diff --git a/common/streambase.cpp b/common/streambase.cpp
index 0333eb9..7977c8a 100644
--- a/common/streambase.cpp
+++ b/common/streambase.cpp
@@ -444,6 +444,27 @@ _exit:
     return true;
 }
 
+int StreamBase::frameSizeVariableCount() const
+{
+    int count = 1;
+
+    switch(lenMode())
+    {
+        case OstProto::StreamCore::e_fl_fixed:
+            break;
+        case OstProto::StreamCore::e_fl_inc:
+        case OstProto::StreamCore::e_fl_dec:
+        case OstProto::StreamCore::e_fl_random:
+            count = frameLenMax() - frameLenMin() + 1;
+            break;
+        default:
+            qWarning("%s: Unhandled len mode %d",  __FUNCTION__, lenMode());
+            break;
+    }
+
+    return count;
+}
+
 int StreamBase::frameVariableCount() const
 {
     ProtocolListIterator    *iter;
@@ -466,7 +487,7 @@ int StreamBase::frameVariableCount() const
     }
     delete iter;
 
-    return frameCount;
+    return AbstractProtocol::lcm(frameCount, frameSizeVariableCount());
 }
 
 // frameProtocolLength() returns the sum of all the individual protocol sizes
diff --git a/common/streambase.h b/common/streambase.h
index 9ef3ba1..11ac2c2 100644
--- a/common/streambase.h
+++ b/common/streambase.h
@@ -138,6 +138,7 @@ public:
 
