diff --git a/framework-t/api/system-current.txt b/framework-t/api/system-current.txt
index 08129eb..5f8f0e3 100644
--- a/framework-t/api/system-current.txt
+++ b/framework-t/api/system-current.txt
@@ -500,7 +500,6 @@
 
   @FlaggedApi("com.android.net.thread.flags.configuration_enabled") public final class ThreadConfiguration implements android.os.Parcelable {
     method public int describeContents();
-    method public boolean isDhcpv6PdEnabled();
     method public boolean isNat64Enabled();
     method public void writeToParcel(@NonNull android.os.Parcel, int);
     field @NonNull public static final android.os.Parcelable.Creator<android.net.thread.ThreadConfiguration> CREATOR;
diff --git a/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyDownloader.java b/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyDownloader.java
index fd73b29..16f32c4 100644
--- a/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyDownloader.java
+++ b/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyDownloader.java
@@ -73,7 +73,9 @@
                 new CertificateTransparencyInstaller());
     }
 
-    void registerReceiver() {
+    void initialize() {
+        mInstaller.addCompatibilityVersion(Config.COMPATIBILITY_VERSION);
+
         IntentFilter intentFilter = new IntentFilter();
         intentFilter.addAction(DownloadManager.ACTION_DOWNLOAD_COMPLETE);
         mContext.registerReceiver(this, intentFilter, Context.RECEIVER_EXPORTED);
@@ -185,7 +187,7 @@
         String contentUrl = mDataStore.getProperty(Config.CONTENT_URL_PENDING);
         String metadataUrl = mDataStore.getProperty(Config.METADATA_URL_PENDING);
         try (InputStream inputStream = mContext.getContentResolver().openInputStream(contentUri)) {
-            success = mInstaller.install(inputStream, version);
+            success = mInstaller.install(Config.COMPATIBILITY_VERSION, inputStream, version);
         } catch (IOException e) {
             Log.e(TAG, "Could not install new content", e);
             return;
diff --git a/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyFlagsListener.java b/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyFlagsListener.java
index 914af06..0ae982d 100644
--- a/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyFlagsListener.java
+++ b/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyFlagsListener.java
@@ -43,7 +43,7 @@
 
     void initialize() {
         mDataStore.load();
-        mCertificateTransparencyDownloader.registerReceiver();
+        mCertificateTransparencyDownloader.initialize();
         DeviceConfig.addOnPropertiesChangedListener(
                 Config.NAMESPACE_NETWORK_SECURITY, Executors.newSingleThreadExecutor(), this);
         if (Config.DEBUG) {
diff --git a/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyInstaller.java b/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyInstaller.java
index 82dcadf..4ca97eb 100644
--- a/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyInstaller.java
+++ b/networksecurity/service/src/com/android/server/net/ct/CertificateTransparencyInstaller.java
@@ -15,148 +15,78 @@
  */
 package com.android.server.net.ct;
 
-import android.annotation.SuppressLint;
-import android.system.ErrnoException;
-import android.system.Os;
 import android.util.Log;
 
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
-import java.nio.file.Files;
+import java.util.HashMap;
+import java.util.Map;
 
 /** Installer of CT log lists. */
 public class CertificateTransparencyInstaller {
 
     private static final String TAG = "CertificateTransparencyInstaller";
-    private static final String CT_DIR_NAME = "/data/misc/keychain/ct/";
 
-    static final String LOGS_DIR_PREFIX = "logs-";
-    static final String LOGS_LIST_FILE_NAME = "log_list.json";
-    static final String CURRENT_DIR_SYMLINK_NAME = "current";
+    private final Map<String, CompatibilityVersion> mCompatVersions = new HashMap<>();
 
-    private final File mCertificateTransparencyDir;
-    private final File mCurrentDirSymlink;
+    // The CT root directory.
+    private final File mRootDirectory;
 
-    CertificateTransparencyInstaller(File certificateTransparencyDir) {
-        mCertificateTransparencyDir = certificateTransparencyDir;
-        mCurrentDirSymlink = new File(certificateTransparencyDir, CURRENT_DIR_SYMLINK_NAME);
+    public CertificateTransparencyInstaller(File rootDirectory) {
+        mRootDirectory = rootDirectory;
     }
 
-    CertificateTransparencyInstaller() {
-        this(new File(CT_DIR_NAME));
+    public CertificateTransparencyInstaller(String rootDirectoryPath) {
+        this(new File(rootDirectoryPath));
+    }
+
+    public CertificateTransparencyInstaller() {
+        this(Config.CT_ROOT_DIRECTORY_PATH);
+    }
+
+    void addCompatibilityVersion(String versionName) {
+        removeCompatibilityVersion(versionName);
+        CompatibilityVersion newCompatVersion =
+                new CompatibilityVersion(new File(mRootDirectory, versionName));
+        mCompatVersions.put(versionName, newCompatVersion);
+    }
+
+    void removeCompatibilityVersion(String versionName) {
+        CompatibilityVersion compatVersion = mCompatVersions.remove(versionName);
+        if (compatVersion != null && !compatVersion.delete()) {
+            Log.w(TAG, "Could not delete compatibility version directory.");
+        }
+    }
+
+    CompatibilityVersion getCompatibilityVersion(String versionName) {
+        return mCompatVersions.get(versionName);
     }
 
     /**
      * Install a new log list to use during SCT verification.
      *
+     * @param compatibilityVersion the compatibility version of the new log list
      * @param newContent an input stream providing the log list
-     * @param version the version of the new log list
+     * @param version the minor version of the new log list
      * @return true if the log list was installed successfully, false otherwise.
      * @throws IOException if the list cannot be saved in the CT directory.
      */
-    public boolean install(InputStream newContent, String version) throws IOException {
-        // To support atomically replacing the old configuration directory with the new there's a
-        // bunch of steps. We create a new directory with the logs and then do an atomic update of
-        // the current symlink to point to the new directory.
-        // 1. Ensure that the update dir exists and is readable.
-        makeDir(mCertificateTransparencyDir);
-
-        File newLogsDir = new File(mCertificateTransparencyDir, LOGS_DIR_PREFIX + version);
-        // 2. Handle the corner case where the new directory already exists.
-        if (newLogsDir.exists()) {
-            // If the symlink has already been updated then the update died between steps 6 and 7
-            // and so we cannot delete the directory since it is in use.
-            if (newLogsDir.getCanonicalPath().equals(mCurrentDirSymlink.getCanonicalPath())) {
-                deleteOldLogDirectories();
-                return false;
-            }
-            // If the symlink has not been updated then the previous installation failed and this is
-            // a re-attempt. Clean-up leftover files and try again.
-            deleteContentsAndDir(newLogsDir);
-        }
-        try {
-            // 3. Create /data/misc/keychain/ct/logs-<new_version>/ .
-            makeDir(newLogsDir);
-
-            // 4. Move the log list json file in logs-<new_version>/ .
-            File logListFile = new File(newLogsDir, LOGS_LIST_FILE_NAME);
-            if (Files.copy(newContent, logListFile.toPath()) == 0) {
-                throw new IOException("The log list appears empty");
-            }
-            setWorldReadable(logListFile);
-
-            // 5. Create temp symlink. We rename this to the target symlink to get an atomic update.
-            File tempSymlink = new File(mCertificateTransparencyDir, "new_symlink");
-            try {
-                Os.symlink(newLogsDir.getCanonicalPath(), tempSymlink.getCanonicalPath());
-            } catch (ErrnoException e) {
-                throw new IOException("Failed to create symlink", e);
-            }
-
-            // 6. Update the symlink target, this is the actual update step.
-            tempSymlink.renameTo(mCurrentDirSymlink.getAbsoluteFile());
-        } catch (IOException | RuntimeException e) {
-            deleteContentsAndDir(newLogsDir);
-            throw e;
-        }
-        Log.i(TAG, "CT log directory updated to " + newLogsDir.getAbsolutePath());
-        // 7. Cleanup
-        deleteOldLogDirectories();
-        return true;
-    }
-
-    private void makeDir(File dir) throws IOException {
-        dir.mkdir();
-        if (!dir.isDirectory()) {
-            throw new IOException("Unable to make directory " + dir.getCanonicalPath());
-        }
-        setWorldReadable(dir);
-    }
-
-    // CT files and directories are readable by all apps.
-    @SuppressLint("SetWorldReadable")
-    private void setWorldReadable(File file) throws IOException {
-        if (!file.setReadable(true, false)) {
-            throw new IOException("Failed to set " + file.getCanonicalPath() + " readable");
-        }
-    }
-
-    private void deleteOldLogDirectories() throws IOException {
-        if (!mCertificateTransparencyDir.exists()) {
-            return;
-        }
-        File currentTarget = mCurrentDirSymlink.getCanonicalFile();
-        for (File file : mCertificateTransparencyDir.listFiles()) {
-            if (!currentTarget.equals(file.getCanonicalFile())
-                    && file.getName().startsWith(LOGS_DIR_PREFIX)) {
-                deleteContentsAndDir(file);
-            }
-        }
-    }
-
-    static boolean deleteContentsAndDir(File dir) {
-        if (deleteContents(dir)) {
-            return dir.delete();
-        } else {
+    public boolean install(String compatibilityVersion, InputStream newContent, String version)
+            throws IOException {
+        CompatibilityVersion compatVersion = mCompatVersions.get(compatibilityVersion);
+        if (compatVersion == null) {
+            Log.e(TAG, "No compatibility version for " + compatibilityVersion);
             return false;
         }
-    }
+        // Ensure root directory exists and is readable.
+        DirectoryUtils.makeDir(mRootDirectory);
 
-    private static boolean deleteContents(File dir) {
-        File[] files = dir.listFiles();
-        boolean success = true;
-        if (files != null) {
-            for (File file : files) {
-                if (file.isDirectory()) {
-                    success &= deleteContents(file);
-                }
-                if (!file.delete()) {
-                    Log.w(TAG, "Failed to delete " + file);
-                    success = false;
-                }
-            }
+        if (!compatVersion.install(newContent, version)) {
+            Log.e(TAG, "Failed to install logs for compatibility version " + compatibilityVersion);
+            return false;
         }
-        return success;
+        Log.i(TAG, "New logs installed at " + compatVersion.getLogsDir());
+        return true;
     }
 }
diff --git a/networksecurity/service/src/com/android/server/net/ct/CompatibilityVersion.java b/networksecurity/service/src/com/android/server/net/ct/CompatibilityVersion.java
new file mode 100644
index 0000000..27488b5
--- /dev/null
+++ b/networksecurity/service/src/com/android/server/net/ct/CompatibilityVersion.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.server.net.ct;
+
+import android.system.ErrnoException;
+import android.system.Os;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+
+/** Represents a compatibility version directory. */
+class CompatibilityVersion {
+
+    static final String LOGS_DIR_PREFIX = "logs-";
+    static final String LOGS_LIST_FILE_NAME = "log_list.json";
+
+    private static final String CURRENT_LOGS_DIR_SYMLINK_NAME = "current";
+
+    private final File mRootDirectory;
+    private final File mCurrentLogsDirSymlink;
+
+    private File mCurrentLogsDir = null;
+
+    CompatibilityVersion(File rootDirectory) {
+        mRootDirectory = rootDirectory;
+        mCurrentLogsDirSymlink = new File(mRootDirectory, CURRENT_LOGS_DIR_SYMLINK_NAME);
+    }
+
+    /**
+     * Installs a log list within this compatibility version directory.
+     *
+     * @param newContent an input stream providing the log list
+     * @param version the version number of the log list
+     * @return true if the log list was installed successfully, false otherwise.
+     * @throws IOException if the list cannot be saved in the CT directory.
+     */
+    boolean install(InputStream newContent, String version) throws IOException {
+        // To support atomically replacing the old configuration directory with the new there's a
+        // bunch of steps. We create a new directory with the logs and then do an atomic update of
+        // the current symlink to point to the new directory.
+        // 1. Ensure that the root directory exists and is readable.
+        DirectoryUtils.makeDir(mRootDirectory);
+
+        File newLogsDir = new File(mRootDirectory, LOGS_DIR_PREFIX + version);
+        // 2. Handle the corner case where the new directory already exists.
+        if (newLogsDir.exists()) {
+            // If the symlink has already been updated then the update died between steps 6 and 7
+            // and so we cannot delete the directory since it is in use.
+            if (newLogsDir.getCanonicalPath().equals(mCurrentLogsDirSymlink.getCanonicalPath())) {
+                deleteOldLogDirectories();
+                return false;
+            }
+            // If the symlink has not been updated then the previous installation failed and this is
+            // a re-attempt. Clean-up leftover files and try again.
+            DirectoryUtils.removeDir(newLogsDir);
+        }
+        try {
+            // 3. Create a new logs-<new_version>/ directory to store the new list.
+            DirectoryUtils.makeDir(newLogsDir);
+
+            // 4. Move the log list json file in logs-<new_version>/ .
+            File logListFile = new File(newLogsDir, LOGS_LIST_FILE_NAME);
+            if (Files.copy(newContent, logListFile.toPath()) == 0) {
+                throw new IOException("The log list appears empty");
+            }
+            DirectoryUtils.setWorldReadable(logListFile);
+
+            // 5. Create temp symlink. We rename this to the target symlink to get an atomic update.
+            File tempSymlink = new File(mRootDirectory, "new_symlink");
+            try {
+                Os.symlink(newLogsDir.getCanonicalPath(), tempSymlink.getCanonicalPath());
+            } catch (ErrnoException e) {
+                throw new IOException("Failed to create symlink", e);
+            }
+
+            // 6. Update the symlink target, this is the actual update step.
+            tempSymlink.renameTo(mCurrentLogsDirSymlink.getAbsoluteFile());
+        } catch (IOException | RuntimeException e) {
+            DirectoryUtils.removeDir(newLogsDir);
+            throw e;
+        }
+        // 7. Cleanup
+        mCurrentLogsDir = newLogsDir;
+        deleteOldLogDirectories();
+        return true;
+    }
+
+    File getRootDir() {
+        return mRootDirectory;
+    }
+
+    File getLogsDir() {
+        return mCurrentLogsDir;
+    }
+
+    File getLogsDirSymlink() {
+        return mCurrentLogsDirSymlink;
+    }
+
+    File getLogsFile() {
+        return new File(mCurrentLogsDir, LOGS_LIST_FILE_NAME);
+    }
+
+    boolean delete() {
+        return DirectoryUtils.removeDir(mRootDirectory);
+    }
+
+    private void deleteOldLogDirectories() throws IOException {
+        if (!mRootDirectory.exists()) {
+            return;
+        }
+        File currentTarget = mCurrentLogsDirSymlink.getCanonicalFile();
+        for (File file : mRootDirectory.listFiles()) {
+            if (!currentTarget.equals(file.getCanonicalFile())
+                    && file.getName().startsWith(LOGS_DIR_PREFIX)) {
+                DirectoryUtils.removeDir(file);
+            }
+        }
+    }
+}
diff --git a/networksecurity/service/src/com/android/server/net/ct/Config.java b/networksecurity/service/src/com/android/server/net/ct/Config.java
index 611a5c7..242f13a 100644
--- a/networksecurity/service/src/com/android/server/net/ct/Config.java
+++ b/networksecurity/service/src/com/android/server/net/ct/Config.java
@@ -33,6 +33,10 @@
     private static final String PREFERENCES_FILE_NAME = "ct.preferences";
     static final File PREFERENCES_FILE = new File(DEVICE_PROTECTED_DATA_DIR, PREFERENCES_FILE_NAME);
 
+    // CT directory
+    static final String CT_ROOT_DIRECTORY_PATH = "/data/misc/keychain/ct/";
+    static final String COMPATIBILITY_VERSION = "v1";
+
     // Phenotype flags
     static final String NAMESPACE_NETWORK_SECURITY = "network_security";
     private static final String FLAGS_PREFIX = "CertificateTransparencyLogList__";
diff --git a/networksecurity/service/src/com/android/server/net/ct/DirectoryUtils.java b/networksecurity/service/src/com/android/server/net/ct/DirectoryUtils.java
new file mode 100644
index 0000000..e3b4124
--- /dev/null
+++ b/networksecurity/service/src/com/android/server/net/ct/DirectoryUtils.java
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.server.net.ct;
+
+import android.annotation.SuppressLint;
+
+import java.io.File;
+import java.io.IOException;
+
+/** Utility class to manipulate CT directories. */
+class DirectoryUtils {
+
+    static void makeDir(File dir) throws IOException {
+        dir.mkdir();
+        if (!dir.isDirectory()) {
+            throw new IOException("Unable to make directory " + dir.getCanonicalPath());
+        }
+        setWorldReadable(dir);
+    }
+
+    // CT files and directories are readable by all apps.
+    @SuppressLint("SetWorldReadable")
+    static void setWorldReadable(File file) throws IOException {
+        if (!file.setReadable(true, false)) {
+            throw new IOException("Failed to set " + file.getCanonicalPath() + " readable");
+        }
+    }
+
+    static boolean removeDir(File dir) {
+        return deleteContentsAndDir(dir);
+    }
+
+    private static boolean deleteContentsAndDir(File dir) {
+        if (deleteContents(dir)) {
+            return dir.delete();
+        } else {
+            return false;
+        }
+    }
+
+    private static boolean deleteContents(File dir) {
+        File[] files = dir.listFiles();
+        boolean success = true;
+        if (files != null) {
+            for (File file : files) {
+                if (file.isDirectory()) {
+                    success &= deleteContents(file);
+                }
+                if (!file.delete()) {
+                    success = false;
+                }
+            }
+        }
+        return success;
+    }
+}
diff --git a/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyDownloaderTest.java b/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyDownloaderTest.java
index 1aad028..df02446 100644
--- a/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyDownloaderTest.java
+++ b/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyDownloaderTest.java
@@ -159,7 +159,9 @@
                 Base64.getEncoder().encodeToString(mPublicKey.getEncoded()));
 
         setUpDownloadComplete(version, metadataId, metadataUri, contentId, contentUri);
-        when(mCertificateTransparencyInstaller.install(any(), eq(version))).thenReturn(true);
+        when(mCertificateTransparencyInstaller.install(
+                        eq(Config.COMPATIBILITY_VERSION), any(), eq(version)))
+                .thenReturn(true);
 
         assertThat(mDataStore.getProperty(Config.VERSION)).isNull();
         assertThat(mDataStore.getProperty(Config.CONTENT_URL)).isNull();
@@ -168,7 +170,8 @@
         mCertificateTransparencyDownloader.onReceive(
                 mContext, makeDownloadCompleteIntent(contentId));
 
