diff --git a/tests/unit/java/com/android/server/connectivity/VpnTest.java b/tests/unit/java/com/android/server/connectivity/VpnTest.java
index 1f965d9..0a0d3ae 100644
--- a/tests/unit/java/com/android/server/connectivity/VpnTest.java
+++ b/tests/unit/java/com/android/server/connectivity/VpnTest.java
@@ -35,15 +35,24 @@
 import static android.net.cts.util.IkeSessionTestUtils.getTestIkeSessionParams;
 import static android.net.ipsec.ike.IkeSessionConfiguration.EXTENSION_TYPE_MOBIKE;
 import static android.net.ipsec.ike.IkeSessionParams.ESP_ENCAP_TYPE_AUTO;
+import static android.net.ipsec.ike.IkeSessionParams.ESP_ENCAP_TYPE_NONE;
+import static android.net.ipsec.ike.IkeSessionParams.ESP_ENCAP_TYPE_UDP;
 import static android.net.ipsec.ike.IkeSessionParams.ESP_IP_VERSION_AUTO;
+import static android.net.ipsec.ike.IkeSessionParams.ESP_IP_VERSION_IPV4;
+import static android.net.ipsec.ike.IkeSessionParams.ESP_IP_VERSION_IPV6;
 import static android.os.Build.VERSION_CODES.S_V2;
 import static android.os.UserHandle.PER_USER_RANGE;
 import static android.telephony.CarrierConfigManager.KEY_CARRIER_CONFIG_APPLIED_BOOL;
 import static android.telephony.CarrierConfigManager.KEY_MIN_UDP_PORT_4500_NAT_TIMEOUT_SEC_INT;
+import static android.telephony.CarrierConfigManager.KEY_PREFERRED_IKE_PROTOCOL_INT;
 
 import static com.android.net.module.util.NetworkStackConstants.IPV6_MIN_MTU;
 import static com.android.server.connectivity.Vpn.AUTOMATIC_KEEPALIVE_DELAY_SECONDS;
 import static com.android.server.connectivity.Vpn.DEFAULT_UDP_PORT_4500_NAT_TIMEOUT_SEC_INT;
+import static com.android.server.connectivity.Vpn.PREFERRED_IKE_PROTOCOL_AUTO;
+import static com.android.server.connectivity.Vpn.PREFERRED_IKE_PROTOCOL_IPV4_UDP;
+import static com.android.server.connectivity.Vpn.PREFERRED_IKE_PROTOCOL_IPV6_ESP;
+import static com.android.server.connectivity.Vpn.PREFERRED_IKE_PROTOCOL_IPV6_UDP;
 import static com.android.testutils.Cleanup.testAndCleanup;
 import static com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo;
 import static com.android.testutils.MiscAsserts.assertThrows;
@@ -277,6 +286,7 @@
     private static final int IKE_NATT_KEEPALIVE_DELAY_SEC_DEFAULT = 10;
     private static final int TEST_KEEPALIVE_TIMER = 800;
     private static final int TEST_SUB_ID = 1234;
+    private static final String TEST_MCCMNC = "12345";
 
     @Mock(answer = Answers.RETURNS_DEEP_STUBS) private Context mContext;
     @Mock private UserManager mUserManager;
@@ -2050,16 +2060,18 @@
         vpnSnapShot.vpn.mVpnRunner.exitVpnRunner();
     }
 
-    private void mockCarrierConfig(int subId, int keepaliveTimer, int simStatus) {
+    private void mockCarrierConfig(int subId, int simStatus, int keepaliveTimer, int ikeProtocol) {
         final SubscriptionInfo subscriptionInfo = mock(SubscriptionInfo.class);
         doReturn(subId).when(subscriptionInfo).getSubscriptionId();
         doReturn(List.of(subscriptionInfo)).when(mSubscriptionManager)
                 .getActiveSubscriptionInfoList();
 
         doReturn(simStatus).when(mTmPerSub).getSimApplicationState();
+        doReturn(TEST_MCCMNC).when(mTmPerSub).getSimOperator(subId);
 
         final PersistableBundle persistableBundle = new PersistableBundle();
         persistableBundle.putInt(KEY_MIN_UDP_PORT_4500_NAT_TIMEOUT_SEC_INT, keepaliveTimer);
+        persistableBundle.putInt(KEY_PREFERRED_IKE_PROTOCOL_INT, ikeProtocol);
         // For CarrierConfigManager.isConfigForIdentifiedCarrier check
         persistableBundle.putBoolean(KEY_CARRIER_CONFIG_APPLIED_BOOL, true);
         doReturn(persistableBundle).when(mConfigManager).getConfigForSubId(subId);
@@ -2076,26 +2088,32 @@
 
