Brain Computer Interface

A Brain Computer Interface is a device that enables people to interact with computer based systems through conscious control of their thoughts. BCI is any system that can derive meaningful information directly from the user’s brain activity in real time. The current and most important application of BCI is the restoration of communication channel for patients with locked-in-syndrome. Most current BCI’s are not invasive. The electrodes pick up the brain’s electrical activity and carry it into amplifiers. These amplifiers amplify the signal approximately ten thousand times and then pass the signal via an analog to digital converter to a computer for processing. The computer processes the EEG signal and uses it in order to accomplish tasks such as communication and environmental control.

Virus

Do viruses and all the other nasties in cyberspace matter? Do they really do much harm? Imagine that no one has updated your anti-virus software for a few months. When they do, you find that your accounts spreadsheets are infected with a new virus that changes figures at random. Naturally you keep backups. But you might have been backing up infected files for months. How do you know which figures to trust? Now imagine that a new email virus has been released. Your company is receiving so many emails that you decide to shut down your email gateway altogether and miss an urgent order from a big customer.

Imagine that a friend emails you some files he found on the Internet. You open them and trigger a virus that mails confidential documents to everyone in your address book including your competitors. Finally, imagine that you accidentally send another company, a report that carries a virus. Will they feel safe to do business with you again? Today new viruses sweep the planet in hours and virus scares are major news. A computer virus is a computer program that can spread across computers and networks by making copies of itself, usually without the user’s knowledge. Viruses can have harmful side effects. These can range from displaying irritating messages to deleting all the files on your computer.

A virus program has to be run before it can infect your computer. Viruses have ways of making sure that this happens. They can attach themselves to other programs or hide in code that is run automatically when you open certain types of files. The virus can copy itself to other files or disks and make changes on your computer. Virus side effects, often called the payload, are the aspect of mostinterest to users. Password-protecting the documents on a particular day, mailing information about the user and machine to an address somewhere are some of the harmful side effects of viruses. Various kinds of viruses include macro virus, parasitic or file virus, Boot virus, E-mails are the biggest source of viruses. Usually they come as attachments with emails.

The Internet caused the spreading of viruses around the globe. The threat level depends on the particular code used in the WebPages and the security measures taken by service providers and by you. One solution to prevent the viruses is anti-virus softwares. Anti-virus software can detect viruses, prevent access to infected files and often eliminate the infection.

Computer viruses are starting to affect mobile phones too. The virus is rare and is unlikely to cause much damage. Anti-virus experts expect that as mobile phones become more sophisticated they will be targeted by virus writers. Some firms are already working on anti-virus software for mobile phones. VBS/Timo-A, Love Bug,Timofonica,CABIR,aka ACE-? and UNAVAILABLE are some of the viruses that affect the mobile phones

BASIC CONCEPTS

What is a virus?

A computer virus is a computer program that can spread across computers and networks by making copies of itself, usually without the user’s knowledge. Viruses can have harmful side-effects. These can range from displaying irritating messages to deleting all the files on your computer.

Evolution of virus

In the mid-1980s Basit and Amjad Alvi of Lahore, Pakistan discovered that people were pirating their software. They responded by writing the first computer virus, a program that would put a copy of itself and a copyright message on any floppy disk copies their customers made. From these simple beginnings, an entire virus counter-culture has emerged. Today new viruses sweep the planet in hours and virus scares are major news

How does a virus infect computers?

A virus program has to be run before it can infect your computer. Viruses have ways of making sure that this happens. They can attach themselves to other programs or hide in code that is run automatically when you open certain types of files. You might receive an infected file on a disk, in an email attachment, or in a download from the internet. As soon as you launch the file, the virus code runs. Then the virus can copy itself to other files or disks and make changes on your computer.

Who writes viruses?

Virus writers don’t gain in financial or career terms; they rarely achieve real fame; and, unlike hackers, they don’t usually target particular victims, since viruses spread too indiscriminately. Virus writers tend to be male, under 25 and single. Viruses also give their writers powers in cyberspace that they could never hope to have in the real world.

Virus side effects(Payload)

Virus side-effects are often called the payload. Viruses can disable our computer hardware, Can change the figures of an accounts spreadsheets at random, Adversely affects our email contacts and business domain, Can attack on web servers…

 Messages -WM97/Jerk displays the message ‘I think (user’s name) is a big stupid jerk!’  Denying access -WM97/NightShade password-protects the current document on Friday 13th. Data theft- Troj/LoveLet-A emails information about the user and machine to an address in the Philippines

. Corrupting data -XM/Compatable makes changes to the data in Excel spreadsheets. Deleting data -Michelangelo overwrites parts of the hard disk on March 6th.

 Disabling Hardware -CIH or Chernobyl (W95/CIH-10xx)

 attempts to overwrite the BIOS on April 26th, making the machine unusable.

 Crashing servers-Melissa or Explore Zip, which spread via email, can generate so much mail that servers crash.

There is a threat to confidentiality too. Melissa can forward documents, which may contain sensitive information, to anyone in your address book. Viruses can seriously damage your credibility. If you send infected documents to customers, they may refuse to do business with you or demand compensation. Sometimes you risk embarrassment as well as a damaged business reputation. WM/Polypost, for example, places copies of your documents in your name on alt.sex usenet newsgroups.

VIRUSES AND VIRUS LIKE PROGRAMMES

Trojan horses

Trojan horses are programs that do things that are not described in their specifications The user runs what they think is a legitimate program, allowing it to carry out hidden, often harmful, functions. For example, Troj/Zulu claims to be a program for fixing the ‘millennium bug’ but actually overwrites the hard disk. Trojan horses are sometimes used as a means of infecting a user with a computer virus.

Backdoor Trojans

A backdoor Trojan is a program that allows someone to take control of another user’s PC via the internet. Like other Trojans, a backdoor Trojan poses as legitimate or desirable software. When it is run (usually on a Windows 95/98 PC), it adds itself to the PC’s startup routine. The Trojan can then monitor the PC until it makes a connection to the internet. Once the PC is on-line, the person who sent the Trojan can use software on their computer to open and close programs on the infected computer, modify files and even send items to the printer. Subseven and Back Orifice are among the best known backdoor Trojans.

