SimGrid  3.15
Versatile Simulation of Distributed Systems
ns-3 as a SimGrid model

You can use the well-known ns-3 packet-level network simulator as a SimGrid model, for example to investigate the validity of your simulation. Just install ns-3 and recompile SimGrid accordingly.

Installing ns-3

The easiest is to install it with the package manager. Under Debian/Ubuntu, simply type as root:

apt-get install libns3-dev ns3

You can also install it from scratch with the following commands:

# Download the source
wget http://www.nsnam.org/release/ns-allinone-3.26.tar.bz2
tar -xf ns-allinone-3.26.tar.bz2
cd ns-allinone-3.26/ns-3.26/
# Configure, build and install
./waf configure --prefix="/opt/ns3" # or give another path if you prefer
./waf
./waf install

For more information, please refer to the ns-3 documentation (official website).

Enabling SimGrid's support for ns-3

Normally, you just have to enable ns-3 in ccmake or cmake as follows. If you installed ns-3 in a regular path, just drop the NS3_HINT configuration item.

cmake . -Denable_ns3=ON -DNS3_HINT=/opt/ns3 # or change the path if needed

By the end of the configuration, cmake reports whether ns-3 was found, and this information is also available in include/simgrid_config.h If your local copy defines the variable HAVE_NS3 to 1, then NS3 was correctly detected. If it's defined to 0, then something went wrong. Explore CMakeFiles/CMakeOutput.log and CMakeFiles/CMakeError.log to diagnose the problem.

Afterward, you can test your installation as follows:

$ ctest -R ns3

Troubleshooting

If you have a ns-3 version that is not known to SimGrid yet, edit tools/cmake/Modules/FindNS3.cmake in your SimGrid tree, according to the comments on top of this file.

If the compilation fails on Debian/Ubuntu when linking the library because of some .a file that cannot be used dynamically, then you are probably using a very old (and buggy) libns3-dev package. Update it, or install libns3-3 manually.

Using ns-3 from SimGrid

The SimGrid-ns3 binding only contains features that are common to both systems: ns-3 wireless models are not available, while SimGrid routes cannot be longer than 1. Also, the platform built in ns-3 from the SimGrid description is very basic.

If your platform have longer routes, simply add some routers to break these routes. SimGrid's routers are similar to hosts, without computational abilities.

Once your platform is OK, just change the "network/model" configuration option to "NS3". The rest remains unchanged.

The following should work from the examples/msg/network-ns3 folder, where the network-ns3 binary example lives.

./network-ns3 ../../platforms/small_platform_one_link_routes.xml 3hosts_2links_d.xml --cfg=network/model:NS3 --log=root.threshold:info

Many other files from the examples/platform directory are usable with the ns-3 model. Check the file examples/msg/network-ns3/network-ns3.tesh to see which ones are used in our regression tests. You may also be interested in the ns-3/SimGrid examples.

A ns-3 platform is automatically created from the provided SimGrid platform. However, there are some known caveats:

  • The default values (e.g., TCP parameters) are the ns3 default values.

  • ns-3 networks are routed using the shortest path algorithm, using ns3::Ipv4GlobalRoutingHelper::PopulateRoutingTables.

  • End hosts cannot have more than one interface card. So, your SimGrid hosts should be connected to the platform through only one link. Otherwise, your SimGrid host will be considered as a router.

Our goal is to keep the ns-3 plugin of SimGrid as easy (and hopefully readable) as possible. If the current state does not fit your needs, you should modify this plugin, and/or create your own plugin from the existing one.