Merge remote-tracking branch 'origin/master'

18 files changed, 713 insertions, 287 deletions

diff --git a/scripts/automation/regression/functional_tests/scapy_pkt_builder_test.py b/scripts/automation/regression/functional_tests/scapy_pkt_builder_test.py
index a3fcd091..5d34e5df 100644
--- a/scripts/automation/regression/functional_tests/scapy_pkt_builder_test.py
+++ b/scripts/automation/regression/functional_tests/scapy_pkt_builder_test.py
@@ -238,7 +238,8 @@ class CTRexPktBuilderSanitySCapy_Test(pkt_bld_general_test.CGeneralPktBld_Test):
     
             d= pkt_builder.get_vm_data()
         except  CTRexPacketBuildException as e:
-            assert_equal(str(e), "[errcode:-11] 'variable my_valn_err does not exists  '")
+            error=str(e) 
+            assert_equal(error.find("[errcode:-11]"),0);
 
     def test_simple_tuple_gen(self):
         vm = STLScVmRaw( [ STLVmTupleGen(name="tuple"), # define tuple gen 
diff --git a/scripts/automation/regression/stateless_tests/stl_client_test.py b/scripts/automation/regression/stateless_tests/stl_client_test.py
new file mode 100644
index 00000000..132109c0
--- /dev/null
+++ b/scripts/automation/regression/stateless_tests/stl_client_test.py
@@ -0,0 +1,274 @@
+#!/router/bin/python
+from stl_general_test import CStlGeneral_Test, CTRexScenario
+from trex_stl_lib.api import *
+import os, sys
+import glob
+
+
+def get_error_in_percentage (golden, value):
+    return abs(golden - value) / float(golden)
+
+def get_stl_profiles ():
+    profiles_path = os.path.join(CTRexScenario.scripts_path, 'stl/')
+    profiles = glob.glob(profiles_path + "/*.py") + glob.glob(profiles_path + "yaml/*.yaml")
+
+    return profiles
+
+
+class STLClient_Test(CStlGeneral_Test):
+    """Tests for stateless client"""
+
+    def setUp(self):
+        CStlGeneral_Test.setUp(self)
+        
+        assert 'bi' in CTRexScenario.stl_ports_map
+
+        self.c = CTRexScenario.stl_trex
+
+        self.tx_port, self.rx_port = CTRexScenario.stl_ports_map['bi'][0]
+
+        self.c.connect()
+        self.c.reset(ports = [self.tx_port, self.rx_port])
+
+        self.pkt = STLPktBuilder(pkt = Ether()/IP(src="16.0.0.1",dst="48.0.0.1")/UDP(dport=12,sport=1025)/IP()/'a_payload_example')
+        self.profiles = get_stl_profiles()
+
+
+    @classmethod
+    def tearDownClass(cls):
+        # connect back at end of tests
+        if not cls.is_connected():
+            CTRexScenario.stl_trex.connect()
+
+
+    def test_basic_connect_disconnect (self):
+        try:
+            self.c.connect()
+            assert self.c.is_connected(), 'client should be connected'
+            self.c.disconnect()
+            assert not self.c.is_connected(), 'client should be disconnected'
+
+        except STLError as e:
+            assert False , '{0}'.format(e)
+  
+
+    def test_basic_single_burst (self):
+        try:                              
+            b1 = STLStream(name = 'burst',
+                           packet = self.pkt,
+                           mode = STLTXSingleBurst(total_pkts = 100,
+                                                   pps = 1000)
+                           )
+
+            for i in range(0, 5):
+                self.c.add_streams([b1], ports = [self.tx_port, self.rx_port])
+
+                self.c.clear_stats()
+                self.c.start(ports = [self.tx_port, self.rx_port])
+
+                assert self.c.ports[self.tx_port].is_transmitting(), 'port should be active'
+                assert self.c.ports[self.rx_port].is_transmitting(), 'port should be active'
+
+                self.c.wait_on_traffic(ports = [self.tx_port, self.rx_port])
+                stats = self.c.get_stats()
+
+                assert self.tx_port in stats
+                assert self.rx_port in stats
+
+                assert stats[self.tx_port]['opackets'] == 100
+                assert stats[self.rx_port]['ipackets'] == 100
+
+                assert stats[self.rx_port]['opackets'] == 100
+                assert stats[self.tx_port]['ipackets'] == 100
+
+                self.c.remove_all_streams(ports = [self.tx_port, self.rx_port])
+
+
+
+        except STLError as e:
+            assert False , '{0}'.format(e)
+
+
+    #
+    def test_basic_multi_burst (self):
+        try:
+            b1 = STLStream(name = 'burst',
+                           packet = self.pkt,
+                           mode = STLTXMultiBurst(pkts_per_burst = 10,
+                                                  count =  20,
+                                                  pps = 1000)
+                           )
+
+            for i in range(0, 5):
+                self.c.add_streams([b1], ports = [self.tx_port, self.rx_port])
+
+                self.c.clear_stats()
+                self.c.start(ports = [self.tx_port, self.rx_port])
+
+                assert self.c.ports[self.tx_port].is_transmitting(), 'port should be active'
+                assert self.c.ports[self.rx_port].is_transmitting(), 'port should be active'
+
+                self.c.wait_on_traffic(ports = [self.tx_port, self.rx_port])
+                stats = self.c.get_stats()
+
+                assert self.tx_port in stats
+                assert self.rx_port in stats
+
+                assert stats[self.tx_port]['opackets'] == 200
+                assert stats[self.rx_port]['ipackets'] == 200
+
+                assert stats[self.rx_port]['opackets'] == 200
+                assert stats[self.tx_port]['ipackets'] == 200
+
+                self.c.remove_all_streams(ports = [self.tx_port, self.rx_port])
+
+
+
+        except STLError as e:
+            assert False , '{0}'.format(e)
+
+
+    #
+    def test_basic_cont (self):
+        pps = 49182
+        duration = 0.1
+        golden = pps * duration
+
+        try:
+            b1 = STLStream(name = 'burst',
+                           packet = self.pkt,
+                           mode = STLTXCont(pps = pps)
+                           )
+
+            for i in range(0, 5):
+                self.c.add_streams([b1], ports = [self.tx_port, self.rx_port])
+
+                self.c.clear_stats()
+                self.c.start(ports = [self.tx_port, self.rx_port], duration = duration)
+
+                assert self.c.ports[self.tx_port].is_transmitting(), 'port should be active'
+                assert self.c.ports[self.rx_port].is_transmitting(), 'port should be active'
+
+                self.c.wait_on_traffic(ports = [self.tx_port, self.rx_port])
+                stats = self.c.get_stats()
+
+                assert self.tx_port in stats
+                assert self.rx_port in stats
+
+                # cont. with duration should be quite percise - 5% error is relaxed enough
+                assert get_error_in_percentage(stats[self.tx_port]['opackets'], golden) < 0.05
+                assert get_error_in_percentage(stats[self.rx_port]['ipackets'], golden) < 0.05
+
+                assert get_error_in_percentage(stats[self.rx_port]['opackets'], golden) < 0.05
+                assert get_error_in_percentage(stats[self.tx_port]['ipackets'], golden) < 0.05
+
+
+                self.c.remove_all_streams(ports = [self.tx_port, self.rx_port])
+
+
+
+        except STLError as e:
+            assert False , '{0}'.format(e)
+
+
+    def test_stress_connect_disconnect (self):
+        try:
+            for i in range(0, 100):
+                self.c.connect()
+                assert self.c.is_connected(), 'client should be connected'
+                self.c.disconnect()
+                assert not self.c.is_connected(), 'client should be disconnected'
+
+
+        except STLError as e:
+            assert False , '{0}'.format(e)
+
+
+
+    def test_stress_tx (self):
+        try:
+            s1 = STLStream(name = 'stress',
+                           packet = self.pkt,
+                           mode = STLTXCont(percentage = 60))
+
+            # add both streams to ports
+            self.c.add_streams([s1], ports = [self.tx_port, self.rx_port])
+            for i in range(0, 100):
+
+                self.c.start(ports = [self.tx_port, self.rx_port])
+
+                assert self.c.ports[self.tx_port].is_transmitting(), 'port should be active'
+                assert self.c.ports[self.rx_port].is_transmitting(), 'port should be active'
+
+                self.c.pause(ports = [self.tx_port, self.rx_port])
+
+                assert self.c.ports[self.tx_port].is_paused(), 'port should be paused'
+                assert self.c.ports[self.rx_port].is_paused(), 'port should be paused'
+
+                self.c.resume(ports = [self.tx_port, self.rx_port])
+
+                assert self.c.ports[self.tx_port].is_transmitting(), 'port should be active'
+                assert self.c.ports[self.rx_port].is_transmitting(), 'port should be active'
+
+                self.c.stop(ports = [self.tx_port, self.rx_port])
+
+                assert not self.c.ports[self.tx_port].is_active(), 'port should be idle'
+                assert not self.c.ports[self.rx_port].is_active(), 'port should be idle'
+
+        except STLError as e:
+            assert False , '{0}'.format(e)
+
+
+    def test_all_profiles (self):
+
+        if self.is_virt_nics or not self.is_loopback:
+            print("skipping for non loopback / virtual")
+            return
+
+        try:
+            self.c.set_port_attr(ports = [self.tx_port, self.rx_port], promiscuous = True)
+
+            for profile in self.profiles:
+                print("now testing profile {0}...\n").format(profile)
+
+                p1 = STLProfile.load(profile, port_id = self.tx_port)
+                p2 = STLProfile.load(profile, port_id = self.rx_port)
+
+                if p1.has_flow_stats():
+                    print("profile needs RX caps - skipping...")
+                    continue
+
+                self.c.add_streams(p1, ports = self.tx_port)
+                self.c.add_streams(p2, ports = self.rx_port)
+
+                self.c.clear_stats()
+
+                self.c.start(ports = [self.tx_port, self.rx_port], mult = "30%")
+                time.sleep(100 / 1000.0)
+
+                if p1.is_pauseable() and p2.is_pauseable():
+                    self.c.pause(ports = [self.tx_port, self.rx_port])
+                    time.sleep(100 / 1000.0)
+
+                    self.c.resume(ports = [self.tx_port, self.rx_port])
+                    time.sleep(100 / 1000.0)
+
+                self.c.stop(ports = [self.tx_port, self.rx_port])
+
+                stats = self.c.get_stats()
+
+                assert self.tx_port in stats, '{0} - no stats for TX port'.format(profile)
+                assert self.rx_port in stats, '{0} - no stats for RX port'.format(profile)
+
+                assert stats[self.tx_port]['opackets'] == stats[self.rx_port]['ipackets'], '{0} - number of TX packets differ from RX packets'.format(profile)
+
+                assert stats[self.rx_port]['opackets'] == stats[self.tx_port]['ipackets'], '{0} - number of TX packets differ from RX packets'.format(profile)
+
+                self.c.remove_all_streams(ports = [self.tx_port, self.rx_port])
+
+        except STLError as e:
+            assert False , '{0}'.format(e)
+
+
+        finally:
+            self.c.set_port_attr(ports = [self.tx_port, self.rx_port], promiscuous = False)
diff --git a/scripts/automation/trex_control_plane/doc_stl/api/client_code.rst b/scripts/automation/trex_control_plane/doc_stl/api/client_code.rst
index 8736e98d..4ae2b9fd 100644..100755
--- a/scripts/automation/trex_control_plane/doc_stl/api/client_code.rst
+++ b/scripts/automation/trex_control_plane/doc_stl/api/client_code.rst
@@ -2,16 +2,26 @@
 Client Module 
 ==================
 
-TRex Client is an object to access TRex server. It is per user. Each user can own number of interfaces. 
-Multi user can interact with one TRex server each user should own a different set of interfaces.
+The TRex Client provides access to the TRex server.
+
+**Client and interfaces**
+
+Multiple users can interact with one TRex server. Each user "owns" a different set of interfaces.
 The protocol is JSON-RPC2 over ZMQ transport.
 