Worms

Worms are similar to viruses but do not need a carrier (like a macro or a boot sector).They are subtype of viruses. Worms simply create exact copies of themselves and use communications between computers to spread. Many viruses, such as Kakworm (VBS/Kakworm) or Love Bug (VBS/LoveLet-A), behave like worms and use email to forward themselves to other users.

Boot sector viruses

Boot sector viruses were the first type of virus to appear. They spread by modifying the boot sector, which contains the program that enables your computer to start up. When you switch on, the hardware looks for the boot sector program – which is usually on the hard disk, but can be on floppy or CD – and runs it. This program then loads the rest of the operating system into memory. A boot sector virus replaces the original boot sector with its own, modified version (and usually hides the original somewhere else on the hard disk). When you next start up, the infected boot sector is used and the virus becomes active. You can only become infected if you boot up your computer from an infected disk, e.g. a floppy disk that has an infected boot sector. Many boot sector viruses are now quite old.

Those written for DOS machines do not usually spread on Windows 95, 98, Me, NT or 2000 computers, though they can sometimes stop them from starting up properly. Boot viruses infect System Boot Sectors (SBS) and Master Boot Sectors (MBS). The MBS is located on all physical hard drives. It contains, among other data, information about the partition table (information about how a physical disk is divided into logical disks), and a short program that can interpret the partition information to find out where the SBS is located. The MBS is operating system independent. The SBS contains, among other data, a program whose purpose is to find and run an operating system. Because floppy diskettes are exchanged more frequently than program files boot viruses are able to propagate more effectively than file viruses.Form -A virus that is still widespread ten years after it first appeared.

The original version triggers on the 18th of each month and produces a click when keys are pressed on the keyboard. Parity Boot - A virus that may randomly display the message ‘PARITY CHECK’ and freeze the operating system. The message resembles a genuine error message displayed when the computer’s memory is faulty.

Parasitic virus (File virus)

Parasitic viruses, also known as file viruses, attach themselves to programs (or ‘executables’) and Acts as a part of the program .When you start a program infected with a file virus, the virus is launched first. To hide itself, the virus then runs the original program. The operating system on your computer sees the virus as part of the program you were trying to run and gives it the same rights. These rights allow the virus to copy itself, install itself in memory or release its payload. these viruses Infects over networks.

The internet has made it easier than ever to distribute programs, giving these viruses new opportunities to spread.

 Jerusalem- On Friday 13th deletes every program run on the computer.

 CIH (Chernobyl) - On the 26th of certain months, this virus will overwrite part of the BIOS chip, making the computer unusable. The virus also overwrites the hard disk.

 Remote Explorer - WNT/RemExp (Remote Explorer) infects Windows NT executables. It was the first virus that could run as a service, i.e. run on NT systems even when no-one is logged in. Parasitic viruses infects executables by companion, link, overwrite, insert, prep end, append techniques

a) Companion virus

A companion virus does not modify its host directly. Instead it maneuvers the operating system to execute itself instead of the host file. Sometimes this is done by renaming the host file into some other name, and then grant the virus file the name of the original program. Or the virus infects an .EXE file by creating a .COM file with the same name in the same directory. DOS will always execute a .COM file first if only the program name is given, so if you type “EDIT” on a DOS prompt, and there is an EDIT.COM and EDIT.EXE in the same directory, the EDIT.COM is executed.

b) Linking Virus

A link virus makes changes in the low-level workings of the file system, so that program names do no longer point to the original program, but to a copy of the virus. It makes it possible to have only one instance of the virus, which all program names point to.

Space Mouse

Space Mouse

Every day of your computing life, you reach out for the mouse whenever you want to move the cursor or activate something. The mouse senses your motion and your clicks and sends them to the computer so it can respond appropriately. An ordinary mouse detects motion in the X and Y plane and acts as a two dimensional controller. It is not well suited for people to use in a 3D graphics environment. Space Mouse is a professional 3D controller specifically designed for manipulating objects in a 3D environment. It permits the simultaneous control of all six degrees of freedom - translation rotation or a combination. . The device serves as an intuitive man-machine interface

The predecessor of the spacemouse was the DLR controller ball. Spacemouse has its origins in the late seventies when the DLR (German Aerospace Research Establishment) started research in its robotics and system dynamics division on devices with six degrees of freedom (6 dof) for controlling robot grippers in Cartesian space. The basic principle behind its construction is mechatronics engineering and the multisensory concept. The spacemouse has different modes of operation in which it can also be used as a two-dimensional mouse.

How does Space mouse Works?

Mice first broke onto the public stage with the introduction of the Apple Macintosh in 1984, and since then they have helped to completely redefine the way we use computers. Every day of your computing life, you reach out for your mouse whenever you want to move your cursor or activate something. Your mouse senses your motion and your clicks and sends them to the computer so it can respond appropriately

Inside a Mouse

The main goal of any mouse is to translate the motion of your hand into signals that the computer can use. Almost all mice today do the translation using five components:

1.A ball inside the mouse touches the desktop and rolls when the mouse moves

2.Two rollers inside the mouse touch the ball. One of the rollers is oriented so that it detects motion in the X direction, and the other is oriented 90 degrees to the first roller so it detects motion in the Y direction. When the ball rotates, one or both of these rollers rotate as well. The following image shows the two white rollers on this mouse:

3. The rollers each connect to a shaft, and the shaft spins a disk with holes in it. When roller rolls, its shaft and disk spin. The following image shows the disk:

4. On either side of the disk there is an infrared LED and an infrared sensor. The holes in the disk break the beam of light coming from the LED so that the infrared sensor sees pulses of light.

The rate of the pulsing is directly related to the speed of the mouse and the distance it travels

5. An on-board processor chip reads the pulses from the infrared sensors and turns them into binary data that the computer can understand. The chip sends the binary data to the computer through the mouse's cord.

In this optomechanical arrangement, the disk moves mechanically, and an optical system counts pulses of light. On this mouse, the ball is 21 mm in diameter. The roller is 7 mm in diameter. The encoding disk has 36 holes. So if the mouse moves 25.4 mm (1 inch), the encoder chip detects 41 pulses of light.

