Skip to main content

INTRODUCTION TO NETWORK SIMULATOR 2

 INTRODUCTION 


Network Simulator Version 2, widely known as NS2, is an event driven simulation tool that is useful in studying the dynamic nature of communication networks. Simulation of wired as well as wireless network functions and protocols (e.g., routing algorithms, TCP, UDP) can be done using NS2. In general, NS2 provides users with a way of specifying such network protocols and simulating their corresponding behaviors. Due to its flexibility and modular nature, NS2 has gained constant popularity in the networking research community since its birth in 1989. Ever since, several revolutions and revisions have marked the growing maturity of the tool, thanks to substantial contributions from the players in the field. Among these are the University of California and Cornell University who developed the REAL network simulator,1 the foundation which NS is based on. Since 1995 the Defense Advanced Research Projects Agency (DARPA) supported development of NS through the Virtual InterNetwork Testbed (VINT) project.Currently the National Science Foundation (NSF) has joined the ride in development. Last but not the least, the group of researchers and developers in the community are constantly working to keep NS2 strong and versatile.

BASIC ARCHITECTURE OF NS2

Figure given below shows the basic architecture of NS2. NS2 provides users with an executable command ns which takes on input argument, the name of a Tcl simulation scripting file. Users are feeding the name of a Tcl simulation script (which sets up a simulation) as an input argument of an NS2 executable command ns. In most cases, a simulation trace file is created, and is used to plot graph and/or to create animation.




NS2 consists of two key languages: C++ and Object-oriented Tool Command Language (OTcl). While the C++ defines the internal mechanism (i.e.,a back end) of the simulation objects, the OTcl sets up simulation by assembling and configuring the objects as well as scheduling discrete events (i.e.,a front end). The C++ and the OTcl are linked together using TclCL. Mapped to a C++ object, variables in the OTcl domains are sometimes referred to as handles. Conceptually, a handle (e.g., n as a Node handle) is just a string (e.g.,o10) in the OTcl domain, and does not contain any functionality. Instead, the functionality(e.g., receiving a packet) is defined in the mapped C++ object (e.g., of class Connector). In the OTcl domain, a handle acts as a front end which interacts with users and other OTcl objects. It may defines its own procedures and variables to facilitate the interaction. Note that the member procedures and variables in the OTcl domain are called instance procedures(instprocs) and instance variables(instvars), respectively. Before proceeding further, the readers are encouraged to learn C++ and OTcl languages and we include it on our previous posts.

NS2 provides a large number of built in C++ objects. It is advisable to use these C++ objects to set up a simulation using a Tcl simulation script. However, advance users may find these objects insufficient. They need to develop their own C++ objects, and use a OTcl configuration interface to put together these objects. After simulation, NS2 outputs either text-based or animation-based simulation results. To interpret these results graphically and interactively, tools such as NAM (Network AniMator) and XGraph are used. To analyze a particular behavior of the network, users can extract a relevant subset of text-based data and transform it to a more conceivable presentation.

INSTALLATION

NS2 is a free simulation tool. It runs on various platforms including UNIX (or Linux), Windows, and Mac systems. Being developed in the Unix environment, with no surprise, NS2 has the smoothest ride there, and so does its installation.

NS2 source codes are distributed in two forms: all-in-one suite and the component-wise. With the all-in-one package, users get all the required components along with some optional components. This is basically a recommended choice for the beginners. This package provides an “install” script which configures the NS2 environment and creates NS2 executable file using the “make” utility. The current all-in-one suite consists of the following main components : 
  • NS release 2.30,
  • Tcl/Tk release 8.4.13,
  • OTcl release 1.12, and
  • TclCL release 1.18.
and the following are the optional components:
  • NAM release 1.12: NAM is an animation tool for viewing network simulation traces and packet traces.
  • Zlib version 1.2.3: This is the required library for NAM.
  • Xgraph version 12.1: This is a data plotter with interactive buttons for panning, zooming, printing, and selecting display options.
The idea of the component-wise approach is to obtain the above pieces and install them individually. This option save considerable amount of downloading time and memory space. However, it could be troublesome for the beginners, and is therefore recommended only for experienced users.

Click the following links to know more about installation:
Labels:

Comments

Post a Comment

Popular posts from this blog

Link State Routing Protocol

Link state routing is a method in which each router shares its neighborhood’s knowledge with every other router on the internetwork. In this algorithm, each router in the network understands the network topology and then makes a routing table depending on this topology. Each router will share data about its connection to its neighbor, who will, consecutively, reproduce the data to its neighbors, etc. This appears just before all routers have constructed a topology of the network. In LSP, each node transmits its IP address and the MAC to its neighbor with its signature. Neighbors determine the signature and maintain a record of the combining IP address and the MAC. The Neighbor Lookup Protocol (NLP) of LSP derives and maintains the MAC and IP address of every network frame accepted by a node. The extracted data can support the mapping of MACs and IP addresses. The link-state flooding algorithm prevents the general issues of broadcast in the existence of loops by having every node mainta...
Post a Comment
Read more

Matter: A next generation home standard

The smart home is evolving. To date, if you've wanted to get into developing a smart home, you've had to deal with the multitude of smart home ecosystems, and making sure that each device you buy is compatible. That, however, may soon change — thanks to new smart home standard called Matter. Matter isn't available just yet, but when it is finally released, it could completely change how you buy smart home products, for the better. All of the best smart home devices could soon support the standard, helping them all work together nicely, and ensuring that no matter what products you buy, you'll be able to use them. Matter is basically the name of a new smart home connectivity standard . But this standard is a little unlike others. That's because of the fact that it's being developed by the Connectivity Standards Alliance, which counts hundreds of companies as members. That includes the likes of Google, Alexa, and Apple. So, whether you prefer to use Google Assista...
1 comment
Read more

New interactive stickers for Stories

Instagram has introduced several new features to Stories, offering interactive ways to share music, photos, and videos. One of the most interesting additions is a feature called Reveal , which blurs the content of a story post and requires viewers to DM the person who shared it in order to see it. Instagram's head, Adam Mosseri, has emphasized the importance of direct messages on the platform, with stories and DMs driving most of Instagram's growth. Requiring a DM to view content represents the next step in boosting engagement, and creators are likely to use it as a tactic to increase their stories' engagement. Another new feature, Frames, adds a Polaroid overlay to images that initially appear gray. Users can shake their phone to reveal the photo, resembling the process many people associate with Polaroid pictures, despite the fact that shaking Polaroids is not recommended by the company during development. Instagram has also introduced a music-based template feature calle...
Post a Comment
Read more