moon_engine/tests/unit_python/api/pipeline/__init__.py


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# Software Name: MOON

# Version: 5.4

# SPDX-FileCopyrightText: Copyright (c) 2018-2020 Orange and its contributors
# SPDX-License-Identifier: Apache-2.0

# This software is distributed under the 'Apache License 2.0',
# the text of which is available at 'http://www.apache.org/licenses/LICENSE-2.0.txt'
# or see the "LICENSE" file for more details.
# Copyright 2016 Cisco Systems, Inc.  All rights reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""Interface to the traffic generator clients including NDR/PDR binary search."""

from math import gcd
import socket
import struct
import time

from attrdict import AttrDict
import bitmath
from netaddr import IPNetwork
# pylint: disable=import-error
from trex.stl.api import Ether
from trex.stl.api import STLError
from trex.stl.api import UDP
# pylint: disable=wrong-import-order
from scapy.contrib.mpls import MPLS  # flake8: noqa
# pylint: enable=wrong-import-order
# pylint: enable=import-error

from .log import LOG
from .packet_stats import InterfaceStats
from .packet_stats import PacketPathStats
from .stats_collector import IntervalCollector
from .stats_collector import IterationCollector
from .traffic_gen import traffic_utils as utils
from .utils import cast_integer

class TrafficClientException(Exception):
    """Generic traffic client exception."""

class TrafficRunner(object):
    """Serialize various steps required to run traffic."""

    def __init__(self, client, duration_sec, interval_sec=0, service_mode=False):
        """Create a traffic runner."""
        self.client = client
        self.start_time = None
        self.duration_sec = duration_sec
        self.interval_sec = interval_sec
        self.service_mode = service_mode

    def run(self):
        """Clear stats and instruct the traffic generator to start generating traffic."""
        if self.is_running():
            return None
        LOG.info('Running traffic generator')
        self.client.gen.clear_stats()
        # Debug use only : new '--service-mode' option available for the NFVBench command line.
        # A read-only mode TRex console would be able to capture the generated traffic.
        self.client.gen.set_service_mode(enabled=self.service_mode)
        LOG.info('Service mode is %sabled', 'en' if self.service_mode else 'dis')
        self.client.gen.start_traffic()
        self.start_time = time.time()
        return self.poll_stats()

    def stop(self):
        """Stop the current run and instruct the traffic generator to stop traffic."""
        if self.is_running():
            self.start_time = None
            self.client.gen.stop_traffic()

    def is_running(self):
        """Check if a run is still pending."""
        return self.start_time is not None

    def time_elapsed(self):
        """Return time elapsed since start of run."""
        if self.is_running():
            return time.time() - self.start_time
        return self.duration_sec

    def poll_stats(self):
        """Poll latest stats from the traffic generator at fixed interval - sleeps if necessary.

        return: latest stats or None if traffic is stopped
        """
        if not self.is_running():
            return None
        if self.client.skip_sleep():
            self.stop()
            return self.client.get_stats()
        time_elapsed = self.time_elapsed()
        if time_elapsed > self.duration_sec:
            self.stop()
            return None
        time_left = self.duration_sec - time_elapsed
        if self.interval_sec > 0.0:
            if time_left <= self.interval_sec:
                time.sleep(time_left)
                self.stop()
            else:
                time.sleep(self.interval_sec)
        else:
            time.sleep(self.duration_sec)
            self.stop()
        return self.client.get_stats()


class IpBlock(object):
    """Manage a block of IP addresses."""

    def __init__(self, base_ip, step_ip, count_ip):
        """Create an IP block."""
        self.base_ip_int = Device.ip_to_int(base_ip)
        self.step = Device.ip_to_int(step_ip)
        self.max_available = count_ip
        self.next_free = 0

    def get_ip(self, index=0):
        """Return the IP address at given index."""
        if index < 0 or index >= self.max_available:
            raise IndexError('Index out of bounds: %d (max=%d)' % (index, self.max_available))
        return Device.int_to_ip(self.base_ip_int + index * self.step)

    def reserve_ip_range(self, count, force_ip_reservation=False):
        """Reserve a range of count consecutive IP addresses spaced by step.
        force_ip_reservation parameter allows to continue the calculation of IPs when
        the 2 sides (ports) have different size and the flow is greater than
        the size as well.
        """
        if self.next_free + count > self.max_available and force_ip_reservation is False:
            raise IndexError('No more IP addresses next free=%d max_available=%d requested=%d' %
                             (self.next_free,
                              self.max_available,
                              count))
        if self.next_free + count > self.max_available and force_ip_reservation is True:
            first_ip = self.get_ip(self.next_free)
            last_ip = self.get_ip(self.next_free + self.max_available - 1)
            self.next_free += self.max_available
        else:
            first_ip = self.get_ip(self.next_free)
            last_ip = self.get_ip(self.next_free + count - 1)
            self.next_free += count
        return (first_ip, last_ip)

    def reset_reservation(self):
        """Reset all reservations and restart with a completely unused IP block."""
        self.next_free = 0


class UdpPorts(object):

    def __init__(self, src_min, src_max, dst_min, dst_max, step):

        self.src_min = src_min
        self.src_max = src_max
        self.dst_min = dst_min
        self.dst_max = dst_max
        self.step = step


class Device(object):
    """Represent a port device and all information associated to it.

    In the curent version we only support 2 port devices for the traffic generator
    identified as port 0 or port 1.
    """

    def __init__(self, port, generator_config):
        """Create a new device for a given port."""
        self.generator_config = generator_config
        self.chain_count = generator_config.service_chain_count
        if generator_config.bidirectional:
            self.flow_count = generator_config.flow_count / 2
        else:
            self.flow_count = generator_config.flow_count

