockTetheringService.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
similarity index 96%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/MockTetheringService.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
index 355ece9..1c81c12 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/MockTetheringService.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static org.mockito.Mockito.mock;
 
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/OffloadControllerTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
similarity index 98%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/OffloadControllerTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
index fe84086..6579720 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/OffloadControllerTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
 import static android.net.NetworkStats.METERED_NO;
@@ -26,9 +26,9 @@
 import static android.net.RouteInfo.RTN_UNICAST;
 import static android.provider.Settings.Global.TETHER_OFFLOAD_DISABLED;
 
-import static com.android.server.connectivity.tethering.OffloadController.StatsType.STATS_PER_IFACE;
-import static com.android.server.connectivity.tethering.OffloadController.StatsType.STATS_PER_UID;
-import static com.android.server.connectivity.tethering.OffloadHardwareInterface.ForwardedStats;
+import static com.android.networkstack.tethering.OffloadController.StatsType.STATS_PER_IFACE;
+import static com.android.networkstack.tethering.OffloadController.StatsType.STATS_PER_UID;
+import static com.android.networkstack.tethering.OffloadHardwareInterface.ForwardedStats;
 import static com.android.testutils.MiscAssertsKt.assertContainsAll;
 import static com.android.testutils.MiscAssertsKt.assertThrows;
 import static com.android.testutils.NetworkStatsUtilsKt.orderInsensitiveEquals;
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringConfigurationTest.java
similarity index 99%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringConfigurationTest.java
index 3635964..07ddea4 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringConfigurationTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.ConnectivityManager.TYPE_ETHERNET;
 import static android.net.ConnectivityManager.TYPE_MOBILE;
@@ -44,7 +44,6 @@
 import androidx.test.runner.AndroidJUnit4;
 
 import com.android.internal.util.test.BroadcastInterceptingContext;
-import com.android.networkstack.tethering.R;
 
 import org.junit.After;
 import org.junit.Before;
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringNotificationUpdaterTest.kt b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringNotificationUpdaterTest.kt
new file mode 100644
index 0000000..5f88588
--- /dev/null
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringNotificationUpdaterTest.kt
@@ -0,0 +1,430 @@
+/*
+ * 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.networkstack.tethering
+
+import android.app.Notification
+import android.app.NotificationManager
+import android.content.Context
+import android.content.res.Resources
+import android.net.ConnectivityManager.TETHERING_BLUETOOTH
+import android.net.ConnectivityManager.TETHERING_USB
+import android.net.ConnectivityManager.TETHERING_WIFI
+import android.net.Network
+import android.os.Handler
+import android.os.HandlerThread
+import android.os.Looper
+import android.os.UserHandle
+import android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID
+import android.telephony.TelephonyManager
+import androidx.test.filters.SmallTest
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.runner.AndroidJUnit4
+import com.android.internal.util.test.BroadcastInterceptingContext
+import com.android.networkstack.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE
+import com.android.networkstack.tethering.TetheringNotificationUpdater.ENABLE_NOTIFICATION_ID
+import com.android.networkstack.tethering.TetheringNotificationUpdater.EVENT_SHOW_NO_UPSTREAM
+import com.android.networkstack.tethering.TetheringNotificationUpdater.NO_UPSTREAM_NOTIFICATION_ID
+import com.android.networkstack.tethering.TetheringNotificationUpdater.RESTRICTED_NOTIFICATION_ID
+import com.android.testutils.waitForIdle
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.fail
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.ArgumentCaptor
+import org.mockito.ArgumentMatchers.any
+import org.mockito.ArgumentMatchers.anyInt
+import org.mockito.ArgumentMatchers.eq
+import org.mockito.Mock
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.never
+import org.mockito.Mockito.reset
+import org.mockito.Mockito.times
+import org.mockito.Mockito.verify
+import org.mockito.Mockito.verifyZeroInteractions
+import org.mockito.MockitoAnnotations
+
+const val TEST_SUBID = 1
+const val WIFI_ICON_ID = 1
+const val USB_ICON_ID = 2
+const val BT_ICON_ID = 3
+const val GENERAL_ICON_ID = 4
+const val WIFI_MASK = 1 shl TETHERING_WIFI
+const val USB_MASK = 1 shl TETHERING_USB
+const val BT_MASK = 1 shl TETHERING_BLUETOOTH
+const val TITLE = "Tethering active"
+const val MESSAGE = "Tap here to set up."