-The API has two type of API 
+In addition to the Python API, a console-based API interface is also available.
+
+Python-like example::
+    
+   c.start(ports = [0, 1], mult = "5mpps", duration = 10)
+   
+Console-like example::
+
+  c.start_line (" -f stl/udp_1pkt_simple.py -m 10mpps --port 0 1 ")
 
-1. Normal API 
-2. xx_line:  this api get a line like the Console and parse it and call the low level api 
 
-Example1::
+
+Example 1 - Typical Python API::
 
     c = STLClient(username = "itay",server = "10.0.0.10", verbose_level = LoggerApi.VERBOSE_HIGH)
 
@@ -49,7 +59,8 @@ STLClient snippet
 -----------------
 
 
-Example1::
+.. code-block:: python
+    :caption: Example 1: Minimal example of client interacting with the TRex server
 
     c = STLClient()
 
@@ -75,8 +86,9 @@ Example1::
         c.disconnect()
 
 
+.. code-block:: python
+    :caption: Example 2: Client can execute other functions while the TRex server is generating traffic
 
-Example2: wait while doing somthing::
 
     c = STLClient()
     try:
@@ -99,7 +111,10 @@ Example2: wait while doing somthing::
         c.disconnect()
 
 
-Example3: Console like::
+
+.. code-block:: python
+    :caption: Example 3: Console-like API interface
+
 
         def simple ():
         
@@ -148,7 +163,8 @@ Example3: Console like::
             finally:
                 c.disconnect()
 
-Example4: Load profile from a file::
+
+Example 4: Load profile from a file::
 
   def simple ():
 
diff --git a/scripts/automation/trex_control_plane/doc_stl/api/field_engine.rst b/scripts/automation/trex_control_plane/doc_stl/api/field_engine.rst
index d134b0b9..541e195f 100644..100755
--- a/scripts/automation/trex_control_plane/doc_stl/api/field_engine.rst
+++ b/scripts/automation/trex_control_plane/doc_stl/api/field_engine.rst
@@ -2,19 +2,19 @@
 Field Engine modules 
 =======================
 
-The Field Engine (FE) has limited number of instructions/operation for supporting most use cases. 
+The Field Engine (FE) has limited number of instructions/operations to support most use cases. 
 There is a plan to add LuaJIT to be more flexible at the cost of performance.
-The FE can allocate stream variables in a Stream context, write a stream variable to a packet offset, change packet size,  etc.
+The FE can allocate stream variables in a stream context, write a stream variable to a packet offset, change packet size, and so on.
 
-*Some examples for what can be done:*
+*Examples of Field Engine uses:*
 
 * Change ipv4.tos 1-10
-* Change packet size to be random in the range 64-9K
-* Create range of flows (change src_ip, dest_ip, src_port, dest_port) 
+* Change packet size to a random value in the range 64 to 9K
+* Create a range of flows (change src_ip, dest_ip, src_port, dest_port) 
 * Update IPv4 checksum 
 
 
-Snippet will create SYN Attack::
+The following snippet creates a SYN attack::
 
     # create attack from random src_ip from 16.0.0.0-18.0.0.254 and random src_port 1025-65000    
     # attack 48.0.0.1 server 
@@ -60,7 +60,7 @@ Snippet will create SYN Attack::
 STLScVmRaw class
 ----------------
 
-Aggregate a raw instructions objects 
+Aggregate raw instructions objects 
 
 .. autoclass:: trex_stl_lib.trex_stl_packet_builder_scapy.STLScVmRaw
     :members: 
diff --git a/scripts/automation/trex_control_plane/doc_stl/api/index.rst b/scripts/automation/trex_control_plane/doc_stl/api/index.rst
index a3c8ad5a..a3c8ad5a 100644..100755
--- a/scripts/automation/trex_control_plane/doc_stl/api/index.rst
+++ b/scripts/automation/trex_control_plane/doc_stl/api/index.rst
diff --git a/scripts/automation/trex_control_plane/doc_stl/api/profile_code.rst b/scripts/automation/trex_control_plane/doc_stl/api/profile_code.rst
index b61f05e4..9afa9df2 100644..100755
--- a/scripts/automation/trex_control_plane/doc_stl/api/profile_code.rst
+++ b/scripts/automation/trex_control_plane/doc_stl/api/profile_code.rst
@@ -2,13 +2,13 @@
 Traffic profile modules 
 =======================
 
-TRex STLProfile profile include a list of STLStream. The profile is a ``program`` of streams with a relation betwean the streams.
-Each stream can trigger another stream. Stream can be given a name for a full examples see here Manual_.
+The TRex STLProfile traffic profile includes a number of streams. The profile is a ``program`` of related streams.
+Each stream can trigger another stream. Each stream can be named. For a full set of examples, see Manual_.
 
-..   _Manual: ../draft_trex_stateless1.html
+..   _Manual: ../trex_stateless.html
 
 
-for example::
+Example::
 
     def create_stream (self):
 
diff --git a/scripts/automation/trex_control_plane/doc_stl/api/scapy_builder.rst b/scripts/automation/trex_control_plane/doc_stl/api/scapy_builder.rst
index 5544df63..2c5790bf 100644..100755
--- a/scripts/automation/trex_control_plane/doc_stl/api/scapy_builder.rst
+++ b/scripts/automation/trex_control_plane/doc_stl/api/scapy_builder.rst
@@ -2,15 +2,15 @@
 Packet builder modules 
 =======================
 
-The packet builder module objective is to build a template packet for a stream and to create a Field engine program to change fields in the packet.
+The packet builder module is used for building a template packet for a stream, and creating a Field Engine program to change fields in the packet.
 
-**Some examples for what can be done:**
+**Examples:**
 
-* Build a IP/UDP/DNS packet and create a range of src_ip = 10.0.0.1-10.0.0.255
-* Build a IP/UDP packets in IMIX sizes 
+* Build a IP/UDP/DNS packet with a src_ip range of 10.0.0.1 to 10.0.0.255
+* Build IP/UDP packets in IMIX sizes 
 
 
-for example this snippet will create SYN Attack::
+For example, this snippet creates a SYN attack::
 
     # create attack from random src_ip from 16.0.0.0-18.0.0.254 and random src_port 1025-65000    
     # attack 48.0.0.1 server 
diff --git a/scripts/automation/trex_control_plane/doc_stl/conf.py b/scripts/automation/trex_control_plane/doc_stl/conf.py
index fe6b27bc..45738b6e 100644
--- a/scripts/automation/trex_control_plane/doc_stl/conf.py
+++ b/scripts/automation/trex_control_plane/doc_stl/conf.py
@@ -69,7 +69,7 @@ author = u'TRex team, Cisco Systems Inc.'
 # The short X.Y version.
 version = '1.94'
 # The full version, including alpha/beta/rc tags.
-release = '1.7.1'
+release = '2.0'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/scripts/automation/trex_control_plane/doc_stl/index.rst b/scripts/automation/trex_control_plane/doc_stl/index.rst
index 97a1037a..aa2abd75 100644
--- a/scripts/automation/trex_control_plane/doc_stl/index.rst
+++ b/scripts/automation/trex_control_plane/doc_stl/index.rst
@@ -20,19 +20,23 @@ How to Install
 | Put it at any place you like, preferably same place as your scripts.
 | (If it's not at same place as your scripts, you will need to ensure trex_client directory is in sys.path)
 
-Un-pack it using command: tar -xzf trex_client.tar.gz
+Un-pack it using command::
 
-How to pyATS/v2.0
+ tar -xzf trex_client.tar.gz
+ 
+
+How to pyATS
 ==================
 
 .. sectionauthor:: David Shen 
 
 pyATS Compatibility 
 
-Trex only supports python2 for now, so it only works for **Python2** pyats.
+TRex supports both Python2 and Python3 pyATS.
      
-* Install python2 pyats
+* Install python2/python3 pyats
   	/auto/pyats/bin/pyats-install --python2
+  	/auto/pyats/bin/pyats-install --python3
 
 * setenv TREX_PATH to the trex stateless lib path 
    	setenv TREX_PATH <your path>/automation/trex_control_plane/stl
diff --git a/scripts/automation/trex_control_plane/stl/examples/stl_imix.py b/scripts/automation/trex_control_plane/stl/examples/stl_imix.py
index 17e017a9..bc7990aa 100644
--- a/scripts/automation/trex_control_plane/stl/examples/stl_imix.py
+++ b/scripts/automation/trex_control_plane/stl/examples/stl_imix.py
@@ -17,6 +17,7 @@ def imix_test (server, mult):
 
     # create client
     c = STLClient(server = server)
+    
     passed = True
 
 
@@ -27,6 +28,7 @@ def imix_test (server, mult):
 
         # take all the ports
         c.reset()
+        
 
         # map ports - identify the routes
         table = stl_map_ports(c)
diff --git a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_client.py b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_client.py
index 6fdc3454..7fbd2808 100644..100755
--- a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_client.py
+++ b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_client.py
@@ -40,15 +40,15 @@ class LoggerApi(object):
 
     # implemented by specific logger
     def write(self, msg, newline = True):
-        raise Exception("implement this")
+        raise Exception("Implement this")
 
     # implemented by specific logger
     def flush(self):
-        raise Exception("implement this")
+        raise Exception("Implement this")
 
     def set_verbose (self, level):
         if not level in range(self.VERBOSE_QUIET, self.VERBOSE_HIGH + 1):
-            raise ValueError("bad value provided for logger")
+            raise ValueError("Bad value provided for logger")
 
         self.level = level
 
@@ -146,7 +146,7 @@ class AsyncEventHandler(object):
 
     def on_async_dead (self):
         if self.client.connected:
-            msg = 'lost connection to server'
+            msg = 'Lost connection to server'
             self.__add_event_log(msg, 'local', True)
             self.client.connected = False
 
