diff --git a/networksecurity/TEST_MAPPING b/networksecurity/TEST_MAPPING
index 448ee84..4fd5a45 100644
--- a/networksecurity/TEST_MAPPING
+++ b/networksecurity/TEST_MAPPING
@@ -1,4 +1,21 @@
 {
+  "tethering-mainline-presubmit": [
+    {
+      "name": "CtsNetSecConfigCertificateTransparencyTestCases"
+    },
+    {
+      "name": "CtsNetSecConfigCertificateTransparencyDefaultTestCases"
+    },
+    {
+      "name": "NetSecConfigCertificateTransparencySctLogListTestCases"
+    },
+    {
+      "name": "NetSecConfigCertificateTransparencySctNoLogListTestCases"
+    },
+    {
+      "name": "NetworkSecurityUnitTests"
+    }
+  ],
   "presubmit": [
     {
       "name": "CtsNetSecConfigCertificateTransparencyTestCases"
diff --git a/service/libconnectivity/include/connectivity_native.h b/service/libconnectivity/include/connectivity_native.h
index f4676a9..f264b68 100644
--- a/service/libconnectivity/include/connectivity_native.h
+++ b/service/libconnectivity/include/connectivity_native.h
@@ -20,12 +20,6 @@
 #include <sys/cdefs.h>
 #include <netinet/in.h>
 
-// For branches that do not yet have __ANDROID_API_U__ defined, like module
-// release branches.
-#ifndef __ANDROID_API_U__
-#define __ANDROID_API_U__ 34
-#endif
-
 __BEGIN_DECLS
 
 /**
@@ -41,7 +35,7 @@
  *
  * @param port Int corresponding to port number.
  */
-int AConnectivityNative_blockPortForBind(in_port_t port) __INTRODUCED_IN(__ANDROID_API_U__);
+int AConnectivityNative_blockPortForBind(in_port_t port) __INTRODUCED_IN(34);
 
 /**
  * Unblocks a port that has previously been blocked.
@@ -54,7 +48,7 @@
  *
  * @param port Int corresponding to port number.
  */
-int AConnectivityNative_unblockPortForBind(in_port_t port) __INTRODUCED_IN(__ANDROID_API_U__);
+int AConnectivityNative_unblockPortForBind(in_port_t port) __INTRODUCED_IN(34);
 
 /**
  * Unblocks all ports that have previously been blocked.
@@ -64,7 +58,7 @@
  *  - EPERM if the UID of the client doesn't have network stack permission
  *  - Other errors as per https://man7.org/linux/man-pages/man2/bpf.2.html
  */
-int AConnectivityNative_unblockAllPortsForBind() __INTRODUCED_IN(__ANDROID_API_U__);
+int AConnectivityNative_unblockAllPortsForBind() __INTRODUCED_IN(34);
 
 /**
  * Gets the list of ports that have been blocked.
@@ -79,7 +73,7 @@
  *              blocked ports, which may be larger than the ports array that was filled.
  */
 int AConnectivityNative_getPortsBlockedForBind(in_port_t* _Nonnull ports, size_t* _Nonnull count)
-    __INTRODUCED_IN(__ANDROID_API_U__);
+    __INTRODUCED_IN(34);
 
 __END_DECLS
 
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 5b415c8..abe4056 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -1023,6 +1023,8 @@
     private final LingerMonitor mLingerMonitor;
     private final SatelliteAccessController mSatelliteAccessController;
 
+    private final L2capNetworkProvider mL2capNetworkProvider;
+
     // sequence number of NetworkRequests
     private int mNextNetworkRequestId = NetworkRequest.FIRST_REQUEST_ID;
 
@@ -1623,6 +1625,11 @@
                     connectivityServiceInternalHandler);
         }
 
+        /** Creates an L2capNetworkProvider */
+        public L2capNetworkProvider makeL2capNetworkProvider(Context context) {
+            return new L2capNetworkProvider(context);
+        }
+
         /** Returns the data inactivity timeout to be used for cellular networks */
         public int getDefaultCellularDataInactivityTimeout() {
             return DeviceConfigUtils.getDeviceConfigPropertyInt(NAMESPACE_TETHERING_BOOT,
@@ -2094,6 +2101,8 @@
         }
         mIngressToVpnAddressFiltering = mDeps.isAtLeastT()
                 && mDeps.isFeatureNotChickenedOut(mContext, INGRESS_TO_VPN_ADDRESS_FILTERING);
+
+        mL2capNetworkProvider = mDeps.makeL2capNetworkProvider(mContext);
     }
 
     /**
@@ -4129,6 +4138,10 @@
             mCarrierPrivilegeAuthenticator.start();
         }
 
+        if (mL2capNetworkProvider != null) {
+            mL2capNetworkProvider.start();
+        }
+
         // On T+ devices, register callback for statsd to pull NETWORK_BPF_MAP_INFO atom
         if (mDeps.isAtLeastT()) {
             mBpfNetMaps.setPullAtomCallback(mContext);
diff --git a/service/src/com/android/server/L2capNetworkProvider.java b/service/src/com/android/server/L2capNetworkProvider.java
index d0b0603..441f084 100644
--- a/service/src/com/android/server/L2capNetworkProvider.java
+++ b/service/src/com/android/server/L2capNetworkProvider.java
@@ -95,8 +95,9 @@
     private final BlanketReservationOffer mBlanketOffer;
     private final Set<ReservedServerOffer> mReservedServerOffers = new ArraySet<>();
     private final ClientOffer mClientOffer;
-    private final BluetoothManager mBluetoothManager;
-    private final boolean mIsSupported;
+    // mBluetoothManager guaranteed non-null when read on handler thread after start() is called
+    @Nullable
+    private BluetoothManager mBluetoothManager;
 
     // Note: IFNAMSIZ is 16.
     private static final String TUN_IFNAME = "l2cap-tun";
@@ -110,12 +111,7 @@
      * requests that do not have a NetworkSpecifier set.
      */
     private class BlanketReservationOffer implements NetworkOfferCallback {
-        // Set as transport primary to ensure that the BlanketReservationOffer always outscores the
-        // ReservedServerOffer, because as soon as the BlanketReservationOffer receives an
-        // onNetworkUnneeded() callback, it will tear down the associated reserved offer.
-        public static final NetworkScore SCORE = new NetworkScore.Builder()
-                .setTransportPrimary(true)
-                .build();
+        public static final NetworkScore SCORE = new NetworkScore.Builder().build();
         // Note the missing NET_CAPABILITY_NOT_RESTRICTED marking the network as restricted.
         public static final NetworkCapabilities CAPABILITIES;
         static {
@@ -654,11 +650,6 @@
 
