diff --git a/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java b/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
index 9f8d9b1..976f5df 100644
--- a/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
+++ b/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
@@ -37,6 +37,7 @@
 
 import android.app.usage.NetworkStatsManager;
 import android.net.INetd;
+import android.net.LinkProperties;
 import android.net.MacAddress;
 import android.net.NetworkStats;
 import android.net.NetworkStats.Entry;
@@ -878,6 +879,27 @@
         return true;
     }
 
+    private int getMtu(@NonNull final String ifaceName, @NonNull final LinkProperties lp) {
+        int mtu = INVALID_MTU;
+
+        if (ifaceName.equals(lp.getInterfaceName())) {
+            mtu = lp.getMtu();
+        }
+
+        // Get mtu via kernel if mtu is not found in LinkProperties.
+        if (mtu == INVALID_MTU) {
+            mtu = mDeps.getNetworkInterfaceMtu(ifaceName);
+        }
+
+        // Use default mtu if can't find any.
+        if (mtu == INVALID_MTU) mtu = NetworkStackConstants.ETHER_MTU;
+
+        // Clamp to minimum ipv4 mtu
+        if (mtu < IPV4_MIN_MTU) mtu = IPV4_MIN_MTU;
+
+        return mtu;
+    }
+
     /**
      * Call when UpstreamNetworkState may be changed.
      * If upstream has ipv4 for tethering, update this new UpstreamNetworkState
@@ -900,16 +922,7 @@
             final String ifaceName = ns.linkProperties.getInterfaceName();
             final InterfaceParams params = mDeps.getInterfaceParams(ifaceName);
             final boolean isVcn = isVcnInterface(ifaceName);
-            mtu = ns.linkProperties.getMtu();
-            if (mtu == INVALID_MTU) {
-                // Get mtu via kernel if mtu is not found in LinkProperties.
-                mtu = mDeps.getNetworkInterfaceMtu(ifaceName);
-            }
-
-            // Use default mtu if can't find any.
-            if (mtu == INVALID_MTU) mtu = NetworkStackConstants.ETHER_MTU;
-            // Clamp to minimum ipv4 mtu
-            if (mtu < IPV4_MIN_MTU) mtu = IPV4_MIN_MTU;
+            mtu = getMtu(ifaceName, ns.linkProperties);
 
             if (!isVcn && params != null && !params.hasMacAddress /* raw ip upstream only */) {
                 upstreamIndex = params.index;
diff --git a/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java b/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
index 7685981..f2cf1d0 100644
--- a/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
+++ b/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
@@ -72,6 +72,8 @@
 
 import com.android.modules.utils.build.SdkLevel;
 import com.android.net.module.util.PacketBuilder;
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.structs.Ipv6Header;
 import com.android.testutils.HandlerUtils;
 import com.android.testutils.TapPacketReader;
 import com.android.testutils.TestNetworkTracker;
@@ -1013,6 +1015,18 @@
         return new TetheringTester(mDownstreamReader, mUpstreamReader);
     }
 
+    @NonNull
+    protected Inet6Address getClatIpv6Address(TetheringTester tester, TetheredDevice tethered)
+            throws Exception {
+        // Send an IPv4 UDP packet from client and check that a CLAT translated IPv6 UDP packet can
+        // be found on upstream interface. Get CLAT IPv6 address from the CLAT translated IPv6 UDP
+        // packet.
+        byte[] expectedPacket = probeV4TetheringConnectivity(tester, tethered, true /* is4To6 */);
+
+        // Above has guaranteed that the found packet is an IPv6 packet without ether header.
+        return Struct.parse(Ipv6Header.class, ByteBuffer.wrap(expectedPacket)).srcIp;
+    }
+
     protected <T> List<T> toList(T... array) {
         return Arrays.asList(array);
     }
diff --git a/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
index fb4b9fa..12ac454 100644
--- a/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
+++ b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
@@ -62,7 +62,6 @@
 import com.android.net.module.util.structs.EthernetHeader;
 import com.android.net.module.util.structs.Icmpv4Header;
 import com.android.net.module.util.structs.Ipv4Header;
-import com.android.net.module.util.structs.Ipv6Header;
 import com.android.net.module.util.structs.UdpHeader;
 import com.android.testutils.DevSdkIgnoreRule;
 import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo;
@@ -522,18 +521,6 @@
         runUdp4Test();
     }
 
-    @NonNull
-    private Inet6Address getClatIpv6Address(TetheringTester tester, TetheredDevice tethered)
-            throws Exception {
-        // Send an IPv4 UDP packet from client and check that a CLAT translated IPv6 UDP packet can
-        // be found on upstream interface. Get CLAT IPv6 address from the CLAT translated IPv6 UDP
-        // packet.
-        byte[] expectedPacket = probeV4TetheringConnectivity(tester, tethered, true /* is4To6 */);
-
-        // Above has guaranteed that the found packet is an IPv6 packet without ether header.
-        return Struct.parse(Ipv6Header.class, ByteBuffer.wrap(expectedPacket)).srcIp;
-    }
-
     // Test network topology:
     //
     //            public network (rawip)                 private network