@@ -319,7 +319,7 @@ class AsyncEventHandler(object):
 ############################                   #############################
 
 class CCommLink(object):
-    """describes the connectivity of the stateless client method"""
+    """Describes the connectivity of the stateless client method"""
     def __init__(self, server="localhost", port=5050, virtual=False, prn_func = None):
         self.virtual = virtual
         self.server = server
@@ -380,7 +380,7 @@ class CCommLink(object):
 ############################                #############################
 
 class STLClient(object):
-    """TRex Stateless client object- gives operations per TRex/user"""
+    """TRex Stateless client object - gives operations per TRex/user"""
 
     def __init__(self,
                  username = common.get_current_user(),
@@ -391,7 +391,7 @@ class STLClient(object):
                  logger = None,
                  virtual = False):
         """ 
-        Set the connection setting 
+        Configure the connection settings 
 
         :parameters:
              username : string 
@@ -496,11 +496,11 @@ class STLClient(object):
             port_id_list = [port_id_list]
 
         if not isinstance(port_id_list, list):
-             raise ValueError("bad port id list: {0}".format(port_id_list))
+             raise ValueError("Bad port id list: {0}".format(port_id_list))
 
         for port_id in port_id_list:
             if not isinstance(port_id, int) or (port_id < 0) or (port_id > self.get_port_count()):
-                raise ValueError("bad port id {0}".format(port_id))
+                raise ValueError("Bad port id {0}".format(port_id))
 
         return port_id_list
 
@@ -727,7 +727,7 @@ class STLClient(object):
 
         
         # connect async channel
-        self.logger.pre_cmd("connecting to publisher server on {0}:{1}".format(self.connection_info['server'], self.connection_info['async_port']))
+        self.logger.pre_cmd("Connecting to publisher server on {0}:{1}".format(self.connection_info['server'], self.connection_info['async_port']))
         rc = self.async_client.connect()
         self.logger.post_cmd(rc)
 
@@ -765,7 +765,7 @@ class STLClient(object):
         if clear_flow_stats:
             self.flow_stats.clear_stats()
 
-        self.logger.log_cmd("clearing stats on port(s) {0}:".format(port_id_list))
+        self.logger.log_cmd("Clearing stats on port(s) {0}:".format(port_id_list))
 
         return RC
 
@@ -852,8 +852,26 @@ class STLClient(object):
         return RC_OK()
 
 
- 
- 
+    # remove all RX filters in a safe manner
+    def _remove_rx_filters (self, ports, rx_delay_ms):
+
+        # get the enabled RX ports
+        rx_ports = [port_id for port_id in ports if self.ports[port_id].has_rx_enabled()]
+
+        if not rx_ports:
+            return RC_OK()
+
+        # block while any RX configured port has not yet have it's delay expired
+        while any([not self.ports[port_id].has_rx_delay_expired(rx_delay_ms) for port_id in rx_ports]):
+            time.sleep(0.01)
+
+        # remove RX filters
+        rc = RC()
+        for port_id in rx_ports:
+            rc.add(self.ports[port_id].remove_rx_filters())
+
+        return rc
+
 
     #################################
     # ------ private methods ------ #
@@ -914,13 +932,13 @@ class STLClient(object):
     # return verbose level of the logger
     def get_verbose (self):
         """ 
-        get the verbose mode  
+        Get the verbose mode  
 
         :parameters:
           none
 
         :return:
-            get the verbose mode as Bool
+            Get the verbose mode as Bool
 
         :raises:
           None
@@ -934,10 +952,10 @@ class STLClient(object):
          is_all_ports_acquired
 
         :parameters:
-          none
+          None
 
         :return:
-            return  True if all ports are acquired
+            Returns True if all ports are acquired
 
         :raises:
           None
@@ -951,7 +969,7 @@ class STLClient(object):
         """ 
 
         :parameters:
-          none
+          None
 
         :return:
             is_connected
@@ -969,10 +987,10 @@ class STLClient(object):
         """ 
 
         :parameters:
-          none
+          None
 
         :return:
-            connection dict 
+            Connection dict 
 
         :raises:
           None
@@ -987,10 +1005,10 @@ class STLClient(object):
         """ 
 
         :parameters:
-          none
+          None
 
         :return:
-            connection dict 
+            Connection dict 
 
         :raises:
           None
@@ -1004,10 +1022,10 @@ class STLClient(object):
         """ 
 
         :parameters:
-          none
+          None
 
         :return:
-            connection dict 
+            Connection dict 
 
         :raises:
           None
@@ -1021,10 +1039,10 @@ class STLClient(object):
         """ 
 
         :parameters:
-          none
+          None
 
         :return:
-            connection dict 
+            Connection dict 
 
         :raises:
           None
@@ -1038,10 +1056,10 @@ class STLClient(object):
         """ 
 
         :parameters:
-          none
+          None
 
         :return:
-            connection dict 
+            Connection dict 
 
         :raises:
           None
@@ -1065,10 +1083,10 @@ class STLClient(object):
         """ 
 
         :parameters:
-          none
+          None
 
         :return:
-            connection dict 
+            Connection dict 
 
         :raises:
           None
@@ -1089,6 +1107,7 @@ class STLClient(object):
                 for port_id, port_obj in self.ports.items()
                 if port_obj.is_active()]
 
+
     # get paused ports
     def get_paused_ports (self):
         return [port_id
@@ -1189,9 +1208,9 @@ class STLClient(object):
 
             :parameters:
                 stop_traffic : bool
-                    tries to stop traffic before disconnecting
+                    Attempts to stop traffic before disconnecting.
                 release_ports : bool
-                    tries to release all the acquired ports
+                    Attempts to release all the acquired ports.
 
         """
 
@@ -1217,9 +1236,9 @@ class STLClient(object):
 
             :parameters:
                 ports : list
-                    ports to execute the command
+                    Ports on which to execute the command
                 force : bool
-                    force acquire the ports
+                    Force acquire the ports.
 
             :raises:
                 + :exc:`STLError`
@@ -1252,7 +1271,7 @@ class STLClient(object):
 
             :parameters:
                 ports : list
-                    ports to execute the command
+                    Ports on which to execute the command
 
             :raises:
                 + :exc:`STLError`
@@ -1295,7 +1314,7 @@ class STLClient(object):
     @__api_check(True)
     def get_active_pgids(self):
         """
-            Get active group ids
+            Get active group IDs
 
             :parameters:
                 None
@@ -1319,11 +1338,11 @@ class STLClient(object):
     @__api_check(True)
     def reset(self, ports = None):
         """
-            force acquire ports, stop the traffic, remove all streams and clear stats
+            Force acquire ports, stop the traffic, remove all streams and clear stats
 
             :parameters:
                 ports : list
-                   ports to execute the command
+                   Ports on which to execute the command
 
 
             :raises:
@@ -1336,7 +1355,7 @@ class STLClient(object):
         ports = self._validate_port_list(ports)
 
         self.acquire(ports, force = True)
-        self.stop(ports)
+        self.stop(ports, rx_delay_ms = 0)
         self.remove_all_streams(ports)
         self.clear_stats(ports)
 
@@ -1348,7 +1367,7 @@ class STLClient(object):
 
             :parameters:
                 ports : list
-                    ports to execute the command
+                    Ports on which to execute the command
 
 
             :raises:
@@ -1371,16 +1390,16 @@ class STLClient(object):
     @__api_check(True)
     def add_streams (self, streams, ports = None):
         """
-            add a list of streams to port(s)
+            Add a list of streams to port(s)
 
             :parameters:
                 ports : list
-                    ports to execute the command
+                    Ports on which to execute the command
                 streams: list
-                    streams to attach (or profile)
+                    Streams to attach (or profile)
 
             :returns:
-                list of stream IDs in order of the stream list
+                List of stream IDs in order of the stream list
 
             :raises:
                 + :exc:`STLError`
@@ -1416,13 +1435,13 @@ class STLClient(object):
     @__api_check(True)
     def remove_streams (self, stream_id_list, ports = None):
         """
-            remove a list of streams from ports
+            Remove a list of streams from ports
 
             :parameters:
                 ports : list
-                    ports to execute the command
+                    Ports on which to execute the command
                 stream_id_list: list
-                    stream id list to remove
+                    Stream id list to remove
 
 
             :raises:
@@ -1460,27 +1479,29 @@ class STLClient(object):
                duration = -1,
                total = False):
         """
-            start traffic on port(s)
+            Start traffic on port(s)
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
                 mult : str
-                    multiplier in a form of pps, bps, or line util in %
-                    examples: "5kpps", "10gbps", "85%", "32mbps"
+                    Multiplier in a form of pps, bps, or line util in %
+                    Examples: "5kpps", "10gbps", "85%", "32mbps"
 
                 force : bool
-                    imply stopping the port of active and also
-                    forces a profile that exceeds the L1 BW
+                    If the ports are not in stopped mode or do not have sufficient bandwidth for the traffic, determines whether to stop the current traffic and force start.
+                    True: Force start
+                    False: Do not force start
 
                 duration : int
-                    limit the run for time in seconds
-                    -1 means unlimited
+                    Limit the run time (seconds)
+                    -1 = unlimited
 
                 total : bool
-                    should the B/W be divided by the ports
-                    or duplicated for each
+                    Determines whether to divide the configured bandwidth among the ports, or to duplicate the bandwidth for each port.
+                    True: Divide bandwidth among the ports
+                    False: Duplicate
 
 
             :raises:
@@ -1535,13 +1556,20 @@ class STLClient(object):
 
     
     @__api_check(True)
-    def stop (self, ports = None):
+    def stop (self, ports = None, rx_delay_ms = 10):
         """
-            stop port(s)
+            Stop port(s)
 
             :parameters:
                 ports : list
-                    ports to execute the command
+                    Ports on which to execute the command
+
+                rx_delay_ms : int
+                    time to wait until RX filters are removed
+                    this value should reflect the time it takes
+                    packets which were transmitted to arrive
+                    to the destination.
+                    after this time the RX filters will be removed
 
             :raises:
                 + :exc:`STLError`
@@ -1561,27 +1589,35 @@ class STLClient(object):
         if not rc:
             raise STLError(rc)
 
+        # remove any RX filters
+        rc = self._remove_rx_filters(ports, rx_delay_ms = rx_delay_ms)
+        if not rc:
+            raise STLError(rc)
+
         