     @VisibleForTesting
     public static class Dependencies {
-        /** Get NetworkProvider */
-        public NetworkProvider getNetworkProvider(Context context, Looper looper) {
-            return new NetworkProvider(context, looper, TAG);
-        }
-
         /** Get the HandlerThread for L2capNetworkProvider to run on */
         public HandlerThread getHandlerThread() {
             final HandlerThread thread = new HandlerThread("L2capNetworkProviderThread");
@@ -677,11 +668,9 @@
         mContext = context;
         mHandlerThread = mDeps.getHandlerThread();
         mHandler = new Handler(mHandlerThread.getLooper());
-        mProvider = mDeps.getNetworkProvider(context, mHandlerThread.getLooper());
+        mProvider = new NetworkProvider(context, mHandlerThread.getLooper(), TAG);
         mBlanketOffer = new BlanketReservationOffer();
         mClientOffer = new ClientOffer();
-        mBluetoothManager = context.getSystemService(BluetoothManager.class);
-        mIsSupported = mContext.getPackageManager().hasSystemFeature(FEATURE_BLUETOOTH_LE);
     }
 
     /**
@@ -690,19 +679,17 @@
      * Called on CS Handler thread.
      */
     public void start() {
-        if (!mIsSupported) {
-            // In order to make mHandler final, the HandlerThread needs to be started before
-            // HandlerThread.getLooper() is called during the construction of the Handler.
-            mHandlerThread.quitSafely();
-            try {
-                mHandlerThread.join();
-            } catch (InterruptedException e) {
-                // join() interrupted. Do nothing.
-            }
-            return;
-        }
-
         mHandler.post(() -> {
+            final PackageManager pm = mContext.getPackageManager();
+            if (!pm.hasSystemFeature(FEATURE_BLUETOOTH_LE)) {
+                return;
+            }
+            mBluetoothManager = mContext.getSystemService(BluetoothManager.class);
+            if (mBluetoothManager == null) {
+                // Can this ever happen?
+                Log.wtf(TAG, "BluetoothManager not found");
+                return;
+            }
             mContext.getSystemService(ConnectivityManager.class).registerNetworkProvider(mProvider);
             mProvider.registerNetworkOffer(BlanketReservationOffer.SCORE,
                     BlanketReservationOffer.CAPABILITIES, mHandler::post, mBlanketOffer);
diff --git a/service/src/com/android/server/net/HeaderCompressionUtils.java b/service/src/com/android/server/net/HeaderCompressionUtils.java
new file mode 100644
index 0000000..5bd3a76
--- /dev/null
+++ b/service/src/com/android/server/net/HeaderCompressionUtils.java
@@ -0,0 +1,275 @@
+/*
+ * Copyright (C) 2025 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;
+
+import android.util.Log;
+
+import java.io.IOException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+
+public class HeaderCompressionUtils {
+    private static final String TAG = "L2capHeaderCompressionUtils";
+    private static final int IPV6_HEADER_SIZE = 40;
+
+    private static byte[] decodeIpv6Address(ByteBuffer buffer, int mode, boolean isMulticast)
+            throws BufferUnderflowException, IOException {
+        // Mode is equivalent between SAM and DAM; however, isMulticast only applies to DAM.
+        final byte[] address = new byte[16];
+        // If multicast bit is set, mix it in the mode, so that the lower two bits represent the
+        // address mode, and the upper bit represents multicast compression.
+        switch ((isMulticast ? 0b100 : 0) | mode) {
+            case 0b000: // 128 bits. The full address is carried in-line.
+            case 0b100:
+                buffer.get(address);
+                break;
+            case 0b001: // 64 bits. The first 64-bits of the fe80:: address are elided.
+                address[0] = (byte) 0xfe;
+                address[1] = (byte) 0x80;
+                buffer.get(address, 8 /*off*/, 8 /*len*/);
+                break;
+            case 0b010: // 16 bits. fe80::ff:fe00:XXXX, where XXXX are the bits carried in-line
+                address[0] = (byte) 0xfe;
+                address[1] = (byte) 0x80;
+                address[11] = (byte) 0xff;
+                address[12] = (byte) 0xfe;
+                buffer.get(address, 14 /*off*/, 2 /*len*/);
+                break;
+            case 0b011: // 0 bits. The address is fully elided and derived from BLE MAC address
+                // Note that on Android, the BLE MAC addresses are not exposed via the API;
+                // therefore, this compression mode cannot be supported.
+                throw new IOException("Address cannot be fully elided");
+            case 0b101: // 48 bits. The address takes the form ffXX::00XX:XXXX:XXXX.
+                address[0] = (byte) 0xff;
+                address[1] = buffer.get();
+                buffer.get(address, 11 /*off*/, 5 /*len*/);
+                break;
+            case 0b110: // 32 bits. The address takes the form ffXX::00XX:XXXX
+                address[0] = (byte) 0xff;
+                address[1] = buffer.get();
+                buffer.get(address, 13 /*off*/, 3 /*len*/);
+                break;
+            case 0b111: // 8 bits. The address takes the form ff02::00XX.
+                address[0] = (byte) 0xff;
+                address[1] = (byte) 0x02;
+                address[15] = buffer.get();
+                break;
+        }
+        return address;
+    }
+
+    /**
+     * Performs 6lowpan header decompression in place.
+     *
+     * Note that the passed in buffer must have enough capacity for successful decompression.
+     *
+     * @param bytes The buffer containing the packet.
+     * @param len The size of the packet
+     * @return decompressed size or zero
+     * @throws BufferUnderflowException if an illegal packet is encountered.
+     * @throws IOException if an unsupported option is encountered.
+     */
+    public static int decompress6lowpan(byte[] bytes, int len)
+            throws BufferUnderflowException, IOException {
+        // Note that ByteBuffer's default byte order is big endian.
+        final ByteBuffer inBuffer = ByteBuffer.wrap(bytes);
+        inBuffer.limit(len);
+
+        // LOWPAN_IPHC base encoding:
+        //   0   1   2   3   4   5   6   7 | 8   9  10  11  12  13  14  15
+        // +---+---+---+---+---+---+---+---|---+---+---+---+---+---+---+---+
+        // | 0 | 1 | 1 |  TF   |NH | HLIM  |CID|SAC|  SAM  | M |DAC|  DAM  |
+        // +---+---+---+---+---+---+---+---|---+---+---+---+---+---+---+---+
+        final int iphc1 = inBuffer.get() & 0xff;
+        final int iphc2 = inBuffer.get() & 0xff;
+        // Dispatch must start with 0b011.
+        if ((iphc1 & 0xe0) != 0x60) {
+            throw new IOException("LOWPAN_IPHC does not start with 011");
+        }
+
+        final int tf = (iphc1 >> 3) & 3;         // Traffic class
+        final boolean nh = (iphc1 & 4) != 0;     // Next header
+        final int hlim = iphc1 & 3;              // Hop limit
+        final boolean cid = (iphc2 & 0x80) != 0; // Context identifier extension
+        final boolean sac = (iphc2 & 0x40) != 0; // Source address compression
+        final int sam = (iphc2 >> 4) & 3;        // Source address mode
+        final boolean m = (iphc2 & 8) != 0;      // Multicast compression
+        final boolean dac = (iphc2 & 4) != 0;    // Destination address compression
+        final int dam = iphc2 & 3;               // Destination address mode
+
