- NS2 Projects
- Tcl/Tk Tutorial
- Install NS2 (Network Simulator) on Ubuntu 18.04
- Tcl - Basic Syntax
- Basics of NS2 and Otcl/tcl script
NS2 ProjectsA special simulator object is defined in NS2 that perform process-based simulation on the network objects. You do not need to define a variable before you use it When a new name is encountered, TCL will assume that it is a new variable. Variable names in Tcl can contain any characters and be of any length. To get exotic characters like whitespace into a variable name you may need to quote it i. Auto-typing means that type of the variable depends on the value stored in the variable. Dynamically typed means that type of the variable can change over time A command name Optionally followed by one or more arguments parameters - unlike conventional programming languagethe parameters are not given between brackets! Most Tcl command has a fixed number of arguments There are a few Tcl command such as expr that has a variable number of arguments If you specify an incorrect number of arguments to a command, you will receive an error and the Tcl program will terminate. When using "set b"an error occurs if there is no variable named "b". If a variables name contains characters with special meaning e. Arrays are dynamicand the array size can change! Each array element has an independent from other array elements ; not like Java. Associateive arrays are arrays than are indexed by strings Associative arrays are also called dictionaries.
In this section, you are going to develop a Tcl script for ns which simulates a simple topology. You are going to learn how to set up nodes and links, how to send data from one node to another, how to monitor a queue and how to start nam from your simulation script to visualize your simulation. How to start Now we are going to write a 'template' that you can use for all of the first Tcl scripts. You can write your Tcl scripts in any text editor like joe or emacs. I suggest that you call this first example 'example1. First of all, you need to create a simulator object. This is done with the command set ns [new Simulator]. Now we open a file for writing that is going to be used for the nam trace data. In the second line we tell the simulator object that we created above to write all simulation data that is going to be relevant for nam into this file. The next step is to add a 'finish' procedure that closes the trace file and starts nam. It will get clearer to you once you see what the code does. The next line tells the simulator object to execute the 'finish' procedure after 5. The last line finally starts the simulation. You can actually save the file now and try to run it with 'ns example1. You are going to get an error message like 'nam: empty trace file out. We are going to define the objects in section 2 and the events in section 3. You will have to use the code from this section as starting point in the other sections. You can download it here. 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. The following two lines define the two nodes. The above code creates two nodes and assigns them to the handles 'n0' and 'n1'. The next line connects the two nodes. Now you can save your file and start the script with 'ns example1. You can download the complete example here if it doesn't work for you and you think you might have made a mistake. In ns, data is always being sent from one 'agent' to another. So the next step is to create an agent object that sends data from node n0, and another agent object that receives the data on node n1. CBR stands for 'constant bit rate'. Line 7 and 8 should be self-explaining. The packetSize is being set to bytes and a packet will be sent every 0. You can find the relevant parameters for each agent type in the ns manual page. The next lines create a Null agent which acts as traffic sink and attach it to node n1. Now the two agents have to be connected with each other.
Install NS2 (Network Simulator) on Ubuntu 18.04
Post a Comment. Pages Home. This section shows a simple NS simulation script and explains what each line does. Example 3 is an OTcl script that creates the simple network configuration and runs the simulation scenario. To run this simulation, copy the below code and save as" ns-simple. This network consists of 4 nodes n0, n1, n2, n3 as shown in above figure. The duplex links between n0 and n2, and n1 and n2 have 2 Mbps of bandwidth and 10 ms of delay. The duplex link between n2 and n3 has 1. Each node uses a DropTail queue, of which the maximum size is A "tcp" agent is attached to n0, and a connection is established to a tcp "sink" agent attached to n3. As default, the maximum size of a packet that a "tcp" agent can generate is 1KByte. A tcp "sink" agent generates and sends ACK packets to the sender tcp agent and frees the received packets. A "udp" agent that is attached to n1 is connected to a "null" agent attached to n3. A "null" agent just frees the packets received. A "ftp" and a "cbr" traffic generator are attached to "tcp" and "udp" agents respectively, and the "cbr" is configured to generate 1 KByte packets at the rate of 1 Mbps. The "cbr" is set to start at 0. The following is the explanation of the script above. In general, an NS script starts with making a Simulator object instance. Most of member functions are for simulation setup referred to as plumbing functions in the Overview section and scheduling, however some of them are for the NAM display. This member function of "Simulator" object is for the NAM display, and has no effect on the actual simulation. In this function, post-simulation processes are specified. A node in NS is compound object made of address and port classifiers described in a later section. Users can create a node by separately creating an address and a port classifier objects and connecting them together. However, this member function of Simulator object makes the job easier. In NS, the output queue of a node is implemented as a part of a link, therefore users should specify the queue-type when creating links. In the above simulation script, DropTail queue is used. The NS implementation of a link is shown in a later section. Like a node, a link is a compound object, and users can create its sub-objects and connect them and the nodes. One thing to note is that you can insert error modules in a link component to simulate a lossy link actually users can make and insert any network objects. Refer to the NS documentation to find out how to do this. At this point, the authors do not know how many of these kinds of member functions of Simulator objects are available and what they are. To see the effects of these lines, users can comment these lines out and try the simulation. But in general, users can create any agent or traffic sources in this way. Therefore, there are no specific Simulator object member functions that create these object instances.
Tcl - Basic Syntax
GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Skip to content. Permalink Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Branch: master. Find file Copy path. Cannot retrieve contributors at this time. Raw Blame History. Copyright c Regents of the University of California. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the Computer Systems Engineering Group at Lawrence Berkeley Laboratory. Neither the name of the University nor of the Laboratory may be used to endorse or promote products derived from this software without specific prior written permission. You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Redistribution and use in source and binary forms, with or without. Redistributions of source code must retain the above copyright. Redistributions in binary form must reproduce the above copyright. All advertising materials mentioning features or use of this software. This product includes software developed by the Computer Systems. Engineering Group at Lawrence Berkeley Laboratory. Neither the name of the University nor of the Laboratory may be used. A simple example for wireless simulation. Define options. Main Program. Initialize Global Variables.