        self.port = port
        self.switch_port = generator_config.interfaces[port].get('switch_port', None)
        self.vtep_vlan = None
        self.vtep_src_mac = None
        self.vxlan = False
        self.mpls = False
        self.inner_labels = None
        self.outer_labels = None
        self.pci = generator_config.interfaces[port].pci
        self.mac = None
        self.dest_macs = None
        self.vtep_dst_mac = None
        self.vtep_dst_ip = None
        if generator_config.vteps is None:
            self.vtep_src_ip = None
        else:
            self.vtep_src_ip = generator_config.vteps[port]
        self.vnis = None
        self.vlans = None
        self.ip_addrs = generator_config.ip_addrs[port]
        self.ip_src_static = generator_config.ip_src_static
        self.ip_addrs_step = generator_config.ip_addrs_step
        if self.ip_addrs_step == 'random':
            # Set step to 1 to calculate the IP range size (see check_ip_size below)
            step = '0.0.0.1'
        else:
            step = self.ip_addrs_step
        self.ip_size = self.check_ipsize(IPNetwork(self.ip_addrs).size, Device.ip_to_int(step))
        self.ip = str(IPNetwork(self.ip_addrs).network)
        ip_addrs_left = generator_config.ip_addrs[0]
        ip_addrs_right = generator_config.ip_addrs[1]
        self.ip_addrs_size = {
            'left': self.check_ipsize(IPNetwork(ip_addrs_left).size, Device.ip_to_int(step)),
            'right': self.check_ipsize(IPNetwork(ip_addrs_right).size, Device.ip_to_int(step))}
        udp_src_port = generator_config.gen_config.udp_src_port
        if udp_src_port is None:
            udp_src_port = 53
        udp_dst_port = generator_config.gen_config.udp_dst_port
        if udp_dst_port is None:
            udp_dst_port = 53
        src_max, src_min = self.define_udp_range(udp_src_port, 'udp_src_port')
        dst_max, dst_min = self.define_udp_range(udp_dst_port, 'udp_dst_port')
        udp_src_range = int(src_max) - int(src_min) + 1
        udp_dst_range = int(dst_max) - int(dst_min) + 1
        lcm_port = self.lcm(udp_src_range, udp_dst_range)
        if self.ip_src_static is True:
            lcm_ip = self.lcm(1, min(self.ip_addrs_size['left'], self.ip_addrs_size['right']))
        else:
            lcm_ip = self.lcm(self.ip_addrs_size['left'], self.ip_addrs_size['right'])
        flow_max = self.lcm(lcm_port, lcm_ip)
        if self.flow_count > flow_max:
            raise TrafficClientException('Trying to set unachievable traffic (%d > %d)' %
                                         (self.flow_count, flow_max))

        # manage udp range regarding flow count value
        # UDP dst range is greater than FC => range will be limited to min + FC
        if self.flow_count <= udp_dst_range:
            dst_max = int(dst_min) + self.flow_count - 1
        # UDP src range is greater than FC => range will be limited to min + FC
        if self.flow_count <= udp_src_range:
            src_max = int(src_min) + self.flow_count - 1
        # Define IP block limit regarding flow count
        if self.flow_count <= self.ip_size:
            self.ip_block = IpBlock(self.ip, step, self.flow_count)
        else:
            self.ip_block = IpBlock(self.ip, step, self.ip_size)

        self.udp_ports = UdpPorts(src_min, src_max, dst_min, dst_max,
                                  generator_config.gen_config.udp_port_step)
        self.gw_ip_block = IpBlock(generator_config.gateway_ips[port],
                                   generator_config.gateway_ip_addrs_step,
                                   self.chain_count)
        self.tg_gateway_ip_addrs = generator_config.tg_gateway_ip_addrs[port]
        self.tg_gw_ip_block = IpBlock(self.tg_gateway_ip_addrs,
                                      generator_config.tg_gateway_ip_addrs_step,
                                      self.chain_count)

    @staticmethod
    def define_udp_range(udp_port, property_name):
        if isinstance(udp_port, int):
            min = udp_port
            max = min
        elif isinstance(udp_port, tuple):
            min = udp_port[0]
            max = udp_port[1]
        else:
            raise TrafficClientException('Invalid %s property value (53 or [\'53\',\'1024\'])'
                                         % property_name)
        return max, min

    @staticmethod
    def lcm(a, b):
        """Calculate the maximum possible value for both IP and ports,
        eventually for maximum possible flux."""
        if a != 0 and b != 0:
            lcm_value = a * b // gcd(a, b)
            return lcm_value
        raise TypeError(" IP size or port range can't be zero !")

    @staticmethod
    def check_ipsize(ip_size, step):
        """Check and set the available IPs, considering the step."""
        try:
            if ip_size % step == 0:
                value = int(ip_size / step)
            else:
                value = int((ip_size / step)) + 1
            return value
        except ZeroDivisionError:
            raise ZeroDivisionError("step can't be zero !")

    def set_mac(self, mac):
        """Set the local MAC for this port device."""
        if mac is None:
            raise TrafficClientException('Trying to set traffic generator MAC address as None')
        self.mac = mac

    def get_peer_device(self):
        """Get the peer device (device 0 -> device 1, or device 1 -> device 0)."""
        return self.generator_config.devices[1 - self.port]

    def set_vtep_dst_mac(self, dest_macs):
        """Set the list of dest MACs indexed by the chain id.

        This is only called in 2 cases:
        - VM macs discovered using openstack API
        - dest MACs provisioned in config file
        """
        self.vtep_dst_mac = list(map(str, dest_macs))

    def set_dest_macs(self, dest_macs):
        """Set the list of dest MACs indexed by the chain id.

        This is only called in 2 cases:
        - VM macs discovered using openstack API
        - dest MACs provisioned in config file
        """
        self.dest_macs = list(map(str, dest_macs))

    def get_dest_macs(self):
        """Get the list of dest macs for this device.

        If set_dest_macs was never called, assumes l2-loopback and return
        a list of peer mac (as many as chains but normally only 1 chain)
        """
        if self.dest_macs:
            return self.dest_macs
        # assume this is l2-loopback
        return [self.get_peer_device().mac] * self.chain_count

    def set_vlans(self, vlans):
        """Set the list of vlans to use indexed by the chain id."""
        self.vlans = vlans
        LOG.info("Port %d: VLANs %s", self.port, self.vlans)

    def set_vtep_vlan(self, vlan):
        """Set the vtep vlan to use indexed by specific port."""
        self.vtep_vlan = vlan
        self.vxlan = True
        self.vlan_tagging = None
        LOG.info("Port %d: VTEP VLANs %s", self.port, self.vtep_vlan)

    def set_vxlan_endpoints(self, src_ip, dst_ip):
        self.vtep_dst_ip = dst_ip
        self.vtep_src_ip = src_ip
        LOG.info("Port %d: src_vtep %s, dst_vtep %s", self.port,
                 self.vtep_src_ip, self.vtep_dst_ip)

    def set_mpls_peers(self, src_ip, dst_ip):
        self.mpls = True
        self.vtep_dst_ip = dst_ip
        self.vtep_src_ip = src_ip
        LOG.info("Port %d: src_mpls_vtep %s, mpls_peer_ip %s", self.port,
                 self.vtep_src_ip, self.vtep_dst_ip)

    def set_vxlans(self, vnis):
        self.vnis = vnis
        LOG.info("Port %d: VNIs %s", self.port, self.vnis)

    def set_mpls_inner_labels(self, labels):
        self.inner_labels = labels
        LOG.info("Port %d: MPLS Inner Labels %s", self.port, self.inner_labels)

    def set_mpls_outer_labels(self, labels):
        self.outer_labels = labels
        LOG.info("Port %d: MPLS Outer Labels %s", self.port, self.outer_labels)

    def set_gw_ip(self, gateway_ip):
        self.gw_ip_block = IpBlock(gateway_ip,
                                   self.generator_config.gateway_ip_addrs_step,
                                   self.chain_count)

    def get_gw_ip(self, chain_index):
        """Retrieve the IP address assigned for the gateway of a given chain."""
        return self.gw_ip_block.get_ip(chain_index)

    def get_stream_configs(self):
        """Get the stream config for a given chain on this device.

