diff --git a/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java b/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
index 2ef1d5b..225bd58 100644
--- a/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
+++ b/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
@@ -1487,7 +1487,8 @@
     }
 
     @NonNull
-    private byte[] toIpv4MappedAddressBytes(Inet4Address ia4) {
+    @VisibleForTesting
+    static byte[] toIpv4MappedAddressBytes(Inet4Address ia4) {
         final byte[] addr4 = ia4.getAddress();
         final byte[] addr6 = new byte[16];
         addr6[10] = (byte) 0xff;
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/BpfCoordinatorTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/BpfCoordinatorTest.java
index c614046..179fc8a 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/BpfCoordinatorTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/BpfCoordinatorTest.java
@@ -47,6 +47,7 @@
 import static com.android.networkstack.tethering.BpfCoordinator.StatsType;
 import static com.android.networkstack.tethering.BpfCoordinator.StatsType.STATS_PER_IFACE;
 import static com.android.networkstack.tethering.BpfCoordinator.StatsType.STATS_PER_UID;
+import static com.android.networkstack.tethering.BpfCoordinator.toIpv4MappedAddressBytes;
 import static com.android.networkstack.tethering.BpfUtils.DOWNSTREAM;
 import static com.android.networkstack.tethering.BpfUtils.UPSTREAM;
 import static com.android.networkstack.tethering.TetheringConfiguration.DEFAULT_TETHER_OFFLOAD_POLL_INTERVAL_MS;
@@ -129,6 +130,7 @@
 import java.net.InetAddress;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.LinkedHashMap;
 
 @RunWith(AndroidJUnit4.class)
@@ -138,22 +140,225 @@
     public final DevSdkIgnoreRule mIgnoreRule = new DevSdkIgnoreRule();
 
     private static final int TEST_NET_ID = 24;
+    private static final int TEST_NET_ID2 = 25;
 
+    private static final int INVALID_IFINDEX = 0;
     private static final int UPSTREAM_IFINDEX = 1001;
-    private static final int DOWNSTREAM_IFINDEX = 1002;
+    private static final int UPSTREAM_IFINDEX2 = 1002;
+    private static final int DOWNSTREAM_IFINDEX = 1003;
+    private static final int DOWNSTREAM_IFINDEX2 = 1004;
 
     private static final String UPSTREAM_IFACE = "rmnet0";
+    private static final String UPSTREAM_IFACE2 = "wlan0";
 
     private static final MacAddress DOWNSTREAM_MAC = MacAddress.fromString("12:34:56:78:90:ab");
+    private static final MacAddress DOWNSTREAM_MAC2 = MacAddress.fromString("ab:90:78:56:34:12");
+
     private static final MacAddress MAC_A = MacAddress.fromString("00:00:00:00:00:0a");
     private static final MacAddress MAC_B = MacAddress.fromString("11:22:33:00:00:0b");
 
     private static final InetAddress NEIGH_A = InetAddresses.parseNumericAddress("2001:db8::1");
     private static final InetAddress NEIGH_B = InetAddresses.parseNumericAddress("2001:db8::2");
 