+        final ByteBuffer ipv6Header = ByteBuffer.allocate(IPV6_HEADER_SIZE);
+
+        final int trafficClass;
+        final int flowLabel;
+        switch (tf) {
+            case 0b00: // ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
+                trafficClass = inBuffer.get() & 0xff;
+                flowLabel = (inBuffer.get() & 0x0f) << 16
+                        | (inBuffer.get() & 0xff) << 8
+                        | (inBuffer.get() & 0xff);
+                break;
+            case 0b01: // ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided.
+                final int firstByte = inBuffer.get() & 0xff;
+                //     0     1     2     3     4     5     6     7
+                // +-----+-----+-----+-----+-----+-----+-----+-----+
+                // |          DS FIELD, DSCP           | ECN FIELD |
+                // +-----+-----+-----+-----+-----+-----+-----+-----+
+                // rfc6282 does not explicitly state what value to use for DSCP, assuming 0.
+                trafficClass = firstByte >> 6;
+                flowLabel = (firstByte & 0x0f) << 16
+                        | (inBuffer.get() & 0xff) << 8
+                        | (inBuffer.get() & 0xff);
+                break;
+            case 0b10: // ECN + DSCP (1 byte), Flow Label is elided.
+                trafficClass = inBuffer.get() & 0xff;
+                // rfc6282 does not explicitly state what value to use, assuming 0.
+                flowLabel = 0;
+                break;
+            case 0b11: // Traffic Class and Flow Label are elided.
+                // rfc6282 does not explicitly state what value to use, assuming 0.
+                trafficClass = 0;
+                flowLabel = 0;
+                break;
+            default:
+                // This cannot happen. Crash if it does.
+                throw new IllegalStateException("Illegal TF value");
+        }
+
+        // Write version, traffic class, and flow label
+        final int versionTcFlowLabel = (6 << 28) | (trafficClass << 20) | flowLabel;
+        ipv6Header.putInt(versionTcFlowLabel);
+
+        // Payload length is still unknown. Use 0 for now.
+        ipv6Header.putShort((short) 0);
+
+        // We do not use UDP or extension header compression, therefore the next header
+        // cannot be compressed.
+        if (nh) throw new IOException("Next header cannot be compressed");
+        // Write next header
+        ipv6Header.put(inBuffer.get());
+
+        final byte hopLimit;
+        switch (hlim) {
+            case 0b00: // The Hop Limit field is carried in-line.
+                hopLimit = inBuffer.get();
+                break;
+            case 0b01: // The Hop Limit field is compressed and the hop limit is 1.
+                hopLimit = 1;
+                break;
+            case 0b10: // The Hop Limit field is compressed and the hop limit is 64.
+                hopLimit = 64;
+                break;
+            case 0b11: // The Hop Limit field is compressed and the hop limit is 255.
+                hopLimit = (byte) 255;
+                break;
+            default:
+                // This cannot happen. Crash if it does.
+                throw new IllegalStateException("Illegal HLIM value");
+        }
+        ipv6Header.put(hopLimit);
+
+        if (cid) throw new IOException("Context based compression not supported");
+        if (sac) throw new IOException("Context based compression not supported");
+        if (dac) throw new IOException("Context based compression not supported");
+
+        // Write source address
+        ipv6Header.put(decodeIpv6Address(inBuffer, sam, false /* isMulticast */));
+
+        // Write destination address
+        ipv6Header.put(decodeIpv6Address(inBuffer, dam, m));
+
+        // Go back and fix up payloadLength
+        final short payloadLength = (short) inBuffer.remaining();
+        ipv6Header.putShort(4, payloadLength);
+
+        // Done! Check that 40 bytes were written.
+        if (ipv6Header.position() != IPV6_HEADER_SIZE) {
+            // This indicates a bug in our code -> crash.
+            throw new IllegalStateException("Faulty decompression wrote less than 40 bytes");
+        }
+
+        // Ensure there is enough room in the buffer
+        final int packetLength = payloadLength + IPV6_HEADER_SIZE;
+        if (bytes.length < packetLength) {
+            throw new IOException("Decompressed packet exceeds buffer size");
+        }
+
+        // Move payload bytes back to make room for the header
+        inBuffer.limit(packetLength);
+        System.arraycopy(bytes, inBuffer.position(), bytes, IPV6_HEADER_SIZE, payloadLength);
+        // Copy IPv6 header to the beginning of the buffer.
+        inBuffer.position(0);
+        ipv6Header.flip();
+        inBuffer.put(ipv6Header);
+
+        return packetLength;
+    }
+
+    /**
+     * Performs 6lowpan header compression in place.
+     *
+     * @param bytes The buffer containing the packet.
+     * @param len The size of the packet
+     * @return compressed size or zero
+     * @throws BufferUnderflowException if an illegal packet is encountered.
+     * @throws IOException if an unsupported option is encountered.
+     */
+    public static int compress6lowpan(byte[] bytes, final int len)
+            throws BufferUnderflowException, IOException {
+        // Compression only happens on egress, i.e. the packet is read from the tun fd.
+        // This means that this code can be a bit more lenient.
+        if (len < 40) {
+            Log.wtf(TAG, "Encountered short (<40 byte) packet");
+            return 0;
+        }
+
+        // Note that ByteBuffer's default byte order is big endian.
+        final ByteBuffer inBuffer = ByteBuffer.wrap(bytes);
+        inBuffer.limit(len);
+
+        // Check that the packet is an IPv6 packet
+        final int versionTcFlowLabel = inBuffer.getInt() & 0xffffffff;
+        if ((versionTcFlowLabel >> 28) != 6) {
+            return 0;
+        }
+
+        // Check that the payload length matches the packet length - 40.
+        int payloadLength = inBuffer.getShort();
+        if (payloadLength != len - IPV6_HEADER_SIZE) {
+            throw new IOException("Encountered packet with payload length mismatch");
+        }
+
+        // Implements rfc 6282 6lowpan header compression using iphc 0110 0000 0000 0000 (all
+        // fields are carried inline).
+        inBuffer.position(0);
+        inBuffer.put((byte) 0x60);
+        inBuffer.put((byte) 0x00);
+        final byte trafficClass = (byte) ((versionTcFlowLabel >> 20) & 0xff);
+        inBuffer.put(trafficClass);
+        final byte flowLabelMsb = (byte) ((versionTcFlowLabel >> 16) & 0x0f);
+        final short flowLabelLsb = (short) (versionTcFlowLabel & 0xffff);
+        inBuffer.put(flowLabelMsb);
+        // Note: the next putShort overrides the payload length. This is WAI as the payload length
+        // is reconstructed via L2CAP packet length.
+        inBuffer.putShort(flowLabelLsb);
+
+        // Since the iphc (2 bytes) matches the payload length that was elided (2 bytes), the length
+        // of the packet did not change.
+        return len;
+    }
+}
diff --git a/service/src/com/android/server/net/L2capNetwork.java b/service/src/com/android/server/net/L2capNetwork.java
index b9d5f13..594d273 100644
--- a/service/src/com/android/server/net/L2capNetwork.java
+++ b/service/src/com/android/server/net/L2capNetwork.java
@@ -16,9 +16,12 @@
 
 package com.android.server.net;
 