        Called by the traffic generator driver to program the traffic generator properly
        before generating traffic
        """
        configs = []
        # exact flow count for each chain is calculated as follows:
        # - all chains except the first will have the same flow count
        #   calculated as (total_flows + chain_count - 1) / chain_count
        # - the first chain will have the remainder
        # example 11 flows and 3 chains => 3, 4, 4
        flows_per_chain = int((self.flow_count + self.chain_count - 1) / self.chain_count)
        cur_chain_flow_count = int(self.flow_count - flows_per_chain * (self.chain_count - 1))
        force_ip_reservation = False
        # use case example of this parameter:
        # - static IP addresses (source & destination), netmask = /30
        # - 4 varying UDP source ports | 1 UDP destination port
        # - Flow count = 8
        # --> parameter 'reserve_ip_range' should have flag 'force_ip_reservation'
        # in order to assign the maximum available IP on each iteration
        if self.ip_size < cur_chain_flow_count \
                or self.ip_addrs_size['left'] != self.ip_addrs_size['right']:
            force_ip_reservation = True

        peer = self.get_peer_device()
        self.ip_block.reset_reservation()
        peer.ip_block.reset_reservation()
        dest_macs = self.get_dest_macs()

        for chain_idx in range(self.chain_count):
            src_ip_first, src_ip_last = self.ip_block.reserve_ip_range\
            (cur_chain_flow_count, force_ip_reservation)
            dst_ip_first, dst_ip_last = peer.ip_block.reserve_ip_range\
            (cur_chain_flow_count, force_ip_reservation)

            configs.append({
                'count': cur_chain_flow_count,
                'mac_src': self.mac,
                'mac_dst': dest_macs[chain_idx],
                'ip_src_addr': src_ip_first,
                'ip_src_addr_max': src_ip_last,
                'ip_src_count': cur_chain_flow_count,
                'ip_dst_addr': dst_ip_first,
                'ip_dst_addr_max': dst_ip_last,
                'ip_dst_count': cur_chain_flow_count,
                'ip_addrs_step': self.ip_addrs_step,
                'ip_src_static': self.ip_src_static,
                'udp_src_port': self.udp_ports.src_min,
                'udp_src_port_max': self.udp_ports.src_max,
                'udp_src_count': int(self.udp_ports.src_max) - int(self.udp_ports.src_min) + 1,
                'udp_dst_port': self.udp_ports.dst_min,
                'udp_dst_port_max': self.udp_ports.dst_max,
                'udp_dst_count': int(self.udp_ports.dst_max) - int(self.udp_ports.dst_min) + 1,
                'udp_port_step': self.udp_ports.step,
                'mac_discovery_gw': self.get_gw_ip(chain_idx),
                'ip_src_tg_gw': self.tg_gw_ip_block.get_ip(chain_idx),
                'ip_dst_tg_gw': peer.tg_gw_ip_block.get_ip(chain_idx),
                'vlan_tag': self.vlans[chain_idx] if self.vlans else None,
                'vxlan': self.vxlan,
                'vtep_vlan': self.vtep_vlan if self.vtep_vlan else None,
                'vtep_src_mac': self.mac if (self.vxlan or self.mpls) else None,
                'vtep_dst_mac': self.vtep_dst_mac if (self.vxlan or self.mpls) else None,
                'vtep_dst_ip': self.vtep_dst_ip if self.vxlan is True else None,
                'vtep_src_ip': self.vtep_src_ip if self.vxlan is True else None,
                'net_vni': self.vnis[chain_idx] if self.vxlan is True else None,
                'mpls': self.mpls,
                'mpls_outer_label': self.outer_labels[chain_idx] if self.mpls is True else None,
                'mpls_inner_label': self.inner_labels[chain_idx] if self.mpls is True else None

            })
            # after first chain, fall back to the flow count for all other chains
            cur_chain_flow_count = flows_per_chain
        return configs

    @staticmethod
    def ip_to_int(addr):
        """Convert an IP address from string to numeric."""
        return struct.unpack("!I", socket.inet_aton(addr))[0]

    @staticmethod
    def int_to_ip(nvalue):
        """Convert an IP address from numeric to string."""
        return socket.inet_ntoa(struct.pack("!I", int(nvalue)))


class GeneratorConfig(object):
    """Represents traffic configuration for currently running traffic profile."""

    DEFAULT_IP_STEP = '0.0.0.1'
    DEFAULT_SRC_DST_IP_STEP = '0.0.0.1'

    def __init__(self, config):
        """Create a generator config."""
        self.config = config
        # name of the generator profile (normally trex or dummy)
        # pick the default one if not specified explicitly from cli options
        if not config.generator_profile:
            config.generator_profile = config.traffic_generator.default_profile
        # pick up the profile dict based on the name
        gen_config = self.__match_generator_profile(config.traffic_generator,
                                                    config.generator_profile)
        self.gen_config = gen_config
        # copy over fields from the dict
        self.tool = gen_config.tool
        self.ip = gen_config.ip
        # overrides on config.cores and config.mbuf_factor
        if config.cores:
            self.cores = config.cores
        else:
            self.cores = gen_config.get('cores', 1)
        self.mbuf_factor = config.mbuf_factor
        self.mbuf_64 = config.mbuf_64
        self.hdrh = not config.disable_hdrh
        if gen_config.intf_speed:
            # interface speed is overriden from config
            self.intf_speed = bitmath.parse_string(gen_config.intf_speed.replace('ps', '')).bits
        else:
            # interface speed is discovered/provided by the traffic generator
            self.intf_speed = 0
        self.name = gen_config.name
        self.zmq_pub_port = gen_config.get('zmq_pub_port', 4500)
        self.zmq_rpc_port = gen_config.get('zmq_rpc_port', 4501)
        self.limit_memory = gen_config.get('limit_memory', 1024)
        self.software_mode = gen_config.get('software_mode', False)
        self.interfaces = gen_config.interfaces
        if self.interfaces[0].port != 0 or self.interfaces[1].port != 1:
            raise TrafficClientException('Invalid port order/id in generator_profile.interfaces')
        self.service_chain = config.service_chain
        self.service_chain_count = config.service_chain_count
        self.flow_count = config.flow_count
        self.host_name = gen_config.host_name
        self.bidirectional = config.traffic.bidirectional
        self.tg_gateway_ip_addrs = gen_config.tg_gateway_ip_addrs
        self.ip_addrs = gen_config.ip_addrs
        self.ip_addrs_step = gen_config.ip_addrs_step or self.DEFAULT_SRC_DST_IP_STEP
        self.tg_gateway_ip_addrs_step = \
            gen_config.tg_gateway_ip_addrs_step or self.DEFAULT_IP_STEP
        self.gateway_ip_addrs_step = gen_config.gateway_ip_addrs_step or self.DEFAULT_IP_STEP
        self.gateway_ips = gen_config.gateway_ip_addrs
        self.ip_src_static = gen_config.ip_src_static
        self.vteps = gen_config.get('vteps')
        self.devices = [Device(port, self) for port in [0, 1]]
        # This should normally always be [0, 1]
        self.ports = [device.port for device in self.devices]