+    private static final Inet4Address REMOTE_ADDR =
+            (Inet4Address) InetAddresses.parseNumericAddress("140.112.8.116");
+    private static final Inet4Address PUBLIC_ADDR =
+            (Inet4Address) InetAddresses.parseNumericAddress("1.0.0.1");
+    private static final Inet4Address PUBLIC_ADDR2 =
+            (Inet4Address) InetAddresses.parseNumericAddress("1.0.0.2");
+    private static final Inet4Address PRIVATE_ADDR =
+            (Inet4Address) InetAddresses.parseNumericAddress("192.168.80.12");
+    private static final Inet4Address PRIVATE_ADDR2 =
+            (Inet4Address) InetAddresses.parseNumericAddress("192.168.90.12");
+
+    // Generally, public port and private port are the same in the NAT conntrack message.
+    // TODO: consider using different private port and public port for testing.
+    private static final short REMOTE_PORT = (short) 443;
+    private static final short PUBLIC_PORT = (short) 62449;
+    private static final short PUBLIC_PORT2 = (short) 62450;
+    private static final short PRIVATE_PORT = (short) 62449;
+    private static final short PRIVATE_PORT2 = (short) 62450;
+
     private static final InterfaceParams UPSTREAM_IFACE_PARAMS = new InterfaceParams(
             UPSTREAM_IFACE, UPSTREAM_IFINDEX, null /* macAddr, rawip */,
             NetworkStackConstants.ETHER_MTU);
+    private static final InterfaceParams UPSTREAM_IFACE_PARAMS2 = new InterfaceParams(
+            UPSTREAM_IFACE2, UPSTREAM_IFINDEX2, MacAddress.fromString("44:55:66:00:00:0c"),
+            NetworkStackConstants.ETHER_MTU);
+
+    private static final HashMap<Integer, UpstreamInformation> UPSTREAM_INFORMATIONS =
+            new HashMap<Integer, UpstreamInformation>() {{
+                    put(UPSTREAM_IFINDEX, new UpstreamInformation(UPSTREAM_IFACE_PARAMS,
+                            PUBLIC_ADDR, NetworkCapabilities.TRANSPORT_CELLULAR, TEST_NET_ID));
+                    put(UPSTREAM_IFINDEX2, new UpstreamInformation(UPSTREAM_IFACE_PARAMS2,
+                            PUBLIC_ADDR2, NetworkCapabilities.TRANSPORT_WIFI, TEST_NET_ID2));
+            }};
+
+    private static final ClientInfo CLIENT_INFO_A = new ClientInfo(DOWNSTREAM_IFINDEX,
+            DOWNSTREAM_MAC, PRIVATE_ADDR, MAC_A);
+    private static final ClientInfo CLIENT_INFO_B = new ClientInfo(DOWNSTREAM_IFINDEX2,
+            DOWNSTREAM_MAC2, PRIVATE_ADDR2, MAC_B);
+
+    private static class UpstreamInformation {
+        public final InterfaceParams interfaceParams;
+        public final Inet4Address address;
+        public final int transportType;
+        public final int netId;
+
+        UpstreamInformation(final InterfaceParams interfaceParams,
+                final Inet4Address address, int transportType, int netId) {
+            this.interfaceParams = interfaceParams;
+            this.address = address;
+            this.transportType = transportType;
+            this.netId = netId;
+        }
+    }
+
+    private static class TestUpstream4Key {
+        public static class Builder {
+            private long mIif = DOWNSTREAM_IFINDEX;
+            private MacAddress mDstMac = DOWNSTREAM_MAC;
+            private short mL4proto = (short) IPPROTO_TCP;
+            private byte[] mSrc4 = PRIVATE_ADDR.getAddress();
+            private byte[] mDst4 = REMOTE_ADDR.getAddress();
+            private int mSrcPort = PRIVATE_PORT;
+            private int mDstPort = REMOTE_PORT;
+
+            Builder() {}
+
+            public Builder setProto(int proto) {
+                if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
+                    fail("Not support protocol " + proto);
+                }
+                mL4proto = (short) proto;
+                return this;
+            }
+
+            public Tether4Key build() {
+                return new Tether4Key(mIif, mDstMac, mL4proto, mSrc4, mDst4, mSrcPort, mDstPort);
+            }
+        }
+    }
+
+    private static class TestDownstream4Key {
+        public static class Builder {
+            private long mIif = UPSTREAM_IFINDEX;
+            private MacAddress mDstMac = MacAddress.ALL_ZEROS_ADDRESS /* dstMac (rawip) */;
+            private short mL4proto = (short) IPPROTO_TCP;
+            private byte[] mSrc4 = REMOTE_ADDR.getAddress();
+            private byte[] mDst4 = PUBLIC_ADDR.getAddress();
+            private int mSrcPort = REMOTE_PORT;
+            private int mDstPort = PUBLIC_PORT;
+
+            Builder() {}
+
+            public Builder setProto(int proto) {
+                if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
+                    fail("Not support protocol " + proto);
+                }
+                mL4proto = (short) proto;
+                return this;
+            }
+
+            public Tether4Key build() {
+                return new Tether4Key(mIif, mDstMac, mL4proto, mSrc4, mDst4, mSrcPort, mDstPort);
+            }
+        }
+    }
+
+    private static class TestUpstream4Value {
+        public static class Builder {
+            private long mOif = UPSTREAM_IFINDEX;
+            private MacAddress mEthDstMac = MacAddress.ALL_ZEROS_ADDRESS /* dstMac (rawip) */;
+            private MacAddress mEthSrcMac = MacAddress.ALL_ZEROS_ADDRESS /* dstMac (rawip) */;
+            private int mEthProto = ETH_P_IP;
+            private short mPmtu = NetworkStackConstants.ETHER_MTU;
+            private byte[] mSrc46 = toIpv4MappedAddressBytes(PUBLIC_ADDR);
+            private byte[] mDst46 = toIpv4MappedAddressBytes(REMOTE_ADDR);
+            private int mSrcPort = PUBLIC_PORT;
+            private int mDstPort = REMOTE_PORT;
+            private long mLastUsed = 0;
+
+            Builder() {}
+
+            public Tether4Value build() {
+                return new Tether4Value(mOif, mEthDstMac, mEthSrcMac, mEthProto, mPmtu,
+                        mSrc46, mDst46, mSrcPort, mDstPort, mLastUsed);
+            }
+        }
+    }
+
+    private static class TestDownstream4Value {
+        public static class Builder {
+            private long mOif = DOWNSTREAM_IFINDEX;
+            private MacAddress mEthDstMac = MAC_A /* client mac */;
+            private MacAddress mEthSrcMac = DOWNSTREAM_MAC;
+            private int mEthProto = ETH_P_IP;
+            private short mPmtu = NetworkStackConstants.ETHER_MTU;
+            private byte[] mSrc46 = toIpv4MappedAddressBytes(REMOTE_ADDR);
+            private byte[] mDst46 = toIpv4MappedAddressBytes(PRIVATE_ADDR);
+            private int mSrcPort = REMOTE_PORT;
+            private int mDstPort = PRIVATE_PORT;
+            private long mLastUsed = 0;
+
+            Builder() {}
+
+            public Tether4Value build() {
+                return new Tether4Value(mOif, mEthDstMac, mEthSrcMac, mEthProto, mPmtu,
+                        mSrc46, mDst46, mSrcPort, mDstPort, mLastUsed);
+            }
+        }
+    }
+
+    private static class TestConntrackEvent {
+        public static class Builder {
+            private short mMsgType = IPCTNL_MSG_CT_NEW;
+            private short mProto = (short) IPPROTO_TCP;
+            private Inet4Address mPrivateAddr = PRIVATE_ADDR;
+            private Inet4Address mPublicAddr = PUBLIC_ADDR;
+            private Inet4Address mRemoteAddr = REMOTE_ADDR;
+            private short mPrivatePort = PRIVATE_PORT;
+            private short mPublicPort = PUBLIC_PORT;
+            private short mRemotePort = REMOTE_PORT;
+
+            Builder() {}
+
+            public Builder setMsgType(short msgType) {
+                if (msgType != IPCTNL_MSG_CT_NEW && msgType != IPCTNL_MSG_CT_DELETE) {
+                    fail("Not support message type " + msgType);
+                }
+                mMsgType = (short) msgType;
+                return this;
+            }
+
+            public Builder setProto(int proto) {
+                if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
+                    fail("Not support protocol " + proto);
+                }
+                mProto = (short) proto;
+                return this;
+            }
+
+            public Builder setRemotePort(int remotePort) {
+                mRemotePort = (short) remotePort;
+                return this;
+            }
+
+            public ConntrackEvent build() {
+                final int status = (mMsgType == IPCTNL_MSG_CT_NEW) ? ESTABLISHED_MASK : DYING_MASK;
+                final int timeoutSec = (mMsgType == IPCTNL_MSG_CT_NEW) ? 100 /* nonzero, new */
+                        : 0 /* unused, delete */;
+                return new ConntrackEvent(
+                        (short) (NetlinkConstants.NFNL_SUBSYS_CTNETLINK << 8 | mMsgType),
+                        new Tuple(new TupleIpv4(mPrivateAddr, mRemoteAddr),
+                                new TupleProto((byte) mProto, mPrivatePort, mRemotePort)),
+                        new Tuple(new TupleIpv4(mRemoteAddr, mPublicAddr),
+                                new TupleProto((byte) mProto, mRemotePort, mPublicPort)),
+                        status,
+                        timeoutSec);
+            }
+        }
+    }
 