+import static android.net.L2capNetworkSpecifier.HEADER_COMPRESSION_6LOWPAN;
+
 import android.annotation.Nullable;
 import android.bluetooth.BluetoothSocket;
 import android.content.Context;
+import android.net.L2capNetworkSpecifier;
 import android.net.LinkProperties;
 import android.net.NetworkAgent;
 import android.net.NetworkAgentConfig;
@@ -106,7 +109,12 @@
         mLogTag = String.format("L2capNetwork[%s]", ifname);
         mHandler = handler;
         mIfname = ifname;
-        mForwarder = new L2capPacketForwarder(handler, tunFd, socket, () -> {
+
+        // Guaranteed non-null.
+        final L2capNetworkSpecifier spec =
+                (L2capNetworkSpecifier) networkCapabilities.getNetworkSpecifier();
+        final boolean compressHeaders = spec.getHeaderCompression() == HEADER_COMPRESSION_6LOWPAN;
+        mForwarder = new L2capPacketForwarder(handler, tunFd, socket, compressHeaders, () -> {
             // TODO: add a check that this callback is invoked on the handler thread.
             cb.onError(L2capNetwork.this);
         });
diff --git a/service/src/com/android/server/net/L2capPacketForwarder.java b/service/src/com/android/server/net/L2capPacketForwarder.java
index cef351c..00faecf 100644
--- a/service/src/com/android/server/net/L2capPacketForwarder.java
+++ b/service/src/com/android/server/net/L2capPacketForwarder.java
@@ -16,6 +16,9 @@
 
 package com.android.server.net;
 
+import static com.android.server.net.HeaderCompressionUtils.compress6lowpan;
+import static com.android.server.net.HeaderCompressionUtils.decompress6lowpan;
+
 import android.bluetooth.BluetoothSocket;
 import android.os.Handler;
 import android.os.ParcelFileDescriptor;
@@ -29,6 +32,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.nio.BufferUnderflowException;
 
 /**
  * Forwards packets from a BluetoothSocket of type L2CAP to a tun fd and vice versa.
@@ -222,13 +226,18 @@
         private volatile boolean mIsRunning = true;
 
         private final String mLogTag;
-        private IReadWriteFd mReadFd;
-        private IReadWriteFd mWriteFd;
+        private final IReadWriteFd mReadFd;
+        private final IReadWriteFd mWriteFd;
+        private final boolean mIsIngress;
+        private final boolean mCompressHeaders;
 
-        L2capThread(String logTag, IReadWriteFd readFd, IReadWriteFd writeFd) {
-            mLogTag = logTag;
+        L2capThread(IReadWriteFd readFd, IReadWriteFd writeFd, boolean isIngress,
+                boolean compressHeaders) {
+            mLogTag = isIngress ? "L2capForwarderThread-Ingress" : "L2capForwarderThread-Egress";
             mReadFd = readFd;
             mWriteFd = writeFd;
+            mIsIngress = isIngress;
+            mCompressHeaders = compressHeaders;
         }
 
         private void postOnError() {
@@ -242,20 +251,28 @@
         public void run() {
             while (mIsRunning) {
                 try {
-                    final int readBytes = mReadFd.read(mBuffer, 0 /*off*/, mBuffer.length);
+                    int readBytes = mReadFd.read(mBuffer, 0 /*off*/, mBuffer.length);
                     // No bytes to write, continue.
                     if (readBytes <= 0) {
                         Log.w(mLogTag, "Zero-byte read encountered: " + readBytes);
                         continue;
                     }
 
-                    // If the packet exceeds MTU, drop it.
+                    if (mCompressHeaders) {
+                        if (mIsIngress) {
+                            readBytes = decompress6lowpan(mBuffer, readBytes);
+                        } else {
+                            readBytes = compress6lowpan(mBuffer, readBytes);
+                        }
+                    }
+
+                    // If the packet is 0-length post de/compression or exceeds MTU, drop it.
                     // Note that a large read on BluetoothSocket throws an IOException to tear down
                     // the network.
-                    if (readBytes > MTU) continue;
+                    if (readBytes <= 0 || readBytes > MTU) continue;
 
                     mWriteFd.write(mBuffer, 0 /*off*/, readBytes);
-                } catch (IOException e) {
+                } catch (IOException|BufferUnderflowException e) {
                     Log.e(mLogTag, "L2capThread exception", e);
                     // Tear down the network on any error.
                     mIsRunning = false;
@@ -273,19 +290,20 @@
     }
 
     public L2capPacketForwarder(Handler handler, ParcelFileDescriptor tunFd, BluetoothSocket socket,
-            ICallback cb) {
-        this(handler, new FdWrapper(tunFd), new BluetoothSocketWrapper(socket), cb);
+            boolean compressHdrs, ICallback cb) {
+        this(handler, new FdWrapper(tunFd), new BluetoothSocketWrapper(socket), compressHdrs, cb);
     }
 
     @VisibleForTesting
-    L2capPacketForwarder(Handler handler, IReadWriteFd tunFd, IReadWriteFd l2capFd, ICallback cb) {
+    L2capPacketForwarder(Handler handler, IReadWriteFd tunFd, IReadWriteFd l2capFd,
+            boolean compressHeaders, ICallback cb) {
         mHandler = handler;
         mTunFd = tunFd;
         mL2capFd = l2capFd;
         mCallback = cb;
 
-        mIngressThread = new L2capThread("L2capThread-Ingress", l2capFd, tunFd);
-        mEgressThread = new L2capThread("L2capThread-Egress", tunFd, l2capFd);
+        mIngressThread = new L2capThread(l2capFd, tunFd, true /*isIngress*/, compressHeaders);
+        mEgressThread = new L2capThread(tunFd, l2capFd, false /*isIngress*/, compressHeaders);
 
         mIngressThread.start();
         mEgressThread.start();
diff --git a/tests/cts/net/src/android/net/cts/ApfIntegrationTest.kt b/tests/cts/net/src/android/net/cts/ApfIntegrationTest.kt
index ee2e7db..8e790ca 100644
--- a/tests/cts/net/src/android/net/cts/ApfIntegrationTest.kt
+++ b/tests/cts/net/src/android/net/cts/ApfIntegrationTest.kt
@@ -489,15 +489,15 @@
 
     fun ApfV4GeneratorBase<*>.addPassIfNotIcmpv6EchoReply() {
         // If not IPv6 -> PASS
-        addLoad16(R0, ETH_ETHERTYPE_OFFSET)
+        addLoad16intoR0(ETH_ETHERTYPE_OFFSET)
         addJumpIfR0NotEquals(ETH_P_IPV6.toLong(), BaseApfGenerator.PASS_LABEL)
 
         // If not ICMPv6 -> PASS
-        addLoad8(R0, IPV6_NEXT_HEADER_OFFSET)
+        addLoad8intoR0(IPV6_NEXT_HEADER_OFFSET)
         addJumpIfR0NotEquals(IPPROTO_ICMPV6.toLong(), BaseApfGenerator.PASS_LABEL)
 
