The Increasing Reach of Virtual Reality (VR)

Whats is Virtual Reality?

Virtual Reality (VR) is a technology that makes users feel in a Virtual Environment with the help of computing systems and specifically designed software.

The term “Virtual Reality “ itself is comprised of two words i.e. Virtual and Reality .Virtual means “not real” but “like real” and reality. Thus Virtual Reality means anything that is near to reality. Technically Virtual Reality is described as “a computer generated three dimensional environment” in which a person can interact or manipulate objects of such environment.
As Wikipedia states

Virtual reality or virtual realities (VR), also known as immersive multimedia or computer-simulated reality, is a computer technology that replicates an environment, real or imagined, and simulates a user’s physical presence and environment in a way that allows the user to interact with it. Virtual realities artificially create sensory experience, which can include sight, touch, hearing, and smell.

How Virtual Reality is achieved?

In Virtual Reality (VR) with the help of computer technology a simulated environmen
t is created in which the computer is transformed into a gatekeeper to an artificial world. Unlike usual graphic experienc
e instead of viewing a screen in front of users and keyboard or mouse for input, VR places the user inside that sim
ulated environment. Users can also interact within that given environment and manipulate objects in the virtual world with their sense such as hearing, touching and watching. There are a range of systems that are used for this purpose, such as headsets, Omni-directional treadmills and special gloves. These are used to actually stimulate our senses together in order to create the illusion of reality.

Following are the main components of a virtual environment:

1. The visual displays that immerse the user in the virtual world.
2. The graphics rendering system that generates the ever changing images at 20 to 30 frames per second.
3. A tracking system that continuously informs the position and orientation of the user’s movements.
4. The database construction and maintenance system to build and maintain a detailed and realistic model of the virtual world.
5. A sound system that can produce high quality directional sounds and simulated sound fields.
6. Devices like tracked gloves with pushbuttons to enable users to specify their interactions with the virtual objects.

Span of Virtual Reality:

Virtual Reality can lead to a new exciting world of innovations and entertainment. Entertainment industry is Billion Dollar market where new technologies play major role to create a huge user base. Virtual Reality is getting popular nowadays for such an immersed experience in Gaming, Entertainment and training areas. Whether it’s an expensive, dangerous or impractical to do something in reality, VR makes it real for you.

VR is increasingly playing major significance in following areas:

• Architecture
• Construction
• Sports
• Medical
• Gaming
• Entertainment
• Cinema

Military training to Medical surgery training can be experienced more deeply than real. It will not be surprising if we say

Virtual Reality or Immersed System can change digital interface systems we see today.

Bootstrap: A complete package for WEB

Bootstrap

BOOTSTRAP is  a complete package for web who wants to become a web designer. Bootstrap is the most popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web sites.

HTML:

Defines data and structure of a page using elements under html.

CSS:

Defines how the data and elements actually looks and behave when interact with them.

JS: 

This is actually programming language of a web know as java script.

History of Bootstrap:

Bootstrap is a front-end development framework that enables developers & designers to quickly build fully responsive websites. The framework contains global CSS settings with built-in components and extensible classes in the form of typography, navigation, buttons,form,tabbing and much more.

Bootstrap was originally developed by former Twitter employees Mark Otto and Jacob Thornton, as an internal development tool to improve consistency and efficiency of web page.

It was in August 2011, released as a open source project on github and become a most popular repository platform.

Very easy Installation: 

Installation is very easy, just download the source file of bootstrap and upload on server and just put the references or  links of available files into your header. The installation process work is covered with that work.

example-

<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="link of your file" > (this is for .css file)

<!-- Latest compiled and minified JavaScript --> <script src="link of .js file" ></script>

How to start:

You should remember this format to start ..

<!DOCTYPE html>
<html>
<head>
<title>Title Name</title>
</head>
<body>

<h1>This is a Heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

Basic HTML elements-

• Title- <title></title>- this is use for give title of the page.
• Header- <h1>…<h6>- this element is use for give the heading of content.
• Paragraph-<p></p>- This element is use for give a paragraph.
• Simple block element-<div></div>

How to use CSS:

• Internal / Embedded Styles. Internal Styles are placed inside the head section of a particular web page via the style tag.

