1 # Copyright (c) 2019 Cisco and/or its affiliates.
2 # Licensed under the Apache License, Version 2.0 (the "License");
3 # you may not use this file except in compliance with the License.
4 # You may obtain a copy of the License at:
6 # http://www.apache.org/licenses/LICENSE-2.0
8 # Unless required by applicable law or agreed to in writing, software
9 # distributed under the License is distributed on an "AS IS" BASIS,
10 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 # See the License for the specific language governing permissions and
12 # limitations under the License.
14 """Performance testing traffic generator library."""
16 from robot.api import logger
17 from robot.libraries.BuiltIn import BuiltIn
19 from .DropRateSearch import DropRateSearch
20 from .Constants import Constants
22 from .topology import NodeType
23 from .topology import NodeSubTypeTG
24 from .topology import Topology
25 from .MLRsearch.AbstractMeasurer import AbstractMeasurer
26 from .MLRsearch.MultipleLossRatioSearch import MultipleLossRatioSearch
27 from .MLRsearch.ReceiveRateMeasurement import ReceiveRateMeasurement
28 from .PLRsearch.PLRsearch import PLRsearch
30 __all__ = ['TGDropRateSearchImpl', 'TrafficGenerator', 'OptimizedSearch']
33 class TGDropRateSearchImpl(DropRateSearch):
34 """Drop Rate Search implementation."""
37 super(TGDropRateSearchImpl, self).__init__()
39 def measure_loss(self, rate, frame_size, loss_acceptance,
40 loss_acceptance_type, traffic_profile, skip_warmup=False):
41 """Runs the traffic and evaluate the measured results.
43 :param rate: Offered traffic load.
44 :param frame_size: Size of frame.
45 :param loss_acceptance: Permitted drop ratio or frames count.
46 :param loss_acceptance_type: Type of permitted loss.
47 :param traffic_profile: Module name as a traffic profile identifier.
48 See resources/traffic_profiles/trex for implemented modules.
49 :param skip_warmup: Start TRex without warmup traffic if true.
52 :type loss_acceptance: float
53 :type loss_acceptance_type: LossAcceptanceType
54 :type traffic_profile: str
55 :type skip_warmup: bool
56 :returns: Drop threshold exceeded? (True/False)
58 :raises NotImplementedError: If TG is not supported.
59 :raises RuntimeError: If TG is not specified.
61 # we need instance of TrafficGenerator instantiated by Robot Framework
62 # to be able to use trex_stl-*()
63 tg_instance = BuiltIn().get_library_instance(
64 'resources.libraries.python.TrafficGenerator')
66 if tg_instance.node['subtype'] is None:
67 raise RuntimeError('TG subtype not defined')
68 elif tg_instance.node['subtype'] == NodeSubTypeTG.TREX:
69 unit_rate = str(rate) + self.get_rate_type_str()
71 tg_instance.trex_stl_start_remote_exec(self.get_duration(),
72 unit_rate, frame_size,
76 tg_instance.trex_stl_start_remote_exec(self.get_duration(),
77 unit_rate, frame_size,
79 loss = tg_instance.get_loss()
80 sent = tg_instance.get_sent()
81 if self.loss_acceptance_type_is_percentage():
82 loss = (float(loss) / float(sent)) * 100
84 logger.trace("comparing: {} < {} {}".format(loss,
86 loss_acceptance_type))
87 if float(loss) > float(loss_acceptance):
92 raise NotImplementedError("TG subtype not supported")
94 def get_latency(self):
95 """Returns min/avg/max latency.
97 :returns: Latency stats.
100 tg_instance = BuiltIn().get_library_instance(
101 'resources.libraries.python.TrafficGenerator')
102 return tg_instance.get_latency_int()
105 class TrafficGenerator(AbstractMeasurer):
106 """Traffic Generator.
108 FIXME: Describe API."""
110 # TODO: Decrease friction between various search and rate provider APIs.
111 # TODO: Remove "trex" from lines which could work with other TGs.
113 # Use one instance of TrafficGenerator for all tests in test suite
114 ROBOT_LIBRARY_SCOPE = 'TEST SUITE'
121 self._received = None
123 # T-REX interface order mapping
124 self._ifaces_reordered = False
125 # Parameters not given by measure().
126 self.frame_size = None
127 self.traffic_profile = None
128 self.warmup_time = None
134 :returns: Traffic generator node.