     @Mock private NetworkStatsManager mStatsManager;
     @Mock private INetd mNetd;
@@ -161,8 +366,6 @@
     @Mock private IpServer mIpServer2;
     @Mock private TetheringConfiguration mTetherConfig;
     @Mock private ConntrackMonitor mConntrackMonitor;
-    @Mock private BpfMap<Tether4Key, Tether4Value> mBpfDownstream4Map;
-    @Mock private BpfMap<Tether4Key, Tether4Value> mBpfUpstream4Map;
     @Mock private BpfMap<TetherDownstream6Key, Tether6Value> mBpfDownstream6Map;
     @Mock private BpfMap<TetherUpstream6Key, Tether6Value> mBpfUpstream6Map;
     @Mock private BpfMap<TetherDevKey, TetherDevValue> mBpfDevMap;
@@ -179,6 +382,10 @@
     private final ArgumentCaptor<ArrayList> mStringArrayCaptor =
             ArgumentCaptor.forClass(ArrayList.class);
     private final TestLooper mTestLooper = new TestLooper();
+    private final BpfMap<Tether4Key, Tether4Value> mBpfDownstream4Map =
+            spy(new TestBpfMap<>(Tether4Key.class, Tether4Value.class));
+    private final BpfMap<Tether4Key, Tether4Value> mBpfUpstream4Map =
+            spy(new TestBpfMap<>(Tether4Key.class, Tether4Value.class));
     private final TestBpfMap<TetherStatsKey, TetherStatsValue> mBpfStatsMap =
             spy(new TestBpfMap<>(TetherStatsKey.class, TetherStatsValue.class));
     private final TestBpfMap<TetherLimitKey, TetherLimitValue> mBpfLimitMap =
@@ -1244,140 +1451,67 @@
     // |   Sever    +---------+  Upstream  | Downstream +---------+   Client   |
     // +------------+         +------------+------------+         +------------+
     // remote ip              public ip                           private ip
-    // 140.112.8.116:443      100.81.179.1:62449                  192.168.80.12:62449
+    // 140.112.8.116:443      1.0.0.1:62449                       192.168.80.12:62449
     //
-    private static final Inet4Address REMOTE_ADDR =
-            (Inet4Address) InetAddresses.parseNumericAddress("140.112.8.116");
-    private static final Inet4Address PUBLIC_ADDR =
-            (Inet4Address) InetAddresses.parseNumericAddress("100.81.179.1");
-    private static final Inet4Address PRIVATE_ADDR =
-            (Inet4Address) InetAddresses.parseNumericAddress("192.168.80.12");
 
