COMP 561 Computer Networks

Introducing NS-2 and NAM

In this exercise you will be introduced to the Network Simulator NS-2 and the Network Animator (NAM) which is part of the NS-2 tool suite. You can find more information about NS-2 and NAM through the simple presentation on NS-2 and NAM available online and the NS-2 tutorials available online. The links are available in the Course Website under Useful Links. This exercise is to demonstrate to you the use of network simulation to understand the behavior of network protocols.

The files required for this lab exercise are available in the course directory under /course/comp561/ns/labs/intro. Please log on to one of the Unix machines in Lab 2, i.e., csl2su00-csl2su41.cs.ust.hk, and change directory to the above.

In this exercise, you will see the animations of the TCP congestion control that you were shown in the class. For details of each animation, please refer to the Javis TCP Visualization Web page (http://cs.baylor.edu/~donahoo/NIUNet/tcpvis.html) and A Quick Tour around TCP webpage (http://www.ce.chalmers.se/%7Efcela/tcp-tour.html). The NAM trace files for each of the animations are already downloaded to your course directory and available under /course/comp561/ns/labs/intro. You can execute each of the animations by typing “nam <NAM TRACE FILE>”.

To further understand how these NAM trace files are generated, you can execute the simulation for one simulation using the TCL script provided to you in a-first.tcl file. You can execute the simulation by typing “ns a-first.tcl”.