140 """Return number of lost packets.
142 :returns: Number of lost packets.
148 """Return number of sent packets.
150 :returns: Number of sent packets.
155 def get_received(self):
156 """Return number of received packets.
158 :returns: Number of received packets.
161 return self._received
163 def get_latency_int(self):
164 """Return rounded min/avg/max latency.
166 :returns: Latency stats.
171 def initialize_traffic_generator(
172 self, tg_node, tg_if1, tg_if2, tg_if1_adj_node, tg_if1_adj_if,
173 tg_if2_adj_node, tg_if2_adj_if, test_type, tg_if1_dst_mac=None,
174 tg_if2_dst_mac=None):
175 """TG initialization.
177 TODO: Document why do we need (and how do we use) _ifaces_reordered.
179 :param tg_node: Traffic generator node.
180 :param tg_if1: TG - name of first interface.
181 :param tg_if2: TG - name of second interface.
182 :param tg_if1_adj_node: TG if1 adjecent node.
183 :param tg_if1_adj_if: TG if1 adjecent interface.
184 :param tg_if2_adj_node: TG if2 adjecent node.
185 :param tg_if2_adj_if: TG if2 adjecent interface.
186 :param test_type: 'L2', 'L3' or 'L7' - OSI Layer testing type.
187 :param tg_if1_dst_mac: Interface 1 destination MAC address.
188 :param tg_if2_dst_mac: Interface 2 destination MAC address.
192 :type tg_if1_adj_node: dict
193 :type tg_if1_adj_if: str
194 :type tg_if2_adj_node: dict
195 :type tg_if2_adj_if: str
197 :type tg_if1_dst_mac: str
198 :type tg_if2_dst_mac: str
200 :raises RuntimeError: In case of issue during initialization.
202 if tg_node['type'] != NodeType.TG:
203 raise RuntimeError('Node type is not a TG')
206 if tg_node['subtype'] == NodeSubTypeTG.TREX:
210 (ret, _, _) = ssh.exec_command(
211 "sudo -E sh -c '{0}/resources/tools/trex/"
212 "trex_installer.sh {1}'".format(Constants.REMOTE_FW_DIR,
213 Constants.TREX_INSTALL_VERSION),
216 raise RuntimeError('TRex installation failed.')
218 if1_pci = Topology().get_interface_pci_addr(tg_node, tg_if1)
219 if2_pci = Topology().get_interface_pci_addr(tg_node, tg_if2)
220 if1_addr = Topology().get_interface_mac(tg_node, tg_if1)
221 if2_addr = Topology().get_interface_mac(tg_node, tg_if2)
223 if test_type == 'L2':
224 if1_adj_addr = if2_addr
225 if2_adj_addr = if1_addr
226 elif test_type == 'L3':
227 if1_adj_addr = Topology().get_interface_mac(tg_if1_adj_node,
229 if2_adj_addr = Topology().get_interface_mac(tg_if2_adj_node,
231 elif test_type == 'L7':
232 if1_addr = Topology().get_interface_ip4(tg_node, tg_if1)
233 if2_addr = Topology().get_interface_ip4(tg_node, tg_if2)
234 if1_adj_addr = Topology().get_interface_ip4(tg_if1_adj_node,
236 if2_adj_addr = Topology().get_interface_ip4(tg_if2_adj_node,
239 raise ValueError("Unknown Test Type")
241 # in case of switched environment we can override MAC addresses
242 if tg_if1_dst_mac is not None and tg_if2_dst_mac is not None:
243 if1_adj_addr = tg_if1_dst_mac
244 if2_adj_addr = tg_if2_dst_mac
246 if min(if1_pci, if2_pci) != if1_pci:
247 if1_pci, if2_pci = if2_pci, if1_pci
248 if1_addr, if2_addr = if2_addr, if1_addr
249 if1_adj_addr, if2_adj_addr = if2_adj_addr, if1_adj_addr
250 self._ifaces_reordered = True
252 if test_type == 'L2' or test_type == 'L3':
253 (ret, _, _) = ssh.exec_command(
254 "sudo sh -c 'cat << EOF > /etc/trex_cfg.yaml\n"
257 " interfaces: [\"{0}\",\"{1}\"]\n"
259 " - dest_mac: [{2}]\n"
261 " - dest_mac: [{4}]\n"
264 .format(if1_pci, if2_pci,
265 "0x"+if1_adj_addr.replace(":", ",0x"),
