diff --git a/netpfga/minip4/testdata/gen_testdata_nat64_500byte.py b/netpfga/minip4/testdata/gen_testdata_nat64_500byte.py
new file mode 100755
index 0000000..2055c03
--- /dev/null
+++ b/netpfga/minip4/testdata/gen_testdata_nat64_500byte.py
@@ -0,0 +1,147 @@
+#!/usr/bin/env python
+
+# from switch_calc_headers import *
+from scapy.all import *
+from nf_sim_tools import *
+from collections import OrderedDict
+import sss_sdnet_tuples
+
+########################
+# pkt generation tools #
+########################
+
+pktsApplied = []
+pktsExpected = []
+
+# Pkt lists for SUME simulations
+nf_applied = OrderedDict()
+nf_applied[0] = []
+nf_applied[1] = []
+nf_applied[2] = []
+nf_applied[3] = []
+nf_expected = OrderedDict()
+nf_expected[0] = []
+nf_expected[1] = []
+nf_expected[2] = []
+nf_expected[3] = []
+
+nf_port_map = {
+    "nf0":0b00000001,
+    "nf1":0b00000100,
+    "nf2":0b00010000,
+    "nf3":0b01000000,
+    "dma0":0b00000010
+}
+
+nf_id_map = {
+    "nf0":0,
+    "nf1":1,
+    "nf2":2,
+    "nf3":3
+}
+
+sss_sdnet_tuples.clear_tuple_files()
+
+def applyPkt(pkt, ingress, time):
+    print("Applying pkt on {} at {}: ".format(ingress, time))
+    pktsApplied.append(pkt)
+    sss_sdnet_tuples.sume_tuple_in['src_port'] = nf_port_map[ingress]
+    sss_sdnet_tuples.sume_tuple_expect['src_port'] = nf_port_map[ingress]
+    pkt.time = time
+    nf_applied[nf_id_map[ingress]].append(pkt)
+
+def expPkt(pkt, egress):
+    pktsExpected.append(pkt)
+    sss_sdnet_tuples.sume_tuple_expect['dst_port'] = nf_port_map[egress]
+    sss_sdnet_tuples.write_tuples()
+    if egress in ["nf0","nf1","nf2","nf3"]:
+        nf_expected[nf_id_map[egress]].append(pkt)
+    elif egress == 'bcast':
+        nf_expected[0].append(pkt)
+        nf_expected[1].append(pkt)
+        nf_expected[2].append(pkt)
+        nf_expected[3].append(pkt)
+
+def print_summary(pkts):
+    for pkt in pkts:
+        print "summary = ", pkt.summary()
+
+def write_pcap_files():
+    wrpcap("src.pcap", pktsApplied)
+    wrpcap("dst.pcap", pktsExpected)
+
+    for i in nf_applied.keys():
+        if (len(nf_applied[i]) > 0):
+            wrpcap('nf{0}_applied.pcap'.format(i), nf_applied[i])
+
+    for i in nf_expected.keys():
+        if (len(nf_expected[i]) > 0):
+            wrpcap('nf{0}_expected.pcap'.format(i), nf_expected[i])
+
+    # i = 0..3
+    for i in nf_applied.keys():
+        print "nf{0}_applied times: ".format(i), [p.time for p in nf_applied[i]]
+
+#####################
+# generate testdata #
+#####################
+
+MAC1 = "08:11:11:11:11:08"
+MAC2 = "08:22:22:22:22:08"
+pktCnt = 0
+
+INDEX_WIDTH = 4
+REG_DEPTH = 2**INDEX_WIDTH
+
+# Not sure what this is used for
+NUM_KEYS = 4
+lookup_table = {
+    0: 0x00000001,
+    1: 0x00000010,
+    2: 0x00000100,
+    3: 0x00001000
+}
+
+def test_nat64():
+    """ packets for a certain mac always go to nf0 """
+    pktCnt = 1
+
+
+    # From v4 to v6
+    e4 = Ether(dst=MAC2, src=MAC1)
+    i4 = IP(src = "10.0.0.42", dst = "10.0.0.66")
+    u4 = UDP(sport=5000, dport=2345)
+    p4 = 500 * "A"
+    pkg4 = e4 / i4 / u4 / p4
+
+    applyPkt(pkt4, "nf2", pktCnt)
+
+    e6 = e4
+    i6 = IPv6(src = "2001:db8:42::a00:2a", dst = "2001:db8:42::42")
+    u6 = u4
+    p6 = p4
+    pkg6 = e6 / i6 / u6 / p6
+
+    expPkt(pkt6,   'nf3')
+
+    pktCnt += 1
+
+    # From v6 to v4
+    e6 = Ether(dst=MAC1, src=MAC2)
+    i6 = IPv6(dst = "2001:db8:42::a00:2a", src = "2001:db8:42::42")
+    u6 = UDP(dport=5000, sport=2345)
+    p6 = 500 * "A"
+    pkg6 = e6 / i6 / u6 / p6
+
+    e4 = e6
+    i4 = IP(dst = "10.0.0.42", src = "10.0.0.66")
+    u4 = u6
+    p4 = p6
+    pkg4 = e4 / i4 / u4 / p4
+
+    applyPkt(pkt6, "nf3", pktCnt)
+    expPkt(pkt4,   'nf2')
+
+
+test_nat64()
+write_pcap_files()