        # check that pci is not empty
        if not gen_config.interfaces[0].get('pci', None) or \
           not gen_config.interfaces[1].get('pci', None):
            raise TrafficClientException("configuration interfaces pci fields cannot be empty")

        self.pcis = [tgif['pci'] for tgif in gen_config.interfaces]
        self.vlan_tagging = config.vlan_tagging

        # needed for result/summarizer
        config['tg-name'] = gen_config.name
        config['tg-tool'] = self.tool

    def to_json(self):
        """Get json form to display the content into the overall result dict."""
        return dict(self.gen_config)

    def set_dest_macs(self, port_index, dest_macs):
        """Set the list of dest MACs indexed by the chain id on given port.

        port_index: the port for which dest macs must be set
        dest_macs: a list of dest MACs indexed by chain id
        """
        if len(dest_macs) < self.config.service_chain_count:
            raise TrafficClientException('Dest MAC list %s must have %d entries' %
                                         (dest_macs, self.config.service_chain_count))
        # only pass the first scc dest MACs
        self.devices[port_index].set_dest_macs(dest_macs[:self.config.service_chain_count])
        LOG.info('Port %d: dst MAC %s', port_index, [str(mac) for mac in dest_macs])

    def set_vtep_dest_macs(self, port_index, dest_macs):
        """Set the list of dest MACs indexed by the chain id on given port.

        port_index: the port for which dest macs must be set
        dest_macs: a list of dest MACs indexed by chain id
        """
        if len(dest_macs) != self.config.service_chain_count:
            raise TrafficClientException('Dest MAC list %s must have %d entries' %
                                         (dest_macs, self.config.service_chain_count))
        self.devices[port_index].set_vtep_dst_mac(dest_macs)
        LOG.info('Port %d: vtep dst MAC %s', port_index, {str(mac) for mac in dest_macs})

    def get_dest_macs(self):
        """Return the list of dest macs indexed by port."""
        return [dev.get_dest_macs() for dev in self.devices]

    def set_vlans(self, port_index, vlans):
        """Set the list of vlans to use indexed by the chain id on given port.

        port_index: the port for which VLANs must be set
        vlans: a  list of vlan lists indexed by chain id
        """
        if len(vlans) != self.config.service_chain_count:
            raise TrafficClientException('VLAN list %s must have %d entries' %
                                         (vlans, self.config.service_chain_count))
        self.devices[port_index].set_vlans(vlans)

    def set_vxlans(self, port_index, vxlans):
        """Set the list of vxlans (VNIs) to use indexed by the chain id on given port.

        port_index: the port for which VXLANs must be set
        VXLANs: a  list of VNIs lists indexed by chain id
        """
        if len(vxlans) != self.config.service_chain_count:
            raise TrafficClientException('VXLAN list %s must have %d entries' %
                                         (vxlans, self.config.service_chain_count))
        self.devices[port_index].set_vxlans(vxlans)

    def set_mpls_inner_labels(self, port_index, labels):
        """Set the list of MPLS Labels to use indexed by the chain id on given port.

        port_index: the port for which Labels must be set
        Labels: a list of Labels lists indexed by chain id
        """
        if len(labels) != self.config.service_chain_count:
            raise TrafficClientException('Inner MPLS list %s must have %d entries' %
                                         (labels, self.config.service_chain_count))
        self.devices[port_index].set_mpls_inner_labels(labels)

    def set_mpls_outer_labels(self, port_index, labels):
        """Set the list of MPLS Labels to use indexed by the chain id on given port.

        port_index: the port for which Labels must be set
        Labels: a list of Labels lists indexed by chain id
        """
        if len(labels) != self.config.service_chain_count:
            raise TrafficClientException('Outer MPLS list %s must have %d entries' %
                                         (labels, self.config.service_chain_count))
        self.devices[port_index].set_mpls_outer_labels(labels)

    def set_vtep_vlan(self, port_index, vlan):
        """Set the vtep vlan to use indexed by the chain id on given port.
        port_index: the port for which VLAN must be set
        """
        self.devices[port_index].set_vtep_vlan(vlan)

    def set_vxlan_endpoints(self, port_index, src_ip, dst_ip):
        self.devices[port_index].set_vxlan_endpoints(src_ip, dst_ip)

    def set_mpls_peers(self, port_index, src_ip, dst_ip):
        self.devices[port_index].set_mpls_peers(src_ip, dst_ip)

    @staticmethod
    def __match_generator_profile(traffic_generator, generator_profile):
        gen_config = AttrDict(traffic_generator)
        gen_config.pop('default_profile')
        gen_config.pop('generator_profile')
        matching_profile = [profile for profile in traffic_generator.generator_profile if
                            profile.name == generator_profile]
        if len(matching_profile) != 1:
            raise Exception('Traffic generator profile not found: ' + generator_profile)

        gen_config.update(matching_profile[0])
        return gen_config


class TrafficClient(object):
    """Traffic generator client with NDR/PDR binary seearch."""