266 "0x"+if1_addr.replace(":", ",0x"),
267 "0x"+if2_adj_addr.replace(":", ",0x"),
268 "0x"+if2_addr.replace(":", ",0x")))
269 elif test_type == 'L7':
270 (ret, _, _) = ssh.exec_command(
271 "sudo sh -c 'cat << EOF > /etc/trex_cfg.yaml\n"
274 " interfaces: [\"{0}\",\"{1}\"]\n"
277 " default_gw: [{3}]\n"
279 " default_gw: [{5}]\n"
281 .format(if1_pci, if2_pci,
282 if1_addr, if1_adj_addr,
283 if2_addr, if2_adj_addr))
285 raise ValueError("Unknown Test Type")
287 raise RuntimeError('TRex config generation error')
289 for _ in range(0, 3):
290 # kill TRex only if it is already running
292 "sh -c 'pgrep t-rex && sudo pkill t-rex && sleep 3'")
295 (ret, _, _) = ssh.exec_command(
296 "sh -c 'cd {0}/scripts/ && sudo ./trex-cfg'"\
297 .format(Constants.TREX_INSTALL_DIR))
299 raise RuntimeError('trex-cfg failed')
302 if test_type == 'L2' or test_type == 'L3':
303 (ret, _, _) = ssh.exec_command(
304 "sh -c 'cd {0}/scripts/ && "
305 "sudo nohup ./t-rex-64 -i -c 7 --iom 0 > /tmp/trex.log "
306 "2>&1 &' > /dev/null"\
307 .format(Constants.TREX_INSTALL_DIR))
308 elif test_type == 'L7':
309 (ret, _, _) = ssh.exec_command(
310 "sh -c 'cd {0}/scripts/ && "
311 "sudo nohup ./t-rex-64 --astf -i -c 7 --iom 0 > "
312 "/tmp/trex.log 2>&1 &' > /dev/null"\
313 .format(Constants.TREX_INSTALL_DIR))
315 raise ValueError("Unknown Test Type")
317 ssh.exec_command("sh -c 'cat /tmp/trex.log'")
318 raise RuntimeError('t-rex-64 startup failed')
320 # get TRex server info
321 (ret, _, _) = ssh.exec_command(
323 "{0}/resources/tools/trex/trex_server_info.py'"\
324 .format(Constants.REMOTE_FW_DIR),
327 # If we get info TRex is running
329 # after max retries TRex is still not responding to API
330 # critical error occurred
331 raise RuntimeError('t-rex-64 startup failed')
334 def is_trex_running(node):
335 """Check if TRex is running using pidof.
337 :param node: Traffic generator node.
339 :returns: True if TRex is running otherwise False.
341 :raises RuntimeError: If node type is not a TG.
343 if node['type'] != NodeType.TG:
344 raise RuntimeError('Node type is not a TG')
348 ret, _, _ = ssh.exec_command_sudo("pidof t-rex")
349 return bool(int(ret) == 0)
352 def teardown_traffic_generator(node):
355 :param node: Traffic generator node.
358 :raises RuntimeError: If node type is not a TG,
359 or if TRex teardown fails.
361 if node['type'] != NodeType.TG:
362 raise RuntimeError('Node type is not a TG')
363 if node['subtype'] == NodeSubTypeTG.TREX:
366 (ret, _, _) = ssh.exec_command(
367 "sh -c 'sudo pkill t-rex && sleep 3'")
369 raise RuntimeError('pkill t-rex failed')
372 def trex_stl_stop_remote_exec(node):
373 """Execute script on remote node over ssh to stop running traffic.
375 :param node: TRex generator node.
378 :raises RuntimeError: If stop traffic script fails.
383 (ret, _, _) = ssh.exec_command(
384 "sh -c '{}/resources/tools/trex/"
385 "trex_stateless_stop.py'".format(Constants.REMOTE_FW_DIR))
388 raise RuntimeError('TRex stateless runtime error')
390 def trex_stl_start_remote_exec(
391 self, duration, rate, frame_size, traffic_profile, async_call=False,
392 latency=True, warmup_time=5.0, unidirection=False, tx_port=0,
394 """Execute script on remote node over ssh to start traffic.
396 :param duration: Time expresed in seconds for how long to send traffic.
397 :param rate: Traffic rate expressed with units (pps, %)
398 :param frame_size: L2 frame size to send (without padding and IPG).
