diff --git a/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java b/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java
index 50f82cf..db97986 100644
--- a/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java
+++ b/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java
@@ -24,7 +24,6 @@
 import static com.android.net.module.util.Inet4AddressUtils.inet4AddressToIntHTH;
 import static com.android.net.module.util.Inet4AddressUtils.intToInet4AddressHTH;
 import static com.android.net.module.util.Inet4AddressUtils.prefixLengthToV4NetmaskIntHTH;
-import static com.android.networkstack.tethering.util.PrefixUtils.asIpPrefix;
 
 import static java.util.Arrays.asList;
 
@@ -34,16 +33,13 @@
 import android.net.LinkProperties;
 import android.net.Network;
 import android.net.NetworkCapabilities;
-import android.net.ip.IpServer;
+import android.os.RemoteException;
 import android.util.ArrayMap;
-import android.util.ArraySet;
+import android.util.IndentingPrintWriter;
 
-import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.internal.annotations.VisibleForTesting;
-import com.android.internal.util.IndentingPrintWriter;
-import com.android.net.module.util.DeviceConfigUtils;
 
 import java.net.Inet4Address;
 import java.net.InetAddress;
@@ -51,6 +47,8 @@
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Objects;
 import java.util.Random;
 import java.util.Set;
 import java.util.function.Supplier;
@@ -62,7 +60,7 @@
  * coordinator is responsible for recording all of network assigned addresses and dispatched
  * free address to downstream interfaces.
  *
- * This class is not thread-safe and should be accessed on the same tethering internal thread.
+ * This class is not thread-safe.
  * @hide
  */
 public class PrivateAddressCoordinator {
@@ -78,7 +76,9 @@
     // when tethering is down. Instead tethering would remove all deprecated upstreams from
     // mUpstreamPrefixMap when tethering is starting. See #maybeRemoveDeprecatedUpstreams().
     private final ArrayMap<Network, List<IpPrefix>> mUpstreamPrefixMap;
-    private final ArraySet<IpServer> mDownstreams;
+    // The downstreams are indexed by Ipv4PrefixRequest, which is a wrapper of the Binder object of
+    // IIpv4PrefixRequest.
+    private final ArrayMap<Ipv4PrefixRequest, Downstream> mDownstreams;
     private static final String LEGACY_WIFI_P2P_IFACE_ADDRESS = "192.168.49.1/24";
     private static final String LEGACY_BLUETOOTH_IFACE_ADDRESS = "192.168.44.1/24";
     private final List<IpPrefix> mTetheringPrefixes;
@@ -116,7 +116,7 @@
     @VisibleForTesting
     public PrivateAddressCoordinator(Supplier<Network[]> getAllNetworksSupplier,
                                      Dependencies deps) {
-        mDownstreams = new ArraySet<>();
+        mDownstreams = new ArrayMap<>();
         mUpstreamPrefixMap = new ArrayMap<>();
         mGetAllNetworksSupplier = getAllNetworksSupplier;
         mDeps = deps;
@@ -168,12 +168,18 @@
     }
 
     private void handleMaybePrefixConflict(final List<IpPrefix> prefixes) {
-        for (IpServer downstream : mDownstreams) {
-            final IpPrefix target = getDownstreamPrefix(downstream);
+        for (Map.Entry<Ipv4PrefixRequest, Downstream> entry : mDownstreams.entrySet()) {
+            final Ipv4PrefixRequest request = entry.getKey();
+            final Downstream downstream = entry.getValue();
+            final IpPrefix target = asIpPrefix(downstream.getAddress());
 
             for (IpPrefix source : prefixes) {
                 if (isConflictPrefix(source, target)) {
-                    downstream.sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
+                    try {
+                        request.getRequest().onIpv4PrefixConflict(target);
+                    } catch (RemoteException ignored) {
+                        // ignore
+                    }
                     break;
                 }
             }
@@ -199,21 +205,26 @@
         mUpstreamPrefixMap.removeAll(toBeRemoved);
     }
 
