diff --git a/framework/pktgen_base.py b/framework/pktgen_base.py
index 023652cc..16eae93f 100644
--- a/framework/pktgen_base.py
+++ b/framework/pktgen_base.py
@@ -64,10 +64,17 @@ class PacketGenerator(object):
         self.tester = tester
         self.__streams = []
         self._ports_map = []
+        self.pktgen_type = None
+
+    def _prepare_generator(self):
+        raise NotImplementedError
 
     def prepare_generator(self):
         self._prepare_generator()
 
+    def _get_port_pci(self, port_id):
+        raise NotImplementedError
+
     def _convert_pktgen_port(self, port_id):
         '''
         :param port_id:
@@ -94,6 +101,9 @@ class PacketGenerator(object):
 
         return port
 
+    def _get_gen_port(self, tester_pci):
+        raise NotImplementedError
+
     def _convert_tester_port(self, port_id):
         '''
         :param port_id:
@@ -143,6 +153,9 @@ class PacketGenerator(object):
     def get_streams(self):
         return self.__streams
 
+    def _clear_streams(self):
+        raise NotImplementedError
+
     def clear_streams(self):
         ''' clear streams '''
         self._clear_streams()
@@ -525,7 +538,7 @@ class PacketGenerator(object):
                 break
             pps = (traffic_pps_max - traffic_pps_min)/2 + traffic_pps_min
 
-        self.logger.info("zero loss pps is %f" % last_no_lost_mult)
+        self.logger.info("zero loss pps is %f" % pps)
         # use last result as return data to keep the same with dts/etgen format
         # In fact, multiple link peer have multiple loss rate value,
         # here only pick one
diff --git a/framework/pktgen_ixia.py b/framework/pktgen_ixia.py
index 06667047..03dac3de 100644
--- a/framework/pktgen_ixia.py
+++ b/framework/pktgen_ixia.py
@@ -1082,7 +1082,7 @@ class Ixia(SSHConnection):
         Tells IXIA to prepare the internal buffers were the frames were captured.
         """
         ixia_port = self.get_ixia_port(port_number)
-        command = 'capture get {0} {1} {2}'.format(ixia_port)
+        command = 'capture get {0}'.format(ixia_port)
         self.send_expect(command, '% ', 30)
 
     def stat_get_rate_stat_all_stats(self, port_number):
@@ -1369,6 +1369,7 @@ class IxiaPacketGenerator(PacketGenerator):
     Ixia packet generator
     """
     def __init__(self, tester):
+        super(IxiaPacketGenerator, self).__init__(tester)
         # ixia management
         self.pktgen_type = PKTGEN_IXIA
         self._conn = None
@@ -1388,7 +1389,6 @@ class IxiaPacketGenerator(PacketGenerator):
         self.ip_keys = ['start', 'end','action', 'step', 'mask',]
         self.vlan_keys = ['start', 'end', 'action', 'step', 'count',]
 
-        super(IxiaPacketGenerator, self).__init__(tester)
         self.tester = tester
 
     def get_ports(self):
diff --git a/framework/pktgen_ixia_network.py b/framework/pktgen_ixia_network.py
index f3a232d2..3a58abe5 100644
--- a/framework/pktgen_ixia_network.py
+++ b/framework/pktgen_ixia_network.py
@@ -41,6 +41,7 @@ class IxNetworkPacketGenerator(PacketGenerator):
     ixNetwork packet generator
     """
     def __init__(self, tester):
+        super(IxNetworkPacketGenerator, self).__init__(tester)
         self.pktgen_type = PKTGEN_IXIA_NETWORK
         self._conn = None
         # ixNetwork configuration information of dts
@@ -51,7 +52,6 @@ class IxNetworkPacketGenerator(PacketGenerator):
         self._ports = []
         self._rx_ports = []
 
-        super(IxNetworkPacketGenerator, self).__init__(tester)
 
     def get_ports(self):
         ''' used for ixNetwork packet generator '''
diff --git a/framework/pktgen_trex.py b/framework/pktgen_trex.py
index 2ad05fe6..2f537a0b 100644
--- a/framework/pktgen_trex.py
+++ b/framework/pktgen_trex.py
@@ -35,6 +35,9 @@ import sys
 import time
 from pprint import pformat
 
+from scapy.layers.inet import IP
+from scapy.layers.l2 import Ether
+
 from .pktgen_base import (
     PKTGEN,
     PKTGEN_TREX,
@@ -414,6 +417,7 @@ class TrexPacketGenerator(PacketGenerator):
     https://trex-tgn.cisco.com/trex/doc/trex_manual.html
     """
     def __init__(self, tester):
+        super(TrexPacketGenerator, self).__init__(tester)
         self.pktgen_type = PKTGEN_TREX
         self.trex_app = "t-rex-64"
         self._conn = None
@@ -432,7 +436,6 @@ class TrexPacketGenerator(PacketGenerator):
         self.ip_keys = ['start', 'end','action', 'mask', 'step']
         self.vlan_keys = ['start', 'end', 'action', 'step', 'count']
 
-        super(TrexPacketGenerator, self).__init__(tester)
 
         # check trex binary file
         trex_bin = os.sep.join([self.conf.get('trex_root_path'), self.trex_app])