<style>

.clr{

color:red;

background-color:yellow;

}

#code{

font-size:12px;

}

</style>

• Inline Styles. Inline Styles cannot be resused at all, period.

<div style="color:red,margin:12px 0 0 0"></div>

• External Style Sheet. For the most part, we will want to place the majority of our Style Rules on an External Style Sheet.

<link href=”link of your file” rel=”stylesheet” type=”text/css”/>

How to use Javascript (JS File):

• Internal: Internal script are placed inside the page wherever you want via the sscript tag.

<script type="text/javascript">

$(document).ready(function(){

Your code here.....

});

</script>

• External- For the external link first you have to create a .js file in and set link in html page.

<script src="js file address" type="text/javascript" ></script>

Features:

• css resetting for cross browser compatibility.
• grid scaffolding for design.
• Multi screen support.(Fully Responsive)

Javascript plugin:

• Dialogs
• Tabs
• Alerts
• Carousel
• tooltips and many more..

Customization:

• You can customize the css according to your requirements.
• You can use LESS to compile your a bootstrap css version on your own.
• You can just download the customize version from http:/bootswatch.com

Adding Twitter Bootstrap:

You should use CDN links also..like

For CSS-

<link href=”https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css” rel=”stylesheet”/>

For Javascript File- 

<script type=”text/javascript” src=”https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js”></script>

[box] An Example of Bootstrap:[/box]

Awadhesh Kumar

Jain Software Developers

IP Spoofing

IP SPOOFING:

“IP address spoofing” is a technique that involves replacing the IP address of an IP packet’s sender with another machine’s IP address.

IP spoofing refers to connection hijacking through a fake Internet Protocol (IP) address. IP spoofing is the action of masking a computer IP address,so that it looks like it is authentic.

• IP Spoofing is a technique used to gain unauthorized access to computers.
  • `IP: Internet Protocol
  • `Spoofing: using somebody else’s information
• Exploits the trust relationships.

Types of IP Address:

1. IP is connectionless, unreliable
2. TCP connection-oriented

A Blind Attack:

Host I can not see what Host V send back

 IP SPOOFING STEPS:

1. Selecting a target host (the victim)
2. Identify a host that the target “trust”
3. Disable the trusted host, sampled the target’s TCP sequence
4. The trusted host is impersonated and the ISN forged.
5. Connection attempt to a service that only requires address-based authentication.
6. If successfully connected, executes a simple command to leave a back-door.

IP Spoofing Attacks:

• Man in the middle-Packet sniffs on link between the two end points, and therefore can pretend to be one end of the connection.
• Routing-redirects routing information from the original host to the attacker’s host.
• Flooding / Smurfing-The attacker redirects individual packets by the hacker’s host.

Attacks:

Flooding: SYN flood fills up the receive queue from random source addresses.

Smurfing:  ICMP packet spoofed to originate from the victim, destined for the broadcast address, causing all hosts on the network to respond to the victim at once.

IP-Spoofing Facts:

• IP protocol is inherently weak
• Makes no assumption about sender/recipient
• Nodes on path do not check sender’s identity
• There is no way to completely eliminate IP spoofing
• Can only reduce the possibility of attack

Disable Ping Command:

• ping command has rare use
• Can be used to trigger a DOS attack by flooding the victim with ICMP packets
• This attack does not crash victim, but consume network bandwidth and system resources
• Victim fails to provide other services, and halts if runs out of memory

FIREWALL:

• Limit traffic to services that are offered
• Control access from within the network
• Free software: ipchains, iptables
• Commercial firewall software
• Packet filters: router with firewall built-in
• Multiple layer of firewall

Google Glass

What is Google Glass?