+    // TODO: There needs to be a reserveDownstreamAddress() method for the cases where
+    // TetheringRequest has been set a static IPv4 address.
+
     /**
      * Pick a random available address and mark its prefix as in use for the provided IpServer,
      * returns null if there is no available address.
      */
     @Nullable
-    public LinkAddress requestDownstreamAddress(final IpServer ipServer, final int scope,
-            boolean useLastAddress) {
-        final AddressKey addrKey = new AddressKey(ipServer.interfaceType(), scope);
+    public LinkAddress requestDownstreamAddress(int interfaceType, final int scope,
+            boolean useLastAddress,
+            IIpv4PrefixRequest request) {
+        final Ipv4PrefixRequest wrappedRequest = new Ipv4PrefixRequest(request);
+        final AddressKey addrKey = new AddressKey(interfaceType, scope);
         // This ensures that tethering isn't started on 2 different interfaces with the same type.
         // Once tethering could support multiple interface with the same type,
         // TetheringSoftApCallback would need to handle it among others.
         final LinkAddress cachedAddress = mCachedAddresses.get(addrKey);
         if (useLastAddress && cachedAddress != null
                 && !isConflictWithUpstream(asIpPrefix(cachedAddress))) {
-            mDownstreams.add(ipServer);
+            mDownstreams.put(wrappedRequest, new Downstream(interfaceType, cachedAddress));
             return cachedAddress;
         }
 
@@ -223,7 +234,7 @@
                     (prefixIndex + i) % mTetheringPrefixes.size());
             final LinkAddress newAddress = chooseDownstreamAddress(prefixRange);
             if (newAddress != null) {
-                mDownstreams.add(ipServer);
+                mDownstreams.put(wrappedRequest, new Downstream(interfaceType, newAddress));
                 mCachedAddresses.put(addrKey, newAddress);
                 return newAddress;
             }
@@ -327,8 +338,8 @@
     }
 
     /** Release downstream record for IpServer. */
-    public void releaseDownstream(final IpServer ipServer) {
-        mDownstreams.remove(ipServer);
+    public void releaseDownstream(IIpv4PrefixRequest request) {
+        mDownstreams.remove(new Ipv4PrefixRequest(request));
     }
 
     /** Clear current upstream prefixes records. */
@@ -368,8 +379,8 @@
 
         // IpServer may use manually-defined address (mStaticIpv4ServerAddr) which does not include
         // in mCachedAddresses.
-        for (IpServer downstream : mDownstreams) {
-            final IpPrefix target = getDownstreamPrefix(downstream);
+        for (Downstream downstream : mDownstreams.values()) {
+            final IpPrefix target = asIpPrefix(downstream.getAddress());
 
             if (isConflictPrefix(prefix, target)) return target;
         }
@@ -377,11 +388,51 @@
         return null;
     }
 
-    @NonNull
-    private IpPrefix getDownstreamPrefix(final IpServer downstream) {
-        final LinkAddress address = downstream.getAddress();
+    private static IpPrefix asIpPrefix(LinkAddress addr) {
+        return new IpPrefix(addr.getAddress(), addr.getPrefixLength());
+    }
 
-        return asIpPrefix(address);
+    private static final class Ipv4PrefixRequest {
+        private final IIpv4PrefixRequest mRequest;
+
+        Ipv4PrefixRequest(IIpv4PrefixRequest request) {
+            mRequest = request;
+        }
+
+        public IIpv4PrefixRequest getRequest() {
+            return mRequest;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) return true;
+            if (!(obj instanceof Ipv4PrefixRequest)) return false;
+            return Objects.equals(
+                    mRequest.asBinder(), ((Ipv4PrefixRequest) obj).mRequest.asBinder());
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hashCode(mRequest.asBinder());
+        }
+    }
+
+    private static final class Downstream {
+        private final int mInterfaceType;
+        private final LinkAddress mAddress;
+
+        private Downstream(int interfaceType, LinkAddress address) {
+            mInterfaceType = interfaceType;
+            mAddress = address;
+        }
+
+        public int getInterfaceType() {
+            return mInterfaceType;
+        }
+
+        public LinkAddress getAddress() {
+            return mAddress;
+        }
     }
 
     private static class AddressKey {
@@ -412,6 +463,7 @@
         }
     }
 
+    // TODO: dump PrivateAddressCoordinator when dumping RoutingCoordinatorService.
     void dump(final IndentingPrintWriter pw) {
         pw.println("mTetheringPrefixes:");
         pw.increaseIndent();
@@ -429,8 +481,8 @@
 