Each encoder disk has two infrared LEDs and two infrared sensors, one on each side of the disk (so there are four LED/sensor pairs inside a mouse). This arrangement allows the processor to detect the disk's direction of rotation. There is a piece of plastic with a small, precisely located hole that sits between the encoder disk and each infrared sensor. This piece of plastic provides a window through which the infrared sensor can "see." The window on one side of the disk is located slightly higher than it is on the other -- one-half the height of one of the holes in the encoder disk, to be exact. That difference causes the two infrared sensors to see pulses of light at slightly different times. There are times when one of the sensors will see a pulse of light when the other does not, and vice versa

ASSYMETRIC DIGITAL SUBSCRIBER LINE

ASSYMETRIC DIGITAL SUBSCRIBER LINE

Digital Subscriber Lines (DSL) are used to deliver high-rate digital data over existing ordinary phone-lines. A new modulation technology called Discrete Multitone (DMT) allows the transmission of high speed data. DSL facilitates the simultaneous use of normal telephone services, ISDN, and high speed data transmission, e.g., video. DMT-based DSL can be seen as the transition from existing copper-lines to the future fiber-cables. This makes DSL economically interesting for the local telephone companies. They can offer customers high speed data services even before switching to fiber-optics.


DSL is a newly standardized transmission technology facilitating simultaneous use of normal telephone services, data transmission of 6 M bit/s in the downstream and Basic- rate Access (BRA). DSL can be seen as a FDM system in which the available bandwidth of a single copper-loop is divided into three parts. The base band occupied by POTS is split from the data channels by using a method which guarantees POTS services in the case of ADSL-system failure (e.g. passive filters).

INTRODUCTION
The past decade has seen extensive growth of the telecommunications industry, with the increased popularity of the Internet and other data communication services. While offering the world many more services than were previously available, they are limited by the fact that they are being used on technology that was not designed for that purpose.

The majority of Internet users access their service via modems connects to the Plain Old Telephone System (POTS). In the early stages of the technology, modems were extremely slow by today’s standards, but this was not a major issue. A POTS connection provided an adequate medium for the relatively small amounts of data that required transmission, and so was the existing system was the logical choice over special cabling.

Technological advances have seen these rates increase up to a point where the average Internet user can now download at rates approaching 50Kbps, and send at 33.6Kps. However, POTS was designed for voice transmission, at frequencies below 3kHz, and this severely limits the obtainable data rates of the system. To increase performance of new online services, such as steaming audio and video, and improve general access speed, the bandwidth hungry public must therefore consider other alternatives. Technologies, such as ISDN or cable connections, have been in development for sometime but require special cabling. This makes them expensive to set up, and therefore have not been a viable alternative for most people.

DIFFERENT VARIANTS OF DSL .

HDSL- is the pioneering high speed format, but is not a commercially viable option due to its need for two twisted pairs and does not have support for normal telephone services.
SDSL- is symmetric DSL, and operates over a single twisted pair with support for standard voice transmission. The problem with this system is that it is limited to relatively short distances and suffers NEXT limitation due to the use of the same frequencies for transmitting and receiving.
IDSL- stands for ISDN DSL, and is in many ways similar to ISDN technology. It’s disadvantages are the lack of support for analog voice, and that its 128kbps rate is not much greater than that offered by standard 56kbps V90 modems.

VDSL- provides very high bit rate DSL, up to 52Mbps, but requires shorter connections lengths than are generally practical. It has been used in conjunction with an experimental project, FTTC (Fiber to the Curb), but development in this area has slowed due to commercial viability issues.

ADSL- is the most promising DSL technology, proving suitable for personal broadband requirements and allowing for the same channel to still act as a traditional POTS service.
Rate Adaptive DSL, RADSL-, is a further advancement which is able to automatically optimize the ADSL data rate to suit the conditions of the line being used.

PRO LOGIC II

Pro Logic II,

The next generation of Dolby Surround Pro Logic decoding technology. Pro Logic II brings exciting new features and advanced performance for decoding the many thousands of existing Dolby Surround programs, making them sound more like a discrete Dolby Digital 5.1-channel version than ever before.

The world is rapidly transitioning to digital delivery formats like DVD, and digital television (DTV), satellite and cable, all of which offer Dolby Digital 5.1 audio capability. The music industry is on the verge of transitioning from stereo to 5.1-channel sound with the new DVD-Audio format. Consumers enthusiastically demand 5.1-channel sound in new programs of all kinds. But vast numbers of programs already exist in stereo and Dolby Surround, and many more will continue to arrive in years to come. Pro Logic ­II lets consumers enjoy these programs with a convincing io5.1-likelc presentation.

Pro Logic II is able to decode the thousands of existing Dolby Surround movies and TV shows already on the shelf, compatibly, and with enhanced image stability. The improvements in decoding techniques mean that the discreteness of the sound field elements are better-preserved in the decoding process than was possible with the now universally standard Pro Logic technology, developed in the mid 80s.

“The technology in Pro Logic II is the first fundamentally new approach in matrix decoder design since the basic design which is still at the core of every other active matrix surround decoder” said Roger Dressler, Director of Technology Strategy for Dolby Laboratories.

“Pro Logic II was designed from the outset to convert conventional stereo music recordings, which will be with us for some time to come, to a natural, believable surround experience. The result is a decoder that can handle a wide range of movie and music program material with equal skill.

Dolby is proud to be handling the licensing and technical support of this exciting new technology”This new system was invented by Jim Fosgate, one of the most prolific developers of surround decoding technologies since the quadraphonic era of the late 1960s. Mr. Fosgate said,” I have spent the past 25 years figuring out how to expose the hidden information in standard two-channel stereo recordings, both new and old. This breakthrough in matrix decoding technology allows users to enjoy all their existing two-channel programs, whether Dolby Surround encoded or not, with an enhanced level of spatiality and directionality.”

Pro Logic II also incorporates special features for controlling the overall spatial dimensionality and frontal sound field imaging that are particularly suited for auto sound applications. A standard four-channel Pro Logic decoding mode is also included in the technology package.Dolby Surround Pro Logic II decoding can be implemented economically in either analog or digital circuitry, making it ideal for use in all traditional home theater products and in a range of new “music surround” products.

RFID for Automatic Authentication in Banks

RFID for Automatic Authentication in Banks

Abstract of this Seminar Topic.

RFID can be used to provide an easy and efficient way to authenticate people working in an organization. Authentication is necessary to restrict access to data stored in computers. Information stored in a bank’s database contains crucial data about consumers and the bank’s functioning. These data need to be kept securely. Unauthorized access to such information can’t be allowed. As a consequence authentication of personnel having access to such information is necessary.