• Google Glass is a wearable, voice-controlled Android device that resembles a pair of eyeglasses and displays information directly in the user’s field of vision.
• Google’s project program for developing a line of hands-free,intelligent devices that can be worn by users as “wearable computing” eyewear. The first product release from Project Glass, Google Glass, was available for beta testers (U.S. residents only) to purchase in 2013, for $1,500 plus tax.
• Google Glass is a headset, or optical head-mounted display, that is worn like a pair of eyeglasses. It was developed with the mission of producing a ubiquitous computer.

Google Glass Features:

1. Record Videos, Take Pictures:

Just say the word and Google Glass will take a picture or record a video ` you will never have to touch the hardware.

2. Show Messages:

Google Glass will show you text messages as well as emails you receive and allow you to reply to them via voice commands.

3. Find Information:

If you are in the habit of Googling things a lot, you will find that your task has been made easier by the new Glass. You simply need to ask a question and the device will pull the answer from the internet.

4. Show Maps:

The widely used Google Maps are integrated into Glass, so that users will be able to chart the course of their journey or look up locations or establishments via voice commands.

5. Live Video Sharing:

Google Glass can show the world what you are seeing ` live! If you are attending a family function, your child’s school play or a concert, you can share the feed with your friends and family in real-time and make them a part of the experience.

6. Integrates Google Now:

Google Now, the digital voice assistant from the search giant, has been integrated in this device. It will keep track of your daily habits, such as when you leave for office or the route you take.

7. Translate:

This is a neat feature that may come in handy when you travel abroad. You simply need to ask Google Glass to translate a phrase or sentence from one language to another and it will speak that out.

 

Applications of Google Glass:

Google Glass applications are free applications built by third-party developers. Glass also uses many existing Google applications, such as Google Now, Google Maps, Google+, and Gmail.

Third-party applications announced at South by Southwest (SXSW) include Evernote, Skitch, The New York Times, and Path.

Awadhesh Kumar

Jain Software Developers

TRENDS IN DATA MINING

What is Data Mining:

•  Data mining is the process of extraction of interesting patterns or knowledge from huge amount of data.
• Using information contained within data warehouse, data mining can often provide answers to questions. Like….
  • Which products should be promoted to a particular customer?
  • Which securities will be most profitable to buy or sell during the next trading session?

Application of data mining:

Here is the list of areas where data mining is widely used −

• Healthcare
• Finance
• Retail industry
• Telecommunication
• Text Mining & Web Mining
• Higher Education

Trends in data mining:

• Application Exploration
• Scalable data mining methods
•  Combination of data mining with database systems, data warehouse systems, and web  database systems
• Standardization of data mining language
•  Visual data mining
• New methods for mining complex types of data
• Web mining

Application Exploration of Data Mining:

• Earlier data mining was mainly used for business purpose, to overcome the competitors.
• Data mining is gaining wide acceptance in other fields also. And many new explorations are being done for this purpose.
• Data mining for business continues to expand as e-commerce and marketing becomes mainstream elements of the retail industry.

Scalable Data Mining Methods:

• As data is expanding at a massive rate, there is a need to develop new data mining methods which are scalable and can handle different types and large volume of data.
• The data mining methods should be more interactive and user friendly.
• One important direction towards improving the repair efficiency of the timing process while increasing user interaction is constraint-based mining.

Combination of data mining with database, data warehouse, and web database systems:

• Database, data warehouse, and WWW are loaded with huge amounts of data and are major information processing systems.
• The desired architecture for data mining system is the tight coupling with database and data warehouse systems.
• Transaction management query processing, online analytical processing and online analytical mining should be integrated into one unified framework.

Standardization of data mining language: 

Today few data mining languages are commercially available in the market like Microsoft’s SQL server 2005, IBM Intelligent Miner and many more…..

Standard data mining language or other standardization efforts will provide the orderly development of data mining solutions, improved interpret-ability among multiple data mining systems and functions.

Visual Data Mining:

• The result of the mined data can be shown in the visual form So it will further enhance the worth of the mined data.
• Visual data mining is an effective way to discover knowledge from huge amounts of data.
• The systematic study and development of visual data mining techniques will promote the use for data mining analysis.