         pw.println("mDownstreams:");
         pw.increaseIndent();
-        for (IpServer ipServer : mDownstreams) {
-            pw.println(ipServer.interfaceType() + " - " + ipServer.getAddress());
+        for (Downstream downstream : mDownstreams.values()) {
+            pw.println(downstream.getInterfaceType() + " - " + downstream.getAddress());
         }
         pw.decreaseIndent();
 
diff --git a/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
index cc878d5..34f2897 100644
--- a/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
@@ -136,7 +136,10 @@
     public RoutingCoordinatorManager getRoutingCoordinator(Context context, SharedLog log) {
         IBinder binder;
         if (!SdkLevel.isAtLeastS()) {
-            binder = new RoutingCoordinatorService(getINetd(context, log));
+            final ConnectivityManager cm = context.getSystemService(ConnectivityManager.class);
+            binder =
+                    new RoutingCoordinatorService(
+                            getINetd(context, log), cm::getAllNetworks, context);
         } else {
             binder = ConnectivityInternalApiUtil.getRoutingCoordinator(context);
         }
@@ -175,14 +178,6 @@
     }
 
     /**
-     * Make PrivateAddressCoordinator to be used by Tethering.
-     */
-    public PrivateAddressCoordinator makePrivateAddressCoordinator(Context ctx) {
-        final ConnectivityManager cm = ctx.getSystemService(ConnectivityManager.class);
-        return new PrivateAddressCoordinator(cm::getAllNetworks, ctx);
-    }
-
-    /**
      * Make BluetoothPanShim object to enable/disable bluetooth tethering.
      *
      * TODO: use BluetoothPan directly when mainline module is built with API 32.
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index cb62ae1..a04ebdd 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -2028,7 +2028,8 @@
             mCdmps = null;
         }
 
-        mRoutingCoordinatorService = new RoutingCoordinatorService(netd);
+        mRoutingCoordinatorService =
+                new RoutingCoordinatorService(netd, this::getAllNetworks, mContext);
         mMulticastRoutingCoordinatorService =
                 mDeps.makeMulticastRoutingCoordinatorService(mHandler);
 
diff --git a/staticlibs/device/com/android/net/module/util/IIpv4PrefixRequest.aidl b/staticlibs/device/com/android/net/module/util/IIpv4PrefixRequest.aidl
new file mode 100644
index 0000000..cc1c19c
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/IIpv4PrefixRequest.aidl
@@ -0,0 +1,29 @@
+/*
+ * 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.net.module.util;
+
+import android.net.IpPrefix;
+import android.net.LinkAddress;
+
+/** @hide */
+// TODO: b/350630377 - This @Descriptor annotation workaround is to prevent the class from being
+// jarjared which changes the DESCRIPTOR and casues "java.lang.SecurityException: Binder invocation
+// to an incorrect interface" when calling the IPC.
+@Descriptor("value=no.jarjar.com.android.net.module.util.IIpv4PrefixRequest")
+interface IIpv4PrefixRequest {
+    void onIpv4PrefixConflict(in IpPrefix ipPrefix);
+}
diff --git a/staticlibs/device/com/android/net/module/util/IRoutingCoordinator.aidl b/staticlibs/device/com/android/net/module/util/IRoutingCoordinator.aidl
index 72a4a94..097824f 100644
--- a/staticlibs/device/com/android/net/module/util/IRoutingCoordinator.aidl
+++ b/staticlibs/device/com/android/net/module/util/IRoutingCoordinator.aidl
@@ -16,8 +16,14 @@
 
 package com.android.net.module.util;
 
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.NetworkCapabilities;
 import android.net.RouteInfo;
 