         // If not echo reply -> PASS
-        addLoad8(R0, ICMP6_TYPE_OFFSET)
+        addLoad8intoR0(ICMP6_TYPE_OFFSET)
         addJumpIfR0NotEquals(0x81, BaseApfGenerator.PASS_LABEL)
     }
 
@@ -744,11 +744,11 @@
         //     transmit 3 ICMPv6 echo requests with random first byte
         //     increase DROPPED_IPV6_NS_REPLIED_NON_DAD counter
         //     drop
-        gen.addLoad16(R0, ETH_ETHERTYPE_OFFSET)
+        gen.addLoad16intoR0(ETH_ETHERTYPE_OFFSET)
                 .addJumpIfR0NotEquals(ETH_P_IPV6.toLong(), skipPacketLabel)
-                .addLoad8(R0, IPV6_NEXT_HEADER_OFFSET)
+                .addLoad8intoR0(IPV6_NEXT_HEADER_OFFSET)
                 .addJumpIfR0NotEquals(IPPROTO_ICMPV6.toLong(), skipPacketLabel)
-                .addLoad8(R0, ICMP6_TYPE_OFFSET)
+                .addLoad8intoR0(ICMP6_TYPE_OFFSET)
                 .addJumpIfR0NotEquals(ICMP6_ECHO_REPLY.toLong(), skipPacketLabel)
                 .addLoadFromMemory(R0, MemorySlot.PACKET_SIZE)
                 .addCountAndPassIfR0Equals(
diff --git a/tests/cts/net/src/android/net/cts/NetworkReservationTest.kt b/tests/cts/net/src/android/net/cts/NetworkReservationTest.kt
index f05bf15..a9af34f 100644
--- a/tests/cts/net/src/android/net/cts/NetworkReservationTest.kt
+++ b/tests/cts/net/src/android/net/cts/NetworkReservationTest.kt
@@ -16,15 +16,21 @@
 
 package android.net.cts
 
+import android.Manifest.permission.CONNECTIVITY_USE_RESTRICTED_NETWORKS
 import android.Manifest.permission.MANAGE_TEST_NETWORKS
 import android.Manifest.permission.NETWORK_SETTINGS
 import android.net.ConnectivityManager
+import android.net.L2capNetworkSpecifier
+import android.net.L2capNetworkSpecifier.HEADER_COMPRESSION_6LOWPAN
+import android.net.L2capNetworkSpecifier.ROLE_SERVER
 import android.net.NetworkCapabilities
 import android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET
 import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_CONGESTED
+import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED
 import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VCN_MANAGED
 import android.net.NetworkCapabilities.NET_CAPABILITY_TRUSTED
 import android.net.NetworkCapabilities.RES_ID_MATCH_ALL_RESERVATIONS
+import android.net.NetworkCapabilities.TRANSPORT_BLUETOOTH
 import android.net.NetworkCapabilities.TRANSPORT_ETHERNET
 import android.net.NetworkCapabilities.TRANSPORT_TEST
 import android.net.NetworkProvider
@@ -43,7 +49,10 @@
 import com.android.testutils.TestableNetworkCallback
 import com.android.testutils.TestableNetworkOfferCallback
 import com.android.testutils.runAsShell
+import kotlin.test.assertContains
 import kotlin.test.assertEquals
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
 import org.junit.After
 import org.junit.Before
 import org.junit.Test
@@ -83,6 +92,8 @@
     private val handler = Handler(handlerThread.looper)
     private val provider = NetworkProvider(context, handlerThread.looper, TAG)
 
+    private val registeredCallbacks = ArrayList<TestableNetworkCallback>()
+
     @Before
     fun setUp() {
         runAsShell(NETWORK_SETTINGS) {
@@ -92,6 +103,7 @@
 
     @After
     fun tearDown() {
+        registeredCallbacks.forEach { cm.unregisterNetworkCallback(it) }
         runAsShell(NETWORK_SETTINGS) {
             // unregisterNetworkProvider unregisters all associated NetworkOffers.
             cm.unregisterNetworkProvider(provider)
@@ -104,6 +116,13 @@
         it.reservationId = resId
     }
 
+    fun reserveNetwork(nr: NetworkRequest): TestableNetworkCallback {
+        return TestableNetworkCallback().also {
+            cm.reserveNetwork(nr, handler, it)
+            registeredCallbacks.add(it)
+        }
+    }
+
     @Test
     fun testReserveNetwork() {
         // register blanket offer
@@ -112,8 +131,7 @@
             provider.registerNetworkOffer(NETWORK_SCORE, BLANKET_CAPS, handler::post, blanketOffer)
         }
 
-        val cb = TestableNetworkCallback()
-        cm.reserveNetwork(ETHERNET_REQUEST, handler, cb)
+        val cb = reserveNetwork(ETHERNET_REQUEST)
 
         // validate the reservation matches the blanket offer.
         val reservationReq = blanketOffer.expectOnNetworkNeeded(BLANKET_CAPS).request
@@ -137,4 +155,28 @@
         provider.unregisterNetworkOffer(reservedOffer)
         cb.expect<Unavailable>()
     }
+
+    @Test
+    fun testReserveL2capNetwork() {
+        val l2capReservationSpecifier = L2capNetworkSpecifier.Builder()
+                .setRole(ROLE_SERVER)
+                .setHeaderCompression(HEADER_COMPRESSION_6LOWPAN)
+                .build()
+        val l2capRequest = NetworkRequest.Builder()
+                .addTransportType(TRANSPORT_BLUETOOTH)
+                .removeCapability(NET_CAPABILITY_TRUSTED)
+                .removeCapability(NET_CAPABILITY_NOT_RESTRICTED)
+                .setNetworkSpecifier(l2capReservationSpecifier)
+                .build()
+        val cb = runAsShell(CONNECTIVITY_USE_RESTRICTED_NETWORKS) {
+            reserveNetwork(l2capRequest)
+        }
+
+        val caps = cb.expect<Reserved>().caps
+        val reservedSpec = caps.networkSpecifier
+        assertTrue(reservedSpec is L2capNetworkSpecifier)
+        assertContains(0x80..0xFF, reservedSpec.psm, "PSM is outside of dynamic range")
+        assertEquals(HEADER_COMPRESSION_6LOWPAN, reservedSpec.headerCompression)
+        assertNull(reservedSpec.remoteAddress)
+    }
 }
diff --git a/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt b/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
index 375d604..cc9445d 100644
--- a/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
+++ b/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
@@ -55,6 +55,7 @@
 import com.android.networkstack.apishim.TelephonyManagerShimImpl
 import com.android.server.BpfNetMaps
 import com.android.server.ConnectivityService
+import com.android.server.L2capNetworkProvider
 import com.android.server.NetworkAgentWrapper
 import com.android.server.TestNetIdManager
 import com.android.server.connectivity.CarrierPrivilegeAuthenticator
@@ -272,6 +273,8 @@
             connectivityServiceInternalHandler: Handler
         ): SatelliteAccessController? = mock(
             SatelliteAccessController::class.java)
+
+        override fun makeL2capNetworkProvider(context: Context) = null
     }
 