Presently passwords are used for authentication. In case a person leaves after she has logged in using a password, any unscrupulous person can get access to the data and be in a position to change it. In situations where the passwords have been forgotten or have been changed the access to data is denied causing disruption in work. This can be detrimental to the running of the bank. Since authentication using passwords involves limitations related to human behavior there is a need for a better method for the same. Here is where RFID comes into play.

Radio frequency identification (RFID) is a method of remotely storing and retrieving data using devices called RFID tags. An RFID tag is a small object, such as an adhesive sticker, that can be attached to or incorporated into a product. RFID tags contain antennae to enable them to receive and respond to radio-frequency queries from an RFID transceiver. In the proposed system authentication of workers will be done with the help of RFID tag provided to them, which will uniquely identify them and give access to information meant only for them.

This is an economical alternative to the present system, which will have additional features like
Ø performance monitoring
Ø automatic attendance system
Ø providing mobility of data
Ø improved ATM service.


There is a centralized database having all the information. Readers will be positioned at appropriate places. Only with the tag can a person get access to her domain of information. There will be different levels of privileges for different people ranging from the customer to the manager of the bank.

TOUCH SCREEN MONITORS

SEMINAR ON TOUCH SCREEN MONITORS

Introduction

A touch screen is an easy to use input device that allows users to control PC software and DVD video by touching the display screen. A touch screen can be used with most PC systems as easily as other input devices such as track balls or touch pads.

Why Touch Technology?

 Touch screens enable people to use computers instantly, without any training whatsoever.

 Touch screens virtually eliminate operator errors because users select from clearly defined menus.

 Touch screens eliminate keyboards and mice, which many find intimidating and cumbersome to use.

 Touch screens are rugged enough to stand up to harsh environments where keyboards and mice often get damaged.

 Touch screens provide fast access to any and all types of digital media, with no text-bound interface getting in the way.

 Touch screens ensure that no space - on the desktop or elsewhere - is wasted, as the input device is completely integrated in to the monitors.

How Does a Touch Screen Works?

 Touch Screen Sensor: It is a clear glass panel with a touch responsive surface.

The touch sensor/panel is placed over a display screen so that the responsive area of the panel covers the viewable area of the video screen.

 Controller: I t is a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates it into information that PC can understand.

 Software Driver: The driver is a software update for the PC system that allows the touch screen and computer to work together. It tells the computer's operating system how to interpret the touch event information that is sent from the controller.

Types of Touch Screen Technology

 Resistive

 Capacitive

 Surface acoustic wave

 Infrared

ResistiveTwo types:

 4 wire resistive type

 5 wire resistive type

Advantages

 High touch resolution

 Pressure sensitive, works with any stylus

 Not affected by dirt, dust, water, or light

 Affordable touch screen technologyDisadvantages

 75 % clarity

 Resistive layers can be damaged by a sharp object

 Less durable then 5-Wire Resistive technology

CaptiveTwo types

 Capacitive technology

 Pentouch Capacitive

Advantages

 High touch resolution

 High image clarity

 Not affected by dirt ,grease, moisture Disadvantages

 Must be touched by finger, will not work with any non conductive input.

Surface WaveAdvantages

 High touch resolution

 Highest image clarity

 All glass panel, no coatingsDisadvantages

 Must be touched by finger, gloved hand, or soft-tip stylus. Something hard like a pen won’t work.

 Not completely scalable, can be affected by large amounts of dirt, dust and water in the environment.

Infrared Touch Screen

This is the only type of touch technology that is available for large displays such as Plasma screens. It is a durable technology that offers high image clarity. Responds to any input device or stylus.

Advantages

 Best image quality as there is no overlay

 Impervious to scratchingDisadvantages

 Low resolution

 May cause unintended activation of target proir to finger contact with CRT caused by IR light beam location above surface of CRT.

 Dust, oil or grease buildup on frame that impedes light beam may cause malfunction
Applications

 Public Information DisplaysTourism displays, trade show displays, and other electronic displays are used by many people that have little or no computing experience.

 Customer self-serviceCustomers can quickly place their own orders or check themselves in or out, saving them time, and decreasing wait times for other customers.

Example:

ATM

 Computer Based TrainingSince the touch screen interface is more user-friendly than other input devices, overall training time for computer novices and therefore training expense can be reduced. Also make learning more interactive and fun.

 Other applications include computerized gaming, student registration systems, financial and scientific applications.

Benefits

 Fast, faster, fastest

 Touch makes everyone an expert

 Reduced cost

 Compact & handy

 Durable and easy to clean

 When ease of use is required

Conclusion

A touch screen is the simplest, most direct way for a person to interact with a computer. The basic way users interact with a touch screen is age-old. You point to what you want. It's intuitive for virtually every child and adult in the world today.

Flash Memory Card

Introduction to Flash Memory Card
Flash memory refers to a particular type of EEPROM, or electrically erasable programmable read only memory. It is a memory chip that maintains stored information without requiring a power source.



Flash memory is

 Non volatile.

 Considered as solid state storage devices.

 Used more as hard drive.


Why Flash Memory Cards Popular?

Flash Ram storage devices are shock proof, dust proof, immune to magnetic fields and really small too. Flash Memory provides storage for today’s electronic devices such as iPods, PDA, digital cameras,

CAMCORDERS utilize flash cards. Important Methods in Flash Memory Working TUNNELING  ERASING
Different Types of Flash Memory Cards SMART MEDIA CARD COMPACT FLASH xD PICTURE CARD SECURE DIGITAL or MULTIMEDIA CARD MEMORY STICK
Smart Media Card Better known as smart media 2MB to 128 MB Developed By ToshibaCompact Flash Developed by Sandisk  8MB to 6 GB They are thicker Utilize controller chip
Compactable flash card comes from 2 ways Type I Type II
Xd Picture Card xD means “extreme digital” Currently available from 64MB to 1GB Found in Fuji and Olympus digital camera
SECURE DIGITAL or MULTIMEDIACARD They designed to hold copyrighted musical content. Small size. Low power consumption. 16MB to 2GB.
MEMORY STICK Shaped like a stick of gum Smaller size Storage capacity up to 128 MB Ideal for mobile application
EXTERNAL CARD READERSIt is used to access digital cameras images very fast. These come in many varieties depending on the computer interface. Most common type are made for PCs and connected to the usb port.
Advantages of Flash Memory Cards Power consumption. Portability. Capacity. Durability. Performance. Reliability. Plug-and –play.