Web Mining:

• The WWW is globally distributed collection of news, advertisements, consumer records, financial, education, government, e-commerce and many other services.
•  The WWW also contains huge and dynamic collection hyper linked information, providing a large source for data mining.
• Based on the above facts, the web also poses great challenges for efficient resource and knowledge discovery.

Need of Data Mining:

•  The massive growth of data from terabytes to perabytes is due to the wide availability of data in automated form from various sources as WWW, Business, Society etc….
• We are drowning in data but deficient of knowledge Data is useless, if it cannot deliver knowledge.
• That is why data mining is gaining wide acceptance in today’s world.

Awadhesh Kumar

Jain Software Developers

Cell Phone Jammer

What is Jammer?

• Cell phone jammers are devices that create a temporary “dead zone” to all cell phone traffic in their air system.
• A cell phone jammer is an instrument used to prevent cellular phones and their mobile signals to a base station. When used, the jammer effectively disables cellular phones in the area.
• Other types of jammers -radar jammer  and radio jammer.

Size of Jammer:

Some cell-phone jammers are made to look like actual phones. Others are briefcase-sized or larger. The biggest jammers used by police and the military can be mounted in vehicles for convoy security.

Why Jammers are used?

• Cell phone jamming devices were originally developed for law enforcement and the military to interrupt communications by criminals and terrorists.
• Examples include: security zones public transport,classrooms,temples,jails,govt.buildings,military bases, industries etc.

How Jammer Works:

A jamming device transmits – same radio frequencies as the cell phone, the communication between the phone and the cell-phone base station in the tower. It’s a called a denial-of-service attack.

• Jammers block cell phone use by sending out radio waves along the same frequencies that cellular phones use at a  high enough power that the two signals collide and cancel each other out.
• This causes  interference with communication of cell phones and towers to render the phones  unusable.On most  phones, the network would be out of range.

What is Inside the jammer?

Antenna: 

Every jamming – antenna to send the signal. Some are contained within an electrical cabinet. On stronger devices, antennas are external to provide longer range and may be tuned for individual frequencies.

Power supply
Smaller jamming – battery operated.

Some look like cell phone and use cell-phone batteries. Stronger devices – plugged into a standard outlet or wired into a vehicle’s electrical system.

Circuitry
The main electronic components of a jammer are:

                Voltage-controlled oscillator – Generates the radio signal – interfere with the cell phone signal.

                Tuning circuit – Controls the frequency at which the jammer broadcasts its signal by sending a particular voltage to the oscillator.

                Noise generator – Produces random electronic output in a specified frequency range to jam the cell-phone network signal.

RF amplification (gain stage) – Boosts the power of the radio frequency output to high enough levels to jam a signal.

Applications of jammer?

1. Cell phone jamming devices were originally developed for law enforcement and the military to interrupt communications by criminals and terrorists
2. It has been widely reported that a cell-phone jammer thwarted an assassination attempt on Pakistani President Musharraf in December 2003.
3. Used in areas where radio transmissions are dangerous, such as areas with a potentially explosive atmosphere, such as chemical storage facilities or grain elevators.

Awadhesh Kumar

jain software developers

Introduction of Tripwire

What is Tripwire ?

• —Reliable intrusion detection system.—
• —Tool that checks
  400 × 150 – gardnertackle.co.uk

  to see what changes have been made in your system.—

• —Pinpoints, notifies, determines the nature, and provides information on the changes on how to manage the change.—
• —Mainly monitors the key attributes(like binary signature, size and other related data) of your files.—
• —Changes are compared to the established good baseline.—
• —Security is compromised, if there is no control over the various operations taking place.

How does it works:

1. —First, a baseline database is created, storing the original attributes like binary values in registry.—
2. —If the host computer is intruded, the intruder changes these values to go undetected.—
3. —The TripWire software constantly checks the system logs to check if any unauthorized changes were made.—
4. —If so, then it reports to the user.
5. —User can then undo those changes to revert the system back to the original state.