     @After
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index f7d7c87..1562dad 100755
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -412,6 +412,7 @@
 import com.android.server.ConnectivityService.NetworkRequestInfo;
 import com.android.server.ConnectivityServiceTest.ConnectivityServiceDependencies.DestroySocketsWrapper;
 import com.android.server.ConnectivityServiceTest.ConnectivityServiceDependencies.ReportedInterfaces;
+import com.android.server.L2capNetworkProvider;
 import com.android.server.connectivity.ApplicationSelfCertifiedNetworkCapabilities;
 import com.android.server.connectivity.AutomaticOnOffKeepaliveTracker;
 import com.android.server.connectivity.CarrierPrivilegeAuthenticator;
@@ -2381,6 +2382,11 @@
             // Needed to mock out the dependency on DeviceConfig
             return 15;
         }
+
+        @Override
+        public L2capNetworkProvider makeL2capNetworkProvider(Context context) {
+            return null;
+        }
     }
 
     private class AutomaticOnOffKeepaliveTrackerDependencies
diff --git a/tests/unit/java/com/android/server/connectivityservice/CSL2capProviderTest.kt b/tests/unit/java/com/android/server/connectivityservice/CSL2capProviderTest.kt
new file mode 100644
index 0000000..d44bd0a
--- /dev/null
+++ b/tests/unit/java/com/android/server/connectivityservice/CSL2capProviderTest.kt
@@ -0,0 +1,191 @@
+/*
+ * 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
+
+import android.bluetooth.BluetoothAdapter
+import android.bluetooth.BluetoothManager
+import android.bluetooth.BluetoothServerSocket
+import android.bluetooth.BluetoothSocket
+import android.content.Context
+import android.net.L2capNetworkSpecifier
+import android.net.L2capNetworkSpecifier.HEADER_COMPRESSION_6LOWPAN
+import android.net.L2capNetworkSpecifier.HEADER_COMPRESSION_NONE
+import android.net.L2capNetworkSpecifier.ROLE_SERVER
+import android.net.NetworkCapabilities
+import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED
+import android.net.NetworkCapabilities.NET_CAPABILITY_TRUSTED
+import android.net.NetworkCapabilities.TRANSPORT_BLUETOOTH
+import android.net.NetworkProvider
+import android.net.NetworkProvider.NetworkOfferCallback
+import android.net.NetworkRequest
+import android.net.NetworkScore
+import android.net.NetworkSpecifier
+import android.os.Build
+import android.os.HandlerThread
+import android.os.Looper
+import com.android.server.L2capNetworkProvider
+import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
+import com.android.testutils.DevSdkIgnoreRunner
+import com.android.testutils.RecorderCallback.CallbackEntry.Reserved
+import com.android.testutils.TestableNetworkCallback
+import java.io.IOException
+import java.util.concurrent.Executor
+import java.util.concurrent.LinkedBlockingQueue
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.Mockito.doAnswer
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.mock
+import org.mockito.MockitoAnnotations
+
+private const val PSM = 0x85
+private val REMOTE_MAC = byteArrayOf(1, 2, 3, 4, 5, 6)
+private val REQUEST = NetworkRequest.Builder()
+        .addTransportType(TRANSPORT_BLUETOOTH)
+        .removeCapability(NET_CAPABILITY_TRUSTED)
+        .removeCapability(NET_CAPABILITY_NOT_RESTRICTED)
+        .build()
+
+@RunWith(DevSdkIgnoreRunner::class)
+@IgnoreUpTo(Build.VERSION_CODES.R)
+class CSL2capProviderTest : CSTest() {
+    private val btAdapter = mock<BluetoothAdapter>()
+    private val btServerSocket = mock<BluetoothServerSocket>()
+    private val btSocket = mock<BluetoothSocket>()
+    private val providerDeps = mock<L2capNetworkProvider.Dependencies>()
+    private val acceptQueue = LinkedBlockingQueue<BluetoothSocket>()
+
+    private val handlerThread = HandlerThread("CSL2capProviderTest thread").apply { start() }
+
+    // Requires Dependencies mock to be setup before creation.
+    private lateinit var provider: L2capNetworkProvider
+
+    @Before
+    fun innerSetUp() {
+        doReturn(btAdapter).`when`(bluetoothManager).getAdapter()
+        doReturn(btServerSocket).`when`(btAdapter).listenUsingInsecureL2capChannel()
+        doReturn(PSM).`when`(btServerSocket).getPsm();
+
+        doAnswer {
+            val sock = acceptQueue.take()
+            sock ?: throw IOException()
+        }.`when`(btServerSocket).accept()
+
+        doAnswer {
+            acceptQueue.put(null)
+        }.`when`(btServerSocket).close()
+
+        doReturn(handlerThread).`when`(providerDeps).getHandlerThread()
+        provider = L2capNetworkProvider(providerDeps, context)
+        provider.start()
+    }
+
+    @After
+    fun innerTearDown() {
+        handlerThread.quitSafely()
+        handlerThread.join()
+    }
+
+    private fun reserveNetwork(nr: NetworkRequest) = TestableNetworkCallback().also {
+        cm.reserveNetwork(nr, csHandler, it)
+    }
+
+    private fun requestNetwork(nr: NetworkRequest) = TestableNetworkCallback().also {
+        cm.requestNetwork(nr, it, csHandler)
+    }
+
+    private fun NetworkRequest.copyWithSpecifier(specifier: NetworkSpecifier): NetworkRequest {
+        // Note: NetworkRequest.Builder(NetworkRequest) *does not* perform a defensive copy but
+        // changes the underlying request.
+        return NetworkRequest.Builder(NetworkRequest(this))
+                .setNetworkSpecifier(specifier)
+                .build()
+    }
+
+    @Test
+    fun testReservation() {
+        val l2capServerSpecifier = L2capNetworkSpecifier.Builder()
+                .setRole(ROLE_SERVER)
+                .setHeaderCompression(HEADER_COMPRESSION_6LOWPAN)
+                .build()
+        val l2capReservation = REQUEST.copyWithSpecifier(l2capServerSpecifier)
+        val reservationCb = reserveNetwork(l2capReservation)
+
+        val reservedCaps = reservationCb.expect<Reserved>().caps
+        val reservedSpec = reservedCaps.networkSpecifier as L2capNetworkSpecifier
+
+        assertEquals(PSM, reservedSpec.getPsm())
+        assertEquals(HEADER_COMPRESSION_6LOWPAN, reservedSpec.headerCompression)
+        assertNull(reservedSpec.remoteAddress)
+
+        reservationCb.assertNoCallback()
+    }
+
+    @Test
+    fun testBlanketOffer_reservationWithoutSpecifier() {
+        reserveNetwork(REQUEST).assertNoCallback()
+    }
+
+    @Test
+    fun testBlanketOffer_reservationWithCorrectSpecifier() {
+        var specifier = L2capNetworkSpecifier.Builder()
+                .setRole(ROLE_SERVER)
+                .setHeaderCompression(HEADER_COMPRESSION_6LOWPAN)
+                .build()
+        var nr = REQUEST.copyWithSpecifier(specifier)
+        reserveNetwork(nr).expect<Reserved>()
+
+        specifier = L2capNetworkSpecifier.Builder()
+                .setRole(ROLE_SERVER)
+                .setHeaderCompression(HEADER_COMPRESSION_NONE)
+                .build()
+        nr = REQUEST.copyWithSpecifier(specifier)
+        reserveNetwork(nr).expect<Reserved>()
+    }
+
+    @Test
+    fun testBlanketOffer_reservationWithIncorrectSpecifier() {
+        var specifier = L2capNetworkSpecifier.Builder().build()
+        var nr = REQUEST.copyWithSpecifier(specifier)
+        reserveNetwork(nr).assertNoCallback()
+
+        specifier = L2capNetworkSpecifier.Builder()
+                .setRole(ROLE_SERVER)
+                .build()
+        nr = REQUEST.copyWithSpecifier(specifier)
+        reserveNetwork(nr).assertNoCallback()
+
+        specifier = L2capNetworkSpecifier.Builder()
+                .setRole(ROLE_SERVER)
+                .setHeaderCompression(HEADER_COMPRESSION_NONE)
+                .setPsm(0x81)
+                .build()
+        nr = REQUEST.copyWithSpecifier(specifier)
+        reserveNetwork(nr).assertNoCallback()
+
+        specifier = L2capNetworkSpecifier.Builder()
+                .setHeaderCompression(HEADER_COMPRESSION_NONE)
+                .build()
+        nr = REQUEST.copyWithSpecifier(specifier)
+        reserveNetwork(nr).assertNoCallback()
+    }
+}
diff --git a/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt b/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt
index ae196a6..350a140 100644
--- a/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt
+++ b/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt
@@ -18,6 +18,7 @@
 