-        verify(mCertificateTransparencyInstaller, times(1)).install(any(), eq(version));
+        verify(mCertificateTransparencyInstaller, times(1))
+                .install(eq(Config.COMPATIBILITY_VERSION), any(), eq(version));
         assertThat(mDataStore.getProperty(Config.VERSION)).isEqualTo(version);
         assertThat(mDataStore.getProperty(Config.CONTENT_URL)).isEqualTo(contentUri.toString());
         assertThat(mDataStore.getProperty(Config.METADATA_URL)).isEqualTo(metadataUri.toString());
@@ -185,7 +188,9 @@
         Uri metadataUri = Uri.fromFile(metadataFile);
 
         setUpDownloadComplete(version, metadataId, metadataUri, contentId, contentUri);
-        when(mCertificateTransparencyInstaller.install(any(), eq(version))).thenReturn(false);
+        when(mCertificateTransparencyInstaller.install(
+                        eq(Config.COMPATIBILITY_VERSION), any(), eq(version)))
+                .thenReturn(false);
 
         mCertificateTransparencyDownloader.onReceive(
                 mContext, makeDownloadCompleteIntent(contentId));
@@ -208,7 +213,8 @@
         mCertificateTransparencyDownloader.onReceive(
                 mContext, makeDownloadCompleteIntent(contentId));
 
-        verify(mCertificateTransparencyInstaller, never()).install(any(), eq(version));
+        verify(mCertificateTransparencyInstaller, never())
+                .install(eq(Config.COMPATIBILITY_VERSION), any(), eq(version));
         assertThat(mDataStore.getProperty(Config.VERSION)).isNull();
         assertThat(mDataStore.getProperty(Config.CONTENT_URL)).isNull();
         assertThat(mDataStore.getProperty(Config.METADATA_URL)).isNull();
@@ -230,7 +236,8 @@
         mCertificateTransparencyDownloader.onReceive(
                 mContext, makeDownloadCompleteIntent(contentId));
 
-        verify(mCertificateTransparencyInstaller, never()).install(any(), eq(version));
+        verify(mCertificateTransparencyInstaller, never())
+                .install(eq(Config.COMPATIBILITY_VERSION), any(), eq(version));
         assertThat(mDataStore.getProperty(Config.VERSION)).isNull();
         assertThat(mDataStore.getProperty(Config.CONTENT_URL)).isNull();
         assertThat(mDataStore.getProperty(Config.METADATA_URL)).isNull();
diff --git a/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyInstallerTest.java b/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyInstallerTest.java
index bfb8bdf..50d3f23 100644
--- a/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyInstallerTest.java
+++ b/networksecurity/tests/unit/src/com/android/server/net/ct/CertificateTransparencyInstallerTest.java
@@ -17,11 +17,9 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
-import android.system.ErrnoException;
-import android.system.Os;
-
 import androidx.test.platform.app.InstrumentationRegistry;
 
+import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -39,98 +37,134 @@
 @RunWith(JUnit4.class)
 public class CertificateTransparencyInstallerTest {
 
+    private static final String TEST_VERSION = "test-v1";
+
     private File mTestDir =
             new File(
                     InstrumentationRegistry.getInstrumentation().getContext().getFilesDir(),
                     "test-dir");
-    private File mTestSymlink =
-            new File(mTestDir, CertificateTransparencyInstaller.CURRENT_DIR_SYMLINK_NAME);
     private CertificateTransparencyInstaller mCertificateTransparencyInstaller =
             new CertificateTransparencyInstaller(mTestDir);
 
     @Before
     public void setUp() {
-        CertificateTransparencyInstaller.deleteContentsAndDir(mTestDir);
+        mCertificateTransparencyInstaller.addCompatibilityVersion(TEST_VERSION);
+    }
+
+    @After
+    public void tearDown() {
+        mCertificateTransparencyInstaller.removeCompatibilityVersion(TEST_VERSION);
+        DirectoryUtils.removeDir(mTestDir);
+    }
+
+    @Test
+    public void testCompatibilityVersion_installSuccessful() throws IOException {
+        assertThat(mTestDir.mkdir()).isTrue();
+        String content = "i_am_compatible";
+        String version = "i_am_version";
+        CompatibilityVersion compatVersion =
+                mCertificateTransparencyInstaller.getCompatibilityVersion(TEST_VERSION);
+
+        try (InputStream inputStream = asStream(content)) {
+            assertThat(compatVersion.install(inputStream, version)).isTrue();
+        }
+        File logsDir = compatVersion.getLogsDir();
+        assertThat(logsDir.exists()).isTrue();
+        assertThat(logsDir.isDirectory()).isTrue();
+        assertThat(logsDir.getAbsolutePath())
+                .startsWith(mTestDir.getAbsolutePath() + "/" + TEST_VERSION);
+        File logsListFile = compatVersion.getLogsFile();
+        assertThat(logsListFile.exists()).isTrue();
+        assertThat(logsListFile.getAbsolutePath()).startsWith(logsDir.getAbsolutePath());
+        assertThat(readAsString(logsListFile)).isEqualTo(content);
+        File logsSymlink = compatVersion.getLogsDirSymlink();
+        assertThat(logsSymlink.exists()).isTrue();
+        assertThat(logsSymlink.isDirectory()).isTrue();
+        assertThat(logsSymlink.getAbsolutePath())
+                .startsWith(mTestDir.getAbsolutePath() + "/" + TEST_VERSION + "/current");
+        assertThat(logsSymlink.getCanonicalPath()).isEqualTo(logsDir.getCanonicalPath());
+
+        assertThat(compatVersion.delete()).isTrue();
+        assertThat(logsDir.exists()).isFalse();
+        assertThat(logsSymlink.exists()).isFalse();
+        assertThat(logsListFile.exists()).isFalse();
+    }
+
+    @Test
+    public void testCompatibilityVersion_versionInstalledFailed() throws IOException {
+        assertThat(mTestDir.mkdir()).isTrue();
+
+        CompatibilityVersion compatVersion =
+                mCertificateTransparencyInstaller.getCompatibilityVersion(TEST_VERSION);
+        File rootDir = compatVersion.getRootDir();
+        assertThat(rootDir.mkdir()).isTrue();
+
+        String existingVersion = "666";
+        File existingLogDir =
+                new File(rootDir, CompatibilityVersion.LOGS_DIR_PREFIX + existingVersion);
+        assertThat(existingLogDir.mkdir()).isTrue();
+
+        String existingContent = "somebody_tried_to_install_me_but_failed_halfway_through";
+        File logsListFile = new File(existingLogDir, CompatibilityVersion.LOGS_LIST_FILE_NAME);
+        assertThat(logsListFile.createNewFile()).isTrue();
+        writeToFile(logsListFile, existingContent);
+
+        String newContent = "i_am_the_real_content";
+        try (InputStream inputStream = asStream(newContent)) {
+            assertThat(compatVersion.install(inputStream, existingVersion)).isTrue();
+        }
+
+        assertThat(readAsString(logsListFile)).isEqualTo(newContent);
     }
 
     @Test
     public void testCertificateTransparencyInstaller_installSuccessfully() throws IOException {
         String content = "i_am_a_certificate_and_i_am_transparent";
         String version = "666";
-        boolean success = false;
 
         try (InputStream inputStream = asStream(content)) {
-            success = mCertificateTransparencyInstaller.install(inputStream, version);
+            assertThat(
+                            mCertificateTransparencyInstaller.install(
+                                    TEST_VERSION, inputStream, version))
+                    .isTrue();
         }
 