+import com.android.net.module.util.IIpv4PrefixRequest;
+
 /** @hide */
 // TODO: b/350630377 - This @Descriptor annotation workaround is to prevent the DESCRIPTOR from
 // being jarjared which changes the DESCRIPTOR and casues "java.lang.SecurityException: Binder
@@ -96,4 +102,34 @@
     *         cause of the failure.
     */
     void removeInterfaceForward(in String fromIface, in String toIface);
+
+    /** Update the prefix of an upstream. */
+    void updateUpstreamPrefix(in @nullable LinkProperties lp,
+                              in @nullable NetworkCapabilities nc,
+                              in Network network);
+
+    /** Remove the upstream prefix of the given {@link Network}. */
+    void removeUpstreamPrefix(in Network network);
+
+    /** Remove the deprecated upstream networks if any. */
+    void maybeRemoveDeprecatedUpstreams();
+
+   /**
+    * Request an IPv4 address for the downstream.
+    *
+    * @param interfaceType the Tethering type (see TetheringManager#TETHERING_*).
+    * @param scope CONNECTIVITY_SCOPE_GLOBAL or CONNECTIVITY_SCOPE_LOCAL
+    * @param useLastAddress whether to use the last address
+    * @param request a {@link IIpv4PrefixRequest} to report conflicts
+    * @return an IPv4 address allocated for the downstream, could be null
+    */
+    @nullable
+    LinkAddress requestDownstreamAddress(
+            in int interfaceType,
+            in int scope,
+            in boolean useLastAddress,
+            in IIpv4PrefixRequest request);
+
+    /** Release the IPv4 address allocated for the downstream. */
+    void releaseDownstream(in IIpv4PrefixRequest request);
 }
diff --git a/staticlibs/device/com/android/net/module/util/RoutingCoordinatorManager.java b/staticlibs/device/com/android/net/module/util/RoutingCoordinatorManager.java
index 02e3643..9ea0947 100644
--- a/staticlibs/device/com/android/net/module/util/RoutingCoordinatorManager.java
+++ b/staticlibs/device/com/android/net/module/util/RoutingCoordinatorManager.java
@@ -17,17 +17,27 @@
 package com.android.net.module.util;
 
 import android.content.Context;
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.NetworkCapabilities;
 import android.net.RouteInfo;
 import android.os.IBinder;
 import android.os.RemoteException;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 /**
  * A manager class for talking to the routing coordinator service.
  *
  * This class should only be used by the connectivity and tethering module. This is enforced
  * by the build rules. Do not change build rules to gain access to this class from elsewhere.
+ *
+ * This class has following functionalities:
+ * - Manage routes and forwarding for networks.
+ * - Manage IPv4 prefix allocation for network interfaces.
+ *
  * @hide
  */
 public class RoutingCoordinatorManager {
@@ -154,4 +164,65 @@
             throw e.rethrowFromSystemServer();
         }
     }
+
+    // PrivateAddressCoordinator methods:
+
+    /** Update the prefix of an upstream. */
+    public void updateUpstreamPrefix(LinkProperties lp, NetworkCapabilities nc, Network network) {
+        try {
+            mService.updateUpstreamPrefix(lp, nc, network);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /** Remove the upstream prefix of the given {@link Network}. */
+    public void removeUpstreamPrefix(Network network) {
+        try {
+            mService.removeUpstreamPrefix(network);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /** Remove the deprecated upstream networks if any. */
+    public void maybeRemoveDeprecatedUpstreams() {
+        try {
+            mService.maybeRemoveDeprecatedUpstreams();
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Request an IPv4 address for the downstream.
+     *
+     * @param interfaceType the Tethering type (see TetheringManager#TETHERING_*).
+     * @param scope CONNECTIVITY_SCOPE_GLOBAL or CONNECTIVITY_SCOPE_LOCAL
+     * @param useLastAddress whether to use the last address
+     * @param request a {@link IIpv4PrefixRequest} to report conflicts
+     * @return an IPv4 address allocated for the downstream, could be null
+     */
+    @Nullable
+    public LinkAddress requestDownstreamAddress(
+            int interfaceType,
+            int scope,
+            boolean useLastAddress,
+            IIpv4PrefixRequest request) {
+        try {
+            return mService.requestDownstreamAddress(
+                    interfaceType, scope, useLastAddress, request);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /** Release the IPv4 address allocated for the downstream. */
+    public void releaseDownstream(IIpv4PrefixRequest request) {
+        try {
+            mService.releaseDownstream(request);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
 }
diff --git a/staticlibs/device/com/android/net/module/util/RoutingCoordinatorService.java b/staticlibs/device/com/android/net/module/util/RoutingCoordinatorService.java
index c75b860..d16c234 100644
--- a/staticlibs/device/com/android/net/module/util/RoutingCoordinatorService.java
+++ b/staticlibs/device/com/android/net/module/util/RoutingCoordinatorService.java
@@ -19,8 +19,13 @@
 import static com.android.net.module.util.NetdUtils.toRouteInfoParcel;
 
 import android.annotation.NonNull;
+import android.content.Context;
 import android.net.INetd;
 