     bool isFrameVariable() const;
     bool isFrameSizeVariable() const;
+    int frameSizeVariableCount() const;
     int frameVariableCount() const;
     int frameProtocolLength(int frameIndex) const;
     int frameCount() const;
diff --git a/test/pktlentest.py b/test/pktlentest.py
new file mode 100644
index 0000000..8b4f0ad
--- /dev/null
+++ b/test/pktlentest.py
@@ -0,0 +1,214 @@
+#! /usr/bin/env python
+
+# standard modules
+import logging
+import os
+import pytest
+import subprocess
+import sys
+import time
+
+from harness import extract_column
+
+sys.path.insert(1, '../binding')
+from core import ost_pb, DroneProxy
+from rpc import RpcError
+#from protocols.mac_pb2 import mac
+#from protocols.payload_pb2 import payload, Payload
+
+# initialize defaults
+host_name = '127.0.0.1'
+tx_number = -1
+rx_number = -1
+
+if sys.platform == 'win32':
+    tshark = r'C:\Program Files\Wireshark\tshark.exe'
+else:
+    tshark = 'tshark'
+
+fmt = 'column.format:"Packet#","%m","Time","%t","Source","%uns","Destination","%und","Protocol","%p","Size","%L","Info","%i","Expert","%a"'
+fmt_col = 7 # col# in fmt for Size/PktLength
+
+# setup protocol number dictionary
+proto_number = {}
+proto_number['mac'] = ost_pb.Protocol.kMacFieldNumber
+proto_number['eth2'] = ost_pb.Protocol.kEth2FieldNumber
+proto_number['ip4'] = ost_pb.Protocol.kIp4FieldNumber
+proto_number['udp'] = ost_pb.Protocol.kUdpFieldNumber
+proto_number['payload'] = ost_pb.Protocol.kPayloadFieldNumber
+
+# setup logging
+log = logging.getLogger(__name__)
+logging.basicConfig(level=logging.INFO)
+
+print('')
+print('This test uses the following topology -')
+print('')
+print(' +-------+           ')
+print(' |       |Tx--->----+')
+print(' | Drone |          |')
+print(' |       |Rx---<----+')
+print(' +-------+           ')
+print('')
+print('A loopback port is used as both the Tx and Rx ports')
+print('')
+
+@pytest.fixture(scope='module')
+def drone(request):
+    """Baseline Configuration for all testcases in this module"""
+
+    dut = DroneProxy(host_name)
+
+    log.info('connecting to drone(%s:%d)' % (dut.hostName(), dut.portNumber()))
+    dut.connect()
+
+    def fin():
+        dut.disconnect()
+
+    request.addfinalizer(fin)
+
+    return dut
+
+@pytest.fixture(scope='module')
+def ports(request, drone):
+    # retreive port id list
+    log.info('retreiving port list')
+    port_id_list = drone.getPortIdList()
+
+    # retreive port config list
+    log.info('retreiving port config for all ports')
+    port_config_list = drone.getPortConfig(port_id_list)
+
+    if len(port_config_list.port) == 0:
+        log.warning('drone has no ports!')
+        sys.exit(1)
+
+    # iterate port list to find a loopback port to use as the tx/rx port id
+    print('Port List')
+    print('---------')
+    for port in port_config_list.port:
+        print('%d.%s (%s)' % (port.port_id.id, port.name, port.description))
+        # use a loopback port as default tx/rx port
+        if ('lo' in port.name or 'loopback' in port.description.lower()):
+            tx_number = port.port_id.id
+            rx_number = port.port_id.id
+
+    if tx_number < 0 or rx_number < 0:
+        log.warning('loopback port not found')
+        sys.exit(1)
+
+    print('Using port %d as tx/rx port(s)' % tx_number)
+
+    ports.tx = ost_pb.PortIdList()
+    ports.tx.port_id.add().id = tx_number;
+
+    ports.rx = ost_pb.PortIdList()
+    ports.rx.port_id.add().id = rx_number;
+
+    # delete existing streams, if any, on tx port
+    sid_list = drone.getStreamIdList(ports.tx.port_id[0])
+    drone.deleteStream(sid_list)
+
+    return ports
+
+protolist=['mac eth2 ip4 udp payload', 'mac eth2 ip4 udp']
+@pytest.fixture(scope='module', params=protolist)
+def stream(request, drone, ports):
+    global proto_number
+
+    # add a stream
+    stream_id = ost_pb.StreamIdList()
+    stream_id.port_id.CopyFrom(ports.tx.port_id[0])
+    stream_id.stream_id.add().id = 1
+    log.info('adding tx_stream %d' % stream_id.stream_id[0].id)
+    drone.addStream(stream_id)
+
+    # configure the stream
+    stream_cfg = ost_pb.StreamConfigList()
+    stream_cfg.port_id.CopyFrom(ports.tx.port_id[0])
+    s = stream_cfg.stream.add()
+    s.stream_id.id = stream_id.stream_id[0].id
+    s.core.is_enabled = True
+    s.control.packets_per_sec = 100
+    s.control.num_packets = 10
+
+    # setup stream protocols as mac:eth2:ip:udp:payload
+    s.ClearField("protocol")
+    protos = request.param.split()
+    for p in protos:
+        s.protocol.add().protocol_id.id = proto_number[p]
+
+    def fin():
+        # delete streams
+        log.info('deleting tx_stream %d' % stream_id.stream_id[0].id)
+        drone.deleteStream(stream_id)
+
+    request.addfinalizer(fin)
+
+    return stream_cfg
+
+@pytest.mark.parametrize("mode", [
+    ost_pb.StreamCore.e_fl_inc,
+    ost_pb.StreamCore.e_fl_dec,
+    ost_pb.StreamCore.e_fl_random
+])
+def test_packet_length(drone, ports, stream, mode):
+    """ Test random length packets """
+
+    min_pkt_len = 100
+    max_pkt_len = 1000
+    stream.stream[0].core.len_mode = mode
+    stream.stream[0].core.frame_len_min = min_pkt_len
+    stream.stream[0].core.frame_len_max = max_pkt_len
+
+    log.info('configuring tx_stream %d' % stream.stream[0].stream_id.id)
+    drone.modifyStream(stream)
+
+    # clear tx/rx stats
+    log.info('clearing tx/rx stats')
+    drone.clearStats(ports.tx)
+    drone.clearStats(ports.rx)
+
+    try:
+        drone.startCapture(ports.rx)
+        drone.startTransmit(ports.tx)
+        log.info('waiting for transmit to finish ...')
+        time.sleep(3)
+        drone.stopTransmit(ports.tx)
+        drone.stopCapture(ports.rx)
+
+        log.info('getting Rx capture buffer')
+        buff = drone.getCaptureBuffer(ports.rx.port_id[0])
+        drone.saveCaptureBuffer(buff, 'capture.pcap')
+        log.info('dumping Rx capture buffer')
+        cap_pkts = subprocess.check_output([tshark, '-n', '-r', 'capture.pcap',
+                        '-R', 'udp'])
+        cap_pkts = subprocess.check_output([tshark, '-n', '-r', 'capture.pcap',
+                        '-R', 'udp', '-o', fmt])
+        print(cap_pkts)
+        result = extract_column(cap_pkts, fmt_col)
+        diffSum = 0
+        for i in range(len(result)):
+            l = int(result[i]) + 4 # add FCS to length
+            assert (l >= min_pkt_len) and (l <= max_pkt_len)
+
+            # check current packet length to last
+            if (i > 0):
+                ll = int(result[i-1]) + 4
+                if mode == ost_pb.StreamCore.e_fl_inc:
+                    assert l == (ll+1)
+                elif mode == ost_pb.StreamCore.e_fl_dec:
+                    assert l == (ll-1)
+                elif mode == ost_pb.StreamCore.e_fl_random:
+                    diffSum += (l-ll)
+
+        # TODO: find a better way to check for randomness
+        if mode == ost_pb.StreamCore.e_fl_random:
+            assert (diffSum % (len(result) - 1)) != 0
+
+        os.remove('capture.pcap')
+    except RpcError as e:
+            raise
+    finally:
+        drone.stopTransmit(ports.tx)
+
diff --git a/test/pytest.ini b/test/pytest.ini
new file mode 100644
index 0000000..015c471
--- /dev/null
+++ b/test/pytest.ini
@@ -0,0 +1,3 @@
+[pytest]
+; change file glob pattern after converting old test files to pytest
+python_files=pktlentest.py