This document (ns Notes and Documentation) provides reference documentation for ns. Although we begin with a simple

simulation scr ipt, resources like Marc Greis’s tutorial web pages (originally at his web site, now at http://www.isi.

edu/nsnam/ns/tutorial/) or the slides from one of the ns tutorials are problably better places to begin for the ns

novice.

We first begin by showing a simple simulation scr ipt. This scr ipt is also available in the sources in ~ns/tcl/ex/simple.tcl.

This scr ipt defines a simple topology of four nodes, and two agents, a UDP agent with a CBR traffic generator, and a TCP

agent. The simulation runs for 3s. The output is two trace files, out.tr and out.nam. When the simulation completes at

the end of 3s, it will attempt to run a nam visualisation of the simulation on your screen.