    PORTS = [0, 1]

    def __init__(self, config, notifier=None):
        """Create a new TrafficClient instance.

        config: nfvbench config
        notifier: notifier (optional)

        A new instance is created everytime the nfvbench config may have changed.
        """
        self.config = config
        self.generator_config = GeneratorConfig(config)
        self.tool = self.generator_config.tool
        self.gen = self._get_generator()
        self.notifier = notifier
        self.interval_collector = None
        self.iteration_collector = None
        self.runner = TrafficRunner(self, self.config.duration_sec, self.config.interval_sec,
                                    self.config.service_mode)
        self.config.frame_sizes = self._get_frame_sizes()
        self.run_config = {
            'l2frame_size': None,
            'duration_sec': self.config.duration_sec,
            'bidirectional': True,
            'rates': []  # to avoid unsbuscriptable-obj warning
        }
        self.current_total_rate = {'rate_percent': '10'}
        if self.config.single_run:
            self.current_total_rate = utils.parse_rate_str(self.config.rate)
        self.ifstats = None
        # Speed is either discovered when connecting to TG or set from config
        # This variable is 0 if not yet discovered from TG or must be the speed of
        # each interface in bits per second
        self.intf_speed = self.generator_config.intf_speed

    def _get_generator(self):
        tool = self.tool.lower()
        if tool == 'trex':
            from .traffic_gen import trex_gen
            return trex_gen.TRex(self)
        if tool == 'dummy':
            from .traffic_gen import dummy
            return dummy.DummyTG(self)
        raise TrafficClientException('Unsupported generator tool name:' + self.tool)

    def skip_sleep(self):
        """Skip all sleeps when doing unit testing with dummy TG.

        Must be overriden using mock.patch
        """
        return False

    def _get_frame_sizes(self):
        traffic_profile_name = self.config.traffic.profile
        matching_profiles = [profile for profile in self.config.traffic_profile if
                             profile.name == traffic_profile_name]
        if len(matching_profiles) > 1:
            raise TrafficClientException('Multiple traffic profiles with name: ' +
                                         traffic_profile_name)
        if not matching_profiles:
            raise TrafficClientException('Cannot find traffic profile: ' + traffic_profile_name)
        return matching_profiles[0].l2frame_size

    def start_traffic_generator(self):
        """Start the traffic generator process (traffic not started yet)."""
        self.gen.connect()
        # pick up the interface speed if it is not set from config
        intf_speeds = self.gen.get_port_speed_gbps()
        # convert Gbps unit into bps
        tg_if_speed = bitmath.parse_string(str(intf_speeds[0]) + 'Gb').bits
        if self.intf_speed:
            # interface speed is overriden from config
            if self.intf_speed != tg_if_speed:
                # Warn the user if the speed in the config is different
                LOG.warning('Interface speed provided is different from actual speed (%d Gbps)',
                            intf_speeds[0])
        else:
            # interface speed not provisioned by config
            self.intf_speed = tg_if_speed
            # also update the speed in the tg config
            self.generator_config.intf_speed = tg_if_speed

        # Save the traffic generator local MAC
        for mac, device in zip(self.gen.get_macs(), self.generator_config.devices):
            device.set_mac(mac)

    def setup(self):
        """Set up the traffic client."""
        self.gen.clear_stats()

    def get_version(self):
        """Get the traffic generator version."""
        return self.gen.get_version()

    def ensure_end_to_end(self):
        """Ensure traffic generator receives packets it has transmitted.

        This ensures end to end connectivity and also waits until VMs are ready to forward packets.

        VMs that are started and in active state may not pass traffic yet. It is imperative to make
        sure that all VMs are passing traffic in both directions before starting any benchmarking.
        To verify this, we need to send at a low frequency bi-directional packets and make sure
        that we receive all packets back from all VMs. The number of flows is equal to 2 times
        the number of chains (1 per direction) and we need to make sure we receive packets coming
        from exactly 2 x chain count different source MAC addresses.

        Example:
            PVP chain (1 VM per chain)
            N = 10 (number of chains)
            Flow count = 20 (number of flows)
            If the number of unique source MAC addresses from received packets is 20 then
            all 10 VMs 10 VMs are in operational state.
        """
        LOG.info('Starting traffic generator to ensure end-to-end connectivity')
        # send 2pps on each chain and each direction
        rate_pps = {'rate_pps': str(self.config.service_chain_count * 2)}
        self.gen.create_traffic('64', [rate_pps, rate_pps], bidirectional=True, latency=False,
                                e2e=True)
        # ensures enough traffic is coming back
        retry_count = int((self.config.check_traffic_time_sec +
                           self.config.generic_poll_sec - 1) / self.config.generic_poll_sec)

        # we expect to see packets coming from 2 unique MAC per chain
        # because there can be flooding in the case of shared net
        # we must verify that packets from the right VMs are received
        # and not just count unique src MAC
        # create a dict of (port, chain) tuples indexed by dest mac
        mac_map = {}
        for port, dest_macs in enumerate(self.generator_config.get_dest_macs()):
            for chain, mac in enumerate(dest_macs):
                mac_map[mac] = (port, chain)
        unique_src_mac_count = len(mac_map)
        if self.config.vxlan and self.config.traffic_generator.vtep_vlan:
            get_mac_id = lambda packet: packet['binary'][60:66]
        elif self.config.vxlan:
            get_mac_id = lambda packet: packet['binary'][56:62]
        elif self.config.mpls:
            get_mac_id = lambda packet: packet['binary'][24:30]
            # mpls_transport_label = lambda packet: packet['binary'][14:18]
        else:
            get_mac_id = lambda packet: packet['binary'][6:12]
        for it in range(retry_count):
            self.gen.clear_stats()
            self.gen.start_traffic()
            self.gen.start_capture()
            LOG.info('Captured unique src mac %d/%d, capturing return packets (retry %d/%d)...',
                     unique_src_mac_count - len(mac_map), unique_src_mac_count,
                     it + 1, retry_count)
            if not self.skip_sleep():
                time.sleep(self.config.generic_poll_sec)
            self.gen.stop_traffic()
            self.gen.fetch_capture_packets()
            self.gen.stop_capture()
            for packet in self.gen.packet_list:
                mac_id = get_mac_id(packet).decode('latin-1')
                src_mac = ':'.join(["%02x" % ord(x) for x in mac_id])
                if self.config.mpls:
                    if src_mac in mac_map and self.is_mpls(packet):
                        port, chain = mac_map[src_mac]
                        LOG.info('Received mpls packet from mac: %s (chain=%d, port=%d)',
                                 src_mac, chain, port)
                        mac_map.pop(src_mac, None)
                else:
                    if src_mac in mac_map and self.is_udp(packet):
                        port, chain = mac_map[src_mac]
                        LOG.info('Received udp packet from mac: %s (chain=%d, port=%d)',
                                 src_mac, chain, port)
                        mac_map.pop(src_mac, None)

                if not mac_map:
                    LOG.info('End-to-end connectivity established')
                    return
            if self.config.l3_router and not self.config.no_arp:
                # In case of L3 traffic mode, routers are not able to route traffic
                # until VM interfaces are up and ARP requests are done
                LOG.info('Waiting for loopback service completely started...')
                LOG.info('Sending ARP request to assure end-to-end connectivity established')
                self.ensure_arp_successful()
        raise TrafficClientException('End-to-end connectivity cannot be ensured')