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.NetworkCapabilities;
 import android.net.RouteInfo;
 import android.os.RemoteException;
 import android.os.ServiceSpecificException;
@@ -28,8 +33,10 @@
 import android.util.Log;
 
 import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
 
 import java.util.Objects;
+import java.util.function.Supplier;
 
 /**
  * Class to coordinate routing across multiple clients.
@@ -45,8 +52,22 @@
     private static final String TAG = RoutingCoordinatorService.class.getSimpleName();
     private final INetd mNetd;
 
-    public RoutingCoordinatorService(@NonNull INetd netd) {
+    private final Object mPrivateAddressCoordinatorLock = new Object();
+    @GuardedBy("mPrivateAddressCoordinatorLock")
+    private final PrivateAddressCoordinator mPrivateAddressCoordinator;
+
+    public RoutingCoordinatorService(@NonNull INetd netd,
+                                     @NonNull Supplier<Network[]> getAllNetworksSupplier,
+                                     @NonNull Context context) {
+        this(netd, getAllNetworksSupplier, new PrivateAddressCoordinator.Dependencies(context));
+    }
+
+    @VisibleForTesting
+    public RoutingCoordinatorService(@NonNull INetd netd,
+                                     @NonNull Supplier<Network[]> getAllNetworksSupplier,
+                                     @NonNull PrivateAddressCoordinator.Dependencies pacDeps) {
         mNetd = netd;
+        mPrivateAddressCoordinator = new PrivateAddressCoordinator(getAllNetworksSupplier, pacDeps);
     }
 
     /**
@@ -225,4 +246,74 @@
             }
         }
     }
+
+    // PrivateAddressCoordinator methods:
+
+    /** Update the prefix of an upstream. */
+    @Override
+    public void updateUpstreamPrefix(LinkProperties lp, NetworkCapabilities nc, Network network) {
+        BinderUtils.withCleanCallingIdentity(
+                () -> {
+                    synchronized (mPrivateAddressCoordinatorLock) {
+                        mPrivateAddressCoordinator.updateUpstreamPrefix(lp, nc, network);
+                    }
+                });
+    }
+
+    /** Remove the upstream prefix of the given {@link Network}. */
+    @Override
+    public void removeUpstreamPrefix(Network network) {
+        Objects.requireNonNull(network);
+        BinderUtils.withCleanCallingIdentity(
+                () -> {
+                    synchronized (mPrivateAddressCoordinatorLock) {
+                        mPrivateAddressCoordinator.removeUpstreamPrefix(network);
+                    }
+                });
+    }
+
+    /** Remove the deprecated upstream networks if any. */
+    @Override
+    public void maybeRemoveDeprecatedUpstreams() {
+        BinderUtils.withCleanCallingIdentity(
+                () -> {
+                    synchronized (mPrivateAddressCoordinatorLock) {
+                        mPrivateAddressCoordinator.maybeRemoveDeprecatedUpstreams();
+                    }
+                });
+    }
+
+    /**
+     * Request an IPv4 address for the downstream.
+     *
+     * @param interfaceType the Tethering type (see TetheringManager#TETHERING_*).
+     * @param scope CONNECTIVITY_SCOPE_GLOBAL or CONNECTIVITY_SCOPE_LOCAL
+     * @param useLastAddress whether to use the last address
+     * @param request a {@link IIpv4PrefixRequest} to report conflicts
+     * @return an IPv4 address allocated for the downstream, could be null
+     */
+    @Override
+    public LinkAddress requestDownstreamAddress(int interfaceType, int scope,
+            boolean useLastAddress, IIpv4PrefixRequest request) {
+        Objects.requireNonNull(request);
+        return BinderUtils.withCleanCallingIdentity(
+                () -> {
+                    synchronized (mPrivateAddressCoordinatorLock) {
+                        return mPrivateAddressCoordinator.requestDownstreamAddress(
+                                interfaceType, scope, useLastAddress, request);
+                    }
+                });
+    }
+
+    /** Release the IPv4 address allocated for the downstream. */
+    @Override
+    public void releaseDownstream(IIpv4PrefixRequest request) {
+        Objects.requireNonNull(request);
+        BinderUtils.withCleanCallingIdentity(
+                () -> {
+                    synchronized (mPrivateAddressCoordinatorLock) {
+                        mPrivateAddressCoordinator.releaseDownstream(request);
+                    }
+                });
+    }
 }