.. This work is licensed under a Creative Commons Attribution 4.0 International License.
.. http://creativecommons.org/licenses/by/4.0
.. (c) OPNFV, Intel Corporation, AT&T and others.

===================================
Traffic Generator Integration Guide
===================================

Intended Audience
=================

This document is intended to aid those who want to integrate new traffic
generator into the vsperf code. It is expected, that reader has already
read generic part of `VSPERF Design Document
<http://artifacts.opnfv.org/vswitchperf/docs/design/index.html>`__.

Let us create a sample traffic generator called **sample_tg**, step by step.

Step 1 - create a directory
===========================

Implementation of trafficgens is located at tools/pkt_gen/ directory,
where every implementation has its dedicated sub-directory. It is
required to create a new directory for new traffic generator
implementations.

E.g.

.. code-block:: console

   $ mkdir tools/pkt_gen/sample_tg

Step 2 - create a trafficgen module
===================================

Every trafficgen class must inherit from generic **ITrafficGenerator**
interface class. VSPERF during its initialization scans content of pkt_gen
directory for all python modules, that inherit from **ITrafficGenerator**. These
modules are automatically added into the list of supported traffic generators.

Example:

Let us create a draft of tools/pkt_gen/sample_tg/sample_tg.py module.

.. code-block:: python

    from tools.pkt_gen import trafficgen

    class SampleTG(trafficgen.ITrafficGenerator):
        """
        A sample traffic generator implementation
        """
        pass

VSPERF is immediately aware of the new class:

.. code-block:: console

   $ ./vsperf --list-trafficgen

Output should look like:

.. code-block:: console

   Classes derived from: ITrafficGenerator
   ======

   * Ixia:             A wrapper around the IXIA traffic generator.

   * IxNet:            A wrapper around IXIA IxNetwork applications.

   * Dummy:            A dummy traffic generator whose data is generated by the user.

   * SampleTG:         A sample traffic generator implementation

   * TestCenter:       Spirent TestCenter


Step 3 - configuration
======================

All configuration values, required for correct traffic generator function, are passed
from VSPERF to the traffic generator in a dictionary. Default values shared among
all traffic generators are defined in **tools/pkt_gen/trafficgen/trafficgenhelper.py**
as **TRAFFIC_DEFAULTS** dictionary. Default values are loaded by **ITrafficGenerator**
interface class automatically, so it is not needed to load them explicitly. In case
that there are any traffic generator specific default values, then they should
be set within class specific **__init__** function.

VSPERF passes test specific configuration within **traffic** dictionary to every
start and send function. So implementation of these functions must ensure,
that default values are updated with the testcase specific values. Proper merge
of values is assured by call of **merge_spec** function from **trafficgenhelper**
module.

Example of **merge_spec** usage in **tools/pkt_gen/sample_tg/sample_tg.py** module:

.. code-block:: python

    from tools.pkt_gen.trafficgen.trafficgenhelper import merge_spec

    def start_rfc2544_throughput(self, traffic=None, duration=30):
        self._params = {}
        self._params['traffic'] = self.traffic_defaults.copy()
        if traffic:
            self._params['traffic'] = trafficgen.merge_spec(
                self._params['traffic'], traffic)


Step 4 - generic functions
==========================

There are some generic functions, which every traffic generator should provide.
Although these functions are mainly optional, at least empty implementation must
be provided. This is required, so that developer is explicitly aware of these
functions.

The **connect** function is called from the traffic generator controller from its
**__enter__** method. This function should assure proper connection initialization
between DUT and traffic generator. In case, that such implementation is not needed,
empty implementation is required.

The **disconnect** function should perform clean up of any connection specific
actions called from the **connect** function.

Example in **tools/pkt_gen/sample_tg/sample_tg.py** module:

.. code-block:: python

    def connect(self):
        pass

    def disconnect(self):
        pass

Step 5 - supported traffic types
================================

Currently VSPERF supports three different types of tests for traffic generators,
these are identified in vsperf through the traffic type, which include:

    * RFC2544 throughput - Send fixed size packets at different rates, using
        traffic configuration, until minimum rate at which no packet loss is
        detected is found. Methods with its implementation have suffix
        **_rfc2544_throughput**.