-    // IPv4-mapped IPv6 addresses
-    // Remote addrress ::ffff:140.112.8.116
-    // Public addrress ::ffff:100.81.179.1
-    // Private addrress ::ffff:192.168.80.12
-    private static final byte[] REMOTE_ADDR_V4MAPPED_BYTES = new byte[] {
-            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
-            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0xff, (byte) 0xff,
-            (byte) 0x8c, (byte) 0x70, (byte) 0x08, (byte) 0x74 };
-    private static final byte[] PUBLIC_ADDR_V4MAPPED_BYTES = new byte[] {
-            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
-            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0xff, (byte) 0xff,
-            (byte) 0x64, (byte) 0x51, (byte) 0xb3, (byte) 0x01 };
-    private static final byte[] PRIVATE_ADDR_V4MAPPED_BYTES = new byte[] {
-            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
-            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0xff, (byte) 0xff,
-            (byte) 0xc0, (byte) 0xa8, (byte) 0x50, (byte) 0x0c };
-
-    // Generally, public port and private port are the same in the NAT conntrack message.
-    // TODO: consider using different private port and public port for testing.
-    private static final short REMOTE_PORT = (short) 443;
-    private static final short PUBLIC_PORT = (short) 62449;
-    private static final short PRIVATE_PORT = (short) 62449;
-
-    @NonNull
-    private Tether4Key makeUpstream4Key(int proto) {
-        if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
-            fail("Not support protocol " + proto);
-        }
-        return new Tether4Key(DOWNSTREAM_IFINDEX, DOWNSTREAM_MAC, (short) proto,
-            PRIVATE_ADDR.getAddress(), REMOTE_ADDR.getAddress(), PRIVATE_PORT, REMOTE_PORT);
-    }
-
-    @NonNull
-    private Tether4Key makeDownstream4Key(int proto) {
-        if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
-            fail("Not support protocol " + proto);
-        }
-        return new Tether4Key(UPSTREAM_IFINDEX,
-                MacAddress.ALL_ZEROS_ADDRESS /* dstMac (rawip) */, (short) proto,
-                REMOTE_ADDR.getAddress(), PUBLIC_ADDR.getAddress(), REMOTE_PORT, PUBLIC_PORT);
-    }
-
-    @NonNull
-    private Tether4Value makeUpstream4Value() {
-        return new Tether4Value(UPSTREAM_IFINDEX,
-                MacAddress.ALL_ZEROS_ADDRESS /* ethDstMac (rawip) */,
-                MacAddress.ALL_ZEROS_ADDRESS /* ethSrcMac (rawip) */, ETH_P_IP,
-                NetworkStackConstants.ETHER_MTU, PUBLIC_ADDR_V4MAPPED_BYTES,
-                REMOTE_ADDR_V4MAPPED_BYTES, PUBLIC_PORT, REMOTE_PORT, 0 /* lastUsed */);
-    }
-
-    @NonNull
-    private Tether4Value makeDownstream4Value() {
-        return new Tether4Value(DOWNSTREAM_IFINDEX, MAC_A /* client mac */, DOWNSTREAM_MAC,
-                ETH_P_IP, NetworkStackConstants.ETHER_MTU, REMOTE_ADDR_V4MAPPED_BYTES,
-                PRIVATE_ADDR_V4MAPPED_BYTES, REMOTE_PORT, PRIVATE_PORT, 0 /* lastUsed */);
-    }
-
-    @NonNull
-    private Tether4Key makeDownstream4Key() {
-        return makeDownstream4Key(IPPROTO_TCP);
-    }
-
-    @NonNull
-    private ConntrackEvent makeTestConntrackEvent(short msgType, int proto, short remotePort) {
-        if (msgType != IPCTNL_MSG_CT_NEW && msgType != IPCTNL_MSG_CT_DELETE) {
-            fail("Not support message type " + msgType);
-        }
-        if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
-            fail("Not support protocol " + proto);
+    // Setup upstream interface to BpfCoordinator.
+    //
+    // @param coordinator BpfCoordinator instance.
+    // @param upstreamIfindex upstream interface index. can be the following values.
+    //        INVALID_IFINDEX: no upstream interface
+    //        UPSTREAM_IFINDEX: CELLULAR (raw ip interface)
+    //        UPSTREAM_IFINDEX2: WIFI (ethernet interface)
+    private void setUpstreamInformationTo(final BpfCoordinator coordinator,
+            @Nullable Integer upstreamIfindex) {
+        if (upstreamIfindex == INVALID_IFINDEX) {
+            coordinator.updateUpstreamNetworkState(null);
+            return;
         }
 