-        assertThat(success).isTrue();
         assertThat(mTestDir.exists()).isTrue();
         assertThat(mTestDir.isDirectory()).isTrue();
-        assertThat(mTestSymlink.exists()).isTrue();
-        assertThat(mTestSymlink.isDirectory()).isTrue();
-
-        File logsDir =
-                new File(mTestDir, CertificateTransparencyInstaller.LOGS_DIR_PREFIX + version);
+        CompatibilityVersion compatVersion =
+                mCertificateTransparencyInstaller.getCompatibilityVersion(TEST_VERSION);
+        File logsDir = compatVersion.getLogsDir();
         assertThat(logsDir.exists()).isTrue();
         assertThat(logsDir.isDirectory()).isTrue();
-        assertThat(mTestSymlink.getCanonicalPath()).isEqualTo(logsDir.getCanonicalPath());
-
-        File logsListFile = new File(logsDir, CertificateTransparencyInstaller.LOGS_LIST_FILE_NAME);
+        assertThat(logsDir.getAbsolutePath())
+                .startsWith(mTestDir.getAbsolutePath() + "/" + TEST_VERSION);
+        File logsListFile = compatVersion.getLogsFile();
         assertThat(logsListFile.exists()).isTrue();
+        assertThat(logsListFile.getAbsolutePath()).startsWith(logsDir.getAbsolutePath());
         assertThat(readAsString(logsListFile)).isEqualTo(content);
     }
 
     @Test
     public void testCertificateTransparencyInstaller_versionIsAlreadyInstalled()
-            throws IOException, ErrnoException {
+            throws IOException {
         String existingVersion = "666";
         String existingContent = "i_was_already_installed_successfully";
-        File existingLogDir =
-                new File(
-                        mTestDir,
-                        CertificateTransparencyInstaller.LOGS_DIR_PREFIX + existingVersion);
-        assertThat(mTestDir.mkdir()).isTrue();
-        assertThat(existingLogDir.mkdir()).isTrue();
-        Os.symlink(existingLogDir.getCanonicalPath(), mTestSymlink.getCanonicalPath());
-        File logsListFile =
-                new File(existingLogDir, CertificateTransparencyInstaller.LOGS_LIST_FILE_NAME);
-        logsListFile.createNewFile();
-        writeToFile(logsListFile, existingContent);
-        boolean success = false;
+        CompatibilityVersion compatVersion =
+                mCertificateTransparencyInstaller.getCompatibilityVersion(TEST_VERSION);
+
+        DirectoryUtils.makeDir(mTestDir);
+        try (InputStream inputStream = asStream(existingContent)) {
+            assertThat(compatVersion.install(inputStream, existingVersion)).isTrue();
+        }
 
         try (InputStream inputStream = asStream("i_will_be_ignored")) {
-            success = mCertificateTransparencyInstaller.install(inputStream, existingVersion);
+            assertThat(
+                            mCertificateTransparencyInstaller.install(
+                                    TEST_VERSION, inputStream, existingVersion))
+                    .isFalse();
         }
 
-        assertThat(success).isFalse();
-        assertThat(readAsString(logsListFile)).isEqualTo(existingContent);
-    }
-
-    @Test
-    public void testCertificateTransparencyInstaller_versionInstalledFailed()
-            throws IOException, ErrnoException {
-        String existingVersion = "666";
-        String existingContent = "somebody_tried_to_install_me_but_failed_halfway_through";
-        String newContent = "i_am_the_real_certificate";
-        File existingLogDir =
-                new File(
-                        mTestDir,
-                        CertificateTransparencyInstaller.LOGS_DIR_PREFIX + existingVersion);
-        assertThat(mTestDir.mkdir()).isTrue();
-        assertThat(existingLogDir.mkdir()).isTrue();
-        File logsListFile =
-                new File(existingLogDir, CertificateTransparencyInstaller.LOGS_LIST_FILE_NAME);
-        logsListFile.createNewFile();
-        writeToFile(logsListFile, existingContent);
-        boolean success = false;
-
-        try (InputStream inputStream = asStream(newContent)) {
-            success = mCertificateTransparencyInstaller.install(inputStream, existingVersion);
-        }
-
-        assertThat(success).isTrue();
-        assertThat(mTestSymlink.getCanonicalPath()).isEqualTo(existingLogDir.getCanonicalPath());
-        assertThat(readAsString(logsListFile)).isEqualTo(newContent);
+        assertThat(readAsString(compatVersion.getLogsFile())).isEqualTo(existingContent);
     }
 
     private static InputStream asStream(String string) throws IOException {
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 665e6f9..e503312 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -6003,12 +6003,10 @@
             // TODO : The only way out of this is to diff old defaults and new defaults, and only
             // remove ranges for those requests that won't have a replacement
             final NetworkAgentInfo satisfier = nri.getSatisfier();
-            if (null != satisfier && !satisfier.isDestroyed()) {
+            if (null != satisfier) {
                 try {
-                    mNetd.networkRemoveUidRangesParcel(new NativeUidRangeConfig(
-                            satisfier.network.getNetId(),
-                            toUidRangeStableParcels(nri.getUids()),
-                            nri.getPreferenceOrderForNetd()));
+                    modifyNetworkUidRanges(false /* add */, satisfier, nri.getUids(),
+                            nri.getPreferenceOrderForNetd());
                 } catch (RemoteException e) {
                     loge("Exception setting network preference default network", e);
                 }
@@ -10267,8 +10265,7 @@
         return stableRanges;
     }
 
-    private void maybeCloseSockets(NetworkAgentInfo nai, Set<UidRange> ranges,
-            UidRangeParcel[] uidRangeParcels, int[] exemptUids) {
+    private void maybeCloseSockets(NetworkAgentInfo nai, Set<UidRange> ranges, int[] exemptUids) {
         if (nai.isVPN() && !nai.networkAgentConfig.allowBypass) {
             try {
                 if (mDeps.isAtLeastU()) {
@@ -10278,7 +10275,7 @@
                     }
                     mDeps.destroyLiveTcpSockets(UidRange.toIntRanges(ranges), exemptUidSet);
                 } else {
-                    mNetd.socketDestroy(uidRangeParcels, exemptUids);
+                    mNetd.socketDestroy(toUidRangeStableParcels(ranges), exemptUids);
                 }
             } catch (Exception e) {
                 loge("Exception in socket destroy: ", e);
@@ -10286,6 +10283,28 @@
         }
     }
 
+    private void modifyNetworkUidRanges(boolean add, NetworkAgentInfo nai, UidRangeParcel[] ranges,
+            int preference) throws RemoteException {
+        // UID ranges can be added or removed to a network that has already been destroyed (e.g., if
+        // the network disconnects, or a a multilayer request is filed after
+        // unregisterAfterReplacement is called).
+        if (nai.isDestroyed()) {
+            return;
+        }
+        final NativeUidRangeConfig config = new NativeUidRangeConfig(nai.network.netId,
+                ranges, preference);
+        if (add) {
+            mNetd.networkAddUidRangesParcel(config);
+        } else {
+            mNetd.networkRemoveUidRangesParcel(config);
+        }
+    }
+
+    private void modifyNetworkUidRanges(boolean add, NetworkAgentInfo nai, Set<UidRange> uidRanges,
+            int preference) throws RemoteException {
+        modifyNetworkUidRanges(add, nai, toUidRangeStableParcels(uidRanges), preference);
+    }
+
     private void updateVpnUidRanges(boolean add, NetworkAgentInfo nai, Set<UidRange> uidRanges) {
         int[] exemptUids = new int[2];
         // TODO: Excluding VPN_UID is necessary in order to not to kill the TCP connection used
@@ -10293,24 +10312,17 @@
         // starting a legacy VPN, and remove VPN_UID here. (b/176542831)
         exemptUids[0] = VPN_UID;
         exemptUids[1] = nai.networkCapabilities.getOwnerUid();
-        UidRangeParcel[] ranges = toUidRangeStableParcels(uidRanges);
 
         // Close sockets before modifying uid ranges so that RST packets can reach to the server.
-        maybeCloseSockets(nai, uidRanges, ranges, exemptUids);
+        maybeCloseSockets(nai, uidRanges, exemptUids);
         try {
-            if (add) {
-                mNetd.networkAddUidRangesParcel(new NativeUidRangeConfig(
-                        nai.network.netId, ranges, PREFERENCE_ORDER_VPN));
-            } else {
-                mNetd.networkRemoveUidRangesParcel(new NativeUidRangeConfig(
-                        nai.network.netId, ranges, PREFERENCE_ORDER_VPN));
-            }
+            modifyNetworkUidRanges(add, nai, uidRanges, PREFERENCE_ORDER_VPN);
         } catch (Exception e) {
             loge("Exception while " + (add ? "adding" : "removing") + " uid ranges " + uidRanges +
                     " on netId " + nai.network.netId + ". " + e);
         }
         // Close sockets that established connection while requesting netd.
-        maybeCloseSockets(nai, uidRanges, ranges, exemptUids);
+        maybeCloseSockets(nai, uidRanges, exemptUids);
     }
 