     @Test
     public void testNattKeepaliveTimerFromCarrierConfig_noSubId() throws Exception {
-        doTestNattKeepaliveTimerFromCarrierConfig(new NetworkCapabilities(),
-                TelephonyManager.SIM_STATE_LOADED, AUTOMATIC_KEEPALIVE_DELAY_SECONDS);
+        doTestReadCarrierConfig(new NetworkCapabilities(),
+                TelephonyManager.SIM_STATE_LOADED,
+                PREFERRED_IKE_PROTOCOL_IPV4_UDP,
+                AUTOMATIC_KEEPALIVE_DELAY_SECONDS /* expectedKeepaliveTimer */,
+                ESP_IP_VERSION_AUTO /* expectedIpVersion */,
+                ESP_ENCAP_TYPE_AUTO /* expectedEncapType */);
     }
 
     @Test
     public void testNattKeepaliveTimerFromCarrierConfig_simAbsent() throws Exception {
-        doTestNattKeepaliveTimerFromCarrierConfig(new NetworkCapabilities.Builder().build(),
-                TelephonyManager.SIM_STATE_ABSENT, AUTOMATIC_KEEPALIVE_DELAY_SECONDS);
+        doTestReadCarrierConfig(new NetworkCapabilities.Builder().build(),
+                TelephonyManager.SIM_STATE_ABSENT,
+                PREFERRED_IKE_PROTOCOL_IPV4_UDP,
+                AUTOMATIC_KEEPALIVE_DELAY_SECONDS /* expectedKeepaliveTimer */,
+                ESP_IP_VERSION_AUTO /* expectedIpVersion */,
+                ESP_ENCAP_TYPE_AUTO /* expectedEncapType */);
     }
 
     @Test
     public void testNattKeepaliveTimerFromCarrierConfig() throws Exception {
-        final NetworkCapabilities nc = new NetworkCapabilities.Builder()
-                .addTransportType(TRANSPORT_CELLULAR)
-                .setNetworkSpecifier(new TelephonyNetworkSpecifier.Builder()
-                        .setSubscriptionId(TEST_SUB_ID)
-                        .build())
-                .build();
-        doTestNattKeepaliveTimerFromCarrierConfig(nc,
-                TelephonyManager.SIM_STATE_LOADED, TEST_KEEPALIVE_TIMER);
+        doTestReadCarrierConfig(createTestCellNc(),
+                TelephonyManager.SIM_STATE_LOADED,
+                PREFERRED_IKE_PROTOCOL_AUTO,
+                TEST_KEEPALIVE_TIMER /* expectedKeepaliveTimer */,
+                ESP_IP_VERSION_AUTO /* expectedIpVersion */,
+                ESP_ENCAP_TYPE_AUTO /* expectedEncapType */);
     }
 
     @Test
@@ -2104,17 +2122,62 @@
                 .addTransportType(TRANSPORT_WIFI)
                 .setTransportInfo(new WifiInfo.Builder().build())
                 .build();
-        doTestNattKeepaliveTimerFromCarrierConfig(nc,
-                TelephonyManager.SIM_STATE_LOADED, AUTOMATIC_KEEPALIVE_DELAY_SECONDS);
+        doTestReadCarrierConfig(nc,
+                TelephonyManager.SIM_STATE_LOADED,
+                PREFERRED_IKE_PROTOCOL_IPV4_UDP,
+                AUTOMATIC_KEEPALIVE_DELAY_SECONDS /* expectedKeepaliveTimer */,
+                ESP_IP_VERSION_AUTO /* expectedIpVersion */,
+                ESP_ENCAP_TYPE_AUTO /* expectedEncapType */);
     }
 