-        final int status = (msgType == IPCTNL_MSG_CT_NEW) ? ESTABLISHED_MASK : DYING_MASK;
-        final int timeoutSec = (msgType == IPCTNL_MSG_CT_NEW) ? 100 /* nonzero, new */
-                : 0 /* unused, delete */;
-        return new ConntrackEvent(
-                (short) (NetlinkConstants.NFNL_SUBSYS_CTNETLINK << 8 | msgType),
-                new Tuple(new TupleIpv4(PRIVATE_ADDR, REMOTE_ADDR),
-                        new TupleProto((byte) proto, PRIVATE_PORT, remotePort)),
-                new Tuple(new TupleIpv4(REMOTE_ADDR, PUBLIC_ADDR),
-                        new TupleProto((byte) proto, remotePort, PUBLIC_PORT)),
-                status,
-                timeoutSec);
-    }
-
-    @NonNull
-    private ConntrackEvent makeTestConntrackEvent(short msgType, int proto) {
-        return makeTestConntrackEvent(msgType, proto, REMOTE_PORT);
-    }
-
-    private void setUpstreamInformationTo(final BpfCoordinator coordinator) {
-        final LinkProperties lp = new LinkProperties();
-        lp.setInterfaceName(UPSTREAM_IFACE);
-        lp.addLinkAddress(new LinkAddress(PUBLIC_ADDR, 32 /* prefix length */));
-        final NetworkCapabilities capabilities = new NetworkCapabilities()
-                .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR);
-        coordinator.updateUpstreamNetworkState(new UpstreamNetworkState(lp, capabilities,
-                new Network(TEST_NET_ID)));
-    }
-
-    private void setDownstreamAndClientInformationTo(final BpfCoordinator coordinator) {
-        final ClientInfo clientInfo = new ClientInfo(DOWNSTREAM_IFINDEX, DOWNSTREAM_MAC,
-                PRIVATE_ADDR, MAC_A /* client mac */);
-        coordinator.tetherOffloadClientAdd(mIpServer, clientInfo);
-    }
-
-    private void initBpfCoordinatorForRule4(final BpfCoordinator coordinator) throws Exception {
-        // Needed because addUpstreamIfindexToMap only updates upstream information when polling
-        // was started.
-        coordinator.startPolling();
-
-        // Needed because two reasons: (1) BpfConntrackEventConsumer#accept only performs cleanup
-        // when both upstream and downstream rules are removed. (2) tetherOffloadRuleRemove of
-        // api31.BpfCoordinatorShimImpl only decreases the count while the entry is deleted.
-        // In the other words, deleteEntry returns true.
-        doReturn(true).when(mBpfUpstream4Map).deleteEntry(any());
-        doReturn(true).when(mBpfDownstream4Map).deleteEntry(any());
+        final UpstreamInformation upstreamInfo = UPSTREAM_INFORMATIONS.get(upstreamIfindex);
+        if (upstreamInfo == null) {
+            fail("Not support upstream interface index " + upstreamIfindex);
+        }
 