     private boolean isProxySetOnAnyDefaultNetwork() {
@@ -10424,16 +10436,12 @@
         toAdd.removeAll(prevUids);
         try {
             if (!toAdd.isEmpty()) {
-                mNetd.networkAddUidRangesParcel(new NativeUidRangeConfig(
-                        nai.network.netId,
-                        intsToUidRangeStableParcels(toAdd),
-                        PREFERENCE_ORDER_IRRELEVANT_BECAUSE_NOT_DEFAULT));
+                modifyNetworkUidRanges(true /* add */, nai, intsToUidRangeStableParcels(toAdd),
+                        PREFERENCE_ORDER_IRRELEVANT_BECAUSE_NOT_DEFAULT);
             }
             if (!toRemove.isEmpty()) {
-                mNetd.networkRemoveUidRangesParcel(new NativeUidRangeConfig(
-                        nai.network.netId,
-                        intsToUidRangeStableParcels(toRemove),
-                        PREFERENCE_ORDER_IRRELEVANT_BECAUSE_NOT_DEFAULT));
+                modifyNetworkUidRanges(false /* add */, nai, intsToUidRangeStableParcels(toRemove),
+                        PREFERENCE_ORDER_IRRELEVANT_BECAUSE_NOT_DEFAULT);
             }
         } catch (ServiceSpecificException e) {
             // Has the interface disappeared since the network was built ?
@@ -10788,16 +10796,12 @@
                         + " any applications to set as the default." + nri);
             }
             if (null != newDefaultNetwork) {
-                mNetd.networkAddUidRangesParcel(new NativeUidRangeConfig(
-                        newDefaultNetwork.network.getNetId(),
-                        toUidRangeStableParcels(nri.getUids()),
-                        nri.getPreferenceOrderForNetd()));
+                modifyNetworkUidRanges(true /* add */, newDefaultNetwork, nri.getUids(),
+                        nri.getPreferenceOrderForNetd());
             }
             if (null != oldDefaultNetwork) {
-                mNetd.networkRemoveUidRangesParcel(new NativeUidRangeConfig(
-                        oldDefaultNetwork.network.getNetId(),
-                        toUidRangeStableParcels(nri.getUids()),
-                        nri.getPreferenceOrderForNetd()));
+                modifyNetworkUidRanges(false /* add */, oldDefaultNetwork, nri.getUids(),
+                        nri.getPreferenceOrderForNetd());
             }
         } catch (RemoteException | ServiceSpecificException e) {
             loge("Exception setting app default network", e);
diff --git a/staticlibs/tests/unit/host/python/assert_utils_test.py b/staticlibs/tests/unit/host/python/assert_utils_test.py
index 7a33373..1d85a12 100644
--- a/staticlibs/tests/unit/host/python/assert_utils_test.py
+++ b/staticlibs/tests/unit/host/python/assert_utils_test.py
@@ -14,7 +14,9 @@
 
 from mobly import asserts
 from mobly import base_test
-from net_tests_utils.host.python.assert_utils import UnexpectedBehaviorError, expect_with_retry
+from net_tests_utils.host.python.assert_utils import (
+    UnexpectedBehaviorError, UnexpectedExceptionError, expect_with_retry, expect_throws
+)
 
 
 class TestAssertUtils(base_test.BaseTestClass):
@@ -92,3 +94,22 @@
           retry_interval_sec=0,
       )
     asserts.assert_true(retry_action_called, "retry_action not called.")
+
+  def test_expect_exception_throws(self):
+      def raise_unexpected_behavior_error():
+          raise UnexpectedBehaviorError()
+
+      expect_throws(raise_unexpected_behavior_error, UnexpectedBehaviorError)
+
+  def test_unexpect_exception_throws(self):
+      def raise_value_error():
+          raise ValueError()
+
+      with asserts.assert_raises(UnexpectedExceptionError):
+          expect_throws(raise_value_error, UnexpectedBehaviorError)
+
+  def test_no_exception_throws(self):
+      def raise_no_error():
+          return
+
+      expect_throws(raise_no_error, UnexpectedBehaviorError)
\ No newline at end of file
diff --git a/staticlibs/testutils/host/python/assert_utils.py b/staticlibs/testutils/host/python/assert_utils.py
index da1bb9e..40094a2 100644
--- a/staticlibs/testutils/host/python/assert_utils.py
+++ b/staticlibs/testutils/host/python/assert_utils.py
@@ -19,6 +19,8 @@
 class UnexpectedBehaviorError(Exception):
   """Raised when there is an unexpected behavior during applying a procedure."""
 
+class UnexpectedExceptionError(Exception):
+  """Raised when there is an unexpected exception throws during applying a procedure"""
 
 def expect_with_retry(
     predicate: Callable[[], bool],
@@ -41,3 +43,17 @@
   raise UnexpectedBehaviorError(
       "Predicate didn't become true after " + str(max_retries) + " retries."
   )
+
+def expect_throws(runnable: callable, exception_class) -> None:
+  try:
+    runnable()
+    raise UnexpectedBehaviorError("Expected an exception, but none was thrown")
+  except exception_class:
+    pass
+  except UnexpectedBehaviorError as e:
+    raise e
+  except Exception as e:
+      raise UnexpectedExceptionError(
+        f"Expected exception of type {exception_class.__name__}, "
+        f"but got {type(e).__name__}: {e}"
+      )
\ No newline at end of file
diff --git a/tests/unit/java/com/android/server/connectivityservice/CSSatelliteNetworkTest.kt b/tests/unit/java/com/android/server/connectivityservice/CSSatelliteNetworkTest.kt
index 5ca7fcc..58420c0 100644
--- a/tests/unit/java/com/android/server/connectivityservice/CSSatelliteNetworkTest.kt
+++ b/tests/unit/java/com/android/server/connectivityservice/CSSatelliteNetworkTest.kt
@@ -163,19 +163,36 @@
         doTestSatelliteNeverBecomeDefaultNetwork(restricted = false)
     }
 
-    private fun doTestUnregisterAfterReplacementSatisfier(destroyed: Boolean) {
+    private fun doTestUnregisterAfterReplacementSatisfier(destroyBeforeRequest: Boolean = false,
+                                                          destroyAfterRequest: Boolean = false) {
         val satelliteAgent = createSatelliteAgent("satellite0")
         satelliteAgent.connect()
 
+        if (destroyBeforeRequest) {
+            satelliteAgent.unregisterAfterReplacement(timeoutMs = 5000)
+        }
+
         val uids = setOf(TEST_PACKAGE_UID)
         updateSatelliteNetworkFallbackUids(uids)
 
-        if (destroyed) {
+        if (destroyBeforeRequest) {
+            verify(netd, never()).networkAddUidRangesParcel(any())
+        } else {
+            verify(netd).networkAddUidRangesParcel(
+                NativeUidRangeConfig(
+                    satelliteAgent.network.netId,
+                    toUidRangeStableParcels(uidRangesForUids(uids)),
+                    PREFERENCE_ORDER_SATELLITE_FALLBACK
+                )
+            )
+        }
+
+        if (destroyAfterRequest) {
             satelliteAgent.unregisterAfterReplacement(timeoutMs = 5000)
         }
 
         updateSatelliteNetworkFallbackUids(setOf())
-        if (destroyed) {
+        if (destroyBeforeRequest || destroyAfterRequest) {
             // If the network is already destroyed, networkRemoveUidRangesParcel should not be
             // called.
             verify(netd, never()).networkRemoveUidRangesParcel(any())
@@ -191,13 +208,18 @@
     }
 
     @Test
-    fun testUnregisterAfterReplacementSatisfier_destroyed() {
-        doTestUnregisterAfterReplacementSatisfier(destroyed = true)
+    fun testUnregisterAfterReplacementSatisfier_destroyBeforeRequest() {
+        doTestUnregisterAfterReplacementSatisfier(destroyBeforeRequest = true)
+    }
+
+    @Test
+    fun testUnregisterAfterReplacementSatisfier_destroyAfterRequest() {
+        doTestUnregisterAfterReplacementSatisfier(destroyAfterRequest = true)
     }
 
     @Test
     fun testUnregisterAfterReplacementSatisfier_notDestroyed() {
-        doTestUnregisterAfterReplacementSatisfier(destroyed = false)
+        doTestUnregisterAfterReplacementSatisfier()
     }
 
     private fun assertCreateMultiLayerNrisFromSatelliteNetworkPreferredUids(uids: Set<Int>) {
diff --git a/thread/framework/java/android/net/thread/ThreadConfiguration.java b/thread/framework/java/android/net/thread/ThreadConfiguration.java
index e6fa1ef..edb5021 100644
--- a/thread/framework/java/android/net/thread/ThreadConfiguration.java
+++ b/thread/framework/java/android/net/thread/ThreadConfiguration.java
@@ -61,7 +61,11 @@
         return mNat64Enabled;
     }
 