GRID COMPUTING

GRID COMPUTING

Grid Computing is a technique in which the idle systems in the Network and their “wasted” CPU cycles can be efficiently used by uniting pools of servers, storage systems and networks into a single large virtual system for resource sharing dynamically at runtime.- High performance computer clusters.-share application, data and computing resources.

IMPORTANCE OF GRID COMPUTING
 Flexible, Secure, Coordinated resource sharing.
 Virtualization of distributed computing resources.
 Give worldwide access to a network of distributed resources.

GRID REQUIREMENTS
 Security
 Resource Management
 Data Management
 Information Services
 Fault Detection
 Portability

TYPES OF GRID
 Computational Grid-computing power
 Scavenging Grid-desktop machines
 Data Grid-data access across multiple organizations

ARCHITECTURAL OVERVIEW

• Grid’s computer can be thousands of miles apart and connected with internet networking technologies.
• Grids can share processors and drive space.

Fabric : Provides resources to which shared access is mediated by grid protocols.

Connectivity : Provides authentication solutions.

Resources : Connectivity layer, communication and authentication protocols.

Collective : Coordinates multiple resources.

Application : Constructed by calling upon services defined at any layer.

GRID COMPONENTS

In a world-wide Grid environment, capabilities that the infrastructure needs to support include: Remote storage

 Publication of datasets

 Security

 Uniform access to remote resources

 Publication of services and access cost

 Composition of distributed applications

 Discovery of suitable datasets

 Discovery of suitable computational resources

 Mapping and Scheduling of jobs

 Submission, monitoring, steering of jobs execution

 Movement of code

 Enforcement of quality

 Metering and accounting

GRID LAYERS

 Grid Fabric layer

 Core Grid middleware

 User-level Grid middleware

 Grid application and protocols

OPERATIONAL FLOW FROM USER’S PERSPECTIVE

• Installing Core Gridmiddleware
• Resource brokering and application deployment services

COMPONENT INTERACTION

- Distributed application

- Grid resource broker

- Grid information service

- Grid market directory

- Broker identifies the list of computational resources

- Executes the job and returns results

- Metering system passes the resource information to the accounting system

- Accounting system reports resource share allocation to the user

PROBLEM AND PROMISESPROBLEMS

- Coordinated resource sharing and problem solving in dynamic, institutional organizations

- Improving distributed management

- Improving the availability of data

- Providing researchers with a uniform user friendly environmentPROMISES

- Grid utilizes the idle time

- Its ability to make more cost effective use of resources

- To solve problems that can’t be approached without any enormous amount of computing power.

CONCLUSION

- Grid Computing is becoming the platform for next generation escience experiments

- By Intranet Grid it is very easy to download multiple files

Run Commands in computer

Run Commands in computer.


• appwiz.cpl -- Used to run Add/Remove wizard
• Calc --Calculator
• Cfgwiz32 --ISDN Configuration Wizard
• Charmap --Character Map
• Chkdisk --Repair damaged files
• Cleanmgr --Cleans up hard drives
• Clipbrd --Windows Clipboard viewer
• Control --Displays Control Panel
• Cmd --Opens a new Command Window
• Control mouse --Used to control mouse properties
• Dcomcnfg --DCOM user security
• Debug --Assembly language programming tool
• Defrag --Defragmentation tool
• Drwatson --Records programs crash & snapshots
• Dxdiag --DirectX Diagnostic Utility
• Explorer --Windows Explorer
• Fontview --Graphical font viewer
• Fsmgmt.msc -- Used to open shared folders
• Firewall.cpl -- Used to configure windows firewall
• Ftp -ftp.exe program
• Hostname --Returns Computer's name
• Hdwwiz.cpl -- Used to run Add Hardware wizard
• Ipconfig --Displays IP configuration for all network adapters
• Logoff -- Used to logoff the computer
• MMC --Microsoft Management Console
• Msconfig --Configuration to edit startup files
• Mstsc -- Used to access remote desktop
• Mrc -- Malicious Software Removal Tool
• Msinfo32 --Microsoft System Information Utility
• Nbtstat --Displays stats and current connections using NetBIOS over TCP/IP
• Netstat --Displays all active network connections
• Nslookup--Returns your local DNS server • Osk ---Used to access on screen keyboard
• Perfmon.msc -- Used to configure the performance of Monitor.
• Ping --Sends data to a specified host/IP
• Powercfg.cpl -- Used to configure power option
• Regedit --Registry Editor
• Regwiz -- Registration wizard
• Sfc /scannow -- System File Checker • Sndrec32 --Sound Recorder
• Shutdown -- Used to shutdown the windows
• Spider -- Used to open spider solitaire card game
• Sfc / scannow -- Used to run system file checker utility.
• Sndvol32 --Volume control for soundcard
• Sysedit -- Edit system startup files
• Taskmgr --Task manager
• Telephon.cpl -- Used to configure modem options.
• Telnet --Telnet program
• Tracert --Traces and displays all paths required to reach an internet host
• Winchat -- Used to chat with Microsoft
• Wmplayer -- Used to run Windows Media player
• Wab -- Used to open Windows address Book.
• WinWord -- Used to open Microsoft word
• Winipcfg --Displays IP configuration
• Winver -- Used to check Windows Version
• Wupdmgr --Takes you to Microsoft Windows Update
• Write -- Used to open WordPad

How to restrict user's to access shutdown button?

How to restrict user's to access shutdown button?
Solution: This tip is very interesting for home and some small office users, who wants to restrict user's ability to shutdown their computer. You can hide the Shutdown button from the Start menu using registry editor and also restrict access to shutdown, if a user clicks on Ctrl+Alt+Del.
Follow the given steps to hide system shutdown button from start menu:
• To use this feature, you will need to be logged into your computer with
administrative rights.
* Click Start button and type regedit in Run option then press Enter for next.
* Here locate the location to:
* HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion \Policies\Explorer
* Here in right side panel, right click to create a new DWORD value with name NoClose.
* Now assign number 1 to its value data box.
* Now close the registry editor and restart your computer after any changes to go into effect.
* But next time, if you want to unhide the shutdown button then simply change the value data box to 0 or delete this DWORD item.
* Again close the registry editor and restart your computer after any changes to go into effect.