+const val TEST_TITLE = "Hotspot active"
+const val TEST_MESSAGE = "Tap to set up hotspot."
+const val TEST_NO_UPSTREAM_TITLE = "Hotspot has no internet access"
+const val TEST_NO_UPSTREAM_MESSAGE = "Device cannot connect to internet."
+const val TEST_NO_UPSTREAM_BUTTON = "Turn off hotspot"
+
+@RunWith(AndroidJUnit4::class)
+@SmallTest
+class TetheringNotificationUpdaterTest {
+    // lateinit used here for mocks as they need to be reinitialized between each test and the test
+    // should crash if they are used before being initialized.
+    @Mock private lateinit var mockContext: Context
+    @Mock private lateinit var notificationManager: NotificationManager
+    @Mock private lateinit var telephonyManager: TelephonyManager
+    @Mock private lateinit var defaultResources: Resources
+    @Mock private lateinit var testResources: Resources
+
+    // lateinit for these classes under test, as they should be reset to a different instance for
+    // every test but should always be initialized before use (or the test should crash).
+    private lateinit var context: TestContext
+    private lateinit var notificationUpdater: TetheringNotificationUpdater
+    private lateinit var fakeTetheringThread: HandlerThread
+
+    private val ENABLE_ICON_CONFIGS = arrayOf(
+            "USB;android.test:drawable/usb", "BT;android.test:drawable/bluetooth",
+            "WIFI|BT;android.test:drawable/general", "WIFI|USB;android.test:drawable/general",
+            "USB|BT;android.test:drawable/general", "WIFI|USB|BT;android.test:drawable/general")
+
+    private inner class TestContext(c: Context) : BroadcastInterceptingContext(c) {
+        override fun createContextAsUser(user: UserHandle, flags: Int) =
+                if (user == UserHandle.ALL) mockContext else this
+        override fun getSystemService(name: String) =
+                if (name == Context.TELEPHONY_SERVICE) telephonyManager
+                else super.getSystemService(name)
+    }
+
+    private inner class WrappedNotificationUpdater(c: Context, looper: Looper)
+        : TetheringNotificationUpdater(c, looper) {
+        override fun getResourcesForSubId(context: Context, subId: Int) =
+                when (subId) {
+                    TEST_SUBID -> testResources
+                    INVALID_SUBSCRIPTION_ID -> defaultResources
+                    else -> super.getResourcesForSubId(context, subId)
+                }
+    }
+
+    private fun setupResources() {
+        doReturn(ENABLE_ICON_CONFIGS).`when`(defaultResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        doReturn(arrayOf("WIFI;android.test:drawable/wifi")).`when`(testResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        doReturn(5).`when`(testResources)
+                .getInteger(R.integer.delay_to_show_no_upstream_after_no_backhaul)
+        doReturn(TITLE).`when`(defaultResources).getString(R.string.tethering_notification_title)
+        doReturn(MESSAGE).`when`(defaultResources)
+                .getString(R.string.tethering_notification_message)
+        doReturn(TEST_TITLE).`when`(testResources).getString(R.string.tethering_notification_title)
+        doReturn(TEST_MESSAGE).`when`(testResources)
+                .getString(R.string.tethering_notification_message)
+        doReturn(TEST_NO_UPSTREAM_TITLE).`when`(testResources)
+                .getString(R.string.no_upstream_notification_title)
+        doReturn(TEST_NO_UPSTREAM_MESSAGE).`when`(testResources)
+                .getString(R.string.no_upstream_notification_message)
+        doReturn(TEST_NO_UPSTREAM_BUTTON).`when`(testResources)
+                .getString(R.string.no_upstream_notification_disable_button)
+        doReturn(USB_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/usb"), any(), any())
+        doReturn(BT_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/bluetooth"), any(), any())
+        doReturn(GENERAL_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/general"), any(), any())
+        doReturn(WIFI_ICON_ID).`when`(testResources)
+                .getIdentifier(eq("android.test:drawable/wifi"), any(), any())
+    }
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+        context = TestContext(InstrumentationRegistry.getInstrumentation().context)
+        doReturn(notificationManager).`when`(mockContext)
+                .getSystemService(Context.NOTIFICATION_SERVICE)
+        fakeTetheringThread = HandlerThread(this::class.simpleName)
+        fakeTetheringThread.start()
+        notificationUpdater = WrappedNotificationUpdater(context, fakeTetheringThread.looper)
+        setupResources()
+    }