    * RFC2544 back2back - Send fixed size packets at a fixed rate, using traffic
        configuration, for specified time interval. Methods with its
        implementation have suffix **_rfc2544_back2back**.

    * continuous flow - Send fixed size packets at given framerate, using traffic
        configuration, for specified time interval. Methods with its
        implementation have suffix **_cont_traffic**.

In general, both synchronous and asynchronous interfaces must be implemented
for each traffic type. Synchronous functions start with prefix **send_**.
Asynchronous with prefixes **start_** and **wait_** in case of throughput
and back2back and **start_** and **stop_** in case of continuous traffic type.

Example of synchronous interfaces:

.. code-block:: python

    def send_rfc2544_throughput(self, traffic=None, trials=3, duration=20,
                                lossrate=0.0):
    def send_rfc2544_back2back(self, traffic=None, trials=1, duration=20,
                               lossrate=0.0):
    def send_cont_traffic(self, traffic=None, duration=20):

Example of asynchronous interfaces:

.. code-block:: python

    def start_rfc2544_throughput(self, traffic=None, trials=3, duration=20,
                                 lossrate=0.0):
    def wait_rfc2544_throughput(self):

    def start_rfc2544_back2back(self, traffic=None, trials=1, duration=20,
                                lossrate=0.0):
    def wait_rfc2544_back2back(self):

    def start_cont_traffic(self, traffic=None, duration=20):
    def stop_cont_traffic(self):

Description of parameters used by **send**, **start**, **wait** and **stop**
functions:

    * param **traffic**: A dictionary with detailed definition of traffic
      pattern. It contains following parameters to be implemented by
      traffic generator.

      Note: Traffic dictionary has also virtual switch related parameters,
      which are not listed below.

      Note: There are parameters specific to testing of tunnelling protocols,
      which are discussed in detail at `integration tests userguide`_

      * param **traffic_type**: One of the supported traffic types,
        e.g. **rfc2544**, **continuous** or **back2back**.
      * param **frame_rate**: Defines desired percentage of frame
        rate used during continuous stream tests. It can be set by test
        parameter iLoad or by CLI parameter iload.
      * param **bidir**: Specifies if generated traffic will be full-duplex
        (true) or half-duplex (false).
      * param **multistream**: Defines number of flows simulated by traffic
        generator. Value 0 disables MultiStream feature.
      * param **stream_type**: Stream Type defines ISO OSI network layer
        used for simulation of multiple streams.
        Supported values:

        * **L2** - iteration of destination MAC address
        * **L3** - iteration of destination IP address
        * **L4** - iteration of destination port of selected transport protocol

      * param **l2**: A dictionary with data link layer details, e.g. **srcmac**,
        **dstmac** and **framesize**.
      * param **l3**: A dictionary with network layer details, e.g. **srcip**,
        **dstip** and **proto**.
      * param **l3**: A dictionary with transport layer details, e.g. **srcport**,
        **dstport**.
      * param **vlan**: A dictionary with vlan specific parameters,
        e.g. **priority**, **cfi**, **id** and vlan on/off switch **enabled**.

    * param **trials**: Number of trials to execute.
    * param **duration**: Duration of continuous test or per iteration duration
      in case of RFC2544 throughput or back2back traffic types.
    * param **lossrate**: Acceptable lossrate percentage.

Step 6 - passing back results
=============================

It is expected that methods **send**, **wait** and **stop** will return
values measured by traffic generator within a dictionary. Dictionary keys
are defined in **ResultsConstants** implemented in
**core/results/results_constants.py**. Please check sections for RFC2544
Throughput & Continuous and for Back2Back. The same key names should
be used by all traffic generator implementations.

.. _integration tests userguide: http://artifacts.opnfv.org/vswitchperf/docs/userguide/integration.html