-    private void doTestNattKeepaliveTimerFromCarrierConfig(NetworkCapabilities nc, int simState,
-            int expectedKeepaliveTimer) throws Exception {
+    @Test
+    public void testPreferredIpProtocolFromCarrierConfig_v4UDP() throws Exception {
+        doTestReadCarrierConfig(createTestCellNc(),
+                TelephonyManager.SIM_STATE_LOADED,
+                PREFERRED_IKE_PROTOCOL_IPV4_UDP,
+                TEST_KEEPALIVE_TIMER /* expectedKeepaliveTimer */,
+                ESP_IP_VERSION_IPV4 /* expectedIpVersion */,
+                ESP_ENCAP_TYPE_UDP /* expectedEncapType */);
+    }
+
+    @Test
+    public void testPreferredIpProtocolFromCarrierConfig_v6ESP() throws Exception {
+        doTestReadCarrierConfig(createTestCellNc(),
+                TelephonyManager.SIM_STATE_LOADED,
+                PREFERRED_IKE_PROTOCOL_IPV6_ESP,
+                TEST_KEEPALIVE_TIMER /* expectedKeepaliveTimer */,
+                ESP_IP_VERSION_IPV6 /* expectedIpVersion */,
+                ESP_ENCAP_TYPE_NONE /* expectedEncapType */);
+    }
+
+    @Test
+    public void testPreferredIpProtocolFromCarrierConfig_v6UDP() throws Exception {
+        doTestReadCarrierConfig(createTestCellNc(),
+                TelephonyManager.SIM_STATE_LOADED,
+                PREFERRED_IKE_PROTOCOL_IPV6_UDP,
+                TEST_KEEPALIVE_TIMER /* expectedKeepaliveTimer */,
+                ESP_IP_VERSION_IPV6 /* expectedIpVersion */,
+                ESP_ENCAP_TYPE_UDP /* expectedEncapType */);
+    }
+
+    private NetworkCapabilities createTestCellNc() {
+        return new NetworkCapabilities.Builder()
+                .addTransportType(TRANSPORT_CELLULAR)
+                .setNetworkSpecifier(new TelephonyNetworkSpecifier.Builder()
+                        .setSubscriptionId(TEST_SUB_ID)
+                        .build())
+                .build();
+    }
+
+    private void doTestReadCarrierConfig(NetworkCapabilities nc, int simState, int preferredIpProto,
+            int expectedKeepaliveTimer, int expectedIpVersion, int expectedEncapType)
+            throws Exception {
         final Ikev2VpnProfile ikeProfile =
                 new Ikev2VpnProfile.Builder(TEST_VPN_SERVER, TEST_VPN_IDENTITY)
                         .setAuthPsk(TEST_VPN_PSK)
                         .setBypassable(true /* isBypassable */)
                         .setAutomaticNattKeepaliveTimerEnabled(true)
+                        .setAutomaticIpVersionSelectionEnabled(true)
                         .build();
 
         final PlatformVpnSnapshot vpnSnapShot =
@@ -2131,10 +2194,10 @@
         verify(mIkeSessionWrapper, never()).setNetwork(any(), anyInt(), anyInt(), anyInt());
 
         reset(mIkeSessionWrapper);
-        mockCarrierConfig(TEST_SUB_ID, TEST_KEEPALIVE_TIMER, simState);
+        mockCarrierConfig(TEST_SUB_ID, simState, TEST_KEEPALIVE_TIMER, preferredIpProto);
         vpnSnapShot.nwCb.onCapabilitiesChanged(TEST_NETWORK_2, nc);
         verify(mIkeSessionWrapper).setNetwork(TEST_NETWORK_2,
-                ESP_IP_VERSION_AUTO, ESP_ENCAP_TYPE_AUTO, expectedKeepaliveTimer);
+                expectedIpVersion, expectedEncapType, expectedKeepaliveTimer);
 
         reset(mExecutor);
         reset(mIkeSessionWrapper);
@@ -2143,7 +2206,7 @@
         listener.onCarrierConfigChanged(1 /* logicalSlotIndex */, TEST_SUB_ID,
                 -1 /* carrierId */, -1 /* specificCarrierId */);
         verify(mIkeSessionWrapper).setNetwork(TEST_NETWORK_2,
-                ESP_IP_VERSION_AUTO, ESP_ENCAP_TYPE_AUTO, expectedKeepaliveTimer);
+                expectedIpVersion, expectedEncapType, expectedKeepaliveTimer);
     }
 
     @Test