399 :param traffic_profile: Module name as a traffic profile identifier.
400 See resources/traffic_profiles/trex for implemented modules.
401 :param async_call: If enabled then don't wait for all incomming trafic.
402 :param latency: With latency measurement.
403 :param warmup_time: Warmup time period.
404 :param unidirection: Traffic is unidirectional. Default: False
405 :param tx_port: Traffic generator transmit port for first flow.
407 :param rx_port: Traffic generator receive port for first flow.
409 :type duration: float
411 :type frame_size: str
412 :type traffic_profile: str
413 :type async_call: bool
415 :type warmup_time: float
416 :type unidirection: bool
419 :raises RuntimeError: In case of TG driver issue.
422 ssh.connect(self._node)
423 reorder = self._ifaces_reordered # Just to make the next line fit.
424 p_0, p_1 = (rx_port, tx_port) if reorder else (tx_port, rx_port)
426 "sh -c '{tool}/resources/tools/trex/trex_stateless_profile.py"
427 " --profile {prof}/resources/traffic_profiles/trex/{traffic}.py"
428 " --duration {duration} --frame_size {frame_size} --rate {rate}"
429 " --warmup_time {warmup} --port_0 {p_0} --port_1 {p_1}").format(
430 tool=Constants.REMOTE_FW_DIR, prof=Constants.REMOTE_FW_DIR,
431 traffic=traffic_profile, duration=duration,
432 frame_size=frame_size, rate=rate, warmup=warmup_time, p_0=p_0,
435 command += " --async"
437 command += " --latency"
439 command += " --unidirection"
442 (ret, stdout, _) = ssh.exec_command(
443 command, timeout=float(duration) + 60)
446 raise RuntimeError('TRex stateless runtime error')
449 self._received = None
454 # last line from console output
455 line = stdout.splitlines()[-1]
457 logger.info('TrafficGen result: {0}'.format(self._result))
458 self._received = self._result.split(', ')[1].split('=')[1]
459 self._sent = self._result.split(', ')[2].split('=')[1]
460 self._loss = self._result.split(', ')[3].split('=')[1]
462 self._latency.append(self._result.split(', ')[4].split('=')[1])
463 self._latency.append(self._result.split(', ')[5].split('=')[1])
465 def stop_traffic_on_tg(self):
466 """Stop all traffic on TG.
469 :raises RuntimeError: If TG is not set.
471 if self._node is None:
472 raise RuntimeError("TG is not set")
473 if self._node['subtype'] == NodeSubTypeTG.TREX:
474 self.trex_stl_stop_remote_exec(self._node)
476 def send_traffic_on_tg(
477 self, duration, rate, frame_size, traffic_profile, warmup_time=5,
478 async_call=False, latency=True, unidirection=False, tx_port=0,
480 """Send traffic from all configured interfaces on TG.
482 Note that bidirectional traffic also contains flows
483 transmitted from rx_port and received in tx_port.
484 But some tests use asymmetric traffic, so those arguments are relevant.
486 Also note that traffic generator uses DPDK driver which might
487 reorder port numbers based on wiring and PCI numbering.
488 This method handles that, so argument values are invariant,
489 but you can see swapped valued in debug logs.
491 TODO: Is it better to have less descriptive argument names
492 just to make them less probable to be viewed as misleading or confusing?
493 See https://gerrit.fd.io/r/#/c/17625/11/resources/libraries/python\
494 /TrafficGenerator.py@406
496 :param duration: Duration of test traffic generation in seconds.
497 :param rate: Offered load per interface (e.g. 1%, 3gbps, 4mpps, ...).
498 :param frame_size: Frame size (L2) in Bytes.
499 :param traffic_profile: Module name as a traffic profile identifier.
500 See resources/traffic_profiles/trex for implemented modules.
501 :param warmup_time: Warmup phase in seconds.
502 :param async_call: Async mode.
503 :param latency: With latency measurement.
504 :param unidirection: Traffic is unidirectional. Default: False
505 :param tx_port: Traffic generator transmit port for first flow.
507 :param rx_port: Traffic generator receive port for first flow.
511 :type frame_size: str
512 :type traffic_profile: str
513 :type warmup_time: float
514 :type async_call: bool
516 :type unidirection: bool
521 :raises RuntimeError: If TG is not set, or if node is not TG,
522 or if subtype is not specified.
523 :raises NotImplementedError: If TG is not supported.