     @__api_check(True)
     def update (self, ports = None, mult = "1", total = False, force = False):
         """
-            update traffic on port(s)
+            Update traffic on port(s)
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
                 mult : str
-                    multiplier in a form of pps, bps, or line util in %
-                    and also with +/-
-                    examples: "5kpps+", "10gbps-", "85%", "32mbps", "20%+"
+                    Multiplier in a form of pps, bps, or line util in %
+                    Can also specify +/-
+                    Examples: "5kpps+", "10gbps-", "85%", "32mbps", "20%+"
 
                 force : bool
-                    forces a profile that exceeds the L1 BW
+                    If the ports are not in stopped mode or do not have sufficient bandwidth for the traffic, determines whether to stop the current traffic and force start.
+                    True: Force start
+                    False: Do not force start
 
                 total : bool
-                    should the B/W be divided by the ports
-                    or duplicated for each
+                    Determines whether to divide the configured bandwidth among the ports, or to duplicate the bandwidth for each port.
+                    True: Divide bandwidth among the ports
+                    False: Duplicate
 
 
             :raises:
@@ -1619,11 +1655,11 @@ class STLClient(object):
     @__api_check(True)
     def pause (self, ports = None):
         """
-            pause traffic on port(s). works only for ports that are active and all streams are in cont mode 
+            Pause traffic on port(s). Works only for ports that are active, and only if all streams are in Continuous mode.
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
             :raises:
                 + :exc:`STLError`
@@ -1644,11 +1680,11 @@ class STLClient(object):
     @__api_check(True)
     def resume (self, ports = None):
         """
-            resume traffic on port(s)
+            Resume traffic on port(s)
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
             :raises:
                 + :exc:`STLError`
@@ -1671,23 +1707,24 @@ class STLClient(object):
     @__api_check(True)
     def validate (self, ports = None, mult = "1", duration = "-1", total = False):
         """
-            validate port(s) configuration
+            Validate port(s) configuration
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
              mult : str
-                    multiplier in a form of pps, bps, or line util in %
-                    examples: "5kpps", "10gbps", "85%", "32mbps"
+                    Multiplier in a form of pps, bps, or line util in %
+                    Examples: "5kpps", "10gbps", "85%", "32mbps"
 
             duration : int
-                    limit the run for time in seconds
-                    -1 means unlimited
+                    Limit the run time (seconds)
+                    -1 = unlimited
 
             total : bool
-                    should the B/W be divided by the ports
-                    or duplicated for each
+                    Determines whether to divide the configured bandwidth among the ports, or to duplicate the bandwidth for each port.
+                    True: Divide bandwidth among the ports
+                    False: Duplicate
 
             :raises:
                 + :exc:`STLError`
@@ -1723,17 +1760,17 @@ class STLClient(object):
     @__api_check(False)
     def clear_stats (self, ports = None, clear_global = True, clear_flow_stats = True):
         """
-            clear stats on port(s)
+            Clear stats on port(s)
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
                 clear_global : bool
-                    clear the global stats
+                    Clear the global stats
 
                 clear_flow_stats : bool 
-                    clear the flow stats
+                    Clear the flow stats
 
             :raises:
                 + :exc:`STLError`
@@ -1757,11 +1794,11 @@ class STLClient(object):
     @__api_check(True)
     def is_traffic_active (self, ports = None):
         """
-            retrun if  specify port(s) has traffic 
+            Return if specified port(s) have traffic 
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
 
             :raises:
@@ -1778,17 +1815,25 @@ class STLClient(object):
 
 
     @__api_check(True)
-    def wait_on_traffic (self, ports = None, timeout = 60):
+    def wait_on_traffic (self, ports = None, timeout = 60, rx_delay_ms = 10):
         """
-            block until specify port(s) traffic has ended
+            Block until traffic on specified port(s) has ended
 
             :parameters:
                 ports : list
-                    ports to execute command
+                    Ports on which to execute the command
 
                 timeout : int
                     timeout in seconds
 
+                rx_delay_ms : int
+                    time to wait until RX filters are removed
+                    this value should reflect the time it takes
+                    packets which were transmitted to arrive
+                    to the destination.
+                    after this time the RX filters will be removed
+
+
             :raises:
                 + :exc:`STLTimeoutError` - in case timeout has expired
                 + :exe:'STLError'
@@ -1807,14 +1852,19 @@ class STLClient(object):
             if time.time() > expr:
                 raise STLTimeoutError(timeout)
 
+        # remove any RX filters
+        rc = self._remove_rx_filters(ports, rx_delay_ms = rx_delay_ms)
+        if not rc:
+            raise STLError(rc)
+
 
     @__api_check(True)
     def set_port_attr (self, ports = None, promiscuous = None):
         """
-            set port(s) attributes
+            Set port attributes
 
             :parameters:
-                promiscuous - set this to True or False
+                promiscuous - True or False
 
             :raises:
                 None
@@ -1845,7 +1895,7 @@ class STLClient(object):
 
     def clear_events (self):
         """
-            clear all events
+            Clear all events
 
             :parameters:
                 None
@@ -1921,7 +1971,7 @@ class STLClient(object):
 
     @__console
     def start_line (self, line):
-        '''Start selected traffic in specified ports on TRex\n'''
+        '''Start selected traffic on specified ports on TRex\n'''
         # define a parser
         parser = parsing_opts.gen_parser(self,
                                          "start",
@@ -2008,7 +2058,7 @@ class STLClient(object):
 
     @__console
     def stop_line (self, line):
-        '''Stop active traffic in specified ports on TRex\n'''
+        '''Stop active traffic on specified ports on TRex\n'''
         parser = parsing_opts.gen_parser(self,
                                          "stop",
                                          self.stop_line.__doc__,
@@ -2061,7 +2111,7 @@ class STLClient(object):
 
     @__console
     def pause_line (self, line):
-        '''Pause active traffic in specified ports on TRex\n'''
+        '''Pause active traffic on specified ports on TRex\n'''
         parser = parsing_opts.gen_parser(self,
                                          "pause",
                                          self.pause_line.__doc__,
@@ -2086,7 +2136,7 @@ class STLClient(object):
 
     @__console
     def resume_line (self, line):
-        '''Resume active traffic in specified ports on TRex\n'''
+        '''Resume active traffic on specified ports on TRex\n'''
         parser = parsing_opts.gen_parser(self,
                                          "resume",
                                          self.resume_line.__doc__,
@@ -2130,7 +2180,7 @@ class STLClient(object):
 
     @__console
     def show_stats_line (self, line):
-        '''Fetch statistics from TRex server by port\n'''
+        '''Get statistics from TRex server by port\n'''
         # define a parser
         parser = parsing_opts.gen_parser(self,
                                          "stats",
@@ -2161,7 +2211,7 @@ class STLClient(object):
 
     @__console
     def show_streams_line(self, line):
-        '''Fetch streams statistics from TRex server by port\n'''
+        '''Get stream statistics from TRex server by port\n'''
         # define a parser
         parser = parsing_opts.gen_parser(self,
                                          "streams",
@@ -2190,7 +2240,7 @@ class STLClient(object):
 
     @__console
     def validate_line (self, line):
-        '''validates port(s) stream configuration\n'''
+        '''Validates port(s) stream configuration\n'''
 
         parser = parsing_opts.gen_parser(self,
                                          "validate",
@@ -2208,7 +2258,7 @@ class STLClient(object):
  
     @__console
     def push_line (self, line):
-        '''Push a PCAP file '''
+        '''Push a pcap file '''
 
         parser = parsing_opts.gen_parser(self,
                                          "push",
diff --git a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_packet_builder_scapy.py b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_packet_builder_scapy.py
index a7064853..f8517a47 100644..100755
--- a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_packet_builder_scapy.py
+++ b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_packet_builder_scapy.py
@@ -35,7 +35,7 @@ def safe_ord (c):
     elif type(c) is int:
         return c
     else:
-        raise TypeError("cannot convert: {0} of type: {1}".format(c, type(c)))
+        raise TypeError("Cannot convert: {0} of type: {1}".format(c, type(c)))
 
 def _buffer_to_num(str_buffer):
     validate_type('str_buffer', str_buffer, bytes)
@@ -48,18 +48,18 @@ def _buffer_to_num(str_buffer):
 
 def ipv4_str_to_num (ipv4_buffer):
     validate_type('ipv4_buffer', ipv4_buffer, bytes)
-    assert len(ipv4_buffer)==4, 'size of ipv4_buffer is not 4'
+    assert len(ipv4_buffer)==4, 'Size of ipv4_buffer is not 4'
     return _buffer_to_num(ipv4_buffer)
 
 def mac_str_to_num (mac_buffer):
     validate_type('mac_buffer', mac_buffer, bytes)
-    assert len(mac_buffer)==6, 'size of mac_buffer is not 6'
+    assert len(mac_buffer)==6, 'Size of mac_buffer is not 6'
     return _buffer_to_num(mac_buffer)
 
 
 def is_valid_ipv4(ip_addr):
     """
-    return buffer in network order
+    Return buffer in network order
     """
     if  type(ip_addr) == bytes and len(ip_addr) == 4:
         return ip_addr
@@ -72,12 +72,12 @@ def is_valid_ipv4(ip_addr):
     except AttributeError:  # no inet_pton here, sorry
         return socket.inet_aton(ip_addr)
     except socket.error:  # not a valid address
-        raise CTRexPacketBuildException(-10,"not valid ipv4 format");
+        raise CTRexPacketBuildException(-10,"Not valid ipv4 format");
 
 
 def is_valid_ipv6(ipv6_addr):
     """
-    return buffer in network order
+    Return buffer in network order
     """
     if type(ipv6_addr) == bytes and len(ipv6_addr) == 16:
         return ipv6_addr
@@ -107,12 +107,12 @@ class CTRexScFieldRangeBase(CTRexScriptsBase):
         self.field_name =field_name
         self.field_type =field_type
         if not self.field_type in CTRexScFieldRangeBase.FILED_TYPES :
-            raise CTRexPacketBuildException(-12, 'field type should be in %s' % FILED_TYPES);
+            raise CTRexPacketBuildException(-12, 'Field type should be in %s' % FILED_TYPES);
 
 
 class CTRexScFieldRangeValue(CTRexScFieldRangeBase):
     """
-    range of field value
+    Range of field values
     """
     def __init__(self, field_name,
                        field_type,
@@ -123,14 +123,14 @@ class CTRexScFieldRangeValue(CTRexScFieldRangeBase):
         self.min_value =min_value;
         self.max_value =max_value;
         if min_value > max_value:
-            raise CTRexPacketBuildException(-12, 'min is greater than max');
+            raise CTRexPacketBuildException(-12, 'Invalid range: min is greater than max.');
         if min_value == max_value:
-            raise CTRexPacketBuildException(-13, "min value is equal to max value, you can't use this type of range");
+            raise CTRexPacketBuildException(-13, "Invalid range: min value is equal to max value.");
 
 
 class CTRexScIpv4SimpleRange(CTRexScFieldRangeBase):
     """
-    range of ipv4 ip
+    Range of ipv4 ip
     """
     def __init__(self, field_name, field_type, min_ip, max_ip):
         super(CTRexScIpv4SimpleRange, self).__init__(field_name,field_type)
@@ -144,7 +144,7 @@ class CTRexScIpv4SimpleRange(CTRexScFieldRangeBase):
 
 class CTRexScIpv4TupleGen(CTRexScriptsBase):
     """
-    range tuple
+    Range tuple
     """
     FLAGS_ULIMIT_FLOWS =1
 
@@ -166,7 +166,7 @@ class CTRexScIpv4TupleGen(CTRexScriptsBase):
 
 class CTRexScTrimPacketSize(CTRexScriptsBase):
     """
-    trim packet size. field type is CTRexScFieldRangeBase.FILED_TYPES = ["inc","dec","rand"]
+    Trim packet size. Field type is CTRexScFieldRangeBase.FILED_TYPES = ["inc","dec","rand"]
     """
     def __init__(self,field_type="rand",min_pkt_size=None, max_pkt_size=None):
         super(CTRexScTrimPacketSize, self).__init__()
@@ -183,11 +183,11 @@ class CTRexScTrimPacketSize(CTRexScriptsBase):
 
 class STLScVmRaw(CTRexScriptsBase):
     """
-    raw instructions
+    Raw instructions
     """
     def __init__(self,list_of_commands=None,split_by_field=None):
         """
-        include a list of a basic instructions objects 
+        Include a list of a basic instructions objects.
 
