diff --git a/framework/api/module-lib-current.txt b/framework/api/module-lib-current.txt
index 4ce6add..a2a1ac0 100644
--- a/framework/api/module-lib-current.txt
+++ b/framework/api/module-lib-current.txt
@@ -200,6 +200,8 @@
     method public int describeContents();
     method @NonNull public android.os.ParcelFileDescriptor getFileDescriptor();
     method @NonNull public String getInterfaceName();
+    method @Nullable public android.net.MacAddress getMacAddress();
+    method public int getMtu();
     method public void writeToParcel(@NonNull android.os.Parcel, int);
     field @NonNull public static final android.os.Parcelable.Creator<android.net.TestNetworkInterface> CREATOR;
   }
diff --git a/framework/src/android/net/ITestNetworkManager.aidl b/framework/src/android/net/ITestNetworkManager.aidl
index 27d13c1..d18b931 100644
--- a/framework/src/android/net/ITestNetworkManager.aidl
+++ b/framework/src/android/net/ITestNetworkManager.aidl
@@ -29,8 +29,10 @@
  */
 interface ITestNetworkManager
 {
-    TestNetworkInterface createInterface(boolean isTun, boolean bringUp, in LinkAddress[] addrs,
-            in @nullable String iface);
+    TestNetworkInterface createInterface(boolean isTun, boolean hasCarrier, boolean bringUp,
+            in LinkAddress[] addrs, in @nullable String iface);
+
+    void setCarrierEnabled(in TestNetworkInterface iface, boolean enabled);
 
     void setupTestNetwork(in String iface, in LinkProperties lp, in boolean isMetered,
             in int[] administratorUids, in IBinder binder);
diff --git a/framework/src/android/net/TestNetworkInterface.java b/framework/src/android/net/TestNetworkInterface.java
index 4449ff8..26200e1 100644
--- a/framework/src/android/net/TestNetworkInterface.java
+++ b/framework/src/android/net/TestNetworkInterface.java
@@ -16,22 +16,32 @@
 package android.net;
 
 import android.annotation.NonNull;
+import android.annotation.Nullable;
 import android.annotation.SystemApi;
 import android.os.Parcel;
 import android.os.ParcelFileDescriptor;
 import android.os.Parcelable;
+import android.util.Log;
+
+import java.net.NetworkInterface;
+import java.net.SocketException;
 
 /**
- * This class is used to return the interface name and fd of the test interface
+ * This class is used to return the interface name, fd, MAC, and MTU of the test interface
  *
  * @hide
  */
 @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
 public final class TestNetworkInterface implements Parcelable {
+    private static final String TAG = "TestNetworkInterface";
+
     @NonNull
     private final ParcelFileDescriptor mFileDescriptor;
     @NonNull
     private final String mInterfaceName;
+    @Nullable
+    private final MacAddress mMacAddress;
+    private final int mMtu;
 
     @Override
     public int describeContents() {
@@ -40,18 +50,41 @@
 
     @Override
     public void writeToParcel(@NonNull Parcel out, int flags) {
-        out.writeParcelable(mFileDescriptor, PARCELABLE_WRITE_RETURN_VALUE);
+        out.writeParcelable(mFileDescriptor, flags);
         out.writeString(mInterfaceName);
+        out.writeParcelable(mMacAddress, flags);
+        out.writeInt(mMtu);
     }
 
     public TestNetworkInterface(@NonNull ParcelFileDescriptor pfd, @NonNull String intf) {
         mFileDescriptor = pfd;
         mInterfaceName = intf;
+
+        MacAddress macAddress = null;
+        int mtu = 1500;
+        try {
+            // This constructor is called by TestNetworkManager which runs inside the system server,
+            // which has permission to read the MacAddress.
+            NetworkInterface nif = NetworkInterface.getByName(mInterfaceName);
+
+            // getHardwareAddress() returns null for tun interfaces.
+            byte[] hardwareAddress = nif.getHardwareAddress();
+            if (hardwareAddress != null) {
+                macAddress = MacAddress.fromBytes(nif.getHardwareAddress());
+            }
+            mtu = nif.getMTU();
+        } catch (SocketException e) {
+            Log.e(TAG, "Failed to fetch MacAddress or MTU size from NetworkInterface", e);
+        }
+        mMacAddress = macAddress;
+        mMtu = mtu;
     }
 
     private TestNetworkInterface(@NonNull Parcel in) {
         mFileDescriptor = in.readParcelable(ParcelFileDescriptor.class.getClassLoader());
         mInterfaceName = in.readString();
+        mMacAddress = in.readParcelable(MacAddress.class.getClassLoader());
+        mMtu = in.readInt();
     }
 