+
+    @After
+    fun tearDown() {
+        fakeTetheringThread.quitSafely()
+    }
+
+    private fun Notification.title() = this.extras.getString(Notification.EXTRA_TITLE)
+    private fun Notification.text() = this.extras.getString(Notification.EXTRA_TEXT)
+
+    private fun verifyNotification(iconId: Int, title: String, text: String, id: Int) {
+        verify(notificationManager, never()).cancel(any(), eq(id))
+
+        val notificationCaptor = ArgumentCaptor.forClass(Notification::class.java)
+        verify(notificationManager, times(1))
+                .notify(any(), eq(id), notificationCaptor.capture())
+
+        val notification = notificationCaptor.getValue()
+        assertEquals(iconId, notification.smallIcon.resId)
+        assertEquals(title, notification.title())
+        assertEquals(text, notification.text())
+    }
+
+    private fun verifyNotificationCancelled(id: Int) =
+        verify(notificationManager, times(1)).cancel(any(), eq(id))
+
+    private val tetheringActiveNotifications =
+            listOf(NO_UPSTREAM_NOTIFICATION_ID, ENABLE_NOTIFICATION_ID)
+
+    private fun verifyCancelAllTetheringActiveNotifications() {
+        tetheringActiveNotifications.forEach {
+            verifyNotificationCancelled(it)
+        }
+        reset(notificationManager)
+    }
+
+    private fun verifyOnlyTetheringActiveNotification(
+        notifyId: Int,
+        iconId: Int,
+        title: String,
+        text: String
+    ) {
+        tetheringActiveNotifications.forEach {
+            when (it) {
+                notifyId -> verifyNotification(iconId, title, text, notifyId)
+                else -> verifyNotificationCancelled(it)
+            }
+        }
+        reset(notificationManager)
+    }
+
+    @Test
+    fun testNotificationWithDownstreamChanged() {
+        // Wifi downstream. No notification.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyCancelAllTetheringActiveNotifications()
+
+        // Same downstream changed. Nothing happened.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyZeroInteractions(notificationManager)
+
+        // Wifi and usb downstreams. Show enable notification
+        notificationUpdater.onDownstreamChanged(WIFI_MASK or USB_MASK)
+        verifyOnlyTetheringActiveNotification(
+                ENABLE_NOTIFICATION_ID, GENERAL_ICON_ID, TITLE, MESSAGE)
+
+        // Usb downstream. Still show enable notification.
+        notificationUpdater.onDownstreamChanged(USB_MASK)
+        verifyOnlyTetheringActiveNotification(ENABLE_NOTIFICATION_ID, USB_ICON_ID, TITLE, MESSAGE)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyCancelAllTetheringActiveNotifications()
+    }
+
+    @Test
+    fun testNotificationWithActiveDataSubscriptionIdChanged() {
+        // Usb downstream. Showed enable notification with default resource.
+        notificationUpdater.onDownstreamChanged(USB_MASK)
+        verifyOnlyTetheringActiveNotification(ENABLE_NOTIFICATION_ID, USB_ICON_ID, TITLE, MESSAGE)
+
+        // Same subId changed. Nothing happened.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(INVALID_SUBSCRIPTION_ID)
+        verifyZeroInteractions(notificationManager)
+
+        // Set test sub id. Clear notification with test resource.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyCancelAllTetheringActiveNotifications()
+
+        // Wifi downstream. Show enable notification with test resource.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyOnlyTetheringActiveNotification(
+                ENABLE_NOTIFICATION_ID, WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyCancelAllTetheringActiveNotifications()
+    }
+
+    private fun assertIconNumbers(number: Int, configs: Array<String?>) {
+        doReturn(configs).`when`(defaultResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        assertEquals(number, notificationUpdater.getIcons(
+                R.array.tethering_notification_icons, defaultResources).size())
+    }
+
+    @Test
+    fun testGetIcons() {
+        assertIconNumbers(0, arrayOfNulls<String>(0))
+        assertIconNumbers(0, arrayOf(null, ""))
+        assertIconNumbers(3, arrayOf(
+                // These configurations are invalid with wrong strings or symbols.
+                ";", ",", "|", "|,;", "WIFI", "1;2", " U SB; ", "bt;", "WIFI;USB;BT", "WIFI|USB|BT",
+                "WIFI,BT,USB", " WIFI| |  | USB, test:drawable/test",
+                // This configuration is valid with two downstream types (USB, BT).
+                "USB|,,,,,|BT;drawable/test ",
+                // This configuration is valid with one downstream types (WIFI).