         :parameters:
              list_of_commands : list
@@ -197,7 +197,7 @@ class STLScVmRaw(CTRexScriptsBase):
                 by which field to split to threads
 
 
-        The following example will split the generated traffic by "ip_src" variable
+        The following example splits the generated traffic by "ip_src" variable.
 
         .. code-block:: python
             :caption: Split by 
@@ -241,7 +241,7 @@ class STLScVmRaw(CTRexScriptsBase):
 
 class CTRexVmInsBase(object):
     """
-    instruction base
+    Instruction base
     """
     def __init__(self, ins_type):
         self.type = ins_type
@@ -334,7 +334,7 @@ class CTRexVmEngine(object):
 
        def __init__(self):
             """
-            inlcude list of instruction
+            Inlcude list of instructions.
             """
             super(CTRexVmEngine, self).__init__()
             self.ins=[]
@@ -390,7 +390,7 @@ class CTRexScapyPktUtl(object):
 
     def get_pkt_layers(self):
         """
-        return string 'IP:UDP:TCP'
+        Return string 'IP:UDP:TCP'
         """
         l=self.get_list_iter ();
         l1=map(lambda p: p.name,l );
@@ -398,7 +398,7 @@ class CTRexScapyPktUtl(object):
 
     def _layer_offset(self, name, cnt = 0):
         """
-        return offset of layer e.g 'IP',1 will return offfset of layer ip:1
+        Return offset of layer. Example: 'IP',1 returns offfset of layer ip:1
         """
         save_cnt=cnt
         for pkt in self.pkt_iter ():
@@ -413,7 +413,7 @@ class CTRexScapyPktUtl(object):
 
     def layer_offset(self, name, cnt = 0):
         """
-        return offset of layer e.g 'IP',1 will return offfset of layer ip:1
+        Return offset of layer. Example: 'IP',1 returns offfset of layer ip:1
         """
         save_cnt=cnt
         for pkt in self.pkt_iter ():
@@ -427,7 +427,7 @@ class CTRexScapyPktUtl(object):
 
     def get_field_offet(self, layer, layer_cnt, field_name):
         """
-        return offset of layer e.g 'IP',1 will return offfset of layer ip:1
+        Return offset of layer. Example: 'IP',1 returns offfset of layer ip:1
         """
         t=self._layer_offset(layer,layer_cnt);
         l_offset=t[1];
@@ -439,11 +439,11 @@ class CTRexScapyPktUtl(object):
             if f.name == field_name:
                 return (l_offset+f.offset,f.get_size_bytes ());
 
-        raise CTRexPacketBuildException(-11, "no layer %s-%d." % (name, save_cnt, field_name));
+        raise CTRexPacketBuildException(-11, "No layer %s-%d." % (name, save_cnt, field_name));
 
     def get_layer_offet_by_str(self, layer_des):
         """
-        return layer offset by string
+        Return layer offset by string.
 
        :parameters:
 
@@ -469,21 +469,21 @@ class CTRexScapyPktUtl(object):
 
     def get_field_offet_by_str(self, field_des):
         """
-        return field_des (offset,size) layer:cnt.field
-        for example  
+        Return field_des (offset,size) layer:cnt.field
+        Example:  
         802|1Q.vlan get 802.1Q->valn replace | with .
         IP.src
         IP:0.src  (first IP.src like IP.src)
-        for example IP:1.src  for internal IP
+        Example: IP:1.src  for internal IP
 
-        return (offset, size) as tuple
+        Return (offset, size) as tuple.
 
 
         """
 
         s=field_des.split(".");
         if len(s)!=2:
-            raise CTRexPacketBuildException(-11, ("field desription should be layer:cnt.field e.g IP.src or IP:1.src"));
+            raise CTRexPacketBuildException(-11, ("Field desription should be layer:cnt.field Example: IP.src or IP:1.src"));
 
 
         layer_ex = s[0].replace("|",".")
@@ -514,7 +514,7 @@ class CTRexScapyPktUtl(object):
 
 class CTRexVmDescBase(object):
     """
-    instruction base
+    Instruction base
     """
     def __init__(self):
        pass;
@@ -534,37 +534,37 @@ class CTRexVmDescBase(object):
 
     def get_var_ref (self):
         '''
-          virtual function return a ref var name
+          Virtual function returns a ref var name.
         '''
         return None
 
     def get_var_name(self):
         '''
-          virtual function return the varible name if exists
+          Virtual function returns the varible name if it exists.
         '''
         return None
 
     def compile(self,parent):
         '''
-          virtual function to take parent than has function name_to_offset
+          Virtual function to take parent that has function name_to_offset.
         '''
         pass;
 
 
 def valid_fv_size (size):
     if not (size in CTRexVmInsFlowVar.VALID_SIZES):
-        raise CTRexPacketBuildException(-11,("flow var has not valid size %d ") % size  );
+        raise CTRexPacketBuildException(-11,("Flow var has invalid size %d ") % size  );
 
 def valid_fv_ops (op):
     if not (op in CTRexVmInsFlowVar.OPERATIONS):
-        raise CTRexPacketBuildException(-11,("flow var does not have a valid op %s ") % op  );
+        raise CTRexPacketBuildException(-11,("Flow var has invalid op %s ") % op  );
 
 def convert_val (val):
     if is_integer(val):
         return val
     if type(val) == str:
         return ipv4_str_to_num (is_valid_ipv4(val))
-    raise CTRexPacketBuildException(-11,("init val not valid %s ") % val  );
+    raise CTRexPacketBuildException(-11,("init val invalid %s ") % val  );
 
 def check_for_int (val):
     validate_type('val', val, int)
@@ -574,31 +574,32 @@ class STLVmFlowVar(CTRexVmDescBase):
 
     def __init__(self, name, init_value=None, min_value=0, max_value=255, size=4, step=1,op="inc"):
         """
-        Flow variable instruction. Allocate a variable on a stream context. The size of the variable could be determined 
-        The operation can be inc, dec and random. In case of increment and decrement operation, it is possible to set the "step" size.
-        Initialization value, minimum and maximum value could be set too.
+        Flow variable instruction. Allocates a variable on a stream context. The size argument determines the variable size.
+        The operation can be inc, dec, and random. 
+        For increment and decrement operations, can set the "step" size.
+        For all operations, can set initialization value, minimum and maximum value.
 
         :parameters:
              name : string 
-                The name of the stream variable 
+                Name of the stream variable 
 
              init_value : int
-                The init value of the variable. in case of None it will be min_value 
+                Init value of the variable. If not specified, it will be min_value
 
              min_value  : int
-                The min value 
+                Min value 
 
              max_value  : int
-                The max value 
+                Max value 
 
              size  : int
-                the number of bytes of the variable. could be 1,2,4,8 for uint8_t, uint16_t, uint32_t, uint64_t
+                Number of bytes of the variable. Possible values: 1,2,4,8 for uint8_t, uint16_t, uint32_t, uint64_t
 
              step  : int 
-                step in case of "inc","dec" operation 
+                Step in case of "inc" or "dec" operations
 
              op    : string 
-                could be "inc", "dec", "random"
+                Possible values: "inc", "dec", "random"
 
         .. code-block:: python
             :caption: Example1
@@ -657,7 +658,7 @@ class STLVmFlowVar(CTRexVmDescBase):
 class STLVmFixIpv4(CTRexVmDescBase):
     def __init__(self, offset):
         """
-        Fix IPv4 header checksum. should be added if the packet header was changed and there is a need to fix he checksum
+        Fix IPv4 header checksum. Use this if the packet header has changed and it is necessary to change the checksum.
 
         :parameters:
              offset : uint16_t or string 
@@ -694,26 +695,28 @@ class STLVmWrFlowVar(CTRexVmDescBase):
     def __init__(self, fv_name, pkt_offset, offset_fixup=0, add_val=0, is_big=True):
         """
         Write a stream variable into a packet field. 
-        The write is done in size of the stream variable. 
-        In case there is a need to change the write have a look into the command `STLVmWrMaskFlowVar`. 
-        The Field name/offset can be given by name in this format ``header[:id].field``. 
+        The write position is determined by the packet offset + offset fixup. The size of the write is determined by the stream variable. 
+        Example: Offset 10, fixup 0, variable size 4. This function writes at 10, 11, 12, and 13.
+        
+        For inromation about chaning the write size, offset, or fixup, see the `STLVmWrMaskFlowVar` command. 
+        The Field name/offset can be given by name in the following format: ``header[:id].field``. 
 
         
         :parameters:
             fv_name : string 
-                the stream variable to write to a packet offset 
+                Stream variable to write to a packet offset.
 
             pkt_offset : string or in
-                the name of the field or offset in byte from packet start.
+                Name of the field or offset in bytes from packet start.
 
             offset_fixup : int 
-                how many bytes to go forward. In case of a negative value go backward 
+                Number of bytes to move forward. If negative, move backward.
 
              add_val     : int
-                value to add to stream variable before writing it to packet field. can be used as a constant offset 
+                Value to add to the stream variable before writing it to the packet field. Can be used as a constant offset. 
 
              is_big      : bool 
-                how to write the variable to the the packet. is it big-edian or little edian 
+                How to write the variable to the the packet. True=big-endian, False=little-endian 
 
         .. code-block:: python
             :caption: Example3
@@ -759,7 +762,7 @@ class STLVmWrMaskFlowVar(CTRexVmDescBase):
 
         """
         Write a stream variable into a packet field with some operations. 
-        Using this instruction the variable size and the field could be with different size. 
+        Using this instruction, the variable size and the field can have different sizes. 
 
