Examples
========

.. role:: red

.. note::
   :red:`!!! This page only shows up examples of how to config topology and perform basic operations in ndnSIM (an example equivalent to "Hello, world1") !!!  These are **NOT** examples of real experimentations (just like "Hello, world!" is not a real program).`

.. _simple-scenario:

Simple scenario
---------------

The first example (``ndn-simple.cc``) shows very basics of ndnSIM.  In the simulated
topology there are 3 nodes, connected with point-to-point links, one
NDN consumer, and one NDN producer:

.. aafig::
    :aspect: 60
    :scale: 120

      +----------+                +--------+                +----------+
      |          |     1Mbps      |        |      1Mbps     |          |
      | Consumer |<-------------->| Router |<-------------->| Producer |
      |          |         10ms   |        |         10ms   |          |
      +----------+                +--------+                +----------+

Consumer is simulated using :ndnsim:`ConsumerCbr` reference application and generates Interests towards the producer
with frequency of 10 Interests per second (see :doc:`applications`).

Producer is simulated using :ndnsim:`Producer` class, which is used to satisfy all incoming Interests with virtual payload data (1024 bytes).

FIB on every node is populated using default routes (see :doc:`helpers`).

The following code represents all that is necessary to run such a
simple scenario

.. literalinclude:: ../../examples/ndn-simple.cc
   :language: c++
   :linenos:
   :lines: 20-27,48-
   :emphasize-lines: 30-33,37-49

If this code is placed into ``scratch/ndn-simple.cc`` and NS-3 is compiled in debug mode, you can run and see progress of the
simulation using the following command (in optimized mode nothing will be printed out)::

     NS_LOG=ndn.Consumer:ndn.Producer ./waf --run=ndn-simple

.. _9-node-grid-example:

9-node grid example
-------------------

This scenario (``ndn-grid.cc``) simulates a grid topology, which is constructed using PointToPointLayout NS-3 module

.. aafig::
    :aspect: 60
    :scale: 120

    /--------\	    /-\	        /-\
    |Consumer|<---->| |<------->| |
    \--------/	    \-/	        \-/
	^   	     ^ 	         ^
        |            |           |   1Mbps/10ms delay
        v            v           v
       /-\          /-\         /-\
       | |<-------->| |<------->| |
       \-/          \-/         \-/
	^   	     ^ 	         ^
        |            |           |
        v            v           v
       /-\	    /-\	     /--------\
       | |<-------->| |<---->|Producer|
       \-/          \-/      \--------/


FIB is populated using :ndnsim:`GlobalRoutingHelper` (see :doc:`helpers`).

Consumer is simulated using :ndnsim:`ConsumerCbr` reference application and generates Interests towards the producer
with frequency of 100 interests per second (see :doc:`applications`).

Producer is simulated using :ndnsim:`Producer` class, which is used to satisfy all incoming Interests with virtual payload data (1024 bytes).

The following code represents all that is necessary to run such a simple scenario

.. literalinclude:: ../../examples/ndn-grid.cc
   :language: c++
   :linenos:
   :lines: 20-27,53-
   :emphasize-lines: 28,31-33,35-38,53-57


If this code is placed into ``scratch/ndn-grid.cc`` and NS-3 is compiled in debug mode, you can run and see progress of the
simulation using the following command (in optimized mode nothing will be printed out)::

    NS_LOG=ndn.Consumer:ndn.Producer ./waf --run=ndn-grid

.. _9-node-grid-example-using-topology-plugin:

9-node grid example using topology plugin
-----------------------------------------

Instead of defining topology directly as in :ref:`simple-scenario` or using specialized helpers as in :ref:`9-node-grid-example`, ndnSIM provides experimental extended versions of TopologyReader classes: :ndnsim:`AnnotatedTopologyReader` and :ndnsim:`RocketfuelWeightsReader`.

