Network Simulator 2: a Simulation Tool for Linux

NS2 is an open-source simulation tool that runs on Linux. It is a discreet event simulator targeted at networking research and provides substantial support for simulation of routing, multicast protocols and IP protocols, such as UDP, TCP, RTP and SRM over wired and wireless (local and satellite) networks. It has many advantages that make it a useful tool, such as support for multiple protocols and the capability of graphically detailing network traffic. Additionally, NS2 supports several algorithms in routing and queuing. LAN routing and broadcasts are part of routing algorithms. Queuing algorithms include fair queuing, deficit round-robin and FIFO.

NS2 started as a variant of the REAL network simulator in 1989 (see Resources). REAL is a network simulator originally intended for studying the dynamic behavior of flow and congestion control schemes in packet-switched data networks.

Currently NS2 development by VINT group is supported through Defense Advanced Research Projects Agency (DARPA) with SAMAN and through NSF with CONSER, both in collaboration with other researchers including ACIRI (see Resources). NS2 is available on several platforms such as FreeBSD, Linux, SunOS and Solaris. NS2 also builds and runs under Windows.

Simple scenarios should run on any reasonable machine; however, very large scenarios benefit from large amounts of memory. Additionally, NS2 requires the following packages to run: Tcl release 8.3.2, Tk release 8.3.2, OTcl release 1.0a7 and TclCL release 1.0b11.
Installation and Configuration

The process of installing NS2 is straightforward yet lengthy. At the time of writing, the most recent version was 2.1b8. We are interested in the "all-in-one" package because it includes the source code that we want to patch in SCTP support.

You can download the all-in-one package from the NS2 home page (see Resources) into /usr/src and extract it as follows:
cd /usr/src
tar xzvf ns-allinone-2.1b8.tar.gz
cd ns-allinone-2.1b8

Because we want to examine a case scenario involving SCTP, we need to apply the SCTP patch to NS2 from the University of Delaware. The patch is available for the NS2 all-in-one 2.1b8 version and can be downloaded from the Protocol Engineering Lab home page (see Resources). With the Linux patch utility, you can update the NS2 source code to include support for SCTP by applying the patch:

patch -p0 < ns-allinone-2.1b8.sctp-rel2.2_patch_orig

In the same directory, there is a script named install that will configure, compile and install the required and optional NS2 components. There is no interaction with the user while installing; the script is completely automated. You must execute the script as superuser so that installation of binaries will be completed:

./install

When the installation process is complete, the following message will appear on your shell
Please put
$CUR_PATH/bin:$CUR_PATH/tcl$TCLVER/unix:$CUR_PATH/
tk$TKVER/unix into your PATH environment; so that
you'll be able to run itm/tclsh/wish/xgraph.
IMPORTANT NOTICES: [...]

Carefully follow all instructions given in the notices. The above-mentioned variables can be updated either by editing /etc/profile or changing environment variables directly. In case you updated /etc/profile, you need to source your new environment for the changes to take effect (i.e., source /etc/profile).

The NS2 validation suite will verify that all protocols are functional. This will fail if the install process was not completed; however, running validation is optional, and it consumes twice as much time as the compilation and installation process.

To run the validation suite:
cd ./ns-2.1b8

./validate

source : here