 import android.app.AlarmManager
 import android.app.AppOpsManager
+import android.bluetooth.BluetoothManager
 import android.content.BroadcastReceiver
 import android.content.Context
 import android.content.Intent
@@ -209,6 +210,7 @@
         doReturn(true).`when`(it).isDataCapable()
     }
     val subscriptionManager = mock<SubscriptionManager>()
+    val bluetoothManager = mock<BluetoothManager>()
 
     val multicastRoutingCoordinatorService = mock<MulticastRoutingCoordinatorService>()
     val satelliteAccessController = mock<SatelliteAccessController>()
@@ -393,6 +395,8 @@
             // Call mocked destroyLiveTcpSocketsByOwnerUids so that test can verify this method call
             destroySocketsWrapper.destroyLiveTcpSocketsByOwnerUids(ownerUids)
         }
+
+        override fun makeL2capNetworkProvider(context: Context) = null
     }
 
     inner class CSContext(base: Context) : BroadcastInterceptingContext(base) {
@@ -503,6 +507,7 @@
             Context.BATTERY_STATS_SERVICE -> batteryManager
             Context.STATS_MANAGER -> null // Stats manager is final and can't be mocked
             Context.APP_OPS_SERVICE -> appOpsManager
+            Context.BLUETOOTH_SERVICE -> bluetoothManager
             else -> super.getSystemService(serviceName)
         }
 
diff --git a/tests/unit/java/com/android/server/connectivityservice/base/CSTestHelpers.kt b/tests/unit/java/com/android/server/connectivityservice/base/CSTestHelpers.kt
index 8ff790c..6b560de 100644
--- a/tests/unit/java/com/android/server/connectivityservice/base/CSTestHelpers.kt
+++ b/tests/unit/java/com/android/server/connectivityservice/base/CSTestHelpers.kt
@@ -23,6 +23,7 @@
 import android.content.Context
 import android.content.pm.PackageManager
 import android.content.pm.PackageManager.FEATURE_BLUETOOTH
+import android.content.pm.PackageManager.FEATURE_BLUETOOTH_LE
 import android.content.pm.PackageManager.FEATURE_ETHERNET
 import android.content.pm.PackageManager.FEATURE_WIFI
 import android.content.pm.PackageManager.FEATURE_WIFI_DIRECT
@@ -103,7 +104,13 @@
 }
 