While :ndnsim:`RocketfuelWeightsReader` is a specialized version intended to be used with `Rocketfuel <http://www.cs.washington.edu/research/networking/rocketfuel/>`_ topology and link weights files (examples will be provided later), :ndnsim:`AnnotatedTopologyReader` is a more general-use class that uses simple user-readable format.

:ndnsim:`AnnotatedTopologyReader` expects the following format:

.. literalinclude:: ../../examples/topologies/topo-grid-3x3.txt
   :language: bash
   :linenos:
   :lines: 1-2,19-
   :emphasize-lines: 8,24


This scenario (``ndn-grid-topo-plugin.cc``) duplicates the functionality of :ref:`9-node-grid-example` but with the use of :ndnsim:`AnnotatedTopologyReader`.

.. aafig::
    :aspect: 60
    :scale: 120

    /--------\	    /-\	        /-\
    |Consumer|<---->| |<------->| |
    \--------/	    \-/	        \-/
	^   	     ^ 	         ^
        |            |           |   1Mbps/10ms delay
        v            v           v
       /-\          /-\         /-\
       | |<-------->| |<------->| |
       \-/          \-/         \-/
	^   	     ^ 	         ^
        |            |           |
        v            v           v
       /-\	    /-\	     /--------\
       | |<-------->| |<---->|Producer|
       \-/          \-/      \--------/

.. literalinclude:: ../../examples/ndn-grid-topo-plugin.cc
   :language: c++
   :linenos:
   :lines: 20-26,51-
   :emphasize-lines: 14-16,20,27-30

As you can see, scenario code became more compact and more readable.

:ndnsim:`AnnotatedTopologyReader` provides two ways to access topology nodes.
First, you can use the method :ndnsim:`AnnotatedTopologyReader::GetNodes` which returns NodeContainer.

Alternatively, nodes can be accessed by name using `Names::Find<Node> ("nodename")` call, as in the above example.
For this purpose,:ndnsim:`AnnotatedTopologyReader` automatically registers all created nodes with names specified in topology file.
For more information about `Names` class, please refer to `NS-3 documentation <.. http://www.nsnam.org/doxygen/classns3_1_1_names.html>`_
.

If the topology file is placed into ``src/ndnSIM/examples/topologies/topo-grid-3x3.txt`` and the code is placed into ``scratch/ndn-grid-topo-plugin.cc``, you can run and see progress of the simulation using the following command (in optimized mode nothing will be printed out)::

    NS_LOG=ndn.Consumer:ndn.Producer ./waf --run=ndn-grid-topo-plugin


6-node bottleneck topology
--------------------------

This scenario (``ndn-congestion-topo-plugin.cc``) can be used for congestion-related scenarios

.. aafig::
    :aspect: 60
    :scale: 120

    /------\	                                                /------\
    | Src1 |<--+                                            +-->| Dst1 |
    \------/    \                                          /    \------/
	     	 \                                        /
                  +-->/------\   "bottleneck"  /------\<-+
                      | Rtr1 |<===============>| Rtr2 |
                  +-->\------/                 \------/<-+
                 /                                        \
    /------\    /                                          \    /------\
    | Src2 |<--+                                            +-->| Dst2 |
    \------/                                                    \------/

.. literalinclude:: ../../examples/topologies/topo-6-node.txt
    :language: bash
    :linenos:
    :lines: 1-2,15-
    :emphasize-lines: 3,13

.. literalinclude:: ../../examples/ndn-congestion-topo-plugin.cc
   :language: c++
   :linenos:
   :lines: 20-26,47-
   :emphasize-lines: 15,21-22,29-34,41-47,52-62

.. :lines: 20-25,53-

To run this scenario and see what is happening, use the following command::

        NS_LOG=ndn.Consumer:ndn.Producer ./waf --run=ndn-congestion-topo-plugin

.. _11-node 2-bottleneck topology with custom forwarding strategy:

11-node 2-bottleneck topology with custom forwarding strategy
-------------------------------------------------------------

To effectively use the example :ref:`custom strategy <Writing your own custom strategy>`, we need to make sure that FIB entries contain at least two entries.
In the current version of ndnSIM, this can be accomplished using manual route configuration.

