Network dynamics. [Previous section] I suggest you call the Tcl script for this example ”. You can already . set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] set n3 [$ns node]. VIII. Creating Output Files for Xgraph. [ Previous section] [Next Section] [Back to .

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The next line connects the two nodes. The following tutrial of Tcl code creates three duplex links between the nodes. We see TCP flow starting at You are going to get an error message like ‘nam: You might notice that the topology looks a bit awkward in nam.

Marc Greis’ Tutorial for the UCB/LBNL/VINT Network Simulator “ns”

At the beginning of a wireless simulation, we need to define the type for each of these network components. The above code creates two nodes and assigns them to the handles ‘n0’ and ‘n1’. The following piece of code should look familiar to you by now if you read the first sections of this tutorial.

CBR stands for ‘constant bit rate’. This tutorial was originally developed by Marc Greis. Note that arrays, just like other variables in Tcl, don’t have to be declared first.

Watch the link from node n2 to n3 for a while, and you will notice that after some time the distribution between blue and red packets isn’t too fair anymore at least that’s the way it is on my system.

We are going to use the default value of flat addressing; Also lets turn on only AgentTrace and RouterTrace; You can experiment with the traces by turning all of them on.


The mobilenodes move about within an area whose boundary is defined in this example as mXm. One part of the ns-allinone package is ‘xgraph’, a plotting program which can be used to create graphic representations of simulation results.

III. The Basics

The purpose of these pages is to make it easier for new ns users to use ns and nam, to create their own simulation scenarios for these tools and to eventually add new functionality to ns.

For information on how to write your own Tcl scripts for ns, see section IV. On some systems you will also have to make sure that ns can find the library ‘libotcl. The last line finally starts the simulation. The nominal range is either provided as an argument to the programs, or extracted from the header in node-movement pattern files.

Next we create the 2 mobilenodes as follows: Details on generation of node movement files are covered in section XI. In this tutorial I will lead you through some simple examples, gris more and more new features as we go along. As they move away, packets start getting dropped.

In the first subsection, we discuss how to create and run a simple 2-node wireless network simulation. You can find the relevant parameters for each agent type in the ns manual page.

Two nodes, one link In this section we are going msrc define a very simple topology with two nodes that are connected by a link.

As always, the topology has to be created first, though this time we take a different approach which you will find more comfortable when you want to create larger topologies. For mrc about the Expoo traffic sources, please refer to the documentation for ns.


This tutorial chapter uses new node APIs uttorial are not available in the ns2. This procedure is a good example how reoccuring tasks like attaching a traffic source to several nodes can be handled.

As an extension to the previous sub-sectionwe are going to simulate a simple multihop wireless scenario consisting of 3 mobilenodes here. For a copy of wireless1. Now add the following piece gresi code to your Tcl script, preferably at the beginning after the simulator object has been created, since this is a part of the simulator setup.

You might want to slow nam down then with the ‘Step’ slider. I would recommend that tutoriaal start with the all-in-one package, especially if you’re not entirely sure which packages are installed on your system, and where exactly they are installed. They are listed as follows: The technique I present here is one of many possible ways to create output files suitable for xgraph.

For this purpose I will also try to tell you where I found the information in this tutorlal myself, so you not only learn how to use ns, but also how to use its documentation.