+                "     WIFI     ; android.test:drawable/xxx "))
+    }
+
+    @Test
+    fun testGetDownstreamTypesMask() {
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask(""))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("1"))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("WIFI_P2P"))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("usb"))
+        assertEquals(WIFI_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI "))
+        assertEquals(USB_MASK, notificationUpdater.getDownstreamTypesMask("USB | B T"))
+        assertEquals(BT_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI: | BT"))
+        assertEquals(WIFI_MASK or USB_MASK,
+                notificationUpdater.getDownstreamTypesMask("1|2|USB|WIFI|BLUETOOTH||"))
+    }
+
+    @Test
+    fun testSetupRestrictedNotification() {
+        val title = context.resources.getString(R.string.disable_tether_notification_title)
+        val message = context.resources.getString(R.string.disable_tether_notification_message)
+        val disallowTitle = "Tether function is disallowed"
+        val disallowMessage = "Please contact your admin"
+        doReturn(title).`when`(defaultResources)
+                .getString(R.string.disable_tether_notification_title)
+        doReturn(message).`when`(defaultResources)
+                .getString(R.string.disable_tether_notification_message)
+        doReturn(disallowTitle).`when`(testResources)
+                .getString(R.string.disable_tether_notification_title)
+        doReturn(disallowMessage).`when`(testResources)
+                .getString(R.string.disable_tether_notification_message)
+
+        // User restrictions on. Show restricted notification.
+        notificationUpdater.notifyTetheringDisabledByRestriction()
+        verifyNotification(R.drawable.stat_sys_tether_general, title, message,
+                RESTRICTED_NOTIFICATION_ID)
+        reset(notificationManager)
+
+        // User restrictions off. Clear notification.
+        notificationUpdater.tetheringRestrictionLifted()
+        verifyNotificationCancelled(RESTRICTED_NOTIFICATION_ID)
+        reset(notificationManager)
+
+        // Set test sub id. No notification.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyCancelAllTetheringActiveNotifications()
+
+        // User restrictions on again. Show restricted notification with test resource.
+        notificationUpdater.notifyTetheringDisabledByRestriction()
+        verifyNotification(R.drawable.stat_sys_tether_general, disallowTitle, disallowMessage,
+                RESTRICTED_NOTIFICATION_ID)
+        reset(notificationManager)
+    }
+
+    val MAX_BACKOFF_MS = 200L
+    /**
+     * Waits for all messages, including delayed ones, to be processed.
+     *
+     * This will wait until the handler has no more messages to be processed including
+     * delayed ones, or the timeout has expired. It uses an exponential backoff strategy
+     * to wait longer and longer to consume less CPU, with the max granularity being
+     * MAX_BACKOFF_MS.
+     *
+     * @return true if all messages have been processed including delayed ones, false if timeout
+     *
+     * TODO: Move this method to com.android.testutils.HandlerUtils.kt.
+     */
+    private fun Handler.waitForDelayedMessage(what: Int?, timeoutMs: Long) {
+        fun hasMatchingMessages() =
+                if (what == null) hasMessagesOrCallbacks() else hasMessages(what)
+        val expiry = System.currentTimeMillis() + timeoutMs
+        var delay = 5L
+        while (System.currentTimeMillis() < expiry && hasMatchingMessages()) {
+            // None of Handler, Looper, Message and MessageQueue expose any way to retrieve
+            // the time when the next (let alone the last) message will be processed, so
+            // short of examining the internals with reflection sleep() is the only solution.
+            Thread.sleep(delay)
+            delay = (delay * 2)
+                    .coerceAtMost(expiry - System.currentTimeMillis())
+                    .coerceAtMost(MAX_BACKOFF_MS)
+        }
+
+        val timeout = expiry - System.currentTimeMillis()
+        if (timeout <= 0) fail("Delayed message did not process yet after ${timeoutMs}ms")
+        waitForIdle(timeout)
+    }
+
+    @Test
+    fun testNotificationWithUpstreamNetworkChanged() {
+        // Set test sub id. No notification.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyCancelAllTetheringActiveNotifications()
+
+        // Wifi downstream. Show enable notification with test resource.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyOnlyTetheringActiveNotification(
+                ENABLE_NOTIFICATION_ID, WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE)
+
+        // There is no upstream. Show no upstream notification.
