NS is a great tool for simulating network agents. It allows a user to easily specify an arbitrary network with assigned attributes to network elements (e.g., link speed). The main NS site is here.

• Steps for using NS:

  1. Download the "allinone" copy from the main site. This contains a tarred/compressed version of everything (TCL, NS, TK, ...).
  2. Decompress/untar it in your home directory. I suggest changing the directory name from ns-allionone... to ns.
  3. Change to the ns directory and run "./install". This should compile everything for you.
  4. Make sure you set your LD_LIBRARY_PATH variable to point to the otcl shared library. If your ns installation is at /home/bob/ns, you need to set the variable to /home/bob/ns/otcl. Also make sure that /home/bob/ns/bin is in your path. This directory will hold links to all of the vital binaries.
  5. The ns directory contains everything (NS, TCL, ...). Change to the ns distribution directory (e.g., ns-2.26) and run "./validate" to confirm your version works.
• There is a good NS tutorial.
• Another good way to learn NS is to play with the example TCL files in /home/bob/ns/ns-2/tcl/ex. Try the simple.tcl file in that directory by typing "ns simple.tcl" in the "ex" directory. These TCL files show how to create a network, use existing NS agents to perform a simulation, and create a nam (Network Animator) animation of the simulation. Note that tcl is interpreted so you do not need to compile the scripts. Just write the script in a file (e.g., foo.tcl) and type "ns foo.tcl" to execute it.
• The main site also contains a manual on using NS.
• I have created an FEC agent. You can download the code and installation instruction from here.
• You can now search the NS mailing list archives.
• I maintain a BU FAQ where I try to log answers that I found to various questions.
• A good way to learn about using existing agents to build simulations is looking over the example files (e.g., simple.tcl) in the ns/ns-version/tcl/ex directory. You can interpret these files by using the man page for ns (command: man ns).