    def is_udp(self, packet):
        pkt = Ether(packet['binary'])
        return UDP in pkt

    def is_mpls(self, packet):
        pkt = Ether(packet['binary'])
        return MPLS in pkt

    def ensure_arp_successful(self):
        """Resolve all IP using ARP and throw an exception in case of failure."""
        dest_macs = self.gen.resolve_arp()
        if dest_macs:
            # all dest macs are discovered, saved them into the generator config
            if self.config.vxlan or self.config.mpls:
                self.generator_config.set_vtep_dest_macs(0, dest_macs[0])
                self.generator_config.set_vtep_dest_macs(1, dest_macs[1])
            else:
                self.generator_config.set_dest_macs(0, dest_macs[0])
                self.generator_config.set_dest_macs(1, dest_macs[1])
        else:
            raise TrafficClientException('ARP cannot be resolved')

    def set_traffic(self, frame_size, bidirectional):
        """Reconfigure the traffic generator for a new frame size."""
        self.run_config['bidirectional'] = bidirectional
        self.run_config['l2frame_size'] = frame_size
        self.run_config['rates'] = [self.get_per_direction_rate()]
        if bidirectional:
            self.run_config['rates'].append(self.get_per_direction_rate())
        else:
            unidir_reverse_pps = int(self.config.unidir_reverse_traffic_pps)
            if unidir_reverse_pps > 0:
                self.run_config['rates'].append({'rate_pps': str(unidir_reverse_pps)})
        # Fix for [NFVBENCH-67], convert the rate string to PPS
        for idx, rate in enumerate(self.run_config['rates']):
            if 'rate_pps' not in rate:
                self.run_config['rates'][idx] = {'rate_pps': self.__convert_rates(rate)['rate_pps']}

        self.gen.clear_streamblock()

        if self.config.no_latency_streams:
            LOG.info("Latency streams are disabled")
        self.gen.create_traffic(frame_size, self.run_config['rates'], bidirectional,
                                latency=not self.config.no_latency_streams)

    def _modify_load(self, load):
        self.current_total_rate = {'rate_percent': str(load)}
        rate_per_direction = self.get_per_direction_rate()

        self.gen.modify_rate(rate_per_direction, False)
        self.run_config['rates'][0] = rate_per_direction
        if self.run_config['bidirectional']:
            self.gen.modify_rate(rate_per_direction, True)
            self.run_config['rates'][1] = rate_per_direction

    def get_ndr_and_pdr(self):
        """Start the NDR/PDR iteration and return the results."""
        dst = 'Bidirectional' if self.run_config['bidirectional'] else 'Unidirectional'
        targets = {}
        if self.config.ndr_run:
            LOG.info('*** Searching NDR for %s (%s)...', self.run_config['l2frame_size'], dst)
            targets['ndr'] = self.config.measurement.NDR
        if self.config.pdr_run:
            LOG.info('*** Searching PDR for %s (%s)...', self.run_config['l2frame_size'], dst)
            targets['pdr'] = self.config.measurement.PDR

        self.run_config['start_time'] = time.time()
        self.interval_collector = IntervalCollector(self.run_config['start_time'])
        self.interval_collector.attach_notifier(self.notifier)
        self.iteration_collector = IterationCollector(self.run_config['start_time'])
        results = {}
        self.__range_search(0.0, 200.0, targets, results)

        results['iteration_stats'] = {
            'ndr_pdr': self.iteration_collector.get()
        }

        if self.config.ndr_run:
            LOG.info('NDR load: %s', results['ndr']['rate_percent'])
            results['ndr']['time_taken_sec'] = \
                results['ndr']['timestamp_sec'] - self.run_config['start_time']
            if self.config.pdr_run:
                LOG.info('PDR load: %s', results['pdr']['rate_percent'])
                results['pdr']['time_taken_sec'] = \
                    results['pdr']['timestamp_sec'] - results['ndr']['timestamp_sec']
        else:
            LOG.info('PDR load: %s', results['pdr']['rate_percent'])
            results['pdr']['time_taken_sec'] = \
                results['pdr']['timestamp_sec'] - self.run_config['start_time']
        return results

    def __get_dropped_rate(self, result):
        dropped_pkts = result['rx']['dropped_pkts']
        total_pkts = result['tx']['total_pkts']
        if not total_pkts:
            return float('inf')
        return float(dropped_pkts) / total_pkts * 100

    def get_stats(self):
        """Collect final stats for previous run."""
        stats = self.gen.get_stats()
        retDict = {'total_tx_rate': stats['total_tx_rate']}

        tx_keys = ['total_pkts', 'total_pkt_bytes', 'pkt_rate', 'pkt_bit_rate']
        rx_keys = tx_keys + ['dropped_pkts']

        for port in self.PORTS:
            port_stats = {'tx': {}, 'rx': {}}
            for key in tx_keys:
                port_stats['tx'][key] = int(stats[port]['tx'][key])
            for key in rx_keys:
                try:
                    port_stats['rx'][key] = int(stats[port]['rx'][key])
                except ValueError:
                    port_stats['rx'][key] = 0
            port_stats['rx']['avg_delay_usec'] = cast_integer(
                stats[port]['rx']['avg_delay_usec'])
            port_stats['rx']['min_delay_usec'] = cast_integer(
                stats[port]['rx']['min_delay_usec'])
            port_stats['rx']['max_delay_usec'] = cast_integer(
                stats[port]['rx']['max_delay_usec'])
            port_stats['drop_rate_percent'] = self.__get_dropped_rate(port_stats)
            retDict[str(port)] = port_stats

        ports = sorted(list(retDict.keys()), key=str)
        if self.run_config['bidirectional']:
            retDict['overall'] = {'tx': {}, 'rx': {}}
            for key in tx_keys:
                retDict['overall']['tx'][key] = \
                    retDict[ports[0]]['tx'][key] + retDict[ports[1]]['tx'][key]
            for key in rx_keys:
                retDict['overall']['rx'][key] = \
                    retDict[ports[0]]['rx'][key] + retDict[ports[1]]['rx'][key]
            total_pkts = [retDict[ports[0]]['rx']['total_pkts'],
                          retDict[ports[1]]['rx']['total_pkts']]
            avg_delays = [retDict[ports[0]]['rx']['avg_delay_usec'],
                          retDict[ports[1]]['rx']['avg_delay_usec']]
            max_delays = [retDict[ports[0]]['rx']['max_delay_usec'],
                          retDict[ports[1]]['rx']['max_delay_usec']]
            min_delays = [retDict[ports[0]]['rx']['min_delay_usec'],
                          retDict[ports[1]]['rx']['min_delay_usec']]
            retDict['overall']['rx']['avg_delay_usec'] = utils.weighted_avg(total_pkts, avg_delays)
            retDict['overall']['rx']['min_delay_usec'] = min(min_delays)
            retDict['overall']['rx']['max_delay_usec'] = max(max_delays)
            for key in ['pkt_bit_rate', 'pkt_rate']:
                for dirc in ['tx', 'rx']:
                    retDict['overall'][dirc][key] /= 2.0
        else:
            retDict['overall'] = retDict[ports[0]]
        retDict['overall']['drop_rate_percent'] = self.__get_dropped_rate(retDict['overall'])
        return retDict