 internal fun makeMockPackageManager(realContext: Context) = mock<PackageManager>().also { pm ->
-    val supported = listOf(FEATURE_WIFI, FEATURE_WIFI_DIRECT, FEATURE_BLUETOOTH, FEATURE_ETHERNET)
+    val supported = listOf(
+            FEATURE_WIFI,
+            FEATURE_WIFI_DIRECT,
+            FEATURE_BLUETOOTH,
+            FEATURE_BLUETOOTH_LE,
+            FEATURE_ETHERNET
+    )
     doReturn(true).`when`(pm).hasSystemFeature(argThat { supported.contains(it) })
     val myPackageName = realContext.packageName
     val myPackageInfo = realContext.packageManager.getPackageInfo(myPackageName,
diff --git a/tests/unit/java/com/android/server/net/HeaderCompressionUtilsTest.kt b/tests/unit/java/com/android/server/net/HeaderCompressionUtilsTest.kt
new file mode 100644
index 0000000..8431194
--- /dev/null
+++ b/tests/unit/java/com/android/server/net/HeaderCompressionUtilsTest.kt
@@ -0,0 +1,192 @@
+/*
+ * Copyright (C) 2025 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
+
+import android.os.Build
+import com.android.testutils.ConnectivityModuleTest
+import com.android.testutils.DevSdkIgnoreRule
+import com.android.testutils.DevSdkIgnoreRunner
+import com.android.internal.util.HexDump
+import com.google.common.truth.Truth.assertThat
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+private const val TIMEOUT = 1000L
+
+@ConnectivityModuleTest
+@RunWith(DevSdkIgnoreRunner::class)
+@DevSdkIgnoreRule.IgnoreUpTo(Build.VERSION_CODES.R)
+class HeaderCompressionUtilsTest {
+
+    private fun decompressHex(hex: String): ByteArray {
+        val bytes = HexDump.hexStringToByteArray(hex)
+        val buf = bytes.copyOf(1500)
+        val newLen = HeaderCompressionUtils.decompress6lowpan(buf, bytes.size)
+        return buf.copyOf(newLen)
+    }
+
+    private fun compressHex(hex: String): ByteArray {
+        val buf = HexDump.hexStringToByteArray(hex)
+        val newLen = HeaderCompressionUtils.compress6lowpan(buf, buf.size)
+        return buf.copyOf(newLen)
+    }
+
+    private fun String.decodeHex() = HexDump.hexStringToByteArray(this)
+
+    @Test
+    fun testHeaderDecompression() {
+        // TF: 00, NH: 0, HLIM: 00, CID: 0, SAC: 0, SAM: 00, M: 0, DAC: 0, DAM: 00
+        var input = "6000" +
+                    "ccf" +                               // ECN + DSCP + 4-bit Pad (here "f")
+                    "12345" +                             // flow label
+                    "11" +                                // next header
+                    "e7" +                                // hop limit
+                    "abcdef1234567890abcdef1234567890" +  // source
+                    "aaabbbcccdddeeefff00011122233344" +  // dest
+                    "abcd"                                // payload
+
+        var output = "6" +                                // version
+                     "cc" +                               // traffic class
+                     "12345" +                            // flow label
+                     "0002" +                             // payload length
+                     "11" +                               // next header
+                     "e7" +                               // hop limit
+                     "abcdef1234567890abcdef1234567890" + // source
+                     "aaabbbcccdddeeefff00011122233344" + // dest
+                     "abcd"                               // payload
+        assertThat(decompressHex(input)).isEqualTo(output.decodeHex())
+
+        // TF: 01, NH: 0, HLIM: 01, CID: 0, SAC: 0, SAM: 01, M: 0, DAC: 0, DAM: 01
+        input  = "6911" +
+                 "5" +                                // ECN + 2-bit pad (here "1")
+                 "f100e" +                            // flow label
+                 "42" +                               // next header
+                 "1102030405060708" +                 // source
+                 "aa0b0c0d0e0f1011" +                 // dest
+                 "abcd"                               // payload
+
+        output = "6" +                                // version
+                 "01" +                               // traffic class
+                 "f100e" +                            // flow label
+                 "0002" +                             // payload length
+                 "42" +                               // next header
+                 "01" +                               // hop limit
+                 "fe800000000000001102030405060708" + // source
+                 "fe80000000000000aa0b0c0d0e0f1011" + // dest
+                 "abcd"                               // payload
+        assertThat(decompressHex(input)).isEqualTo(output.decodeHex())
+
+        // TF: 10, NH: 0, HLIM: 10, CID: 0, SAC: 0, SAM: 10, M: 0, DAC: 0, DAM: 10
+        input  = "7222" +
+                 "cc" +                               // traffic class
+                 "43" +                               // next header
+                 "1234" +                             // source
+                 "abcd" +                             // dest
+                 "abcdef"                             // payload
+
+        output = "6" +                                // version
+                 "cc" +                               // traffic class
+                 "00000" +                            // flow label
+                 "0003" +                             // payload length
+                 "43" +                               // next header
+                 "40" +                               // hop limit
+                 "fe80000000000000000000fffe001234" + // source
+                 "fe80000000000000000000fffe00abcd" + // dest
+                 "abcdef"                             // payload
+        assertThat(decompressHex(input)).isEqualTo(output.decodeHex())
+
+        // TF: 11, NH: 0, HLIM: 11, CID: 0, SAC: 0, SAM: 10, M: 1, DAC: 0, DAM: 00
+        input  = "7b28" +
+                 "44" +                               // next header
+                 "1234" +                             // source
+                 "ff020000000000000000000000000001" + // dest
+                 "abcdef01"                           // payload
+
+        output = "6" +                                // version
+                 "00" +                               // traffic class
+                 "00000" +                            // flow label
+                 "0004" +                             // payload length
+                 "44" +                               // next header
+                 "ff" +                               // hop limit
+                 "fe80000000000000000000fffe001234" + // source
+                 "ff020000000000000000000000000001" + // dest
+                 "abcdef01"                           // payload
+        assertThat(decompressHex(input)).isEqualTo(output.decodeHex())
+
+        // TF: 11, NH: 0, HLIM: 11, CID: 0, SAC: 0, SAM: 10, M: 1, DAC: 0, DAM: 01
+        input  = "7b29" +
+                 "44" +                               // next header
+                 "1234" +                             // source
+                 "02abcdef1234" +                     // dest
+                 "abcdef01"                           // payload
+
+        output = "6" +                                // version
+                 "00" +                               // traffic class
+                 "00000" +                            // flow label
+                 "0004" +                             // payload length
+                 "44" +                               // next header
+                 "ff" +                               // hop limit
+                 "fe80000000000000000000fffe001234" + // source
+                 "ff02000000000000000000abcdef1234" + // dest
+                 "abcdef01"                           // payload
+        assertThat(decompressHex(input)).isEqualTo(output.decodeHex())
+
+        // TF: 11, NH: 0, HLIM: 11, CID: 0, SAC: 0, SAM: 10, M: 1, DAC: 0, DAM: 10
+        input  = "7b2a" +
+                 "44" +                               // next header
+                 "1234" +                             // source
+                 "ee123456" +                         // dest
+                 "abcdef01"                           // payload
+
+        output = "6" +                                // version
+                 "00" +                               // traffic class
+                 "00000" +                            // flow label
+                 "0004" +                             // payload length
+                 "44" +                               // next header
+                 "ff" +                               // hop limit
+                 "fe80000000000000000000fffe001234" + // source
+                 "ffee0000000000000000000000123456" + // dest
+                 "abcdef01"                           // payload
+        assertThat(decompressHex(input)).isEqualTo(output.decodeHex())
+
+        // TF: 11, NH: 0, HLIM: 11, CID: 0, SAC: 0, SAM: 10, M: 1, DAC: 0, DAM: 11
+        input  = "7b2b" +
+                 "44" +                               // next header
+                 "1234" +                             // source
+                 "89" +                               // dest
+                 "abcdef01"                           // payload
+
+        output = "6" +                                // version
+                 "00" +                               // traffic class
+                 "00000" +                            // flow label
+                 "0004" +                             // payload length
+                 "44" +                               // next header
+                 "ff" +                               // hop limit
+                 "fe80000000000000000000fffe001234" + // source
+                 "ff020000000000000000000000000089" + // dest
+                 "abcdef01"                           // payload
+        assertThat(decompressHex(input)).isEqualTo(output.decodeHex())
+    }
+
+    @Test
+    fun testHeaderCompression() {
+        val input  = "60120304000011fffe800000000000000000000000000001fe800000000000000000000000000002"
+        val output = "60000102030411fffe800000000000000000000000000001fe800000000000000000000000000002"
+        assertThat(compressHex(input)).isEqualTo(output.decodeHex())
+    }
+}
diff --git a/tests/unit/java/com/android/server/net/L2capPacketForwarderTest.kt b/tests/unit/java/com/android/server/net/L2capPacketForwarderTest.kt
index b3095ee..e261732 100644
--- a/tests/unit/java/com/android/server/net/L2capPacketForwarderTest.kt
+++ b/tests/unit/java/com/android/server/net/L2capPacketForwarderTest.kt
@@ -184,6 +184,7 @@
                 handler,
                 FdWrapper(ParcelFileDescriptor(tunFds[0])),
                 BluetoothSocketWrapper(bluetoothSocket),
+                false /* compressHeaders */,
                 callback
         )
     }
diff --git a/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java b/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java
index d41550b..7a5895f 100644
--- a/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java
+++ b/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java
@@ -130,6 +130,7 @@
     public void setUp() throws Exception {
         mExecutor = Executors.newSingleThreadExecutor();
         mOtCtl = new OtDaemonController();
+        mController.setEnabledAndWait(true);
         mController.leaveAndWait();
 
         // TODO: b/323301831 - This is a workaround to avoid unnecessary delay to re-form a network