-    /** Returns {@code true} if DHCPv6 Prefix Delegation is enabled. */
+    /**
+     * Returns {@code true} if DHCPv6 Prefix Delegation is enabled.
+     *
+     * @hide
+     */
     public boolean isDhcpv6PdEnabled() {
         return mDhcpv6PdEnabled;
     }
diff --git a/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java b/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java
index 653b2fb..d5d24ac 100644
--- a/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java
+++ b/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java
@@ -78,6 +78,8 @@
 import android.content.res.Resources;
 import android.net.ConnectivityManager;
 import android.net.InetAddresses;
+import android.net.IpPrefix;
+import android.net.LinkAddress;
 import android.net.LinkProperties;
 import android.net.LocalNetworkConfig;
 import android.net.LocalNetworkInfo;
@@ -120,6 +122,8 @@
 
 import com.android.connectivity.resources.R;
 import com.android.internal.annotations.VisibleForTesting;
+import com.android.net.module.util.RoutingCoordinatorManager;
+import com.android.net.module.util.IIpv4PrefixRequest;
 import com.android.net.module.util.SharedLog;
 import com.android.server.ServiceManagerWrapper;
 import com.android.server.connectivity.ConnectivityResources;
@@ -193,10 +197,12 @@
     private final NetworkProvider mNetworkProvider;
     private final Supplier<IOtDaemon> mOtDaemonSupplier;
     private final ConnectivityManager mConnectivityManager;
+    private final RoutingCoordinatorManager mRoutingCoordinatorManager;
     private final TunInterfaceController mTunIfController;
     private final InfraInterfaceController mInfraIfController;
     private final NsdPublisher mNsdPublisher;
     private final OtDaemonCallbackProxy mOtDaemonCallbackProxy = new OtDaemonCallbackProxy();
+    private final Nat64CidrController mNat64CidrController = new Nat64CidrController();
     private final ConnectivityResources mResources;
     private final Supplier<String> mCountryCodeSupplier;
     private final Map<IConfigurationReceiver, IBinder.DeathRecipient> mConfigurationReceivers =
@@ -229,6 +235,7 @@
             NetworkProvider networkProvider,
             Supplier<IOtDaemon> otDaemonSupplier,
             ConnectivityManager connectivityManager,
+            RoutingCoordinatorManager routingCoordinatorManager,
             TunInterfaceController tunIfController,
             InfraInterfaceController infraIfController,
             ThreadPersistentSettings persistentSettings,
@@ -242,6 +249,7 @@
         mNetworkProvider = networkProvider;
         mOtDaemonSupplier = otDaemonSupplier;
         mConnectivityManager = connectivityManager;
+        mRoutingCoordinatorManager = routingCoordinatorManager;
         mTunIfController = tunIfController;
         mInfraIfController = infraIfController;
         mUpstreamNetworkRequest = newUpstreamNetworkRequest();
@@ -266,13 +274,19 @@
         NetworkProvider networkProvider =
                 new NetworkProvider(context, handlerThread.getLooper(), "ThreadNetworkProvider");
         Map<Network, LinkProperties> networkToLinkProperties = new HashMap<>();
+        final ConnectivityManager connectivityManager =
+                context.getSystemService(ConnectivityManager.class);
+        final RoutingCoordinatorManager routingCoordinatorManager =
+                new RoutingCoordinatorManager(
+                        context, connectivityManager.getRoutingCoordinatorService());
 
         return new ThreadNetworkControllerService(
                 context,
                 handler,
                 networkProvider,
                 () -> IOtDaemon.Stub.asInterface(ServiceManagerWrapper.waitForService("ot_daemon")),
-                context.getSystemService(ConnectivityManager.class),
+                connectivityManager,
+                routingCoordinatorManager,
                 new TunInterfaceController(TUN_IF_NAME),
                 new InfraInterfaceController(),
                 persistentSettings,
@@ -351,6 +365,7 @@
                 mCountryCodeSupplier.get());
         otDaemon.asBinder().linkToDeath(() -> mHandler.post(this::onOtDaemonDied), 0);
         mOtDaemon = otDaemon;
+        mHandler.post(mNat64CidrController::maybeUpdateNat64Cidr);
         return mOtDaemon;
     }
 
@@ -589,6 +604,7 @@
         } catch (RemoteException | ThreadNetworkException e) {
             LOG.e("otDaemon.setConfiguration failed. Config: " + configuration, e);
         }
+        mNat64CidrController.maybeUpdateNat64Cidr();
     }
 
     private static OtDaemonConfiguration newOtDaemonConfig(
@@ -833,7 +849,7 @@
                 mHandler.getLooper(),
                 LOG.getTag(),
                 netCaps,
-                mTunIfController.getLinkProperties(),
+                getTunIfLinkProperties(),
                 newLocalNetworkConfig(),
                 score,
                 new NetworkAgentConfig.Builder().build(),
@@ -1391,9 +1407,7 @@
 
         // The OT daemon can send link property updates before the networkAgent is
         // registered
-        if (mNetworkAgent != null) {
-            mNetworkAgent.sendLinkProperties(mTunIfController.getLinkProperties());
-        }
+        maybeSendLinkProperties();
     }
 
     private void handlePrefixChanged(List<OnMeshPrefixConfig> onMeshPrefixConfigList) {
@@ -1403,9 +1417,18 @@
 
         // The OT daemon can send link property updates before the networkAgent is
         // registered
-        if (mNetworkAgent != null) {
-            mNetworkAgent.sendLinkProperties(mTunIfController.getLinkProperties());
+        maybeSendLinkProperties();
+    }
+
+    private void maybeSendLinkProperties() {
+        if (mNetworkAgent == null) {
+            return;
         }
+        mNetworkAgent.sendLinkProperties(getTunIfLinkProperties());
+    }
+
+    private LinkProperties getTunIfLinkProperties() {
+        return mTunIfController.getLinkPropertiesWithNat64Cidr(mNat64CidrController.mNat64Cidr);
     }
 
     @RequiresPermission(
@@ -1851,4 +1874,64 @@
             mHandler.post(() -> handlePrefixChanged(onMeshPrefixConfigList));
         }
     }
+
+    private final class Nat64CidrController extends IIpv4PrefixRequest.Stub {
+        private static final int RETRY_DELAY_ON_FAILURE_MILLIS = 600_000; // 10 minutes
+
+        @Nullable private LinkAddress mNat64Cidr;
+
+        @Override
+        public void onIpv4PrefixConflict(IpPrefix prefix) {
+            mHandler.post(() -> onIpv4PrefixConflictInternal(prefix));
+        }
+
+        private void onIpv4PrefixConflictInternal(IpPrefix prefix) {
+            checkOnHandlerThread();
+
+            LOG.i("Conflict on NAT64 CIDR: " + prefix);
+            maybeReleaseNat64Cidr();
+            maybeUpdateNat64Cidr();
+        }
+
+        public void maybeUpdateNat64Cidr() {
+            checkOnHandlerThread();
+
+            if (mPersistentSettings.getConfiguration().isNat64Enabled()) {
+                maybeRequestNat64Cidr();
+            } else {
+                maybeReleaseNat64Cidr();
+            }
+            try {
+                getOtDaemon()
+                        .setNat64Cidr(
+                                mNat64Cidr == null ? null : mNat64Cidr.toString(),
+                                new LoggingOtStatusReceiver("setNat64Cidr"));
+            } catch (RemoteException | ThreadNetworkException e) {
+                LOG.e("Failed to set NAT64 CIDR at otd-daemon", e);
+            }
+            maybeSendLinkProperties();
+        }
+
+        private void maybeRequestNat64Cidr() {
+            if (mNat64Cidr != null) {
+                return;
+            }
+            final LinkAddress downstreamAddress =
+                    mRoutingCoordinatorManager.requestDownstreamAddress(this);
+            if (downstreamAddress == null) {
+                mHandler.postDelayed(() -> maybeUpdateNat64Cidr(), RETRY_DELAY_ON_FAILURE_MILLIS);
+            }
+            mNat64Cidr = downstreamAddress;
+            LOG.i("Allocated NAT64 CIDR: " + mNat64Cidr);
+        }
+
+        private void maybeReleaseNat64Cidr() {
+            if (mNat64Cidr == null) {
+                return;
+            }
+            LOG.i("Released NAT64 CIDR: " + mNat64Cidr);
+            mNat64Cidr = null;
+            mRoutingCoordinatorManager.releaseDownstream(this);
+        }
+    }
 }
diff --git a/thread/service/java/com/android/server/thread/TunInterfaceController.java b/thread/service/java/com/android/server/thread/TunInterfaceController.java
index 3bff9c6..520a434 100644
--- a/thread/service/java/com/android/server/thread/TunInterfaceController.java
+++ b/thread/service/java/com/android/server/thread/TunInterfaceController.java
@@ -92,10 +92,21 @@
     }
 
     /** Returns link properties of the Thread TUN interface. */
-    public LinkProperties getLinkProperties() {
+    private LinkProperties getLinkProperties() {
         return new LinkProperties(mLinkProperties);
     }
 
+    /** Returns link properties of the Thread TUN interface with the given NAT64 CIDR. */
+    // TODO: manage the NAT64 CIDR in the TunInterfaceController
+    public LinkProperties getLinkPropertiesWithNat64Cidr(@Nullable LinkAddress nat64Cidr) {
+        final LinkProperties lp = getLinkProperties();
+        if (nat64Cidr != null) {
+            lp.addLinkAddress(nat64Cidr);
+            lp.addRoute(getRouteForAddress(nat64Cidr));
+        }
+        return lp;
+    }
+
     /**
      * Creates the tunnel interface.
      *
@@ -148,6 +159,9 @@
 