    def __convert_rates(self, rate):
        return utils.convert_rates(self.run_config['l2frame_size'],
                                   rate,
                                   self.intf_speed)

    def __ndr_pdr_found(self, tag, load):
        rates = self.__convert_rates({'rate_percent': load})
        self.iteration_collector.add_ndr_pdr(tag, rates['rate_pps'])
        last_stats = self.iteration_collector.peek()
        self.interval_collector.add_ndr_pdr(tag, last_stats)

    def __format_output_stats(self, stats):
        for key in self.PORTS + ['overall']:
            key = str(key)
            interface = stats[key]
            stats[key] = {
                'tx_pkts': interface['tx']['total_pkts'],
                'rx_pkts': interface['rx']['total_pkts'],
                'drop_percentage': interface['drop_rate_percent'],
                'drop_pct': interface['rx']['dropped_pkts'],
                'avg_delay_usec': interface['rx']['avg_delay_usec'],
                'max_delay_usec': interface['rx']['max_delay_usec'],
                'min_delay_usec': interface['rx']['min_delay_usec'],
            }

        return stats

    def __targets_found(self, rate, targets, results):
        for tag, target in list(targets.items()):
            LOG.info('Found %s (%s) load: %s', tag, target, rate)
            self.__ndr_pdr_found(tag, rate)
            results[tag]['timestamp_sec'] = time.time()

    def __range_search(self, left, right, targets, results):
        """Perform a binary search for a list of targets inside a [left..right] range or rate.

        left    the left side of the range to search as a % the line rate (100 = 100% line rate)
                indicating the rate to send on each interface
        right   the right side of the range to search as a % of line rate
                indicating the rate to send on each interface
        targets a dict of drop rates to search (0.1 = 0.1%), indexed by the DR name or "tag"
                ('ndr', 'pdr')
        results a dict to store results
        """
        if not targets:
            return
        LOG.info('Range search [%s .. %s] targets: %s', left, right, targets)

        # Terminate search when gap is less than load epsilon
        if right - left < self.config.measurement.load_epsilon:
            self.__targets_found(left, targets, results)
            return

        # Obtain the average drop rate in for middle load
        middle = (left + right) / 2.0
        try:
            stats, rates = self.__run_search_iteration(middle)
        except STLError:
            LOG.exception("Got exception from traffic generator during binary search")
            self.__targets_found(left, targets, results)
            return
        # Split target dicts based on the avg drop rate
        left_targets = {}
        right_targets = {}
        for tag, target in list(targets.items()):
            if stats['overall']['drop_rate_percent'] <= target:
                # record the best possible rate found for this target
                results[tag] = rates
                results[tag].update({
                    'load_percent_per_direction': middle,
                    'stats': self.__format_output_stats(dict(stats)),
                    'timestamp_sec': None
                })
                right_targets[tag] = target
            else:
                # initialize to 0 all fields of result for
                # the worst case scenario of the binary search (if ndr/pdr is not found)
                if tag not in results:
                    results[tag] = dict.fromkeys(rates, 0)
                    empty_stats = self.__format_output_stats(dict(stats))
                    for key in empty_stats:
                        if isinstance(empty_stats[key], dict):
                            empty_stats[key] = dict.fromkeys(empty_stats[key], 0)
                        else:
                            empty_stats[key] = 0
                    results[tag].update({
                        'load_percent_per_direction': 0,
                        'stats': empty_stats,
                        'timestamp_sec': None
                    })
                left_targets[tag] = target

        # search lower half
        self.__range_search(left, middle, left_targets, results)

        # search upper half only if the upper rate does not exceed
        # 100%, this only happens when the first search at 100%
        # yields a DR that is < target DR
        if middle >= 100:
            self.__targets_found(100, right_targets, results)
        else:
            self.__range_search(middle, right, right_targets, results)

    def __run_search_iteration(self, rate):
        """Run one iteration at the given rate level.

        rate: the rate to send on each port in percent (0 to 100)
        """
        self._modify_load(rate)

        # poll interval stats and collect them
        for stats in self.run_traffic():
            self.interval_collector.add(stats)
            time_elapsed_ratio = self.runner.time_elapsed() / self.run_config['duration_sec']
            if time_elapsed_ratio >= 1:
                self.cancel_traffic()
                if not self.skip_sleep():
                    time.sleep(self.config.pause_sec)
        self.interval_collector.reset()

        # get stats from the run
        stats = self.runner.client.get_stats()
        current_traffic_config = self._get_traffic_config()
        warning = self.compare_tx_rates(current_traffic_config['direction-total']['rate_pps'],
                                        stats['total_tx_rate'])
        if warning is not None:
            stats['warning'] = warning

        # save reliable stats from whole iteration
        self.iteration_collector.add(stats, current_traffic_config['direction-total']['rate_pps'])
        LOG.info('Average drop rate: %f', stats['overall']['drop_rate_percent'])
        return stats, current_traffic_config['direction-total']

    def log_stats(self, stats):
        """Log estimated stats during run."""
        # Calculate a rolling drop rate based on differential to
        # the previous reading
        cur_tx = stats['overall']['tx']['total_pkts']
        cur_rx = stats['overall']['rx']['total_pkts']
        delta_tx = cur_tx - self.prev_tx
        delta_rx = cur_rx - self.prev_rx
        drops = delta_tx - delta_rx
        drop_rate_pct = 100 * (delta_tx - delta_rx)/delta_tx
        self.prev_tx = cur_tx
        self.prev_rx = cur_rx
        LOG.info('TX: %15s; RX: %15s; (Est.) Dropped: %12s; Drop rate: %8.4f%%',
                 format(cur_tx, ',d'),
                 format(cur_rx, ',d'),
                 format(drops, ',d'),
                 drop_rate_pct)