     @NonNull
@@ -64,6 +97,15 @@
         return mInterfaceName;
     }
 
+    @Nullable
+    public MacAddress getMacAddress() {
+        return mMacAddress;
+    }
+
+    public int getMtu() {
+        return mMtu;
+    }
+
     @NonNull
     public static final Parcelable.Creator<TestNetworkInterface> CREATOR =
             new Parcelable.Creator<TestNetworkInterface>() {
diff --git a/framework/src/android/net/TestNetworkManager.java b/framework/src/android/net/TestNetworkManager.java
index 4e78823..7b18765 100644
--- a/framework/src/android/net/TestNetworkManager.java
+++ b/framework/src/android/net/TestNetworkManager.java
@@ -58,6 +58,7 @@
     private static final boolean TAP = false;
     private static final boolean TUN = true;
     private static final boolean BRING_UP = true;
+    private static final boolean CARRIER_UP = true;
     private static final LinkAddress[] NO_ADDRS = new LinkAddress[0];
 
     /** @hide */
@@ -166,7 +167,7 @@
     public TestNetworkInterface createTunInterface(@NonNull Collection<LinkAddress> linkAddrs) {
         try {
             final LinkAddress[] arr = new LinkAddress[linkAddrs.size()];
-            return mService.createInterface(TUN, BRING_UP, linkAddrs.toArray(arr),
+            return mService.createInterface(TUN, CARRIER_UP, BRING_UP, linkAddrs.toArray(arr),
                     null /* iface */);
         } catch (RemoteException e) {
             throw e.rethrowFromSystemServer();
@@ -185,7 +186,7 @@
     @NonNull
     public TestNetworkInterface createTapInterface() {
         try {
-            return mService.createInterface(TAP, BRING_UP, NO_ADDRS, null /* iface */);
+            return mService.createInterface(TAP, CARRIER_UP, BRING_UP, NO_ADDRS, null /* iface */);
         } catch (RemoteException e) {
             throw e.rethrowFromSystemServer();
         }
@@ -204,7 +205,7 @@
     @NonNull
     public TestNetworkInterface createTapInterface(boolean bringUp) {
         try {
-            return mService.createInterface(TAP, bringUp, NO_ADDRS, null /* iface */);
+            return mService.createInterface(TAP, CARRIER_UP, bringUp, NO_ADDRS, null /* iface */);
         } catch (RemoteException e) {
             throw e.rethrowFromSystemServer();
         }
@@ -226,7 +227,43 @@
     @NonNull
     public TestNetworkInterface createTapInterface(boolean bringUp, @NonNull String iface) {
         try {
-            return mService.createInterface(TAP, bringUp, NO_ADDRS, iface);
+            return mService.createInterface(TAP, CARRIER_UP, bringUp, NO_ADDRS, iface);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Create a tap interface with or without carrier for testing purposes.
+     *
+     * @param carrierUp whether the created interface has a carrier or not.
+     * @param bringUp whether to bring up the interface before returning it.
+     * @hide
+     */
+    @RequiresPermission(Manifest.permission.MANAGE_TEST_NETWORKS)
+    @NonNull
+    public TestNetworkInterface createTapInterface(boolean carrierUp, boolean bringUp) {
+        try {
+            return mService.createInterface(TAP, carrierUp, bringUp, NO_ADDRS, null /* iface */);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Enable / disable carrier on TestNetworkInterface
+     *
+     * Note: TUNSETCARRIER is not supported until kernel version 5.0.
+     * TODO: add RequiresApi annotation.
+     *
+     * @param iface the interface to configure.
+     * @param enabled true to turn carrier on, false to turn carrier off.
+     * @hide
+     */
+    @RequiresPermission(Manifest.permission.MANAGE_TEST_NETWORKS)
+    public void setCarrierEnabled(@NonNull TestNetworkInterface iface, boolean enabled) {
+        try {
+            mService.setCarrierEnabled(iface, enabled);
         } catch (RemoteException e) {
             throw e.rethrowFromSystemServer();
         }
diff --git a/service/jni/com_android_server_TestNetworkService.cpp b/service/jni/com_android_server_TestNetworkService.cpp
index 4efd0e1..9c7a761 100644
--- a/service/jni/com_android_server_TestNetworkService.cpp
+++ b/service/jni/com_android_server_TestNetworkService.cpp
@@ -51,7 +51,15 @@
     jniThrowException(env, "java/lang/IllegalStateException", msg.c_str());
 }
 
-static int createTunTapInterface(JNIEnv* env, bool isTun, const char* iface) {
+// enable or disable  carrier on tun / tap interface.
+static void setTunTapCarrierEnabledImpl(JNIEnv* env, const char* iface, int tunFd, bool enabled) {
+    uint32_t carrierOn = enabled;
+    if (ioctl(tunFd, TUNSETCARRIER, &carrierOn)) {
+        throwException(env, errno, "set carrier", iface);
+    }
+}
+
+static int createTunTapImpl(JNIEnv* env, bool isTun, bool hasCarrier, const char* iface) {
     base::unique_fd tun(open("/dev/tun", O_RDWR | O_NONBLOCK));
     ifreq ifr{};
 