         // Needed because BpfCoordinator#addUpstreamIfindexToMap queries interface parameter for
         // interface index.
-        doReturn(UPSTREAM_IFACE_PARAMS).when(mDeps).getInterfaceParams(UPSTREAM_IFACE);
+        doReturn(upstreamInfo.interfaceParams).when(mDeps).getInterfaceParams(
+                upstreamInfo.interfaceParams.name);
+        coordinator.addUpstreamNameToLookupTable(upstreamInfo.interfaceParams.index,
+                upstreamInfo.interfaceParams.name);
 
-        coordinator.addUpstreamNameToLookupTable(UPSTREAM_IFINDEX, UPSTREAM_IFACE);
-        setUpstreamInformationTo(coordinator);
-        setDownstreamAndClientInformationTo(coordinator);
+        final LinkProperties lp = new LinkProperties();
+        lp.setInterfaceName(upstreamInfo.interfaceParams.name);
+        lp.addLinkAddress(new LinkAddress(upstreamInfo.address, 32 /* prefix length */));
+        final NetworkCapabilities capabilities = new NetworkCapabilities()
+                .addTransportType(upstreamInfo.transportType);
+        coordinator.updateUpstreamNetworkState(new UpstreamNetworkState(lp, capabilities,
+                new Network(upstreamInfo.netId)));
+    }
+
+    // Setup downstream interface and its client information to BpfCoordinator.
+    //
+    // @param coordinator BpfCoordinator instance.
+    // @param downstreamIfindex downstream interface index. can be the following values.
+    //        DOWNSTREAM_IFINDEX: a client information which uses MAC_A is added.
+    //        DOWNSTREAM_IFINDEX2: a client information which uses MAC_B is added.
+    // TODO: refactor this function once the client switches between each downstream interface.
+    private void addDownstreamAndClientInformationTo(final BpfCoordinator coordinator,
+            int downstreamIfindex) {
+        if (downstreamIfindex != DOWNSTREAM_IFINDEX && downstreamIfindex != DOWNSTREAM_IFINDEX2) {
+            fail("Not support downstream interface index " + downstreamIfindex);
+        }
+
+        if (downstreamIfindex == DOWNSTREAM_IFINDEX) {
+            coordinator.tetherOffloadClientAdd(mIpServer, CLIENT_INFO_A);
+        } else {
+            coordinator.tetherOffloadClientAdd(mIpServer2, CLIENT_INFO_B);
+        }
+    }
+
+    private void initBpfCoordinatorForRule4(final BpfCoordinator coordinator) throws Exception {
+        setUpstreamInformationTo(coordinator, UPSTREAM_IFINDEX);
+        addDownstreamAndClientInformationTo(coordinator, DOWNSTREAM_IFINDEX);
     }
 
     // TODO: Test the IPv4 and IPv6 exist concurrently.
@@ -1401,18 +1535,25 @@
         // because the protocol is not an element of the value. Consider using different address
         // or port to make them different for better testing.
         // TODO: Make the values of {TCP, UDP} rules different.
-        final Tether4Key expectedUpstream4KeyTcp = makeUpstream4Key(IPPROTO_TCP);
-        final Tether4Key expectedDownstream4KeyTcp = makeDownstream4Key(IPPROTO_TCP);
-        final Tether4Value expectedUpstream4ValueTcp = makeUpstream4Value();
-        final Tether4Value expectedDownstream4ValueTcp = makeDownstream4Value();
+        final Tether4Key expectedUpstream4KeyTcp = new TestUpstream4Key.Builder()
+                .setProto(IPPROTO_TCP).build();
+        final Tether4Key expectedDownstream4KeyTcp = new TestDownstream4Key.Builder()
+                .setProto(IPPROTO_TCP).build();
+        final Tether4Value expectedUpstream4ValueTcp = new TestUpstream4Value.Builder().build();
+        final Tether4Value expectedDownstream4ValueTcp = new TestDownstream4Value.Builder().build();
 
-        final Tether4Key expectedUpstream4KeyUdp = makeUpstream4Key(IPPROTO_UDP);
-        final Tether4Key expectedDownstream4KeyUdp = makeDownstream4Key(IPPROTO_UDP);
-        final Tether4Value expectedUpstream4ValueUdp = makeUpstream4Value();
-        final Tether4Value expectedDownstream4ValueUdp = makeDownstream4Value();
+        final Tether4Key expectedUpstream4KeyUdp = new TestUpstream4Key.Builder()
+                .setProto(IPPROTO_UDP).build();
+        final Tether4Key expectedDownstream4KeyUdp = new TestDownstream4Key.Builder()
+                .setProto(IPPROTO_UDP).build();
+        final Tether4Value expectedUpstream4ValueUdp = new TestUpstream4Value.Builder().build();
+        final Tether4Value expectedDownstream4ValueUdp = new TestDownstream4Value.Builder().build();
 