Where it is used?

• —Tripwire for Servers(TS) is software used by servers.—
• — Can be installed on any server that needs to be monitored for any changes.—
• —Typical servers include mail servers, web servers, firewalls, transaction server, development server.—
• —It is also used for Host Based Intrusion Detection System(HIDS) and also for Network Intrusion Detection System(NIDS).—
• —It is used for network devices like routers, switches, firewall, etc.
• —If any of these devices are tampered with, it can lead to huge losses for the Organization that supports the network.

Tripwire for Network Devices:

• Tripwire for network devices maintains a log of all significant actions including adding and deleting nodes, rules, tasks and user accounts.
• Automatic notification of changes to your routers, switches and firewalls.
• Automatic restoration of critical network devices.
• Heterogeneous support for today’s most commonly used network devices.

Tripwire for servers:

• For the tripwire for server’s software to work two important things should be present `the policy file and the database.
• The Tripwire for server’s software conducts subsequent file checks automatically comparing the state of system with the baseline database.
• Any inconsistencies are reported to the Tripwire manger and to the host system log file.
• Reports can also be emailed to an administrator.

There are two types of  Tripwire Manager

• Active Tripwire Manager
• Passive Tripwire Manager

• This Active Tripwire Manager gives a user the ability to update the database, schedule integrity checks, update and distribute policy and configuration files and view integrity reports.
• The Passive mode only allows to view the status of the machines and integrity reports.

How to Install and Use:

• —Install Tripwire and customize the policy file.—
• —Initialize the Tripwire database.—
• —Run a Tripwire integrity check.—
• —Examine the Tripwire report file.—
• —Take appropriate security measures.—
• —Update the Tripwire database file.—
• —Update the Tripwire policy file.—

What is the benefits of Tripwires:

—Increase security:  Immediately detects and pinpoints unauthorized changes.

—Instill Accountability:  Tripwire identifies and reports the sources of changes.

—Gain Visibility:  Tripwire software provides a centralized view of changes across the enterprise infrastructure and supports multiple devices from multiple vendors.

—Ensure Availability:  Tripwire software reduces troubleshooting time, enabling rapid discovery and recovery. Enables the fastest possible restoration back to a desired, good state.

What are the features of tripwire?

—The main attractive feature of this system is that the

•  Software generates a report about which file has been violated, when the file has been violated and also what   information in the files have been changed.
• —If properly used it also helps to detect who made the changes.—
• —Proper implementation of the system must be done with a full time manager and crisis management department.

—

Awadhesh Kumar

Jain Software Developers

—

—

Web Based Mobile

The Mobile Web

Definition: The World Wide Web accessed through a mobile device such as :-

•   cellular phones
•   iPod Touch
•   smart phone,
•   Tablet,

Mobile phones that have Web capabilities can search the Internet from anywhere that the phone can get a signal. The cell phone is the desk top or lap top counter part.

History:

The first access to the mobile web was commercially offered in Finland in 1996 on the Nokia 9000 Communicator phone via, the Sonera and Radiolinja networks. This was access to the real internet. The first commercial launch of a mobile-specific browser-based web service was in 1999 in Japan when i-mode was launched by NTT DoCoMo.

Components of Mobile Web:

• Users
• Devices
• operating systems and other software
• Services
• content
• how users currently engage with information on the World Wide Web via their mobile devices.

USERS:Net generation

• Grew up with computers and video games
• Work in multimedia environments
• Figure things out for themselves without consulting manuals
• Work in groups
• Are multi-tasking

Devices: (Mobile)ž

žThe mobile phones are the backbone of mobile communications. They have matured across four generations (1G, 2G 3G and now 4G)ž

Mobile Telephone:

A Mobile Telephone (also known as a Cellular Telephone) is defined as a ‘portable electronic device for the purpose of telecommunications over long distances.’