    def run_traffic(self):
        """Start traffic and return intermediate stats for each interval."""
        stats = self.runner.run()
        self.prev_tx = 0
        self.prev_rx = 0
        while self.runner.is_running:
            self.log_stats(stats)
            yield stats
            stats = self.runner.poll_stats()
            if stats is None:
                return
        self.log_stats(stats)
        LOG.info('Drop rate: %f', stats['overall']['drop_rate_percent'])
        yield stats

    def cancel_traffic(self):
        """Stop traffic."""
        self.runner.stop()

    def _get_traffic_config(self):
        config = {}
        load_total = 0.0
        bps_total = 0.0
        pps_total = 0.0
        for idx, rate in enumerate(self.run_config['rates']):
            key = 'direction-forward' if idx == 0 else 'direction-reverse'
            config[key] = {
                'l2frame_size': self.run_config['l2frame_size'],
                'duration_sec': self.run_config['duration_sec']
            }
            config[key].update(rate)
            config[key].update(self.__convert_rates(rate))
            load_total += float(config[key]['rate_percent'])
            bps_total += float(config[key]['rate_bps'])
            pps_total += float(config[key]['rate_pps'])
        config['direction-total'] = dict(config['direction-forward'])
        config['direction-total'].update({
            'rate_percent': load_total,
            'rate_pps': cast_integer(pps_total),
            'rate_bps': bps_total
        })

        return config

    def get_run_config(self, results):
        """Return configuration which was used for the last run."""
        r = {}
        # because we want each direction to have the far end RX rates,
        # use the far end index (1-idx) to retrieve the RX rates
        for idx, key in enumerate(["direction-forward", "direction-reverse"]):
            tx_rate = results["stats"][str(idx)]["tx"]["total_pkts"] / self.config.duration_sec
            rx_rate = results["stats"][str(1 - idx)]["rx"]["total_pkts"] / self.config.duration_sec
            r[key] = {
                "orig": self.__convert_rates(self.run_config['rates'][idx]),
                "tx": self.__convert_rates({'rate_pps': tx_rate}),
                "rx": self.__convert_rates({'rate_pps': rx_rate})
            }

        total = {}
        for direction in ['orig', 'tx', 'rx']:
            total[direction] = {}
            for unit in ['rate_percent', 'rate_bps', 'rate_pps']:
                total[direction][unit] = sum([float(x[direction][unit]) for x in list(r.values())])

        r['direction-total'] = total
        return r

    def insert_interface_stats(self, pps_list):
        """Insert interface stats to a list of packet path stats.

        pps_list: a list of packet path stats instances indexed by chain index

        This function will insert the packet path stats for the traffic gen ports 0 and 1
        with itemized per chain tx/rx counters.
        There will be as many packet path stats as chains.
        Each packet path stats will have exactly 2 InterfaceStats for port 0 and port 1
        self.pps_list:
        [
        PacketPathStats(InterfaceStats(chain 0, port 0), InterfaceStats(chain 0, port 1)),
        PacketPathStats(InterfaceStats(chain 1, port 0), InterfaceStats(chain 1, port 1)),
        ...
        ]
        """
        def get_if_stats(chain_idx):
            return [InterfaceStats('p' + str(port), self.tool)
                    for port in range(2)]
        # keep the list of list of interface stats indexed by the chain id
        self.ifstats = [get_if_stats(chain_idx)
                        for chain_idx in range(self.config.service_chain_count)]
        # note that we need to make a copy of the ifs list so that any modification in the
        # list from pps will not change the list saved in self.ifstats
        self.pps_list = [PacketPathStats(list(ifs)) for ifs in self.ifstats]
        # insert the corresponding pps in the passed list
        pps_list.extend(self.pps_list)

    def update_interface_stats(self, diff=False):
        """Update all interface stats.

        diff: if False, simply refresh the interface stats values with latest values
              if True, diff the interface stats with the latest values
        Make sure that the interface stats inserted in insert_interface_stats() are updated
        with proper values.
        self.ifstats:
        [
        [InterfaceStats(chain 0, port 0), InterfaceStats(chain 0, port 1)],
        [InterfaceStats(chain 1, port 0), InterfaceStats(chain 1, port 1)],
        ...
        ]
        """
        if diff:
            stats = self.gen.get_stats()
            for chain_idx, ifs in enumerate(self.ifstats):
                # each ifs has exactly 2 InterfaceStats and 2 Latency instances
                # corresponding to the
                # port 0 and port 1 for the given chain_idx
                # Note that we cannot use self.pps_list[chain_idx].if_stats to pick the
                # interface stats for the pps because it could have been modified to contain
                # additional interface stats
                self.gen.get_stream_stats(stats, ifs, self.pps_list[chain_idx].latencies, chain_idx)
            # special handling for vxlan
            # in case of vxlan, flow stats are not available so all rx counters will be
            # zeros when the total rx port counter is non zero.
            # in that case,
            for port in range(2):
                total_rx = 0
                for ifs in self.ifstats:
                    total_rx += ifs[port].rx
                if total_rx == 0:
                    # check if the total port rx from Trex is also zero
                    port_rx = stats[port]['rx']['total_pkts']
                    if port_rx:
                        # the total rx for all chains from port level stats is non zero
                        # which means that the per-chain stats are not available
                        if len(self.ifstats) == 1:
                            # only one chain, simply report the port level rx to the chain rx stats
                            self.ifstats[0][port].rx = port_rx
                        else:
                            for ifs in self.ifstats:
                                # mark this data as unavailable
                                ifs[port].rx = None
                            # pitch in the total rx only in the last chain pps
                            self.ifstats[-1][port].rx_total = port_rx

    @staticmethod
    def compare_tx_rates(required, actual):
        """Compare the actual TX rate to the required TX rate."""
        threshold = 0.9
        are_different = False
        try:
            if float(actual) / required < threshold:
                are_different = True
        except ZeroDivisionError:
            are_different = True

        if are_different:
            msg = "WARNING: There is a significant difference between requested TX rate ({r}) " \
                  "and actual TX rate ({a}). The traffic generator may not have sufficient CPU " \
                  "to achieve the requested TX rate.".format(r=required, a=actual)
            LOG.info(msg)
            return msg

        return None

    def get_per_direction_rate(self):
        """Get the rate for each direction."""
        divisor = 2 if self.run_config['bidirectional'] else 1
        if 'rate_percent' in self.current_total_rate:
            # don't split rate if it's percentage
            divisor = 1

        return utils.divide_rate(self.current_total_rate, divisor)

    def close(self):
        """Close this instance."""
        try:
            self.gen.stop_traffic()
        except Exception:
            pass
        self.gen.clear_stats()
        self.gen.cleanup()