The following example illustrates how the strategy can be used in simulation scenario.

Let us first define a meaningful topology:

.. aafig::
    :aspect: 60
    :scale: 120

     /------\ 0                                                 0 /------\
     |  c1  |<-----+                                       +----->|  p1  |
     \------/       \                                     /       \------/
                     \              /-----\              /
     /------\ 0       \         +==>| r12 |<==+         /       0 /------\
     |  c2  |<--+      \       /    \-----/    \       /      +-->|  p2  |
     \------/    \      \     |                 |     /      /    \------/
                  \      |    |   1Mbps links   |    |      /
                   \  1  v0   v5               1v   2v  3  /
                    +->/------\                 /------\<-+
                      2|  r1  |<===============>|  r2  |4
                    +->\------/4               0\------/<-+
                   /    3^                           ^5    \
                  /      |                           |      \
     /------\ 0  /      /                             \      \  0 /------\
     |  c3  |<--+      /                               \      +-->|  p3  |
     \------/         /                                 \         \------/
                     /     "All consumer-router and"     \
     /------\ 0     /      "router-producer links are"    \    0 /------\
     |  c4  |<-----+       "10Mbps"                        +---->|  p4  |
     \------/                                                    \------/

     "Numbers near nodes denote face IDs. Face ID is assigned based on the order of link"
     "definitions in the topology file"

The corresponding topology file (``topo-11-node-two-bottlenecks.txt``):

.. literalinclude:: ../../examples/topologies/topo-11-node-two-bottlenecks.txt
    :language: bash
    :linenos:
    :lines: 1-2,28-

Example simulation (``ndn-congestion-alt-topo-plugin.cc``) scenario that utilizes CustomStrategy forwarding strategy:

.. literalinclude:: ../../examples/ndn-congestion-alt-topo-plugin.cc
    :language: c++
    :linenos:
    :lines: 21-28,61-
    :emphasize-lines: 16,21,49-50,65-79


To run this scenario and see what is happening, use the following command::

        NS_LOG=ndn.Consumer:ndn.Producer ./waf --run=ndn-congestion-alt-topo-plugin

You can also run using visualizer module to verify that both bottleneck links are utilized::

        ./waf --run=ndn-congestion-alt-topo-plugin --visualize

3-level binary tree with packet-level trace helpers
---------------------------------------------------

:ref:`packet trace helper example`


3-level binary tree with content store trace helper
---------------------------------------------------

:ref:`cs trace helper example`


3-level binary tree with  application-level Interest-Data delay tracer
----------------------------------------------------------------------

:ref:`app delay trace helper example`


3-node topology with Content Store respecting freshness field of ContentObjects
-------------------------------------------------------------------------------

:ref:`Content Store respecting freshness field of ContentObjects`

1-node topology with custom application
---------------------------------------

:ref:`Custom applications`

Simple scenario with pcap dump
------------------------------

The following example (``ndn-simple-with-pcap.cc``) demonstrates how to dump all simulated traffic
in pcap-formatted data, which can be used for later analysis by conventional tools, like tcpdump and wireshark.

.. literalinclude:: ../../examples/ndn-simple-with-pcap.cc
   :language: c++
   :linenos:
   :lines: 20-
   :emphasize-lines: 7-29,70-72

If this code is placed into ``scratch/ndn-simple-with-pcap.cc`` and NS-3 is compiled in debug mode, you can run and see progress of the
simulation using the following command (in optimized mode nothing will be printed out)::

     NS_LOG=ndn.Consumer:ndn.Producer ./waf --run=ndn-simple-with-pcap

This will generate ``ndn-simple-trace.pcap``, which can be fed to tcpdump::

     tcpdump -r ndn-simple-trace.pcap