+        notificationUpdater.onUpstreamNetworkChanged(null)
+        notificationUpdater.handler.waitForDelayedMessage(EVENT_SHOW_NO_UPSTREAM, 500L)
+        verifyNotification(R.drawable.stat_sys_tether_general, TEST_NO_UPSTREAM_TITLE,
+                TEST_NO_UPSTREAM_MESSAGE, NO_UPSTREAM_NOTIFICATION_ID)
+        reset(notificationManager)
+
+        // Same upstream network changed. Nothing happened.
+        notificationUpdater.onUpstreamNetworkChanged(null)
+        verifyZeroInteractions(notificationManager)
+
+        // Upstream come back. Clear no upstream notification.
+        notificationUpdater.onUpstreamNetworkChanged(Network(1000))
+        verifyNotificationCancelled(NO_UPSTREAM_NOTIFICATION_ID)
+        reset(notificationManager)
+
+        // No upstream again. Show no upstream notification.
+        notificationUpdater.onUpstreamNetworkChanged(null)
+        notificationUpdater.handler.waitForDelayedMessage(EVENT_SHOW_NO_UPSTREAM, 500L)
+        verifyNotification(R.drawable.stat_sys_tether_general, TEST_NO_UPSTREAM_TITLE,
+                TEST_NO_UPSTREAM_MESSAGE, NO_UPSTREAM_NOTIFICATION_ID)
+        reset(notificationManager)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyCancelAllTetheringActiveNotifications()
+
+        // Set R.integer.delay_to_show_no_upstream_after_no_backhaul to 0 and have wifi downstream
+        // again. Show enable notification only.
+        doReturn(-1).`when`(testResources)
+                .getInteger(R.integer.delay_to_show_no_upstream_after_no_backhaul)
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        notificationUpdater.handler.waitForDelayedMessage(EVENT_SHOW_NO_UPSTREAM, 500L)
+        verifyOnlyTetheringActiveNotification(
+                ENABLE_NOTIFICATION_ID, WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE)
+    }
+
+    @Test
+    fun testGetResourcesForSubId() {
+        doReturn(telephonyManager).`when`(telephonyManager).createForSubscriptionId(anyInt())
+        doReturn(1234).`when`(telephonyManager).getSimCarrierId()
+        doReturn("000000").`when`(telephonyManager).getSimOperator()
+
+        val subId = -2 // Use invalid subId to avoid getting resource from cache or real subId.
+        val config = context.resources.configuration
+        var res = notificationUpdater.getResourcesForSubId(context, subId)
+        assertEquals(config.mcc, res.configuration.mcc)
+        assertEquals(config.mnc, res.configuration.mnc)
+
+        doReturn(1839).`when`(telephonyManager).getSimCarrierId()
+        res = notificationUpdater.getResourcesForSubId(context, subId)
+        assertEquals(config.mcc, res.configuration.mcc)
+        assertEquals(config.mnc, res.configuration.mnc)
+
+        doReturn("20404").`when`(telephonyManager).getSimOperator()
+        res = notificationUpdater.getResourcesForSubId(context, subId)
+        assertEquals(311, res.configuration.mcc)
+        assertEquals(480, res.configuration.mnc)
+    }
+}
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringServiceTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
similarity index 97%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringServiceTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
index d9d3e73..51bad9a 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringServiceTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.TetheringManager.TETHERING_WIFI;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
@@ -37,7 +37,7 @@
 import androidx.test.rule.ServiceTestRule;
 import androidx.test.runner.AndroidJUnit4;
 
-import com.android.server.connectivity.tethering.MockTetheringService.MockTetheringConnector;
+import com.android.networkstack.tethering.MockTetheringService.MockTetheringConnector;
 
 import org.junit.After;
 import org.junit.Before;
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
similarity index 98%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
index 38059fc..15e253a 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.hardware.usb.UsbManager.USB_CONFIGURED;
 import static android.hardware.usb.UsbManager.USB_CONNECTED;
@@ -47,7 +47,7 @@
 import static android.net.wifi.WifiManager.WIFI_AP_STATE_ENABLED;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
-import static com.android.server.connectivity.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
+import static com.android.networkstack.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
@@ -137,7 +137,6 @@
 import com.android.internal.util.StateMachine;
 import com.android.internal.util.test.BroadcastInterceptingContext;
 import com.android.internal.util.test.FakeSettingsProvider;
-import com.android.networkstack.tethering.R;
 import com.android.testutils.MiscAssertsKt;
 
 import org.junit.After;
@@ -384,7 +383,7 @@
         }
 
         @Override
-        public TetheringNotificationUpdater getNotificationUpdater(Context ctx) {
+        public TetheringNotificationUpdater getNotificationUpdater(Context ctx, Looper looper) {
             return mNotificationUpdater;
         }
     }
@@ -1692,6 +1691,18 @@
         assertEquals(clientAddrParceled, params.clientAddr);
     }
 
+    @Test
+    public void testUpstreamNetworkChanged() {
+        final Tethering.TetherMasterSM stateMachine = (Tethering.TetherMasterSM)
+                mTetheringDependencies.mUpstreamNetworkMonitorMasterSM;
+        final UpstreamNetworkState upstreamState = buildMobileIPv4UpstreamState();
+        when(mUpstreamNetworkMonitor.selectPreferredUpstreamType(any())).thenReturn(upstreamState);
+        stateMachine.chooseUpstreamType(true);
+
+        verify(mUpstreamNetworkMonitor, times(1)).setCurrentUpstream(eq(upstreamState.network));
+        verify(mNotificationUpdater, times(1)).onUpstreamNetworkChanged(eq(upstreamState.network));
+    }
+
     // TODO: Test that a request for hotspot mode doesn't interfere with an
     // already operating tethering mode interface.