There are different kinds:

•  Standard phones–multimedia phones that allow users to download music, ringtone, watch TV and videos and send multimedia messages.
•   Smartphones( blackberry, Nokia N series) which are relatives of the PDA offer computing capabilities. These Include the iphone that presents whole Web pages via its safari browser.

PDA(Personal Digital Assistance):

PDA (personal digital assistant) is a term for any small mobile hand-held device that provides computing and information storage and retrieval capabilities for personal or business use, often for keeping schedule calendars and address book information handy.

Evolution of the Mobile Telephones:

The mobile industry currently offers 1G, 2G and 3G devices. 1G is   being phased out while 4G devices are still under development but   countries such as Japan and China are already using 4G technology.

1G:

•   The first commercially available cellular network using 1G standard   was introduced by NTT (Nippon Telegraph and Telephone) in 1979 in   Japan.
•   1G (First Generation Wireless Technology). Is the analog, voice-only   cellular telephone standard, developed in the 1980s.
•    It was invented by Martin Cooper of Motorola Corp in 1973.
•   In 1G network, voice calls were simply modulated to a higher Frequency, typically to 150MHz and up before 1G technology was the mobile radio telephone or 0G (Zeroth G)
• 1G phones could be cloned

2G-2.5G:

• žThe second generation, 2G, was commercially launched for the GSM standard in 1991 by Radiolinja, currently known as Elisa Oyj, in Finland.ž
• ž2G, voice communications were digitally Signal. This allowed for greater privacyž.
• ž2G (GSM standard)—GPRS (General Packet Radio Service was introduced in) 2001.ž
• žIt added packet switching protocols to mobile communications technology and TCP/IP thus making possible the reading and sending of e-mails, instant messaging (IM), and browsing the Internet. SMS or short message service is heavily used.
• GPRS provided data transfer rates from 56-115kbit/s
• 2.5 G added MMS.
• So, services like WAP (Wireless Application Protocol) and MMS (Multimedia Messaging) were introduced, along with Internet services.
• This is the most widely used generation of mobile telecommunication networks, and is what most mobile phones in India are now using.

3G-3.5G:

• The third generation, 3G, was introduced by NTT(Nippon Telegraph and Telephone) DoCoMo in Japan, in 2001.
• 3G used completely different radio frequencies from 2G
• So it required different equipment to achieve the new high data transfer rates.
• 3G data transfer rates are 384kbits/s to 2Mbits/s
• So it allows for previously unavailable services like video calls, video conferencing, online conference call, mobile TV, online gaming etc. These speeds are broadband equivalent, so the applications and capabilities are enhanced greatly.

4G:

• 4G—The fourth generation cell phone is being championed in Japan. It will boost the data rates to 20 Mbps. These speeds enable high quality video transmission and rapid download of large music files. The first 4G phones appeared in 2006.
• Such speeds are not even present in wired networks commercially.

Services available in the mobile web:

• E-books
• Audio books
• Mobile TV/Video
• Travel Information
• Browsers
• News
• Blogging
• RSS feeds
• Food ordering
• Mobile Web quick piks
• Iphone only
• Iphone quick picks
• Jobs etc.

Benefits of Mobile Web:

1. Constant connectivity- always on

2. Location-Aware—have GPS (global positioning System)

3.Limitless access—Includes the whole Web

4.Interactive capabilities—Can receive and create content, make comments, take photos, write and post blogs, etc.

Limitation:

Small screen size:-This makes it difficult or impossible to see text and graphics dependent on the standard size of a desktop computer screen.-

Lack of windows :-On a desktop computer, the ability to open more than one window at a time allows for multi-tasking and for easy revert to a previous page. Historically on mobile web, only one page can be displayed at a time, and pages can only be viewed in the sequence they were originally accessed.

Navigation:- Most mobile devices do not use a mouselike pointer, but rather simply an up and down function for scrolling, thereby limiting the flexibility in navigation.

Lack of JavaScript and cookies :-Most devices do not support client-side scripting and storage of cookies (smartphones excluded).

Awadhesh Kumar

Jain Software Developers

What is Mobile Switching Center?