         // [1] Adding the first rule on current upstream immediately sends the quota.
-        mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_NEW, IPPROTO_TCP));
+        mConsumer.accept(new TestConntrackEvent.Builder()
+                .setMsgType(IPCTNL_MSG_CT_NEW)
+                .setProto(IPPROTO_TCP)
+                .build());
         verifyTetherOffloadSetInterfaceQuota(inOrder, UPSTREAM_IFINDEX, limit, true /* isInit */);
         inOrder.verify(mBpfUpstream4Map)
                 .insertEntry(eq(expectedUpstream4KeyTcp), eq(expectedUpstream4ValueTcp));
@@ -1421,7 +1562,10 @@
         inOrder.verifyNoMoreInteractions();
 
         // [2] Adding the second rule on current upstream does not send the quota.
-        mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_NEW, IPPROTO_UDP));
+        mConsumer.accept(new TestConntrackEvent.Builder()
+                .setMsgType(IPCTNL_MSG_CT_NEW)
+                .setProto(IPPROTO_UDP)
+                .build());
         verifyNeverTetherOffloadSetInterfaceQuota(inOrder);
         inOrder.verify(mBpfUpstream4Map)
                 .insertEntry(eq(expectedUpstream4KeyUdp), eq(expectedUpstream4ValueUdp));
@@ -1430,7 +1574,10 @@
         inOrder.verifyNoMoreInteractions();
 
         // [3] Removing the second rule on current upstream does not send the quota.
-        mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_DELETE, IPPROTO_UDP));
+        mConsumer.accept(new TestConntrackEvent.Builder()
+                .setMsgType(IPCTNL_MSG_CT_DELETE)
+                .setProto(IPPROTO_UDP)
+                .build());
         verifyNeverTetherOffloadSetInterfaceQuota(inOrder);
         inOrder.verify(mBpfUpstream4Map).deleteEntry(eq(expectedUpstream4KeyUdp));
         inOrder.verify(mBpfDownstream4Map).deleteEntry(eq(expectedDownstream4KeyUdp));
@@ -1439,7 +1586,10 @@
         // [4] Removing the last rule on current upstream immediately sends the cleanup stuff.
         updateStatsEntryForTetherOffloadGetAndClearStats(
                 buildTestTetherStatsParcel(UPSTREAM_IFINDEX, 0, 0, 0, 0));
-        mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_DELETE, IPPROTO_TCP));
+        mConsumer.accept(new TestConntrackEvent.Builder()
+                .setMsgType(IPCTNL_MSG_CT_DELETE)
+                .setProto(IPPROTO_TCP)
+                .build());
         inOrder.verify(mBpfUpstream4Map).deleteEntry(eq(expectedUpstream4KeyTcp));
         inOrder.verify(mBpfDownstream4Map).deleteEntry(eq(expectedDownstream4KeyTcp));
         verifyTetherOffloadGetAndClearStats(inOrder, UPSTREAM_IFINDEX);
@@ -1472,14 +1622,20 @@
         final BpfCoordinator coordinator = makeBpfCoordinator();
         initBpfCoordinatorForRule4(coordinator);
 
-        mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_NEW, IPPROTO_TCP));
+        mConsumer.accept(new TestConntrackEvent.Builder()
+                .setMsgType(IPCTNL_MSG_CT_NEW)
+                .setProto(IPPROTO_TCP)
+                .build());
         verify(mBpfDevMap).updateEntry(eq(new TetherDevKey(UPSTREAM_IFINDEX)),
                 eq(new TetherDevValue(UPSTREAM_IFINDEX)));
         verify(mBpfDevMap).updateEntry(eq(new TetherDevKey(DOWNSTREAM_IFINDEX)),
                 eq(new TetherDevValue(DOWNSTREAM_IFINDEX)));
         clearInvocations(mBpfDevMap);
 
-        mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_NEW, IPPROTO_UDP));
+        mConsumer.accept(new TestConntrackEvent.Builder()
+                .setMsgType(IPCTNL_MSG_CT_NEW)
+                .setProto(IPPROTO_UDP)
+                .build());
         verify(mBpfDevMap, never()).updateEntry(any(), any());
     }
 
@@ -1559,10 +1715,10 @@
                 new TestBpfMap<>(Tether4Key.class, Tether4Value.class);
         doReturn(bpfUpstream4Map).when(mDeps).getBpfUpstream4Map();
 