 }
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
similarity index 99%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
index 7c98f62..232588c 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.ConnectivityManager.TYPE_MOBILE_DUN;
 import static android.net.ConnectivityManager.TYPE_MOBILE_HIPRI;
@@ -24,7 +24,7 @@
 import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
 import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
 
-import static com.android.server.connectivity.tethering.UpstreamNetworkMonitor.TYPE_NONE;
+import static com.android.networkstack.tethering.UpstreamNetworkMonitor.TYPE_NONE;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt
deleted file mode 100644
index b869491..0000000
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt
+++ /dev/null
@@ -1,262 +0,0 @@
-/*
- * 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.connectivity.tethering
-
-import android.app.Notification
-import android.app.NotificationManager
-import android.content.Context
-import android.content.res.Resources
-import android.net.ConnectivityManager.TETHERING_BLUETOOTH
-import android.net.ConnectivityManager.TETHERING_USB
-import android.net.ConnectivityManager.TETHERING_WIFI
-import android.os.UserHandle
-import android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID
-import androidx.test.platform.app.InstrumentationRegistry
-import androidx.test.filters.SmallTest
-import androidx.test.runner.AndroidJUnit4
-import com.android.internal.util.test.BroadcastInterceptingContext
-import com.android.networkstack.tethering.R
-import com.android.server.connectivity.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE
-import org.junit.Assert.assertEquals
-import org.junit.Before
-import org.junit.Test
-import org.junit.runner.RunWith
-import org.mockito.ArgumentCaptor
-import org.mockito.ArgumentMatchers.any
-import org.mockito.ArgumentMatchers.anyInt
-import org.mockito.ArgumentMatchers.eq
-import org.mockito.Mock
-import org.mockito.Mockito.doReturn
-import org.mockito.Mockito.never
-import org.mockito.Mockito.reset
-import org.mockito.Mockito.times
-import org.mockito.Mockito.verifyZeroInteractions
-import org.mockito.Mockito.verify
-import org.mockito.MockitoAnnotations
-
-const val TEST_SUBID = 1
-const val WIFI_ICON_ID = 1
-const val USB_ICON_ID = 2
-const val BT_ICON_ID = 3
-const val GENERAL_ICON_ID = 4
-const val WIFI_MASK = 1 shl TETHERING_WIFI
-const val USB_MASK = 1 shl TETHERING_USB
-const val BT_MASK = 1 shl TETHERING_BLUETOOTH
-const val TITTLE = "Tethering active"
-const val MESSAGE = "Tap here to set up."
-const val TEST_TITTLE = "Hotspot active"
-const val TEST_MESSAGE = "Tap to set up hotspot."
-
-@RunWith(AndroidJUnit4::class)
-@SmallTest
-class TetheringNotificationUpdaterTest {
-    // lateinit used here for mocks as they need to be reinitialized between each test and the test
-    // should crash if they are used before being initialized.
-    @Mock private lateinit var mockContext: Context
-    @Mock private lateinit var notificationManager: NotificationManager
-    @Mock private lateinit var defaultResources: Resources
-    @Mock private lateinit var testResources: Resources
-
-    // lateinit for this class under test, as it should be reset to a different instance for every
-    // tests but should always be initialized before use (or the test should crash).