How to add Items to the Start Button using Registry in Computer

How to add Items to the Start Button using Registry in Computer

Solution: The best technique to edit the windows registry keys, always export or backup the whole windows registry keys on backup drive before editing. Because any mistake in Registry can cause serious problem in your computer to run properly.Follow the given steps to change the Start button setting.First click on Start button then type Regedit in Run option.In Registry Editor go to left hand panel, and find HKey_Classes_Root / Directory / Shell Here Right click on Shell folder option and add any new key with descriptive name and Press Enter.

Now Right click on that key and give the full path of that program you are interested to add in start button. For example if you want to add MS excel, then full path may beC:\program file\msoffice\msexcel.EXE.Now close all open programs and check the changes in your computer Start button.

Clearing the Documents History Automatically

Clearing the Documents History Automatically

The windows Documents Menu display all the information about last used files and programs as a history. Your co-workers, family members can trace your activates on the computer with clicking on Documents menu. If you are using internet at any public place like internet cafe then you should clear your documents menu history to safe yourself from cyber crimes. You can clear the documents menu history manually, but automatically history clean option can be useful if one computer used by multiple people. To clear the document history automatically, edit the computer registry keys.

Click Start button then type regedit in Run option then press Enter for next.Here locate the location to:

Go to HKey_Current_User \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ User Shell Folders Here in right side panel, double click on Recent and change its value of C:\RECYCLED. Now set your Recycle bin, "remove files immediately when deleted". Now close the registry editor and restart your computer after any changes to go into effect.

Disable drives in My Computer from unknown user

Disable drives in My Computer from unknown user


If you want to prevent any users to access your computer or network shared drives using My Computer then you can hide the all drives for example C:/, D:/ and save your data from any unknown user. But next time you can turn on the display of these drives using registry editor. Now edit the computer registry to turn off the display of drives, but be careful to work with computer registry.

Follow the given steps to hide computer drives:First click on Start button then type Regedit in Run option.Here locate the location to:
Key_Current_User \ Software \ Microsoft \ Windows \ Current Version \ Policies \ Explorer Here right click on right side of Registry editor panel and add new DWORD then put its value 3FFFFFF.
Now close the registry editor and restart your computer after any changes to go into effect.

Hide the Desktop Icons

Hide the Desktop Icons

Solution: You can hide the Desktop Icons in Windows 2000 and Windows XP using windows registry editor. This tip is very useful, if you want to safe your personal data and icons of the windows desktop on a single computer. Follow the given steps to to hide Desktop Icons:Click Start button then type regedit in Run option then press Enter for next. Here locate the location to: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer Here in right side panel, right click to create a new DWORD value with name NoDesktop and type REG_DWORD then change its value data 1.

Now close the registry editor and restart your computer after any changes to go into effect.

How to fixing no AutoRun for CDs

How to fixing no AutoRun for CDs


windows environment you can enjoy a good feature to run CD or DVD automatically when you loaded it into you CD drives on your computer. But if you are not happy with this auto run then you can disable it. In user interface mode there is no option to disable this feature, you must edit the registry of windows and be careful to work registry.Click Start button then type regedit in Run option then press Enter for next.Here locate the location to:HKEY_USERS\.Default\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer Change the value of NoDriveTypeAutoRun to 95 00 00 00 for disable. At the end restart your computer for this change.

Computer networking

Computer networking

COMPUTER NETWORKING is the scientific and engineering discipline concerned with communication between computer systems. Such networks involves at least two computers, which can be separated by a few meters (e.g. via Bluetooth) or thousands of kilometers (e.g. via the Internet). Computer networking is sometimes considered a sub-discipline of telecommunications.


Carrying instructions between calculation machines and early computers was done by human users. In September, 1940 George Stibitz used a teletype machine to send instructions for a problem set from his Model K at Dartmouth College in New Hampshire to his Complex Number Calculator in New York and received results back by the same means. Linking output systems like teletypes to computers was an interest at the Advanced Research Projects Agency (ARPA) when, in 1962, J.C.R. Licklider was hired and developed a working group he called the "Intergalactic Network", a precursor to the ARPANet. In 1964, researchers at Dartmouth developed the Dartmouth Time Sharing System for distributed users of large computer systems. The same year, at MIT, a research group supported by General Electric and Bell Labs used a computer (DEC's PDP-8) to route and manage telephone connections. In 1968 Paul Baran proposed a network system consisting of datagrams or packets that could be used in a packet switching network between computer systems. In 1969 the University of California at Los Angeles, SRI (in Stanford), University of California at Santa Barbara, and the University of Utah were connected as the beginning of the ARPANet network using 50 kbit/s circuits.


Networks, and the technologies needed to connect and communicate through and between them, continue to drive computer hardware, software, and peripherals industries. This expansion is mirrored by growth in the numbers and types of users of networks from researchers.


Networks, and the technologies needed to connect and communicate through and between them, continue to drive computer hardware, software, and peripherals industries. This expansion is mirrored by growth in the numbers and types of users of networks from researchers.

CATEGORIZING IN Computer networking

CATEGORIZING IN Computer networking

By scale
• Personal area network (PAN)
• Local area network (LAN) o HomePNA o Power line communication (HomePlug)
• Metropolitan area network (MAN)
• Wide area network (WAN)

By functional relationship

• Active Networking (Low-level code movement versus static data)
• Client-server
• Peer-to-peer (Workgroup)

By network topology
• Bus network
• Star network
• Ring network
• Mesh network
• Star-bus network
• Storage area networks
• Process control networks
• Value added network
• SOHO network
• Wireless community network

Protocol stacks

Computer networks may be implemented using a variety of protocol stack architectures, computer buses or combinations of media and protocol layers, incorporating one or more of:
• ARCNET
• AppleTalk
• ATM
• Bluetooth
• DECnet
• Ethernet
• FDDI
• Frame relay
• IEEE 802.11 aka Wireless LAN (Wi-Fi certification)
• IEEE-488
• QsNet
• RS-232
• System Network Architecture
• Token Ring
• TCP
• USB
• UDP

Layers

Data transmission

Wired transmission

• Public switched telephone network o Modems and dialup

• Dedicated lines – leased lines

• Time-division multiplexing

• Packet switching

• Optical fiber transmission o Synchronous optical networking o Fiber distributed data interface

Wireless transmission

• Short range o Bluetooth

• Medium range o IEEE 802.11

• Long range o Satellite o SMDS o Mobile phone data transmission (channel access methods)
Other
• Computer networking device o Network card

• Naming schemes

• Network monitoring

PERSONAL AREA NETWORK

PERSONAL AREA NETWORK

A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The devices may or may not belong to the person in question. The reach of a PAN is typically a few meters. PANs can be used for communication among the personal devices themselves (intrapersonal communication), or for connecting to a higher level network and the Internet (an uplink).
Personal area networks may be wired with computer buses such as USB and FireWire. A wireless personal area network (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth.