   Mobile Switching Center (MSC)

• The MSC is responsible for handling voice calls and SMS as well as other services (such as conference calls, FAX and circuit switched data).
• The MSC sets up and releases the end-to-end connection and hand-over requirements during the call and takes care of charging and real time pre-paid account monitoring.
• In the mobile phone system, in contrast with earlier analogue services, fax and data information is sent directly digitally encoded to the MSC Only at the MSC is this re-coded into an “analogue” signal.
• The BSS consists of the following network components:– 7BTS: Base Transceiver Station- BSC : Base Station Controller
• The BTSs are connected to the different BSCs thorough E1s links, BSCs are connected in turn to one or more MSC.

Introduction:                                  

• With the technological advances and a rapid growth of optical and wireless communication systems is being developed every day.
• From economical point of view, the operator has to choose the most suitable communication system for the areas to be served.
• Efficient deployment of appropriate communication system according to the topography (Topology), enhances the services, provides higher rate, and increases revenue.
• The systems that may be used in providing telephony services to the rural areas and villages are outdoor optical fiber unit system ,wireless system.

Introduction of Access Network Topologies:

The Access Network (AN) is the physical connection between the core network and the subscriber terminals.

Classification of Access Networks:

1. The wired line access method, utilizes copper wire cables, it is the conventional system. It is normally used for local networks at range of 5 Km maximum.
2. The optical cable access. The fiber cable is connected to a   remote unit,this remote optical unit provides service to   the subscribers through copper wire. This system is used when communities are located apart from each other and far from the host exchange.

Network Topology:

1. — Physical topology:  Actual layout of the media
2. —Logical topology: —How the hosts access the media

Different types of physical topologies are used in MSCs:

1.Mesh topology –

• —Point-to-point network
• —Every two communication nodes(MSC) has a dedicated connection
• —Each pair of MSC performs communications independent of others
• —The number of links(channels) increases fast as the number of nodes (MSC)increases

Number of links（ L ）

L = N(N ` 1) / 2

N：Number of nodes (MSC)——

Advantages:

• Less expensive then a mesh topology.
• Each device needs only one link(Channel) and one I/O to   connect it to any number of MSCs.
• Easy to install and reconfigure.
• Far less cabling is required than mesh topology.
• Fault identification and fault isolation is easy.

Disadvantages:

• More cables are required than Bus and Ring topology.
• Single point of failure is WAN Switch.

3. Ring Topology:

• Each MSCs links to its two neighbors in a circular   arrangement.
• The “last” MSCs connects to the “first”.
• The message travels along the ring and is transferred by each MSCs until it reaches the destination.

 

Advantages

• A ring is relatively easy to install and reconfigure.
• To add or delete a device requires changing only the connections.
• Fault isolation is simplified.

Disadvantages

• Unidirectional traffic is a big disadvantage.
• In a simple ring, a break in the ring can disable the entire network. (But this can be solved by dual ring).

4. Bus Topology:

• —All nodes link to a transmission cable, a shared bus.
• —Any MSCs can send messages to any other nodes through the bus.

Advantages :

• Ease of Installation.
• Uses less cabling than other topologies.

Disadvantages:

• Difficult re-connection and fault isolation.
• Fault or break in the bus cable stops all transmissions.

5. Tree Topology:

• —An alternative form of star topology
• —All the nodes connect to the central Switch, an active Switch.
• —A node may be a MSCs or a LAN Switch.
• —Each LAN Switch has a group of computers connecting to it.
  

  

Advantages:

1. Expansion of Network is possible and easy.
2. Here, we divide the whole network into segments (star networks), which can be easily managed and maintained.
3. Error detection and correction is easy.
4. Each segment is provided with dedicated point-to-point wiring to the central hub.
5. If one segment is damaged, other segments are not affected.

Disadvantages:

1.  As more and more nodes and segments are added, the maintenance becomes difficult.
2. Scalability of the network depends on the type of cable used.

 

Awadhesh Kumar

Jain Software Developers