528 raise RuntimeError("TG is not set")
530 if node['type'] != NodeType.TG:
531 raise RuntimeError('Node type is not a TG')
533 if node['subtype'] is None:
534 raise RuntimeError('TG subtype not defined')
535 elif node['subtype'] == NodeSubTypeTG.TREX:
536 self.trex_stl_start_remote_exec(
537 duration, rate, frame_size, traffic_profile, async_call,
538 latency, warmup_time, unidirection, tx_port, rx_port)
540 raise NotImplementedError("TG subtype not supported")
544 def no_traffic_loss_occurred(self):
545 """Fail if loss occurred in traffic run.
548 :raises Exception: If loss occured.
550 if self._loss is None:
551 raise RuntimeError('The traffic generation has not been issued')
552 if self._loss != '0':
553 raise RuntimeError('Traffic loss occurred: {0}'.format(self._loss))
555 def fail_if_no_traffic_forwarded(self):
556 """Fail if no traffic forwarded.
559 :raises Exception: If no traffic forwarded.
561 if self._received is None:
562 raise RuntimeError('The traffic generation has not been issued')
563 if self._received == '0':
564 raise RuntimeError('No traffic forwarded')
566 def partial_traffic_loss_accepted(self, loss_acceptance,
567 loss_acceptance_type):
568 """Fail if loss is higher then accepted in traffic run.
570 :param loss_acceptance: Permitted drop ratio or frames count.
571 :param loss_acceptance_type: Type of permitted loss.
572 :type loss_acceptance: float
573 :type loss_acceptance_type: LossAcceptanceType
575 :raises Exception: If loss is above acceptance criteria.
577 if self._loss is None:
578 raise Exception('The traffic generation has not been issued')
580 if loss_acceptance_type == 'percentage':
581 loss = (float(self._loss) / float(self._sent)) * 100
582 elif loss_acceptance_type == 'frames':
583 loss = float(self._loss)
585 raise Exception('Loss acceptance type not supported')
587 if loss > float(loss_acceptance):
588 raise Exception("Traffic loss {} above loss acceptance: {}".format(
589 loss, loss_acceptance))
591 def set_rate_provider_defaults(self, frame_size, traffic_profile,
593 """Store values accessed by measure().
595 :param frame_size: Frame size identifier or value [B].
596 :param traffic_profile: Module name as a traffic profile identifier.
597 See resources/traffic_profiles/trex for implemented modules.
598 :param warmup_time: Traffic duration before measurement starts [s].
599 :type frame_size: str or int
600 :type traffic_profile: str
601 :type warmup_time: float
603 self.frame_size = frame_size
604 self.traffic_profile = str(traffic_profile)
605 self.warmup_time = float(warmup_time)
607 def measure(self, duration, transmit_rate):
608 """Run bi-directional measurement, parse and return results.
610 :param duration: Trial duration [s].
611 :param transmit_rate: Target bidirectional transmit rate [pps].
612 :type duration: float
613 :type transmit_rate: float
614 :returns: Structure containing the result of the measurement.
615 :rtype: ReceiveRateMeasurement
616 :raises RuntimeError: If TG is not set, or if node is not TG,
617 or if subtype is not specified.
618 :raises NotImplementedError: If TG is not supported.
620 duration = float(duration)
621 transmit_rate = float(transmit_rate)
622 # Trex needs target Tr per stream, but reports aggregate Tx and Dx.
623 unit_rate = str(transmit_rate / 2.0) + "pps"
624 self.send_traffic_on_tg(
625 duration, unit_rate, self.frame_size, self.traffic_profile,
626 warmup_time=self.warmup_time, latency=True)
627 transmit_count = int(self.get_sent())
628 loss_count = int(self.get_loss())
629 measurement = ReceiveRateMeasurement(
630 duration, transmit_rate, transmit_count, loss_count)
631 measurement.latency = self.get_latency_int()
635 class OptimizedSearch(object):
636 """Class to be imported as Robot Library, containing a single keyword."""
639 def perform_optimized_ndrpdr_search(
640 frame_size, traffic_profile, minimum_transmit_rate,
641 maximum_transmit_rate, packet_loss_ratio=0.005,
642 final_relative_width=0.005, final_trial_duration=30.0,
643 initial_trial_duration=1.0, number_of_intermediate_phases=2,
644 timeout=720.0, doublings=1):
645 """Setup initialized TG, perform optimized search, return intervals.