Wireless

A Bluetooth PAN is also called a piconet, and is composed of up to 8 active devices in a master-slave relationship (up to 255 devices can be connected in "parked" mode). The first Bluetooth device in the piconet is the master, and all other devices are slaves that communicate with the master. A piconet typically has a range of 10 meters, although ranges of up to 100 meters can be reached under ideal circumstances.

Recent innovations in Bluetooth antennas have allowed these devices to far exceed the range for which they were originally designed. At DEF CON 12, with the right equipment a group of hackers known as "Flexilis" was able to achieve connectivity to bluetooth devices more than half a mile away. The type of antenna used was homemade and Yagi-based. They named the antenna "The BlueSniper". This is a rifle stock with a scope and Yagi antenna attached. A cable attaches the antenna to the Bluetooth card, which can be in a PDA or laptop computer. The laptop can be carried in a backpack with the cables connecting into the backpack, giving it the Ghostbusters look.

Another PAN technology, Skinplex, transmits via the capacitive near field of human skin. Skinplex can detect and communicate up to one meter from a human body. It is already used for access control (door locks) and jamming protection (so people are not caught in convertible roofs) in cars.

LOCAL AREA NETWORK

A local area network (LAN) is a computer network covering a small local area, like a home, office, or small group of buildings such as a home, office, or college. Current LANs are most likely to be based on switched Ethernet or Wi-Fi technology running at 10, 100 or 1,000 Mbit/s.
LAN redirects here, for other uses see LAN (disambiguation).

The defining characteristics of LANs in contrast to WANs (wide area networks) are: their much higher data rates; smaller geographic range; and that they do not require leased telecommunication lines.

Technical aspects

Although switched Ethernet is now most common at the physical layer, and TCP/IP as a protocol, historically many different options have been used (see below) and some continue to be popular in niche areas.

Larger LANs will have redundant links, and routers or switches capable of using spanning tree protocol and similar techniques to recover from failed links. LANs will have connections to other LANs via routers and leased lines to create a WAN. Most will also have connections to the large public network known as the Internet, and links to other LANs can be 'tunnelled' across this using VPN technologies.

HOME-PNA

HomePNA (also known as Home PNA, HPNA, Home Phoneline Networking Alliance, Home Phoneline Networking and Homepna) is an incorporated non-profit association of more than 150 companies, including the founding companies Epigram, Inc., 3Com, AMD, AT&T, Compaq,HP, IBM, Intel, Lucent, Rockwell and Tut Systems. The Home Phoneline Networking Alliance seeks to establish standards among telecom, computer and network products such that they are compatible for HomePNA. Home Phoneline Networking Alliance does not enforce standards; it provides advice to the International Telecommunication Union (ITU) which is a standards body

POWER LINE COMMUNICATION

Power line communication (PLC), also called Mains Communication, Power Line Telecoms (PLT), Powerband or Power Line Networking (PLN), is a term describing several different systems for using power distribution wires for simultaneous distribution of data. The carrier can communicate voice and data by superimposing an analog signal over the standard 50 or 60 Hz alternating current (AC). It includes Broadband over Power Lines (BPL) with data rates sometimes above 1 Mbit/s and Narrowband over Power Lines with much lower data rates. Traditionally electrical utilities used low-speed power-line carrier circuits for control of substations, voice communication, and protection of high-voltage transmission lines. High-speed data transmission has been developed using the lower voltage transmission lines used for power distribution. A short-range form of power-line carrier is used for home automation and intercoms.

METROPOLITAN AREA NETWORK

Metropolitan Area Networks or MANs are large computer networks usually spanning a campus or a city. They typically use wireless infrastructure or optical fiber connections to link their sites.
For instance a university or college may have a MAN that joins together many of their local area networks (LANs) situated around site of a fraction of a square kilometer. Then from their MAN they could have several wide area network (WAN) links to other universities or the Internet. Specifically, this type of MAN is known as a campus area network.

Some technologies used for this purpose are ATM, FDDI and SMDS. These older technologies are in the process of being displaced by Ethernet-based MANs (e.g. Metro Ethernet) in most areas. MAN links between LANs have been built without cables using either microwave, radio, or infra-red free-space optical communication links.

DQDB, Distributed Queue Dual Bus, is the Metropolitan Area Network standard for data communication. It is specified in the IEEE 802.6 standard. Using DQDB, networks can be up to 30 miles long and operate at speeds of 34 to 155 Mbit/s.

Several notable networks started as MANs, such as the Internet peering points MAE-West and MAE-East and the Sohonet media network

WIDE AREA NETWORK

A wide area network or WAN is a computer network covering a wide geographical area, involving a vast array of computers. This is different from personal area networks (PANs), metropolitan area networks (MANs) or local area networks (LANs, first invented by the United States military during the Cold War, the network was known as ARPAnet) that are usually limited to a room, building or campus. The most well-known example of a WAN is the Internet.

WANs are used to connect local area networks (LANs) together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet.

WANs are most often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.

Academic research into wide area networks can be broken down into three areas: Mathematical models, network emulation and network simulation.

Such a network generally requires the crossing of public right-of-ways, and rely at least in part on circuits provided by a common carrier, Typically, a WAN consists of a number of interconnected switching nodes. A transmission from any one device is routed through these internal nodes to the specified destination device. These nodes (including the boundary nodes) are not concerned with the contents of data; rather their purpose is to provide a switching facility that will move the data from node to node until they reach their destination. Performance improvements are sometimes delivered via WAFS or WAN Optimization.

Traditionally, WANs have been implemented using one of the two technologies: circuit switching & packet switching. Transmission rate usually range from 1200 bits/second to 2 Mbps. Typical communication links used in WANs are telephone lines, microwave links & satellite channels.

