Differences Between Internet , Intranet and Extranet

Picture," it also offers a global perspective. By providing connectivity to anyone with a computer and a telephone line, the Internet is the networking breakthrough of our lifetime. It includes everything from universal e-mail to transactions between individuals and between companies. Of course, this now includes commerce as well as information exchanges and new directories (such as search engines) that provide phone book-style accessibility for digital communications.

Some of the most important results of this networking revolution are new forms of marketing and outreach, new connections between customers and collaborators, new sources for news and research, and opportunities for new kinds of distribution of products (as well as of information). But because the Internet is the broadest information super-highway, it lacks some of the security and privacy that's needed for the internal workings of business organizations. Advanced features like multimedia are also more likely to be limited because most individuals are still using dial-up connections and, as a result, have very limited data bandwidth.

INTRANETS

Intranets are new kinds of internal networks. Think of "Intra" as it is used in Intramural sports. Intranets tend to resemble the architecture of a closed-circuit video network as opposed to the Internet which is more like broadcasting in terms of its reach. Intranets are used for more private communications, connectivity among work groups and larger organizations. For example, some companies use Intranets to offer corporate services such as benefits programs and other kinds of corporate communications. Also, Intranets enable information sharing that empowers employees who might otherwise be left "out of the loop." (See "Groupware" below.)

Because of their limited geographic range, Intranets offer more bandwidth, frequently Ethernet's 10Kbps or better. As a result of this bandwidth and the "closed loop" structure, more advanced networking features such as video and multimedia, as well as more technological control, are possible. For example, a company can specify that a specific web browser and even a specific version of that browser (licensed by the company) be used on its network. This enables a consistent and more dependable user experience than is possible on the Internet. Even Internet related services such as Pointcast can be customized for a particular company and its Intranet.

EXTRANETS

Extranets are a more complex implementation of the wired world. Just because an employee is telecommuting doesn't mean she shouldn't have access to the company Intranet. Sales people on the road are just as critical to a corporation's success as those who sit behind desks. And in today's world of virtual work groups, suppliers and other vendors are frequently critical members of the team and they may need an insider's degree of access. Extranet's provide these important networking "bridges" by combining the Internet with the Intranet.

By extending the corporate network to include the Internet, team members get the best of both worlds -- mobility with exclusivity. Because of the necessary security involved, Extranets frequently require the development of custom applications. For example, in order to give a remote sales person access to corporate sales statistics, the user needs remote access to a database that cannot be made visible to the competition. Most often, for something this sensitive, encryption is involved because password protection is not sufficient.

In most cases, Extranets do not involve high bandwidth applications like video and multimedia because of the limited bandwidth of remote users who most frequently use dial up connections.

Ethernet is the most widely-installed local area network ( LAN) technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox from an earlier specification called Alohanet (for the Palo Alto Research Center Aloha network) and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless LANs. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds up to 10 Mbps. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD ) protocol.

Fast Ethernet or 100BASE-T provides transmission speeds up to 100 megabits per second and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1000 megabits per second (1 gigabit or 1 billion bits per second). 10-Gigabit Ethernet provides up to 10 billion bits per second.

Ethernet was named by Robert Metcalfe, one of its developers, for the passive substance called "luminiferous (light-transmitting) ether" that was once thought to pervade the universe, carrying light throughout. Ethernet was so- named to describe the way that cabling, also a passive medium, could similarly carry data everywhere throughout the network.