647 :param frame_size: Frame size identifier or value [B].
648 :param traffic_profile: Module name as a traffic profile identifier.
649 See resources/traffic_profiles/trex for implemented modules.
650 :param minimum_transmit_rate: Minimal bidirectional
651 target transmit rate [pps].
652 :param maximum_transmit_rate: Maximal bidirectional
653 target transmit rate [pps].
654 :param packet_loss_ratio: Fraction of packets lost, for PDR [1].
655 :param final_relative_width: Final lower bound transmit rate
656 cannot be more distant that this multiple of upper bound [1].
657 :param final_trial_duration: Trial duration for the final phase [s].
658 :param initial_trial_duration: Trial duration for the initial phase
659 and also for the first intermediate phase [s].
660 :param number_of_intermediate_phases: Number of intermediate phases
661 to perform before the final phase [1].
662 :param timeout: The search will fail itself when not finished
663 before this overall time [s].
664 :param doublings: How many doublings to do in external search step.
665 Default 1 is suitable for fairly stable tests,
666 less stable tests might get better overal duration with 2 or more.
667 :type frame_size: str or int
668 :type traffic_profile: str
669 :type minimum_transmit_rate: float
670 :type maximum_transmit_rate: float
671 :type packet_loss_ratio: float
672 :type final_relative_width: float
673 :type final_trial_duration: float
674 :type initial_trial_duration: float
675 :type number_of_intermediate_phases: int
678 :returns: Structure containing narrowed down NDR and PDR intervals
679 and their measurements.
681 :raises RuntimeError: If total duration is larger than timeout.
683 # we need instance of TrafficGenerator instantiated by Robot Framework
684 # to be able to use trex_stl-*()
685 tg_instance = BuiltIn().get_library_instance(
686 'resources.libraries.python.TrafficGenerator')
687 tg_instance.set_rate_provider_defaults(frame_size, traffic_profile)
688 algorithm = MultipleLossRatioSearch(
689 measurer=tg_instance, final_trial_duration=final_trial_duration,
690 final_relative_width=final_relative_width,
691 number_of_intermediate_phases=number_of_intermediate_phases,
692 initial_trial_duration=initial_trial_duration, timeout=timeout,
694 result = algorithm.narrow_down_ndr_and_pdr(
695 minimum_transmit_rate, maximum_transmit_rate, packet_loss_ratio)
699 def perform_soak_search(
700 frame_size, traffic_profile, minimum_transmit_rate,
701 maximum_transmit_rate, plr_target=1e-7, tdpt=0.2,
702 initial_count=50, timeout=1800.0):
703 """Setup initialized TG, perform soak search, return avg and stdev.
705 :param frame_size: Frame size identifier or value [B].
706 :param traffic_profile: Module name as a traffic profile identifier.
707 See resources/traffic_profiles/trex for implemented modules.
708 :param minimum_transmit_rate: Minimal bidirectional
709 target transmit rate [pps].
710 :param maximum_transmit_rate: Maximal bidirectional
711 target transmit rate [pps].
712 :param plr_target: Fraction of packets lost to achieve [1].
713 :param tdpt: Trial duration per trial.
714 The algorithm linearly increases trial duration with trial number,
715 this is the increment between succesive trials, in seconds.
716 :param initial_count: Offset to apply before the first trial.
717 For example initial_count=50 makes first trial to be 51*tdpt long.
718 This is needed because initial "search" phase of integrator
719 takes significant time even without any trial results.
720 :param timeout: The search will stop after this overall time [s].
721 :type frame_size: str or int
722 :type traffic_profile: str
723 :type minimum_transmit_rate: float
724 :type maximum_transmit_rate: float
725 :type plr_target: float
726 :type initial_count: int
728 :returns: Average and stdev of estimated bidirectional rate giving PLR.
729 :rtype: 2-tuple of float
731 tg_instance = BuiltIn().get_library_instance(
732 'resources.libraries.python.TrafficGenerator')
733 tg_instance.set_rate_provider_defaults(frame_size, traffic_profile)
734 algorithm = PLRsearch(
735 measurer=tg_instance, trial_duration_per_trial=tdpt,
736 packet_loss_ratio_target=plr_target,
737 trial_number_offset=initial_count, timeout=timeout)
738 result = algorithm.search(minimum_transmit_rate, maximum_transmit_rate)