3 ns-3 as a SimGrid model
4 #######################
6 You can use the well-known `ns-3 <http://www.nsnam.org>`_ packet-level network
7 simulator as a SimGrid model, for example to investigate the validity of your
8 simulation. Just install ns-3 and recompile SimGrid accordingly.
13 The easiest is to install it with the package manager. Under Debian/Ubuntu,
18 apt-get install libns3-dev ns3
20 You can also install it from scratch with the following commands:
25 wget http://www.nsnam.org/release/ns-allinone-3.26.tar.bz2
26 tar -xf ns-allinone-3.26.tar.bz2
27 cd ns-allinone-3.26/ns-3.26/
28 # Configure, build and install
29 ./waf configure --prefix="/opt/ns3" # or give another path if you prefer
33 For more information, please refer to the ns-3 documentation
34 (`official website <http://www.nsnam.org>`_).
36 Enabling SimGrid's support for ns-3
37 ***********************************
39 Normally, you just have to enable ns-3 in ccmake or cmake as
40 follows. If you installed ns-3 in a regular path, just drop the
41 NS3_HINT configuration item.
45 cmake . -Denable_ns3=ON -DNS3_HINT=/opt/ns3 # or change the path if needed
47 By the end of the configuration, cmake reports whether ns-3 was found,
48 and this information is also available in ``include/simgrid/config.h``
49 If your local copy defines the variable ``SIMGRID_HAVE_NS3`` to 1, then ns-3
50 was correctly detected. If it's defined to 0, then something went
51 wrong. Explore ``CMakeFiles/CMakeOutput.log`` and
52 ``CMakeFiles/CMakeError.log`` to diagnose the problem.
54 Afterward, you can test your installation as follows:
62 Using ns-3 from SimGrid
63 ***********************
65 The SimGrid-ns3 binding only contains features that are common to both
66 systems: ns-3 wireless models are not available, while SimGrid routes
67 cannot be longer than 1. Also, the platform built in ns-3 from the
68 SimGrid description is very basic.
70 Any route longer than one will be ignored when using ns-3. They are
71 harmless, but you still need to connect your hosts using one-hop routes.
72 The best solution is to add routers to split your route. Here is an
73 example of invalid platform:
78 <host id="alice" speed="1Gf" />
79 <host id="bob" speed="1Gf" />
81 <link id="l1" bw="1Mbps" />
82 <link id="l2" bw="1Mbps" />
84 <route src="alice" dst="bob">
85 <link_ctn id="l1"/> <!-- INVALID WITH NS-3 -->
86 <link_ctn id="l2"/> <!-- length=2 IS TOO MUCH -->
90 Here is the same platform expressed in a way that ns-3 will understand.
91 There is no direct connexion from alice to bob, but that's OK because
92 ns-3 will find the path from point to point.
97 <host id="alice" speed="1Gf" />
98 <host id="bob" speed="1Gf" />
100 <router id="r1" /> <!-- routers are compute-less hosts -->
102 <link id="l1" bw="1Mbps" />
103 <link id="l2" bw="1Mbps" />
105 <route src="alice" dst="r1">
109 <route src="r1" dst="bob">
114 Once your platform is OK, just change the :ref:`network/model
115 <options_model_select>` configuration option to "NS3" as follows. The rest
118 .. code-block:: shell
120 ./network-ns3 --cfg=network/model:NS3 (other parameters)
122 Many other files from the ``examples/platform directory`` are usable with the
123 ns-3 model, such as `examples/platforms/dogbone.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/dogbone.xml>`_.
124 Check the file `examples/deprecated/msg/network-ns3/network-ns3.tesh <https://framagit.org/simgrid/simgrid/tree/master/examples/deprecated/msg/network-ns3/network-ns3.tesh>`_
125 to see which ones are used in our regression tests.
127 Shortcomings of the ns-3 bindings in SimGrid
128 --------------------------------------------
130 A ns-3 platform is automatically created from the provided SimGrid
131 platform. However, there are some known caveats:
133 * The default values (e.g., TCP parameters) are the ns3 default values.
134 * ns-3 networks are routed using the shortest path algorithm, using
135 ``ns3::Ipv4GlobalRoutingHelper::PopulateRoutingTables``.
136 * End hosts cannot have more than one interface card. So, your
137 SimGrid hosts should be connected to the platform through only
138 one link. Otherwise, your SimGrid host will be considered as a
141 Our goal is to keep the ns-3 plugin of SimGrid as easy (and hopefully
142 readable) as possible. If the current state does not fit your needs,
143 you should modify this plugin, and/or create your own plugin from the
146 Troubleshooting with ns-3 and SimGrid
147 *************************************
149 I fail to compile ns-3 within SimGrid
150 -------------------------------------
152 If you have a ns-3 version that is not known to SimGrid yet, edit
153 ``tools/cmake/Modules/FindNS3.cmake`` in your SimGrid tree, according to
154 the comments on top of this file.
156 If the compilation fails on Debian/Ubuntu when linking the library
157 because of some .a file that cannot be used dynamically, then you are
158 probably using a very old (and buggy) ``libns3-dev``
159 package. Update it, or install ``libns3-3`` manually.
161 The simulation hangs at some point
162 ----------------------------------
164 If your simulation hangs in a communication, this is probably because
165 one host is sending data that is not routable in your platform. Make
166 sure that you only use routes of length 1, and that any host is
167 connected to the platform.
169 Arguably, SimGrid could detect this situation and report it, but
170 unfortunately, this is still to be done.
172 I get a warning that some routes are ignored
173 --------------------------------------------
175 Any routes longer than one hop are ignored in ns-3. Please refer to
176 :ref:`ns3_use` for details.