Marc Greis’ ns Tutorial Contents: I. Introduction II. Finding Documentation II For ns&nam II.2 For Tcl II.3 For C++ III. The Basics III.1 Downloading/ Installing. Only the first 94 pages are relevant for Tcl, the rest of the book is about Tk and more complicated aspects of Tcl. I also found a short OTcl Tutorial. Another good . Marc Greis’ Tutorial for the UCB/LBNL/VINT Network Simulator “ns”. I. Introduction [Next section] [Back to the index] Disclaimer: This tutorial was originally.
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In addition to the variables LL, MAC, antenna etc that were declared at the beginning of the script, we now define some more parameters like the connection-pattern and node-movement file, x and y values for the topology boundary, a seed value for the random-number generator, time for the simulation to stop, for convinience. We are going to define the objects in section 2 and the events in section 3. Make sure the connection-pattern and node-movement files exist under the directories as declared above.
The path length information provided to god was used by CMU’s Monarch Project to analyze the path length optimality of ad hoc network routing protocols, and so was printed out as part of the CMUTrace output for each packet. As an extension to the previous sub-sectionwe are going to simulate a simple multihop wireless scenario consisting of 3 mobilenodes here.
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.
The next line connects the two nodes. The next line tells the simulator object to execute the ‘finish’ procedure after 5.
II. Finding Documentation
The mobilenodes move about within an area whose boundary is defined in this example as mXm. See cbrtest to find out more about the traffic flows that are setup. Now you tuorial save your file and start the script with ‘ns example1.
Just as with any other ns simulation, we begin by creating a tcl script for the wireless simulation. Now the two agents have to be connected with each other. However, in order to keep this example simple we avoid using movement pattern files and thus do not provide God with next hop information.
We begin our script simple-wireless. The setdest program see section XI. Both setdest and calcdest calculate the shortest number of hops between nodes based on the nominal radio range, ignoring any effects that might be introduced by the propagation model in an actual simulation. The configuration API can tutoriall defined as follows: Then they greie towards each other in the first half of the simulation and again move away for the second half.
More about this is discussed in section XI. The following two lines define the two nodes. MovementTrace, when turned on, shows the movement of the mobilenodes and the trace is marked with M in their 2nd field. You can download it here.
MARC GREIS TUTORIAL PDF
However the node movements for this example shall be read from a node-movement file called scentest. Dumping of traffic data and thus visualization of data pkt movements in nam for wireless scenarios is still not supported future work. 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.
Also we are going to set up nam traces. If ad-hockey can read your input correctly, its output will be properly formatted for calcdest. The two CBR agents have to be connected to the Null agent. I will explain find a way to distinguish the data flows from the two nodes from each other, and I will show how a queue can be monitored to see how full it is, and how many packets are being discarded.
So even though we may not utilise God for evaluation purposes, as in this example we still need to create God. In addition to the evaluation functionalities, the God object is called internally by MAC objects in mobilenodes.
Random node movement files like scentest can be generated using CMU’s node-movement generator “setdest”. And now we have to tell the CBR agent when to send data and when to stop sending. The node-movement files generated using setdest like scentest already include lines like above to load the god object with the appropriate information at the appropriate time.
Two nodes, one link In this section we are going to define a very simple topology with two nodes that are connected by a link. You can find the relevant parameters for each agent type in the ns manual page. The packetSize is being set to bytes and a packet will be sent every 0. As they move away, packets start getting dropped.
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First, we need to configure nodes before we can create them. If you have any suggestions, find any bugs or problems, have any comments and also if you have any new well-documented examples that could be added here, please send email to ns-users mailing list. 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 titorial quite time consuming.
Next setup traffic flow between the two nodes as follows: The nominal range is either provided as an argument to the programs, or extracted from the header in node-movement pattern files. We will call this file simple-wireless.
Marc Greis’ Tutorial for the UCB/LBNL/VINT Network Simulator “ns”
The array used to define these variables, val is not global as it used to be in the earlier wireless scripts. Now you can save the file and start the simulation again. The geris consists of two parts.
Next we create the 2 mobilenodes as follows: