3 ns-3 as a SimGrid model
4 #######################
6 You can use the well-known `ns-3 packet-level network simulator
7 <http://www.nsnam.org>`_ as a SimGrid model, for example to investigate the
8 validity of your simulation. Just install ns-3 and recompile SimGrid
11 Compiling the ns-3/SimGrid binding
12 **********************************
17 SimGrid requires ns-3 version 3.26 or higher, and you probably want the most
18 recent version of both SimGrid and ns-3. While the Debian package of SimGrid
19 don't have the ns-3 bindings activated, you can still use the packaged version
20 of ns-3 by grabbing the ``libns3-dev ns3`` packages. Alternatively, you can
21 install ns-3 from scratch (see the `ns-3 documentation <http://www.nsnam.org>`_).
23 Enabling ns-3 in SimGrid
24 ========================
26 SimGrid must be recompiled with the ``enable_ns3`` option activated in cmake.
27 Optionally, use ``NS3_HINT`` to tell cmake where ns3 is installed on
32 cmake . -Denable_ns3=ON -DNS3_HINT=/opt/ns3 # or change the path if needed
34 By the end of the configuration, cmake reports whether ns-3 was found,
35 and this information is also available in ``include/simgrid/config.h``
36 If your local copy defines the variable ``SIMGRID_HAVE_NS3`` to 1, then ns-3
37 was correctly detected. Otherwise, explore ``CMakeFiles/CMakeOutput.log`` and
38 ``CMakeFiles/CMakeError.log`` to diagnose the problem.
40 Test your installation after compilation as follows:
49 If you use a version of ns-3 that is not known to SimGrid yet, edit
50 ``tools/cmake/Modules/FindNS3.cmake`` in your SimGrid tree, according to the
51 comments on top of this file. Conversely, if something goes wrong with an old
52 version of either SimGrid or ns-3, try upgrading everything.
56 Using ns-3 from SimGrid
57 ***********************
59 The SimGrid/ns-3 binding only contains features that are common to both
60 systems: ns-3 wireless models are not available, while SimGrid routes
61 cannot be longer than 1. Also, the platform built in ns-3 from the
62 SimGrid description is very basic.
64 Platform files compatibility
65 ============================
67 Any route longer than one will be ignored when using ns-3. They are
68 harmless, but you still need to connect your hosts using one-hop routes.
69 The best solution is to add routers to split your route. Here is an
70 example of an invalid platform:
75 <zone id="zone0" routing="Full">
76 <host id="alice" speed="1Gf" />
77 <host id="bob" speed="1Gf" />
79 <link id="l1" bw="1Mbps" />
80 <link id="l2" bw="1Mbps" />
82 <route src="alice" dst="bob">
83 <link_ctn id="l1"/> <!-- !!!! INVALID WITH ns-3 !!!! -->
84 <link_ctn id="l2"/> <!-- !!!! length=2 IS TOO MUCH !!!! -->
89 This can be reformulated as follows to make it usable with the ns-3 binding.
90 There is no direct connection from alice to bob, but that's OK because
91 ns-3 automatically routes from point to point.
96 <zone id="zone0" routing="Full">
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">
115 Once your platform is OK, just change the :ref:`network/model
116 <options_model_select>` configuration option to "ns-3" as follows. The rest
119 .. code-block:: shell
121 ./network-ns3 --cfg=network/model:ns-3 (other parameters)
123 Many other files from the ``examples/platform directory`` are usable with the
124 ns-3 model, such as `examples/platforms/dogbone.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/dogbone.xml>`_.
125 Check the file `examples/s4u/network-ns3/network-ns3.tesh <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/network-ns3/network-ns3.tesh>`_
126 to see which ones are used in our regression tests.
131 A ns-3 platform is automatically created from the provided SimGrid
132 platform. However, there are some known caveats:
134 * The default values (e.g., TCP parameters) are the ns-3 default values.
135 * ns-3 networks are routed using the shortest path algorithm, using
136 ``ns3::Ipv4GlobalRoutingHelper::PopulateRoutingTables``.
137 * End hosts cannot have more than one interface card. So, your
138 SimGrid hosts should be connected to the platform through only
139 one link. Otherwise, your SimGrid host will be considered as a
142 Our goal is to keep the ns-3 plugin of SimGrid as easy (and hopefully readable)
143 as possible. If the current state does not fit your needs, you should modify
144 this plugin, and/or create your own plugin from the existing one. If you come up
145 with interesting improvements, please contribute them back.
150 If your simulation hangs in a communication, this is probably because one host
151 is sending data that is not routable in your platform. Make sure that you only
152 use routes of length 1, and that any host is connected to the platform.
153 Arguably, SimGrid could detect this situation and report it, but unfortunately,
154 this is still to be done.