     /** Adds a new address to the interface. */
     public void addAddress(LinkAddress address) {
+        if (!(address.getAddress() instanceof Inet6Address)) {
+            return;
+        }
         LOG.v("Adding address " + address + " with flags: " + address.getFlags());
 
         long preferredLifetimeSeconds;
@@ -172,7 +186,7 @@
                             (address.getExpirationTime() - SystemClock.elapsedRealtime()) / 1000L,
                             0L);
         }
-
+        // Only apply to Ipv6 address
         if (!NetlinkUtils.sendRtmNewAddressRequest(
                 Os.if_nametoindex(mIfName),
                 address.getAddress(),
@@ -190,6 +204,9 @@
 
     /** Removes an address from the interface. */
     public void removeAddress(LinkAddress address) {
+        if (!(address.getAddress() instanceof Inet6Address)) {
+            return;
+        }
         LOG.v("Removing address " + address);
 
         // Intentionally update the mLinkProperties before send netlink message because the
@@ -197,6 +214,7 @@
         // when the netlink request below fails
         mLinkProperties.removeLinkAddress(address);
         mLinkProperties.removeRoute(getRouteForAddress(address));
+        // Only apply to Ipv6 address
         if (!NetlinkUtils.sendRtmDelAddressRequest(
                 Os.if_nametoindex(mIfName),
                 (Inet6Address) address.getAddress(),
diff --git a/thread/tests/integration/src/android/net/thread/BorderRoutingTest.java b/thread/tests/integration/src/android/net/thread/BorderRoutingTest.java
index f8e92f0..f6dd6b9 100644
--- a/thread/tests/integration/src/android/net/thread/BorderRoutingTest.java
+++ b/thread/tests/integration/src/android/net/thread/BorderRoutingTest.java
@@ -19,6 +19,7 @@
 import static android.Manifest.permission.MANAGE_TEST_NETWORKS;
 import static android.net.InetAddresses.parseNumericAddress;
 import static android.net.thread.utils.IntegrationTestUtils.DEFAULT_DATASET;
+import static android.net.thread.utils.IntegrationTestUtils.buildIcmpv4EchoReply;
 import static android.net.thread.utils.IntegrationTestUtils.getIpv6LinkAddresses;
 import static android.net.thread.utils.IntegrationTestUtils.isExpectedIcmpv4Packet;
 import static android.net.thread.utils.IntegrationTestUtils.isExpectedIcmpv6Packet;
@@ -77,9 +78,11 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import java.io.IOException;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
 import java.net.InetAddress;
+import java.nio.ByteBuffer;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
@@ -101,7 +104,6 @@
             (Inet6Address) parseNumericAddress("ff03::1234");
     private static final Inet4Address IPV4_SERVER_ADDR =
             (Inet4Address) parseNumericAddress("8.8.8.8");
-    private static final String NAT64_CIDR = "192.168.255.0/24";
     private static final IpPrefix DHCP6_PD_PREFIX = new IpPrefix("2001:db8::/64");
     private static final IpPrefix AIL_NAT64_PREFIX = new IpPrefix("2001:db8:1234::/96");
     private static final Inet6Address AIL_NAT64_SYNTHESIZED_SERVER_ADDR =
@@ -647,16 +649,27 @@
     }
 
     @Test
-    public void nat64_threadDevicePingIpv4InfraDevice_outboundPacketIsForwarded() throws Exception {
+    public void nat64_threadDevicePingIpv4InfraDevice_outboundPacketIsForwardedAndReplyIsReceived()
+            throws Exception {
         FullThreadDevice ftd = mFtds.get(0);
         joinNetworkAndWaitForOmr(ftd, DEFAULT_DATASET);
-        mOtCtl.setNat64Cidr(NAT64_CIDR);
         mController.setNat64EnabledAndWait(true);
         waitFor(() -> mOtCtl.hasNat64PrefixInNetdata(), UPDATE_NAT64_PREFIX_TIMEOUT);
+        Thread echoReplyThread = new Thread(() -> respondToEchoRequestOnce(IPV4_SERVER_ADDR));
+        echoReplyThread.start();
 
-        ftd.ping(IPV4_SERVER_ADDR);
+        assertThat(ftd.ping(IPV4_SERVER_ADDR, 1 /* count */)).isEqualTo(1);
 
-        assertNotNull(pollForIcmpPacketOnInfraNetwork(ICMP_ECHO, null, IPV4_SERVER_ADDR));
+        echoReplyThread.join();
+    }
+
+    private void respondToEchoRequestOnce(Inet4Address dstAddress) {
+        byte[] echoRequest = pollForIcmpPacketOnInfraNetwork(ICMP_ECHO, null, dstAddress);
+        assertNotNull(echoRequest);
+        try {
+            mInfraNetworkReader.sendResponse(buildIcmpv4EchoReply(ByteBuffer.wrap(echoRequest)));
+        } catch (IOException ignored) {
+        }
     }
 
     @Test
diff --git a/thread/tests/integration/src/android/net/thread/utils/IntegrationTestUtils.kt b/thread/tests/integration/src/android/net/thread/utils/IntegrationTestUtils.kt
index d903636..dc2a9c9 100644
--- a/thread/tests/integration/src/android/net/thread/utils/IntegrationTestUtils.kt
+++ b/thread/tests/integration/src/android/net/thread/utils/IntegrationTestUtils.kt
@@ -38,9 +38,15 @@
 import android.os.Handler
 import android.os.SystemClock
 import android.system.OsConstants
+import android.system.OsConstants.IPPROTO_ICMP
 import androidx.test.core.app.ApplicationProvider
 import com.android.compatibility.common.util.SystemUtil.runShellCommandOrThrow
+import com.android.net.module.util.IpUtils
 import com.android.net.module.util.NetworkStackConstants
+import com.android.net.module.util.NetworkStackConstants.ICMP_CHECKSUM_OFFSET
+import com.android.net.module.util.NetworkStackConstants.IPV4_CHECKSUM_OFFSET
+import com.android.net.module.util.NetworkStackConstants.IPV4_HEADER_MIN_LEN
+import com.android.net.module.util.NetworkStackConstants.IPV4_LENGTH_OFFSET
 import com.android.net.module.util.Struct
 import com.android.net.module.util.structs.Icmpv4Header
 import com.android.net.module.util.structs.Icmpv6Header
@@ -307,6 +313,73 @@
         return null
     }
 
+    /** Builds an ICMPv4 Echo Reply packet to respond to the given ICMPv4 Echo Request packet. */
+    @JvmStatic
+    fun buildIcmpv4EchoReply(request: ByteBuffer): ByteBuffer? {
+        val requestIpv4Header = Struct.parse(Ipv4Header::class.java, request) ?: return null
+        val requestIcmpv4Header = Struct.parse(Icmpv4Header::class.java, request) ?: return null
+
+        val id = request.getShort()
+        val seq = request.getShort()
+
+        val payload = ByteBuffer.allocate(4 + request.limit() - request.position())
+        payload.putShort(id)
+        payload.putShort(seq)
+        payload.put(request)
+        payload.rewind()
+
+        val ipv4HeaderLen = Struct.getSize(Ipv4Header::class.java)
+        val Icmpv4HeaderLen = Struct.getSize(Icmpv4Header::class.java)
+        val payloadLen = payload.limit();
+
+        val reply = ByteBuffer.allocate(ipv4HeaderLen + Icmpv4HeaderLen + payloadLen)
+
+        // IPv4 header
+        val replyIpv4Header = Ipv4Header(
+            0 /* TYPE OF SERVICE */,
+            0.toShort().toInt()/* totalLength, calculate later */,
+            requestIpv4Header.id,
+            requestIpv4Header.flagsAndFragmentOffset,
+            0x40 /* ttl */,
+            IPPROTO_ICMP.toByte(),
+            0.toShort()/* checksum, calculate later */,
+            requestIpv4Header.dstIp /* srcIp */,
+            requestIpv4Header.srcIp /* dstIp */
+        )
+        replyIpv4Header.writeToByteBuffer(reply)
+
+        // ICMPv4 header
+        val replyIcmpv4Header = Icmpv4Header(
+            0 /* type, ICMP_ECHOREPLY */,
+            requestIcmpv4Header.code,
+            0.toShort() /* checksum, calculate later */
+        )
+        replyIcmpv4Header.writeToByteBuffer(reply)
+
+        // Payload
+        reply.put(payload)
+        reply.flip()
+
+        // Populate the IPv4 totalLength field.
+        reply.putShort(
+            IPV4_LENGTH_OFFSET, (ipv4HeaderLen + Icmpv4HeaderLen + payloadLen).toShort()
+        )
+
+        // Populate the IPv4 header checksum field.
+        reply.putShort(
+            IPV4_CHECKSUM_OFFSET, IpUtils.ipChecksum(reply, 0 /* headerOffset */)
+        )
+
+        // Populate the ICMP checksum field.
+        reply.putShort(
+            IPV4_HEADER_MIN_LEN + ICMP_CHECKSUM_OFFSET, IpUtils.icmpChecksum(
+                reply, IPV4_HEADER_MIN_LEN, Icmpv4HeaderLen + payloadLen
+            )
+        )
+
+        return reply
+    }
+
     /** Returns the Prefix Information Options (PIO) extracted from an ICMPv6 RA message.  */
     @JvmStatic
     fun getRaPios(raMsg: ByteArray?): List<PrefixInformationOption> {
diff --git a/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java b/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java
index 7ac404f..e188491 100644
--- a/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java
+++ b/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java
@@ -44,6 +44,8 @@
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.ArgumentMatchers.isNotNull;
+import static org.mockito.ArgumentMatchers.isNull;
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.atLeastOnce;
 import static org.mockito.Mockito.clearInvocations;
@@ -64,6 +66,7 @@
 import android.content.Intent;
 import android.content.res.Resources;
 import android.net.ConnectivityManager;
+import android.net.LinkAddress;
 import android.net.LinkProperties;
 import android.net.Network;
 import android.net.NetworkAgent;
@@ -91,9 +94,12 @@
 
