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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Topology and Traffic Sources First of all, we create the following topology:. In this section, you are going to learn to use the mobile wireless simulation model available in ns. In addition to the evaluation functionalities, the God object is called internally by MAC objects in mobilenodes. At the beginning gries a wireless simulation, we need to define the type for each of these network components.
You can click on any packet in the nam window to monitor gres, and you can also click directly on the link to get some graphs with statistics. In this section, I will show you a simple way how you can create output files in your Tcl scripts which can be used as data sets for xgraph. Save the file simple-wireless. The next line connects the two nodes.
Link failure The next step is to send some data from node n 0 to node n 3.
In this tutorial I will lead you through some simple examples, introducing more and more new features as we go along. Watch the link from greks 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.
The packetSize is being set to bytes and a packet will be sent every 0. If you slow nam down enough to click on one of them, you will see that they are ‘rtProtoDV’ packets which are being used to exchange routing information between the nodes. The script might create some output on stdout, it might write a trace file or it might start nam to visualize the simulation. And now we have to tell the CBR agent when to send data and when to stop sending.
Then you change into the new directory and run ‘.
Marc Greis’ Tutorial for the UCB/LBNL/VINT Network Simulator “ns”
Now I will show you how to use dynamic routing to solve that ‘problem’. However note that only node movements can currently be seen in nam. Next setup traffic flow between the two nodes as follows: Dumping of geeis data and thus visualization of data pkt movements in nam for wireless scenarios is still not supported future work.
The options for the orientation of a link are right, left, up, down and combinations of these orientations. Now we use the procedure to attach traffic sources with different peak rates to n0, n1 and n2 and to connect them to three traffic sinks on n4 which have to be created first: There are better sources for that which I am going to list in Section II. On the way there, I will also show you how to use traffic generators. If you think there is a technique which is superior in terms of understandablity which is what I aim for in this tutorialplease let me know.
Download the daily snapshot version if the next release 2. In these pages I describe ns version 2. Next run the simulation in the usual way type at prompt: As they move away, packets start getting dropped. We shall make changes to the script, simple-wireless. When the link goes down again at 1. The next hop information is normally loaded into god object from movement pattern files, before simulation begins, since calculating this on the fly during simulation runs can be quite time consuming.
V. Making it more interesting
The configuration API can be defined as follows: We are going to define the objects in section 2 and the events in section 3. Thus all pkts destined for nodes 0 and 2 are routed through node 1. If you have any problems with your installation, take a look at the installation problems page on their server.
When you run the simulation, an xgraph window should open after some time which should look similar to this one:. How to start Now we are going to write a ‘template’ that you can use for all of the first Tcl scripts. I suggest that now you start some experiments with nam and the Tcl script. The following piece of code might look a bit more complicated at first.
As before, the mobilenodes move within the boundaries of a defined topology. The current snapshot version is updated daily, so please check the validation results for that day before downloading, as these snapshots can sometimes be unstable due to ongoing changes made by ns-developers.
Also we are going to set up nam traces. On some systems you will also have to make sure that ns can find the library ‘libotcl.