         Pseudocode of this code::
 
@@ -805,7 +808,7 @@ class STLVmWrMaskFlowVar(CTRexVmDescBase):
              is_big      : bool 
                 how to write the variable to the the packet. is it big-edian or little edian 
 
-        Example 1- casting from uint16_t (var) to uint8_t (pkt)::
+        Example 1 - Cast from uint16_t (var) to uint8_t (pkt)::
 
 
             base_pkt =  Ether()/IP(src="16.0.0.1",dst="48.0.0.1")/UDP(dport=12,sport=1025)
@@ -824,7 +827,7 @@ class STLVmWrMaskFlowVar(CTRexVmDescBase):
 
             pkt = Ether()/IP(src="16.0.0.1",dst="48.0.0.1")/UDP(dport=12,sport=1025)
 
-        Example 2- change MSB of uint16_t variable::
+        Example 2 - Change MSB of uint16_t variable::
 
 
             vm = STLScVmRaw( [ STLVmFlowVar(name="mac_src", 
@@ -841,7 +844,7 @@ class STLVmWrMaskFlowVar(CTRexVmDescBase):
 
 
 
-        Example 3- Every 2 packet change the MAC (shift right)::
+        Example 3 - Every 2 packets, change the MAC (shift right)::
 
                 vm = STLScVmRaw( [ STLVmFlowVar(name="mac_src", 
                                                 min_value=1, 
@@ -893,12 +896,12 @@ class STLVmWrMaskFlowVar(CTRexVmDescBase):
 
 class STLVmTrimPktSize(CTRexVmDescBase):
     """
-    Trim packet size by stream variable size. This instruction will only change the total packet size and will not fix up the fields to match the new size.  
+    Trim the packet size by the stream variable size. This instruction only changes the total packet size, and does not repair the fields to match the new size.  
 
 
     :parameters:
         fv_name : string 
-            the stream variable name. the value from this variable would be the new total packet size.  
+            Stream variable name. The value of this variable is the new total packet size.  
 
 
     For Example::
@@ -959,8 +962,8 @@ class STLVmTrimPktSize(CTRexVmDescBase):
 class STLVmTupleGen(CTRexVmDescBase):
     def __init__(self,name, ip_min="0.0.0.1", ip_max="0.0.0.10", port_min=1025, port_max=65535, limit_flows=100000, flags=0):
         """
-        Generate a struct with two varibles. ``var_name.ip`` as uint32_t and ``var_name.port`` as uint16_t 
-        The variable are dependent. When the ip variable is wrapped the port is getting increment. 
+        Generate a struct with two variables: ``var_name.ip`` as uint32_t and ``var_name.port`` as uint16_t 
+        The variables are dependent. When the ip variable value reaches its maximum, the port is incremented. 
 
         For:
 
@@ -1001,22 +1004,22 @@ class STLVmTupleGen(CTRexVmDescBase):
 
         :parameters:
             name : string 
-                The name of the stream struct. 
+                Name of the stream struct. 
 
             ip_min : string or int 
-                The min value of the ip value. It can be in IPv4 format
+                Min value of the ip value. Number or IPv4 format.
 
             ip_max : string or int 
-                The max value of the ip value. It can be in IPv4 format
+                Max value of the ip value. Number or IPv4 format.
 
             port_min : int 
-                min value for port variable 
+                Min value of port variable. 
 
             port_max : int 
-                max value for port variable 
+                Max value of port variable. 
 
             limit_flows : int 
-                The limit of number of flows 
+                Limit of number of flows. 
 
             flags       : 0
 
@@ -1093,10 +1096,10 @@ class STLPktBuilder(CTrexPktBuilderInterface):
     def __init__(self, pkt = None, pkt_buffer = None, vm = None, path_relative_to_profile = False, build_raw = False, remove_fcs = True):
         """
 
-        This class defines a way to build a template packet, and Field Engine using scapy package.
-        Using this class the user can also define how TRex will handle the packet by specifying the Field engine setting.
-        pkt could be Scapy pkt or pcap file name 
-        When path_relative_to_profile is a True load pcap file from a path relative to the profile
+        This class defines a method for building a template packet and Field Engine using the Scapy package.
+        Using this class the user can also define how TRex will handle the packet by specifying the Field engine settings.
+        The pkt can be a Scapy pkt or pcap file name.
+        If using a pcap file, and path_relative_to_profile is True, then the function loads the pcap file from a path relative to the profile.
 
         
         .. code-block:: python
@@ -1134,22 +1137,22 @@ class STLPktBuilder(CTrexPktBuilderInterface):
         :parameters:
 
              pkt : string, 
-                Scapy or pcap file filename a scapy packet 
+                Scapy object or pcap filename.
 
              pkt_buffer : bytes 
-                a packet as buffer 
+                Packet as buffer. 
 
              vm   : list or base on :class:`trex_stl_lib.trex_stl_packet_builder_scapy.STLScVmRaw`
-                a list of instructions to manipolate packet fields 
+                List of instructions to manipulate packet fields. 
 
              path_relative_to_profile : bool 
-                in case pkt is pcap file,  do we want to load it relative to profile file
+                If pkt is a pcap file, determines whether to load it relative to profile file.
 
              build_raw : bool 
-                Do we want to build scapy in case buffer was given. good for cases we want offset to be taken from scapy 
+                If a buffer is specified (by pkt_buffer), determines whether to build Scapy. Useful in cases where it is necessary to take the offset from Scapy. 
 
              remove_fcs : bool 
-                in case of buffer do we want to remove fcs 
+                If a buffer is specified (by pkt_buffer), determines whether to remove FCS. 
 
 
 
@@ -1171,7 +1174,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
 
 
         if pkt != None and pkt_buffer != None:
-            raise CTRexPacketBuildException(-15, "packet builder cannot be provided with both pkt and pkt_buffer")
+            raise CTRexPacketBuildException(-15, "Packet builder cannot be provided with both pkt and pkt_buffer.")
 
         # process packet
         if pkt != None:
@@ -1183,7 +1186,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
         # process VM
         if vm != None:
             if not isinstance(vm, (STLScVmRaw, list)):
-                raise CTRexPacketBuildException(-14, "bad value for variable vm")
+                raise CTRexPacketBuildException(-14, "Bad value for variable vm.")
 
             self.add_command(vm if isinstance(vm, STLScVmRaw) else STLScVmRaw(vm))
 
@@ -1219,7 +1222,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
 
     def dump_pkt(self, encode = True):
         """
-        Dumps the packet as a decimal array of bytes (each item x gets value between 0-255)
+        Dumps the packet as a decimal array of bytes (each item x gets value in range 0-255)
 
         :parameters:
             encode : bool
@@ -1254,7 +1257,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
 
     def pkt_layers_desc (self):
         """
-        return layer description like this IP:TCP:Pyload
+        Return layer description in this format: IP:TCP:Pyload
 
         """
         pkt_buf = self._get_pkt_as_str()
@@ -1274,13 +1277,13 @@ class STLPktBuilder(CTrexPktBuilderInterface):
 
     def set_pcap_file (self, pcap_file):
         """
-        load raw pcap file into a buffer. load only the first packet
+        Load raw pcap file into a buffer. Loads only the first packet.
 
         :parameters:
             pcap_file : file_name
 
         :raises:
-            + :exc:`AssertionError`, in case packet is empty.
+            + :exc:`AssertionError`, if packet is empty.
 
         """
         f_path = self._get_pcap_file_path (pcap_file)
@@ -1293,7 +1296,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
             self.pkt_raw = pkt[0]
             break
         if not was_set :
-            raise CTRexPacketBuildException(-14, "no buffer inside the pcap file {0}".format(f_path))
+            raise CTRexPacketBuildException(-14, "No buffer inside the pcap file {0}".format(f_path))
 
     def to_pkt_dump(self):
         p = self.pkt
@@ -1312,7 +1315,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
         """
         Scapy packet 
 
-        For Example::
+        Example::
 
            pkt =Ether()/IP(src="16.0.0.1",dst="48.0.0.1")/UDP(dport=12,sport=1025)/IP()/('x'*10)
 
@@ -1401,7 +1404,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
             if var_names :
                 for var_name in var_names:
                     if var_name in vars:
-                        raise CTRexPacketBuildException(-11,("variable %s define twice ") % (var_name)  );
+                        raise CTRexPacketBuildException(-11,("Variable %s defined twice ") % (var_name)  );
                     else:
                         vars[var_name]=1
 
@@ -1410,7 +1413,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
             var_name =  desc.get_var_ref()
             if var_name :
                 if not var_name in vars:
-                    raise CTRexPacketBuildException(-11,("variable %s does not exists  ") % (var_name) );
+                    raise CTRexPacketBuildException(-11,("Variable %s does not exist  ") % (var_name) );
             desc.compile(self);
 
         for desc in obj.commands:
@@ -1439,7 +1442,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
         # regular scapy packet
         elif not self.pkt:
             # should not reach here
-            raise CTRexPacketBuildException(-11, 'empty packet')
+            raise CTRexPacketBuildException(-11, 'Empty packet')
 
         if self.remove_fcs and self.pkt.lastlayer().name == 'Padding':
             self.pkt.lastlayer().underlayer.remove_payload()
@@ -1469,7 +1472,7 @@ class STLPktBuilder(CTrexPktBuilderInterface):
         if self.pkt_raw:
             return self.pkt_raw
 
-        raise CTRexPacketBuildException(-11, 'empty packet');
+        raise CTRexPacketBuildException(-11, 'Empty packet');
 
     def _add_tuple_gen(self,tuple_gen):
 
diff --git a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_port.py b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_port.py
index 47124114..049929ae 100644
--- a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_port.py
+++ b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_port.py
@@ -7,8 +7,8 @@ from .trex_stl_types import *
 from . import trex_stl_stats
 
 import base64
-import time
 import copy
+from datetime import datetime, timedelta
 
 StreamOnPort = namedtuple('StreamOnPort', ['compiled_stream', 'metadata'])
 
@@ -61,6 +61,8 @@ class Port(object):
         self.port_stats = trex_stl_stats.CPortStats(self)
 
         self.next_available_id = 1
+        self.tx_stopped_ts = None
+        self.has_rx_streams = False
 
 
     def err(self, msg):
@@ -239,6 +241,9 @@ class Port(object):
                                            'rate' : streams_list[i].get_rate()}
 
                 ret.add(RC_OK(data = stream_id))
+
+                self.has_rx_streams = self.has_rx_streams or streams_list[i].has_flow_stats()
+
             else:
                 ret.add(RC(*single_rc))
 