 import com.android.connectivity.resources.R;
 import com.android.dx.mockito.inline.extended.ExtendedMockito;
+import com.android.net.module.util.RoutingCoordinatorManager;
 import com.android.server.connectivity.ConnectivityResources;
 import com.android.server.thread.openthread.DnsTxtAttribute;
+import com.android.server.thread.openthread.IOtStatusReceiver;
 import com.android.server.thread.openthread.MeshcopTxtAttributes;
+import com.android.server.thread.openthread.OtDaemonConfiguration;
 import com.android.server.thread.openthread.testing.FakeOtDaemon;
 
 import org.junit.Before;
@@ -164,8 +170,10 @@
     private static final byte[] TEST_VENDOR_OUI_BYTES = new byte[] {(byte) 0xAC, (byte) 0xDE, 0x48};
     private static final String TEST_VENDOR_NAME = "test vendor";
     private static final String TEST_MODEL_NAME = "test model";
+    private static final LinkAddress TEST_NAT64_CIDR = new LinkAddress("192.168.255.0/24");
 
     @Mock private ConnectivityManager mMockConnectivityManager;
+    @Mock private RoutingCoordinatorManager mMockRoutingCoordinatorManager;
     @Mock private NetworkAgent mMockNetworkAgent;
     @Mock private TunInterfaceController mMockTunIfController;
     @Mock private ParcelFileDescriptor mMockTunFd;
@@ -208,7 +216,10 @@
         NetworkProvider networkProvider =
                 new NetworkProvider(mContext, mTestLooper.getLooper(), "ThreadNetworkProvider");
 
-        mFakeOtDaemon = new FakeOtDaemon(handler);
+        when(mMockRoutingCoordinatorManager.requestDownstreamAddress(any()))
+                .thenReturn(TEST_NAT64_CIDR);
+
+        mFakeOtDaemon = spy(new FakeOtDaemon(handler));
         when(mMockTunIfController.getTunFd()).thenReturn(mMockTunFd);
 
         when(mMockUserManager.hasUserRestriction(eq(DISALLOW_THREAD_NETWORK))).thenReturn(false);
@@ -235,6 +246,7 @@
                         networkProvider,
                         () -> mFakeOtDaemon,
                         mMockConnectivityManager,
+                        mMockRoutingCoordinatorManager,
                         mMockTunIfController,
                         mMockInfraIfController,
                         mPersistentSettings,
@@ -281,6 +293,37 @@
     }
 
     @Test
+    public void initialize_nat64Disabled_doesNotRequestNat64CidrAndConfiguresOtDaemon()
+            throws Exception {
+        ThreadConfiguration config =
+                new ThreadConfiguration.Builder().setNat64Enabled(false).build();
+        mPersistentSettings.putConfiguration(config);
+        mService.initialize();
+        mTestLooper.dispatchAll();
+
+        verify(mMockRoutingCoordinatorManager, never()).requestDownstreamAddress(any());
+        verify(mFakeOtDaemon, times(1)).setNat64Cidr(isNull(), any());
+        verify(mFakeOtDaemon, never()).setNat64Cidr(isNotNull(), any());
+    }
+
+    @Test
+    public void initialize_nat64Enabled_requestsNat64CidrAndConfiguresAtOtDaemon()
+            throws Exception {
+        ThreadConfiguration config =
+                new ThreadConfiguration.Builder().setNat64Enabled(true).build();
+        mPersistentSettings.putConfiguration(config);
+        mService.initialize();
+        mTestLooper.dispatchAll();
+
+        verify(mMockRoutingCoordinatorManager, times(1)).requestDownstreamAddress(any());
+        verify(mFakeOtDaemon, times(1))
+                .setConfiguration(
+                        new OtDaemonConfiguration.Builder().setNat64Enabled(true).build(),
+                        null /* receiver */);
+        verify(mFakeOtDaemon, times(1)).setNat64Cidr(eq(TEST_NAT64_CIDR.toString()), any());
+    }
+
+    @Test
     public void getMeshcopTxtAttributes_emptyVendorName_accepted() {
         when(mResources.getString(eq(R.string.config_thread_vendor_name))).thenReturn("");
 
@@ -758,6 +801,71 @@
     }
 
     @Test
+    public void setConfiguration_enablesNat64_requestsNat64CidrAndConfiguresOtdaemon()
+            throws Exception {
+        mService.initialize();
+        mTestLooper.dispatchAll();
+        clearInvocations(mMockRoutingCoordinatorManager, mFakeOtDaemon);
+
+        final IOperationReceiver mockReceiver = mock(IOperationReceiver.class);
+        mService.setConfiguration(
+                new ThreadConfiguration.Builder().setNat64Enabled(true).build(), mockReceiver);
+        mTestLooper.dispatchAll();
+
+        verify(mockReceiver, times(1)).onSuccess();
+        verify(mMockRoutingCoordinatorManager, times(1)).requestDownstreamAddress(any());
+        verify(mFakeOtDaemon, times(1))
+                .setConfiguration(
+                        eq(new OtDaemonConfiguration.Builder().setNat64Enabled(true).build()),
+                        any(IOtStatusReceiver.class));
+        verify(mFakeOtDaemon, times(1))
+                .setNat64Cidr(eq(TEST_NAT64_CIDR.toString()), any(IOtStatusReceiver.class));
+    }
+
+    @Test
+    public void setConfiguration_enablesNat64_otDaemonRemoteFailure_serviceDoesNotCrash()
+            throws Exception {
+        mService.initialize();
+        mTestLooper.dispatchAll();
+        clearInvocations(mMockRoutingCoordinatorManager, mFakeOtDaemon);
+        mFakeOtDaemon.setSetNat64CidrException(
+                new RemoteException("ot-daemon setNat64Cidr() throws"));
+
+        final IOperationReceiver mockReceiver = mock(IOperationReceiver.class);
+        mService.setConfiguration(
+                new ThreadConfiguration.Builder().setNat64Enabled(true).build(), mockReceiver);
+        mTestLooper.dispatchAll();
+
+        verify(mFakeOtDaemon, times(1))
+                .setNat64Cidr(eq(TEST_NAT64_CIDR.toString()), any(IOtStatusReceiver.class));
+    }
+
+    @Test
+    public void setConfiguration_disablesNat64_releasesNat64CidrAndConfiguresOtdaemon()
+            throws Exception {
+        mPersistentSettings.putConfiguration(
+                new ThreadConfiguration.Builder().setNat64Enabled(true).build());
+        mService.initialize();
+        mTestLooper.dispatchAll();
+        clearInvocations(mMockRoutingCoordinatorManager, mFakeOtDaemon);
+
+        final IOperationReceiver mockReceiver = mock(IOperationReceiver.class);
+        mService.setConfiguration(
+                new ThreadConfiguration.Builder().setNat64Enabled(false).build(), mockReceiver);
+        mTestLooper.dispatchAll();
+
+        verify(mockReceiver, times(1)).onSuccess();
+        verify(mMockRoutingCoordinatorManager, times(1)).releaseDownstream(any());
+        verify(mMockRoutingCoordinatorManager, never()).requestDownstreamAddress(any());
+        verify(mFakeOtDaemon, times(1))
+                .setConfiguration(
+                        eq(new OtDaemonConfiguration.Builder().setNat64Enabled(false).build()),
+                        any(IOtStatusReceiver.class));
+        verify(mFakeOtDaemon, times(1)).setNat64Cidr(isNull(), any(IOtStatusReceiver.class));
+        verify(mFakeOtDaemon, never()).setNat64Cidr(isNotNull(), any(IOtStatusReceiver.class));
+    }
+
+    @Test
     public void initialize_upstreamNetworkRequestHasCertainTransportTypesAndCapabilities() {
         mService.initialize();
         mTestLooper.dispatchAll();