-        final Tether4Key tcpKey = makeUpstream4Key(IPPROTO_TCP);
-        final Tether4Key udpKey = makeUpstream4Key(IPPROTO_UDP);
-        final Tether4Value tcpValue = makeUpstream4Value();
-        final Tether4Value udpValue = makeUpstream4Value();
+        final Tether4Key tcpKey = new TestUpstream4Key.Builder().setProto(IPPROTO_TCP).build();
+        final Tether4Key udpKey = new TestUpstream4Key.Builder().setProto(IPPROTO_UDP).build();
+        final Tether4Value tcpValue = new TestUpstream4Value.Builder().build();
+        final Tether4Value udpValue = new TestUpstream4Value.Builder().build();
 
         checkRefreshConntrackTimeout(bpfUpstream4Map, tcpKey, tcpValue, udpKey, udpValue);
     }
@@ -1575,10 +1731,10 @@
                 new TestBpfMap<>(Tether4Key.class, Tether4Value.class);
         doReturn(bpfDownstream4Map).when(mDeps).getBpfDownstream4Map();
 
-        final Tether4Key tcpKey = makeDownstream4Key(IPPROTO_TCP);
-        final Tether4Key udpKey = makeDownstream4Key(IPPROTO_UDP);
-        final Tether4Value tcpValue = makeDownstream4Value();
-        final Tether4Value udpValue = makeDownstream4Value();
+        final Tether4Key tcpKey = new TestDownstream4Key.Builder().setProto(IPPROTO_TCP).build();
+        final Tether4Key udpKey = new TestDownstream4Key.Builder().setProto(IPPROTO_UDP).build();
+        final Tether4Value tcpValue = new TestDownstream4Value.Builder().build();
+        final Tether4Value udpValue = new TestDownstream4Value.Builder().build();
 
         checkRefreshConntrackTimeout(bpfDownstream4Map, tcpKey, tcpValue, udpKey, udpValue);
     }
@@ -1592,26 +1748,46 @@
         final short offloadedPort = 42;
         assertFalse(CollectionUtils.contains(NON_OFFLOADED_UPSTREAM_IPV4_TCP_PORTS,
                 offloadedPort));
-        mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_NEW, IPPROTO_TCP, offloadedPort));
+        mConsumer.accept(new TestConntrackEvent.Builder()
+                .setMsgType(IPCTNL_MSG_CT_NEW)
+                .setProto(IPPROTO_TCP)
+                .setRemotePort(offloadedPort)
+                .build());
         verify(mBpfUpstream4Map).insertEntry(any(), any());
         verify(mBpfDownstream4Map).insertEntry(any(), any());
         clearInvocations(mBpfUpstream4Map, mBpfDownstream4Map);
 
         for (final short port : NON_OFFLOADED_UPSTREAM_IPV4_TCP_PORTS) {
-            mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_NEW, IPPROTO_TCP, port));
+            mConsumer.accept(new TestConntrackEvent.Builder()
+                    .setMsgType(IPCTNL_MSG_CT_NEW)
+                    .setProto(IPPROTO_TCP)
+                    .setRemotePort(port)
+                    .build());
             verify(mBpfUpstream4Map, never()).insertEntry(any(), any());
             verify(mBpfDownstream4Map, never()).insertEntry(any(), any());
 
-            mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_DELETE, IPPROTO_TCP, port));
+            mConsumer.accept(new TestConntrackEvent.Builder()
+                    .setMsgType(IPCTNL_MSG_CT_DELETE)
+                    .setProto(IPPROTO_TCP)
+                    .setRemotePort(port)
+                    .build());
             verify(mBpfUpstream4Map, never()).deleteEntry(any());
             verify(mBpfDownstream4Map, never()).deleteEntry(any());
 
-            mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_NEW, IPPROTO_UDP, port));
+            mConsumer.accept(new TestConntrackEvent.Builder()
+                    .setMsgType(IPCTNL_MSG_CT_NEW)
+                    .setProto(IPPROTO_UDP)
+                    .setRemotePort(port)
+                    .build());
             verify(mBpfUpstream4Map).insertEntry(any(), any());
             verify(mBpfDownstream4Map).insertEntry(any(), any());
             clearInvocations(mBpfUpstream4Map, mBpfDownstream4Map);
 
-            mConsumer.accept(makeTestConntrackEvent(IPCTNL_MSG_CT_DELETE, IPPROTO_UDP, port));
+            mConsumer.accept(new TestConntrackEvent.Builder()
+                    .setMsgType(IPCTNL_MSG_CT_DELETE)
+                    .setProto(IPPROTO_UDP)
+                    .setRemotePort(port)
+                    .build());
             verify(mBpfUpstream4Map).deleteEntry(any());
             verify(mBpfDownstream4Map).deleteEntry(any());
             clearInvocations(mBpfUpstream4Map, mBpfDownstream4Map);