ACTIVE NETWORKING

Active networking is a communication paradigm that allows packets flowing through a communication telecommunications network to dynamically modify the operation of the network. The active network architecture is comprised of execution environments (similar to a unix shell that can execute active packets), a node operating system capable of supporting one or more execution environments, and active hardware, capable of routing or switching as well as executing code within active packets. This differs from the traditional network architecture which seeks robustness and stability by attempting to remove complexity and the ability to change its fundamental operation from underlying network components. Network processors are one means of implementing active networking concepts. Active networks have also been implemented as overlay networks.

Active networking allows the possibility of highly tailored and rapid "real-time" changes to the underlying network operation enabling such ideas as sending code along with packets of information allowing the data to change its form (code) to match the channel characteristics. The smallest program that can generate a sequence of data can be found in the definition of Kolmogorov Complexity. The use of real-time genetic algorithms within the network to compose network services is also enabled by active networking.

CLIENT-SERVER

Client-server is a network architecture which separates the client (often a graphical user interface) from the server. Each instance of the client software can send requests to a server or application server. There are many different types of servers; some examples include: a file server, terminal server, or mail server. While their purpose varies somewhat, the basic architecture remains the same.

Although this idea is applied in a variety of ways, on many different kinds of applications, the easiest example to visualize is the current use of web pages on the internet. For example, if you are reading this article on Wikipedia, your computer and web browser would be considered a client, and the computers, databases, and applications that make up Wikipedia would be considered the server. When your web browser requests a particular article from Wikipedia, the Wikipedia server finds all of the information required to display the article in the Wikipedia database, assembles it into a web page, and sends it back to your web browser for you to look at.

PEER-TO-PEER

A peer-to-peer (or P2P) computer network is a network that relies primarily on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively low number of servers. P2P networks are typically used for connecting nodes via largely ad hoc connections. Such networks are useful for many purposes. Sharing content files (see file sharing) containing audio, video, data or anything in digital format is very common, and realtime data, such as telephony traffic, is also passed using P2P technology..

A pure peer-to-peer network does not have the notion of clients or servers, but only equal peer nodes that simultaneously function as both "clients" and "servers" to the other nodes on the network. This model of network arrangement differs from the client-server model where communication is usually to and from a central server. A typical example for a non peer-to-peer file transfer is an FTP server where the client and server programs are quite distinct, and the clients initiate the download/uploads and the servers react to and satisfy these requests.

Some networks and channels, such as Napster, OpenNAP, or IRC @find, use a client-server structure for some tasks (e.g., searching) and a peer-to-peer structure for others. Networks such as Gnutella or Freenet use a peer-to-peer structure for all purposes, and are sometimes referred to as true peer-to-peer networks, although Gnutella is greatly facilitated by directory servers that inform peers of the network addresses of other peers.

Peer-to-peer architecture embodies one of the key technical concepts of the internet, described in the first internet Request for Comments, "RFC 1, Host Software" [1] dated 7 April 1969. More recently, the concept has achieved recognition in the general public in the context of the absence of central indexing servers in architectures used for exchanging multimedia files.

NETWORK TOPOLOGY.

NETWORK TOPOLOGY.

A network topology is the pattern of links connecting pairs of nodes of a network. It's the shape of a LAN or other communications system. A given node has one or more links to others, and the links can appear in a variety of different shapes. The simplest connection is a one-way link between two devices. A second return link can be added for two-way communication. Modern communications cables usually include more than one wire in order to facilitate this, although very simple bus-based networks have two-way communication on a single wire.Network topology is determined only by the configuration of connections between nodes; it is therefore a part of graph theory. Distances between nodes, physical interconnections, transmission rates, and/or signal types are not a matter of network topology, although they may be affected by it in an actual physical network.

Centralization

The star topology reduces the chance of network failure by connecting all of the systems to a central node. When applied to a bus-based network, this central hub rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network, sometimes including the originating node. All peripheral nodes may thus communicate with all others by transmitting to, and receiving from, the central node only. The failure of a transmission line linking any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the rest of the systems will be unaffected.

If the central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way transmission time (i.e. to and from the central node) plus any delay generated in the central node. An active star network has an active central node that usually has the means to prevent echo-related problems

A tree topology (a.k.a. hierarchical topology) can be viewed as a collection of star networks arranged in a hierarchy. This tree has individual peripheral nodes (i.e. leaves) which are required to transmit to and receive from one other node only and are not required to act as repeaters or regenerators. Unlike the star network, the function of the central node may be distributed.

As in the conventional star network, individual nodes may thus still be isolated from the network by a single-point failure of a transmission path to the node. If a link connecting a leaf fails, that leaf is isolated; if a connection to a non-leaf node fails, an entire section of the network becomes isolated from the rest.

Decentralization

In a mesh topology, there are at least two nodes with two or more paths between them. A special kind of mesh, limiting the number of hops between two nodes, is a hypercube. The number of arbitrary forks in mesh networks makes them more difficult to design and implement, but their decentralized nature makes them very useful. This is similar in some ways to a grid network, where a linear or ring topology is used to connect systems in multiple directions. A multi-dimensional ring has a toroidal (torus) topology, for instance.

A fully connected, complete topology or full mesh topology is a network topology in which there is a direct link between all pairs of nodes. In a fully connected network with n nodes, there are n(n-1)/2 direct links. Networks designed with this topology are usually very expensive to set up, but have a high amount of reliability due to multiple paths data can travel on. This topology is mostly seen in military applications. However, it can also be seen in the file sharing protocol BitTorrent in which users connect to other users in the "swarm" by allowing each user sharing the file to other users also involved.

Hybrids

Hybrid networks use a combination of any two or more topologies in such a way that the resulting network does not have one of the standard forms. For example, a tree network connected to a tree network is still a tree network, but two star networks connected together (known as extended star) exhibit hybrid network topologies. A hybrid topology is always produced when two different basic network topologies are connected. Two common examples for Hybrid network are: star ring network and star bus network

• A Star ring network consists of two or more star topologies connected using a multistation access unit (MAU) as a centralized hub.

• A Star Bus network consists of two or more star topologies connected using a bus trunk (the bus trunk serves as the network's backbone).

While grid networks have found popularity in high-performance computing applications, some systems have used genetic algorithms to design custom networks that have the fewest possible hops in between different nodes. Some of the resulting layouts are nearly incomprehensible, although they do function quite well.