-    private lateinit var notificationUpdater: TetheringNotificationUpdater
-
-    private val ENABLE_ICON_CONFIGS = arrayOf(
-            "USB;android.test:drawable/usb", "BT;android.test:drawable/bluetooth",
-            "WIFI|BT;android.test:drawable/general", "WIFI|USB;android.test:drawable/general",
-            "USB|BT;android.test:drawable/general", "WIFI|USB|BT;android.test:drawable/general")
-
-    private inner class TestContext(c: Context) : BroadcastInterceptingContext(c) {
-        override fun createContextAsUser(user: UserHandle, flags: Int) =
-                if (user == UserHandle.ALL) mockContext else this
-    }
-
-    private inner class WrappedNotificationUpdater(c: Context) : TetheringNotificationUpdater(c) {
-        override fun getResourcesForSubId(context: Context, subId: Int) =
-                if (subId == TEST_SUBID) testResources else defaultResources
-    }
-
-    private fun setupResources() {
-        doReturn(ENABLE_ICON_CONFIGS).`when`(defaultResources)
-                .getStringArray(R.array.tethering_notification_icons)
-        doReturn(arrayOf("WIFI;android.test:drawable/wifi")).`when`(testResources)
-                .getStringArray(R.array.tethering_notification_icons)
-        doReturn(TITTLE).`when`(defaultResources).getString(R.string.tethering_notification_title)
-        doReturn(MESSAGE).`when`(defaultResources)
-                .getString(R.string.tethering_notification_message)
-        doReturn(TEST_TITTLE).`when`(testResources).getString(R.string.tethering_notification_title)
-        doReturn(TEST_MESSAGE).`when`(testResources)
-                .getString(R.string.tethering_notification_message)
-        doReturn(USB_ICON_ID).`when`(defaultResources)
-                .getIdentifier(eq("android.test:drawable/usb"), any(), any())
-        doReturn(BT_ICON_ID).`when`(defaultResources)
-                .getIdentifier(eq("android.test:drawable/bluetooth"), any(), any())
-        doReturn(GENERAL_ICON_ID).`when`(defaultResources)
-                .getIdentifier(eq("android.test:drawable/general"), any(), any())
-        doReturn(WIFI_ICON_ID).`when`(testResources)
-                .getIdentifier(eq("android.test:drawable/wifi"), any(), any())
-    }
-
-    @Before
-    fun setUp() {
-        MockitoAnnotations.initMocks(this)
-        val context = TestContext(InstrumentationRegistry.getInstrumentation().context)
-        doReturn(notificationManager).`when`(mockContext)
-                .getSystemService(Context.NOTIFICATION_SERVICE)
-        notificationUpdater = WrappedNotificationUpdater(context)
-        setupResources()
-    }
-
-    private fun Notification.title() = this.extras.getString(Notification.EXTRA_TITLE)
-    private fun Notification.text() = this.extras.getString(Notification.EXTRA_TEXT)
-
-    private fun verifyNotification(iconId: Int = 0, title: String = "", text: String = "") {
-        verify(notificationManager, never()).cancel(any(), anyInt())
-
-        val notificationCaptor = ArgumentCaptor.forClass(Notification::class.java)
-        verify(notificationManager, times(1))
-                .notify(any(), anyInt(), notificationCaptor.capture())
-
-        val notification = notificationCaptor.getValue()
-        assertEquals(iconId, notification.smallIcon.resId)
-        assertEquals(title, notification.title())
-        assertEquals(text, notification.text())
-
-        reset(notificationManager)
-    }
-
-    private fun verifyNoNotification() {
-        verify(notificationManager, times(1)).cancel(any(), anyInt())
-        verify(notificationManager, never()).notify(any(), anyInt(), any())
-
-        reset(notificationManager)
-    }
-
-    @Test
-    fun testNotificationWithDownstreamChanged() {
-        // Wifi downstream. No notification.
-        notificationUpdater.onDownstreamChanged(WIFI_MASK)
-        verifyNoNotification()
-
-        // Same downstream changed. Nothing happened.
-        notificationUpdater.onDownstreamChanged(WIFI_MASK)
-        verifyZeroInteractions(notificationManager)
-
-        // Wifi and usb downstreams. Show enable notification
-        notificationUpdater.onDownstreamChanged(WIFI_MASK or USB_MASK)
-        verifyNotification(GENERAL_ICON_ID, TITTLE, MESSAGE)
-
-        // Usb downstream. Still show enable notification.
