6.892 ns Simulator Information

6.892 ns Simulator Information (Fall 1999)

ns on Athena

Running ns.

We have installed a version of the ns simulator onto Athena for your convenience. To run the simulator, you first need to add the 6.892 course locker to your execution path. To do this, type the following command at your athena prompt: add 6.892. For the rest of your login session, you can run ns by simply typing ns at your shell prompt. The simulator is currently only available for Athena Sun workstatations. If you do not have access to Athena, you can build your own copy of the ns simulator from source by downloading it from the official ns website.

Note: You will run into trouble running ns if your UNIX $PATH environment variable lists another directory before the 6.892 locker that contains an ns binary. For example, the sipbnet locker, which many of you may have added to your path to access the "tcpdump" utility, also contains a binary for ns. This version of ns is not supported by 6.892. You should make sure that the 6.892 locker appears before the sipbnet locker in your UNIX path.

Accessing the source code.

You can find all of the source code for ns, as well as other useful course materials, in the course locker. Once you have typed add 6.892 at your athena prompt, you can find the code in the following directory:/mit/6.892/software/ns-2/ns-2.1b6-current

Modifying the source code.

If you wish to modify the ns source code, you have two options. You can either copy the entire distribution into your home directory from the course locker (17 MB), or you can create soft links to the course locker in your own directory. Using this second option, you can modify the source code by copying those files that you wish to modify into your directory. The advantage of this approach is that you will avoid using up your athena disk quota with a 17Mb copy of the ns source distribution. If you do not know how to make soft links, we have written a script for you to automate the process:

Add the course locker to your path by typing add 6.892 at your athena prompt.
Create an area in your home directory for your private copy of the ns source code, for instance: /mit/joeuser/ns-2.
Change to your new directory: cd /mit/joeuser/ns-2.
Create the links: make_nslinks. This command will copy some files into your own directory and create soft links to the ns source code.
In order to make a new version of the simulator, you will need to first type add gnu at your athena prompt. This will put all of the necessary gnu compilers and software into your path.

Whenever you wish to modify a file, you should copy the file from the course locker into your home directory.

Useful ns links

The official ns website. Almost everything you need to know about ns can be accessed from this site.
On-line Tcl man pages.
ns on-line tutorial.
otcl tutorial.
Athena on-line help.
6.892 ns tutorial slides.

If you find other interesting or useful sites related to ns, please send mail to jokulik@lcs.mit.edu she will add them to this page.

Last update: Fri Sep 17 8:30:08 EDT 1999 (jokulik)