@@ -283,6 +288,9 @@ class Port(object):
 
         self.state = self.STATE_STREAMS if (len(self.streams) > 0) else self.STATE_IDLE
 
+        # recheck if any RX stats streams present on the port
+        self.has_rx_streams = any([stream.has_flow_stats() for stream in self.streams])
+
         return self.ok() if rc else self.err(rc.err())
 
 
@@ -305,6 +313,7 @@ class Port(object):
         self.streams = {}
 
         self.state = self.STATE_IDLE
+        self.has_rx_streams = False
 
         return self.ok()
 
@@ -351,7 +360,7 @@ class Port(object):
     # stop traffic
     # with force ignores the cached state and sends the command
     def stop (self, force = False):
-
+        
         if not self.is_acquired():
             return self.err("port is not owned")
 
@@ -360,7 +369,6 @@ class Port(object):
             if (self.state == self.STATE_IDLE) or (self.state == self.state == self.STATE_STREAMS):
                 return self.ok()
 
-
         params = {"handler": self.handler,
                   "port_id": self.port_id}
 
@@ -370,8 +378,56 @@ class Port(object):
 
         self.state = self.STATE_STREAMS
 
+        # timestamp for last tx
+        self.tx_stopped_ts = datetime.now()
+
+        return self.ok()
+
+
+    # return True if port has any stream configured with RX stats
+    def has_rx_enabled (self):
+        return self.has_rx_streams
+
+
+    # return true if rx_delay_ms has passed since the last port stop
+    def has_rx_delay_expired (self, rx_delay_ms):
+        assert(self.has_rx_enabled())
+
+        # if active - it's not safe to remove RX filters
+        if self.is_active():
+            return False
+
+        # either no timestamp present or time has already passed
+        return not self.tx_stopped_ts or (datetime.now() - self.tx_stopped_ts) > timedelta(milliseconds = rx_delay_ms)
+
+
+
+    def remove_rx_filters (self):
+        assert(self.has_rx_enabled())
+
+        if not self.is_acquired():
+            return self.err("port is not owned")
+
+        if self.state == self.STATE_DOWN:
+            return self.err("Unable to remove RX filters - port is down")
+
+        if self.state == self.STATE_TX:
+            return self.err("Unable to remove RX filters - port is transmitting")
+
+        if self.state == self.STATE_IDLE:
+            return self.ok()
+
+
+        params = {"handler": self.handler,
+                  "port_id": self.port_id}
+
+        rc = self.transmit("remove_rx_filters", params)
+        if rc.bad():
+            return self.err(rc.err())
+
         return self.ok()
 
+
     def pause (self):
 
         if not self.is_acquired():
@@ -597,6 +653,8 @@ class Port(object):
 
   ################# events handler ######################
     def async_event_port_job_done (self):
+        # until thread is locked - order is important
+        self.tx_stopped_ts = datetime.now()
         self.state = self.STATE_STREAMS
 
     # rest of the events are used for TUI / read only sessions
diff --git a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_streams.py b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_streams.py
index 4f8ce3e6..aeeddc49 100644..100755
--- a/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_streams.py
+++ b/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_streams.py
@@ -21,22 +21,22 @@ class STLTXMode(object):
 
     def __init__ (self, pps = None, bps_L1 = None, bps_L2 = None, percentage = None):
         """ 
-        Speed could be in packet per second (pps) or L2/L1 bps or port precent 
-        only one of them is valid. 
+        Speed can be given in packets per second (pps), L2/L1 bps, or port percent 
+        Use only one unit. 
         you can enter pps =10000 oe bps_L1=10
 
         :parameters:
             pps : float 
-               packet per second 
+               Packets per second 
 
             bps_L1 : float
-               bit per second L1 (with IPG) 
+               Bits per second L1 (with IPG) 
 
             bps_L2 : float 
-               bit per second L2 (Ethernet-FCS) 
+               Bits per second L2 (Ethernet-FCS) 
 
             percentage : float 
-               link interface precent  0-100 e.g. 10 is 10%% of the port link setup 
+               Link interface percent (0-100). Example: 10 is 10% of the port link setup 
 
         .. code-block:: python
             :caption: STLTXMode Example
@@ -95,11 +95,11 @@ class STLTXMode(object):
 
 # continuous mode
 class STLTXCont(STLTXMode):
-    """ continuous mode """
+    """ Continuous mode """
 
     def __init__ (self, **kwargs):
         """ 
-        continuous mode
+        Continuous mode
         
          see :class:`trex_stl_lib.trex_stl_streams.STLTXMode` for rate 
 
@@ -124,11 +124,11 @@ class STLTXSingleBurst(STLTXMode):
 
     def __init__ (self, total_pkts = 1, **kwargs):
         """ 
-        single burst mode
+        Single burst mode
 
             :parameters:
                  total_pkts : int
-                    how many packets for this burst 
+                    Number of packets for this burst 
 
          see :class:`trex_stl_lib.trex_stl_streams.STLTXMode` for rate 
 
@@ -154,7 +154,7 @@ class STLTXSingleBurst(STLTXMode):
 
 # multi burst mode
 class STLTXMultiBurst(STLTXMode):
-    """ Multi burst mode """
+    """ Multi-burst mode """
 
     def __init__ (self,
                   pkts_per_burst = 1,
@@ -162,18 +162,18 @@ class STLTXMultiBurst(STLTXMode):
                   count = 1,
                   **kwargs):
         """ 
-        Multi burst mode
+        Multi-burst mode
 
         :parameters:
 
              pkts_per_burst: int 
-                how many packets per burst 
+                Number of packets per burst 
 
               ibg : float 
-                inter burst gap in usec 1000,000.0 is 1 sec
+                Inter-burst gap in usec 1,000,000.0 is 1 sec
 
               count : int 
-                how many bursts 
+                Number of bursts 
 
          see :class:`trex_stl_lib.trex_stl_streams.STLTXMode` for rate 
 
@@ -230,7 +230,7 @@ class STLFlowStats(object):
 
 
     def to_json (self):
-        """ dump as json"""
+        """ Dump as json"""
         return dict(self.fields)
 
     @staticmethod
@@ -238,7 +238,7 @@ class STLFlowStats(object):
         return {'enabled' : False}
 
 class STLStream(object):
-    """ One stream object, include mode, Field Engine mode packet template and Rx stats  
+    """ One stream object. Includes mode, Field Engine mode packet template and Rx stats  
 
         .. code-block:: python
             :caption: STLStream Example
@@ -277,42 +277,42 @@ class STLStream(object):
         :parameters:
 
                   name  : string 
-                       The name of the stream. Needed if this stream is dependent on another stream and another stream need to refer to this stream by its name.
+                       Name of the stream. Required if this stream is dependent on another stream, and another stream needs to refer to this stream by name.
 
                   packet :  STLPktBuilder see :class:`trex_stl_lib.trex_stl_packet_builder_scapy.STLPktBuilder`
-                       The template packet and field engine program e.g. packet = STLPktBuilder(pkt = base_pkt/pad) 
+                       Template packet and field engine program. Example: packet = STLPktBuilder(pkt = base_pkt/pad) 
 
                   mode :  :class:`trex_stl_lib.trex_stl_streams.STLTXCont` or :class:`trex_stl_lib.trex_stl_streams.STLTXSingleBurst`  or  :class:`trex_stl_lib.trex_stl_streams.STLTXMultiBurst` 
 
                   enabled : bool 
-                      if the stream is enabled. 
+                      Indicates whether the stream is enabled. 
 
                   self_start : bool 
-                      In case it is False another stream will activate it
+                      If False, another stream activates it.
 
                   isg : float 
-                     Inter stream gap in usec. time to wait until stream will send the first packet  
+                     Inter-stream gap in usec. Time to wait until the stream sends the first packet.
 
                   flow_stats : :class:`trex_stl_lib.trex_stl_streams.STLFlowStats` 
-                      Per stream statistic object see STLFlowStats
+                      Per stream statistic object. See: STLFlowStats
 
                   next : string 
-                      The name of the stream to activate 
+                      Name of the stream to activate.
                     
                   stream_id :
-                        for HLTAPI usage 
+                        For use by HLTAPI.
 
                   action_count : uint16_t
-                        In case there is a next stream how many loops until stopping. Default is zero, which mean unlimited
+                        If there is a next stream, number of loops before stopping. Default: 0 (unlimited).
 
                   random_seed: uint16_t 
-                       If given the seed for this stream will be this value. Good in case you need a deterministic random value 
+                       If given, the seed for this stream will be this value. Useful if you need a deterministic random value.
                         
                   mac_src_override_by_pkt : bool 
-                        Template packet will set src MAC 
+                        Template packet sets src MAC. 
 
                   mac_dst_override_mode=None : STLStreamDstMAC_xx
-                        Template packet will set dst MAC 
+                        Template packet sets dst MAC. 
         """
 
 
@@ -326,7 +326,7 @@ class STLStream(object):
         validate_type('random_seed',random_seed,int);
 
         if (type(mode) == STLTXCont) and (next != None):
-            raise STLError("continuous stream cannot have a next stream ID")
+            raise STLError("Continuous stream cannot have a next stream ID")
 
         # tag for the stream and next - can be anything
         self.name = name
@@ -412,7 +412,7 @@ class STLStream(object):
 
     def to_json (self):
         """ 
-        return json format
+        Return json format
         """
         return dict(self.fields)
 
@@ -430,6 +430,10 @@ class STLStream(object):
         return self.next
 
 
+    def has_flow_stats (self):
+        """ Return True if stream was configured with flow stats """
+        return self.fields['flow_stats']['enabled']
+
     def get_pkt (self):
         """ Get packet as string """
         return self.pkt
@@ -444,7 +448,7 @@ class STLStream(object):
 
 
     def get_pkt_type (self):
-        """ Get packet description for example IP:UDP """
+        """ Get packet description. Example: IP:UDP """
         if self.packet_desc == None:
             self.packet_desc = STLPktBuilder.pkt_layers_desc_from_buffer(self.get_pkt())
 
@@ -472,7 +476,7 @@ class STLStream(object):
         return self.get_rate_from_field(self.fields['mode']['rate'])
 
     def to_pkt_dump (self):
-        """ print packet description from scapy  """
+        """ Print packet description from Scapy  """
         if self.name:
             print("Stream Name: ",self.name)
         scapy_b = self.scapy_pkt_builder;
@@ -484,7 +488,7 @@ class STLStream(object):
 
 
     def to_yaml (self):
-        """ convert to YAML  """
+        """ Convert to YAML  """
         y = {}
 
         if self.name:
@@ -506,7 +510,7 @@ class STLStream(object):
 
