[NFVBENCH-86] In case of lossy loopback device, packet drops are reported incorrectly1.4.0

This is only for fixed rate runs, the chain analysis table at end of run may contain
incorrect drops.

Change-Id: I6656528ed695a60003c672132624a7284db60497
Signed-off-by: ahothan <ahothan@cisco.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/nfvbench/network.py b/nfvbench/network.py
index e097c2b..6c02f04 100644
--- a/nfvbench/network.py
+++ b/nfvbench/network.py
@@ -15,8 +15,10 @@
 
 
 class Interface(object):
+    """A class to hold the RX and TX counters for a virtual or physical interface."""
 
     def __init__(self, name, device, tx_packets, rx_packets):
+        """Create a new interface instance."""
         self.name = name
         self.device = device
         self.packets = {
@@ -25,38 +27,65 @@ class Interface(object):
         }
 
     def set_packets(self, tx, rx):
+        """Set tx and rx counters for this interface."""
         self.packets = {
             'tx': tx,
             'rx': rx
         }
 
     def set_packets_diff(self, tx, rx):
+        """Subtract current counters from new set of counters and update with results."""
         self.packets = {
             'tx': tx - self.packets['tx'],
             'rx': rx - self.packets['rx'],
         }
 
     def is_no_op(self):
+        """Check if this interface is a no-opn interface."""
         return self.name is None
 
     def get_packet_count(self, traffic_type):
+        """Get packet count for given direction."""
         return self.packets.get(traffic_type, 0)
 
     @staticmethod
     def no_op():
+        """Return an interface that doe snot pass any traffic."""
         return Interface(None, None, 0, 0)
 
 
 class Network(object):
+    """This class holds all interfaces that make up a logical neutron network.
+
+    A loopback packet path has exactly 2 networks.
+    The first interface is always one of the 2 traffic gen interface.
+    Subsequent interfaces are sorted along the path from the TG to the loopback point
+    which could be interfaces in a switch, a vswitch or a VM.
+    """
 
     def __init__(self, interfaces=None, reverse=False):
+        """Create a network with initial interface list and direction.
+
+        :param interfaces: initial interface list
+        :param reverse: specifies the order of interfaces returned by get_interfaces
+        """
         if interfaces is None:
             interfaces = []
         self.interfaces = interfaces
         self.reverse = reverse
 
     def add_interface(self, interface):
+        """Add one more interface to this network.
+
+        Order if important as interfaces must be added from traffic generator ports towards then
+        looping back device.
+        """
         self.interfaces.append(interface)
 
     def get_interfaces(self):
+        """Get interfaces associated to this network.
+
+        Returned interface list is ordered from traffic generator port towards looping device if
+        reverse is false. Else returms the list in the reverse order.
+        """
         return self.interfaces[::-1] if self.reverse else self.interfaces