@@ -63,6 +71,11 @@
         return -1;
     }
 
+    if (!hasCarrier) {
+        // disable carrier before setting IFF_UP
+        setTunTapCarrierEnabledImpl(env, iface, tun.get(), hasCarrier);
+    }
+
     // Activate interface using an unconnected datagram socket.
     base::unique_fd inet6CtrlSock(socket(AF_INET6, SOCK_DGRAM, 0));
     ifr.ifr_flags = IFF_UP;
@@ -79,23 +92,31 @@
 
 //------------------------------------------------------------------------------
 
-static jint create(JNIEnv* env, jobject /* thiz */, jboolean isTun, jstring jIface) {
+static void setTunTapCarrierEnabled(JNIEnv* env, jclass /* clazz */, jstring
+                                    jIface, jint tunFd, jboolean enabled) {
+    ScopedUtfChars iface(env, jIface);
+    if (!iface.c_str()) {
+        jniThrowNullPointerException(env, "iface");
+    }
+    setTunTapCarrierEnabledImpl(env, iface.c_str(), tunFd, enabled);
+}
+
+static jint createTunTap(JNIEnv* env, jclass /* clazz */, jboolean isTun,
+                             jboolean hasCarrier, jstring jIface) {
     ScopedUtfChars iface(env, jIface);
     if (!iface.c_str()) {
         jniThrowNullPointerException(env, "iface");
         return -1;
     }
 
-    int tun = createTunTapInterface(env, isTun, iface.c_str());
-
-    // Any exceptions will be thrown from the createTunTapInterface call
-    return tun;
+    return createTunTapImpl(env, isTun, hasCarrier, iface.c_str());
 }
 
 //------------------------------------------------------------------------------
 
 static const JNINativeMethod gMethods[] = {
-    {"jniCreateTunTap", "(ZLjava/lang/String;)I", (void*)create},
+    {"nativeSetTunTapCarrierEnabled", "(Ljava/lang/String;IZ)V", (void*)setTunTapCarrierEnabled},
+    {"nativeCreateTunTap", "(ZZLjava/lang/String;)I", (void*)createTunTap},
 };
 
 int register_com_android_server_TestNetworkService(JNIEnv* env) {
diff --git a/service/src/com/android/server/TestNetworkService.java b/service/src/com/android/server/TestNetworkService.java
index e12190c..1209579 100644
--- a/service/src/com/android/server/TestNetworkService.java
+++ b/service/src/com/android/server/TestNetworkService.java
@@ -50,6 +50,7 @@
 import com.android.net.module.util.NetdUtils;
 import com.android.net.module.util.NetworkStackConstants;
 
+import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
@@ -76,7 +77,11 @@
     @NonNull private final NetworkProvider mNetworkProvider;
 
     // Native method stubs
-    private static native int jniCreateTunTap(boolean isTun, @NonNull String iface);
+    private static native int nativeCreateTunTap(boolean isTun, boolean hasCarrier,
+            @NonNull String iface);
+
+    private static native void nativeSetTunTapCarrierEnabled(@NonNull String iface, int tunFd,
+            boolean enabled);
 
     @VisibleForTesting
     protected TestNetworkService(@NonNull Context context) {
@@ -114,7 +119,7 @@
      * interface.
      */
     @Override
-    public TestNetworkInterface createInterface(boolean isTun, boolean bringUp,
+    public TestNetworkInterface createInterface(boolean isTun, boolean hasCarrier, boolean bringUp,
             LinkAddress[] linkAddrs, @Nullable String iface) {
         enforceTestNetworkPermissions(mContext);
 
@@ -130,8 +135,8 @@
 
         final long token = Binder.clearCallingIdentity();
         try {
-            ParcelFileDescriptor tunIntf =
-                    ParcelFileDescriptor.adoptFd(jniCreateTunTap(isTun, interfaceName));
+            ParcelFileDescriptor tunIntf = ParcelFileDescriptor.adoptFd(
+                    nativeCreateTunTap(isTun, hasCarrier, interfaceName));
             for (LinkAddress addr : linkAddrs) {
                 mNetd.interfaceAddAddress(
                         interfaceName,
@@ -375,4 +380,20 @@
     public static void enforceTestNetworkPermissions(@NonNull Context context) {
         context.enforceCallingOrSelfPermission(PERMISSION_NAME, "TestNetworkService");
     }
+
+    /** Enable / disable TestNetworkInterface carrier */
+    @Override
+    public void setCarrierEnabled(@NonNull TestNetworkInterface iface, boolean enabled) {
+        enforceTestNetworkPermissions(mContext);
+        nativeSetTunTapCarrierEnabled(iface.getInterfaceName(), iface.getFileDescriptor().getFd(),
+                enabled);
+        // Explicitly close fd after use to prevent StrictMode from complaining.
+        // Also, explicitly referencing iface guarantees that the object is not garbage collected
+        // before nativeSetTunTapCarrierEnabled() executes.
+        try {
+            iface.getFileDescriptor().close();
+        } catch (IOException e) {
+            // if the close fails, there is not much that can be done -- move on.
+        }
+    }
 }