     # returns the Python code (text) to build this stream, inside the code it will be in variable "stream"
     def to_code (self):
-        """ convert to Python code as profile  """
+        """ Convert to Python code as profile  """
         packet = Ether(self.pkt)
         layer = packet
         while layer:                    # remove checksums
@@ -621,7 +625,7 @@ class STLStream(object):
         return r'\x{0:02x}'.format(ord(match.group()))
 
     def dump_to_yaml (self, yaml_file = None):
-        """ print as yaml  """
+        """ Print as yaml  """
         yaml_dump = yaml.dump([self.to_yaml()], default_flow_style = False)
 
         # write to file if provided
@@ -642,7 +646,7 @@ class YAMLLoader(object):
 
         packet_type = set(packet_dict).intersection(['binary', 'pcap'])
         if len(packet_type) != 1:
-            raise STLError("packet section must contain either 'binary' or 'pcap'")
+            raise STLError("Packet section must contain either 'binary' or 'pcap'")
 
         if 'binary' in packet_type:
             try:
@@ -707,7 +711,7 @@ class YAMLLoader(object):
 
         pg_id = flow_stats_obj.get('stream_id') 
         if pg_id == None:
-            raise STLError("enabled RX stats section must contain 'stream_id' field")
+            raise STLError("Enabled RX stats section must contain 'stream_id' field")
 
         return STLFlowStats(pg_id = pg_id)
 
@@ -822,16 +826,21 @@ class STLProfile(object):
 
 
     def get_streams (self):
-        """ Get the list of stream"""
+        """ Get the list of streams"""
         return self.streams
 
     def __str__ (self):
         return '\n'.join([str(stream) for stream in self.streams])
 
+    def is_pauseable (self):
+        return all([x.get_mode() == "Continuous" for x in (self.get_streams())])
+
+    def has_flow_stats (self):
+        return any([x.has_flow_stats() for x in self.get_streams()])
 
     @staticmethod
     def load_yaml (yaml_file):
-        """ load from YAML file a profile with number of streams"""
+        """ Load (from YAML file) a profile with a number of streams"""
 
         # check filename
         if not os.path.isfile(yaml_file):
@@ -866,11 +875,11 @@ class STLProfile(object):
 
     @staticmethod
     def load_py (python_file, direction = 0, port_id = 0, **kwargs):
-        """ load from Python profile """
+        """ Load from Python profile """
 
         # check filename
         if not os.path.isfile(python_file):
-            raise STLError("file '{0}' does not exists".format(python_file))
+            raise STLError("File '{0}' does not exist".format(python_file))
 
         basedir = os.path.dirname(python_file)
         sys.path.append(basedir)
@@ -883,7 +892,7 @@ class STLProfile(object):
             t = STLProfile.get_module_tunables(module)
             for arg in kwargs:
                 if not arg in t:
-                    raise STLError("profile {0} does not support tunable '{1}' - supported tunables are: '{2}'".format(python_file, arg, t))
+                    raise STLError("Profile {0} does not support tunable '{1}' - supported tunables are: '{2}'".format(python_file, arg, t))
 
             streams = module.register().get_streams(direction = direction,
                                                     port_id = port_id,
@@ -910,26 +919,26 @@ class STLProfile(object):
     # loop_count = 0 means loop forever
     @staticmethod
     def load_pcap (pcap_file, ipg_usec = None, speedup = 1.0, loop_count = 1, vm = None):
-        """ Convert a pcap file with a number of packets to a list of connected streams  
+        """ Convert a pcap file with a number of packets to a list of connected streams.  
 
         packet1->packet2->packet3 etc 
 
                 :parameters:
 
                   pcap_file  : string 
-                       The name of the pcap file 
+                       Name of the pcap file 
 
                   ipg_usec   : float
-                       The inter packet gap in usec. in case of None IPG is taken from pcap file 
+                       Inter packet gap in usec. If IPG=0, IPG is taken from pcap file
 
                   speedup   : float 
-                       By which factor to get IPG smaller so we will send pcap file in speedup 
+                       When reading the pcap file, divide IPG by this "speedup" factor. Resulting IPG is sped up by this factor. 
 
                   loop_count : uint16_t 
-                       how many loops to repeat the pcap file 
+                       Number of loops to repeat the pcap file 
                     
                   vm        :  list 
-                        A list of Field engine instructions 
+                        List of Field engine instructions 
 
                  :return: STLProfile
 
@@ -987,12 +996,12 @@ class STLProfile(object):
 
     @staticmethod
     def load (filename, direction = 0, port_id = 0, **kwargs):
-        """ load a profile by its type supported type are 
+        """ Load a profile by its type. Supported types are: 
            * py
            * yaml 
            * pcap file that converted to profile automaticly 
 
-           :parameters:
+           :Parameters:
               filename  : string as filename 
               direction : profile's direction (if supported by the profile)
               port_id   : which port ID this profile is being loaded to
@@ -1024,7 +1033,7 @@ class STLProfile(object):
         return profile.meta
 
     def dump_as_pkt (self):
-        """ dump the profile as scapy packet. in case it is raw convert to scapy and dump it"""
+        """ Dump the profile as Scapy packet. If the packet is raw, convert it to Scapy before dumping it."""
         cnt=0;
         for stream in self.streams:
             print("=======================")
@@ -1034,7 +1043,7 @@ class STLProfile(object):
             stream.to_pkt_dump()
 
     def dump_to_yaml (self, yaml_file = None):
-        """ convert it to yaml """
+        """ Convert the profile to yaml """
         yaml_list = [stream.to_yaml() for stream in self.streams]
         yaml_str = yaml.dump(yaml_list, default_flow_style = False)
 
@@ -1046,7 +1055,7 @@ class STLProfile(object):
         return yaml_str
 
     def dump_to_code (self, profile_file = None):
-        """ convert it to Python native profile. yeah this is cool """
+        """ Convert the profile to Python native profile. """
         profile_dump = '''# !!! Auto-generated code !!!
 from trex_stl_lib.api import *
 
diff --git a/scripts/stl/flow_stats.py b/scripts/stl/flow_stats.py
index 69e1166c..cbb5ac21 100644
--- a/scripts/stl/flow_stats.py
+++ b/scripts/stl/flow_stats.py
@@ -1,15 +1,17 @@
 from trex_stl_lib.api import *
+import os
 
 # stream from pcap file. continues pps 10 in sec 
+CP = os.path.join(os.path.dirname(__file__))
 
 class STLS1(object):
 
     def get_streams (self, direction = 0, **kwargs):
-        return [STLStream(packet = STLPktBuilder(pkt ="stl/yaml/udp_64B_no_crc.pcap"), # path relative to pwd 
+        return [STLStream(packet = STLPktBuilder(pkt = os.path.join(CP, "yaml/udp_64B_no_crc.pcap")), # path relative to pwd 
                           mode = STLTXCont(pps=1000),
                           flow_stats = STLFlowStats(pg_id = 7)),
 
-                STLStream(packet = STLPktBuilder(pkt ="stl/yaml/udp_594B_no_crc.pcap"), # path relative to pwd 
+                STLStream(packet = STLPktBuilder(pkt = os.path.join(CP, "yaml/udp_594B_no_crc.pcap")), # path relative to pwd 
                           mode = STLTXCont(pps=5000),
                           flow_stats = STLFlowStats(pg_id = 12))
                ]
diff --git a/scripts/stl/udp_1pkt_pcap.py b/scripts/stl/udp_1pkt_pcap.py
index 9fb0e269..2a364810 100644
--- a/scripts/stl/udp_1pkt_pcap.py
+++ b/scripts/stl/udp_1pkt_pcap.py
@@ -1,11 +1,14 @@
 from trex_stl_lib.api import *
+import os
 
 # stream from pcap file. continues pps 10 in sec 
 
+CP = os.path.join(os.path.dirname(__file__))
+
 class STLS1(object):
 
     def get_streams (self, direction = 0, **kwargs):
-        return [STLStream(packet = STLPktBuilder(pkt ="stl/yaml/udp_64B_no_crc.pcap"), # path relative to pwd 
+        return [STLStream(packet = STLPktBuilder(pkt = os.path.join(CP, "yaml/udp_64B_no_crc.pcap")),
                          mode = STLTXCont(pps=10)) ] #rate continues, could be STLTXSingleBurst,STLTXMultiBurst
 
 
diff --git a/scripts/stl/udp_3pkt_pcap.py b/scripts/stl/udp_3pkt_pcap.py
index fd2c609e..19ff46bc 100644
--- a/scripts/stl/udp_3pkt_pcap.py
+++ b/scripts/stl/udp_3pkt_pcap.py
@@ -1,26 +1,29 @@
 from trex_stl_lib.api import *
+import os
 
 # stream from pcap file. continues pps 10 in sec 
 
+CP = os.path.join(os.path.dirname(__file__))
+
 class STLS1(object):
 
     def create_stream (self):
 
         return STLProfile( [ STLStream( isg = 10.0, # star in delay 
                                         name    ='S0',
-                                        packet = STLPktBuilder(pkt ="stl/yaml/udp_64B_no_crc.pcap"),
+                                        packet = STLPktBuilder(pkt = os.path.join(CP, "yaml/udp_64B_no_crc.pcap")),
                                         mode = STLTXSingleBurst( pps = 10, total_pkts = 10),
                                         next = 'S1'), # point to next stream 
 
                              STLStream( self_start = False, # stream is  disabled enable trow S0
                                         name    ='S1',
-                                        packet  = STLPktBuilder(pkt ="stl/yaml/udp_594B_no_crc.pcap"),
+                                        packet  = STLPktBuilder(pkt = os.path.join(CP, "yaml/udp_594B_no_crc.pcap")),
                                         mode    = STLTXSingleBurst( pps = 10, total_pkts = 20),
                                         next    = 'S2' ),
 
                              STLStream(  self_start = False, # stream is  disabled enable trow S0
                                          name   ='S2',
-                                         packet = STLPktBuilder(pkt ="stl/yaml/udp_1518B_no_crc.pcap"),
+                                         packet = STLPktBuilder(pkt = os.path.join(CP, "yaml/udp_1518B_no_crc.pcap")),
                                          mode = STLTXSingleBurst( pps = 10, total_pkts = 30 )
                                         )
                             ]).get_streams()
diff --git a/scripts/stl/yaml/imix_1pkt_vm_minus.yaml b/scripts/stl/yaml/imix_1pkt_vm_minus.yaml
index e83cfdd0..6d5345df 100644
--- a/scripts/stl/yaml/imix_1pkt_vm_minus.yaml
+++ b/scripts/stl/yaml/imix_1pkt_vm_minus.yaml
@@ -18,7 +18,8 @@
                   "min_value" : 1000,
                   "name" : "l3_src",
                   "op" : "inc",
-                  "size" : 2,
+                  "step": 1,
+                  "size" : 4,
                   "type" : "flow_var"
                },
                {