-        notificationUpdater.onDownstreamChanged(USB_MASK)
-        verifyNotification(USB_ICON_ID, TITTLE, MESSAGE)
-
-        // No downstream. No notification.
-        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
-        verifyNoNotification()
-    }
-
-    @Test
-    fun testNotificationWithActiveDataSubscriptionIdChanged() {
-        // Usb downstream. Showed enable notification with default resource.
-        notificationUpdater.onDownstreamChanged(USB_MASK)
-        verifyNotification(USB_ICON_ID, TITTLE, MESSAGE)
-
-        // Same subId changed. Nothing happened.
-        notificationUpdater.onActiveDataSubscriptionIdChanged(INVALID_SUBSCRIPTION_ID)
-        verifyZeroInteractions(notificationManager)
-
-        // Set test sub id. Clear notification with test resource.
-        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
-        verifyNoNotification()
-
-        // Wifi downstream. Show enable notification with test resource.
-        notificationUpdater.onDownstreamChanged(WIFI_MASK)
-        verifyNotification(WIFI_ICON_ID, TEST_TITTLE, TEST_MESSAGE)
-
-        // No downstream. No notification.
-        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
-        verifyNoNotification()
-    }
-
-    private fun assertIconNumbers(number: Int, configs: Array<String?>) {
-        doReturn(configs).`when`(defaultResources)
-                .getStringArray(R.array.tethering_notification_icons)
-        assertEquals(number, notificationUpdater.getIcons(
-                R.array.tethering_notification_icons, defaultResources).size())
-    }
-
-    @Test
-    fun testGetIcons() {
-        assertIconNumbers(0, arrayOfNulls<String>(0))
-        assertIconNumbers(0, arrayOf(null, ""))
-        assertIconNumbers(3, arrayOf(
-                // These configurations are invalid with wrong strings or symbols.
-                ";", ",", "|", "|,;", "WIFI", "1;2", " U SB; ", "bt;", "WIFI;USB;BT", "WIFI|USB|BT",
-                "WIFI,BT,USB", " WIFI| |  | USB, test:drawable/test",
-                // This configuration is valid with two downstream types (USB, BT).
-                "USB|,,,,,|BT;drawable/test ",
-                // This configuration is valid with one downstream types (WIFI).
-                "     WIFI     ; android.test:drawable/xxx "))
-    }
-
-    @Test
-    fun testGetDownstreamTypesMask() {
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask(""))
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("1"))
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("WIFI_P2P"))
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("usb"))
-        assertEquals(WIFI_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI "))
-        assertEquals(USB_MASK, notificationUpdater.getDownstreamTypesMask("USB | B T"))
-        assertEquals(BT_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI: | BT"))
-        assertEquals(WIFI_MASK or USB_MASK,
-                notificationUpdater.getDownstreamTypesMask("1|2|USB|WIFI|BLUETOOTH||"))
-    }
-
-    @Test
-    fun testSetupRestrictedNotification() {
-        val title = InstrumentationRegistry.getInstrumentation().context.resources
-                .getString(R.string.disable_tether_notification_title)
-        val message = InstrumentationRegistry.getInstrumentation().context.resources
-                .getString(R.string.disable_tether_notification_message)
-        val disallowTitle = "Tether function is disallowed"
-        val disallowMessage = "Please contact your admin"
-        doReturn(title).`when`(defaultResources)
-                .getString(R.string.disable_tether_notification_title)
-        doReturn(message).`when`(defaultResources)
-                .getString(R.string.disable_tether_notification_message)
-        doReturn(disallowTitle).`when`(testResources)
-                .getString(R.string.disable_tether_notification_title)
-        doReturn(disallowMessage).`when`(testResources)
-                .getString(R.string.disable_tether_notification_message)
-
-        // User restrictions on. Show restricted notification.
-        notificationUpdater.notifyTetheringDisabledByRestriction()
-        verifyNotification(R.drawable.stat_sys_tether_general, title, message)
-
-        // User restrictions off. Clear notification.
-        notificationUpdater.tetheringRestrictionLifted()
-        verifyNoNotification()
-
-        // Set test sub id. No notification.
-        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
-        verifyNoNotification()
-
-        // User restrictions on again. Show restricted notification with test resource.
-        notificationUpdater.notifyTetheringDisabledByRestriction()
-        verifyNotification(R.drawable.stat_sys_tether_general, disallowTitle, disallowMessage)
-    }
-}
\ No newline at end of file