Chapters 1 : Internet and the World Wide Web

Sections 1 : Internet : An Introduction

Internet Evolution

The origins of the Internet can be traced back to ARPAnet (Advanced Research Projects Administration NETwork), a project started by the American Department of Defense (DOD). In 1969, the Advanced Research Projects Agency, ARPA, started developing ARPAnet, the Father of the Internet. At that time, it was used exclusively by researchers and the military. Over time, various groups throughout the world formed additional networks, often with government funding. ARPANET used a technology called packet switching to connect computers. Data can be broken down into pieces for transmission to another location. This technology is defined as packet switching. It permits several users to use a single communication line.

The main objective of ARPANET was to link DoD and the various military research establishments, including a large number of universities doing military-funded research. Another objective of ARPANET was to ensure that the data network survived a nuclear attack.

ARPANET, which initially connected only three computers, grew quickly to connect more computers in the United States. For efficient management of research projects, ARPANET was first divided into MILNET, and a smaller ARPANET. MILNET managed the military sites, and the other managed the non-military sites.

Communication in ARPANET was managed using a protocol called Network Control Protocol (NCP). The limitation of this protocol was that it could not be used to connect heterogeneous networks.

In the 1970s, Advanced Research Projects Administration (ARPA) was established to support the development of protocols for transferring data between different computer networks. A protocol is required for two computers to communicate, the information must be in a standard format. In the mid 1970's, two major standards were agreed upon for all Internet communication: Transmission Control Protocol (TCP) and the Internet Protocol (IP), known jointly as TCP/IP. TCP/IP could connect heterogeneous computers on different networks.

Transmission Control Protocol (TCP) controls how individual messages are broken up into packets by the sender and reassembled by the receiver. It provides the appearance to the user that there is a dedicated error-free connection between computers.

Internet Protocol (IP) standardizes routing of packets across multiple networks. There is no central control point which tells how to route a message; instead at each "hop" the decision is made to send the message next based on the destination. The machine which send the message does not know how the message will end up getting to the destination.

The growth of ARPANET prompted other educational institutions and research establishments to start network of their own that did not fall under the guidelines set by the original ARPANET charter, CSNET and BITNET are examples of such networks.

The outgrowth of ARPANET led to the concept of internetworking. Internetworking enables you to connect individual networks into a larger entity using network devices called Gateways. This new internetwork became known as the Internet.

In the late 1980s, the National Science Foundation Network (NSFnet) was created. The NSFnet linked a handful of supercomputers centers across the United States. The NSFnet was to provide the highest quality of computing services. The National Science Foundation still provides a subsidy for the Internet backbone, but that subsidy is being restructured, 2 . The Internet is not a company or individual network.

The Internet is a unique part of the existing national information infrastructure because of the following characteristics : 3

1. It is an open architecture, meaning that one computer system can connect to others simply by adhering to the TCP/IP standards. It is not necessary for users of one computer system to use the same hardware or software as another computing system with which they wish to communicate, or even to know the nature of the hardware and software in the other system.

2. It is a distributed architecture, meaning that different parts of the eventual bundle of information content and related services desired by users may be supplied by different Internet nodes, operated by different persons or entities.

3. Although institutions connecting to the Internet must pay for their own hardware, software, and communications lines, there is no charge for access to other nodes on the Internet nor, with rare exceptions, to information resources made available through those nodes.

4. Historically the vast majority of Internet users were members of institutions like universities that had Internet connections and such users are not charged directly for Internet usage. Now the Internet is evolving to accommodate pay-as-you-go use.

In May 1993, the Internet included 10,000 IP networks interconnecting more than one million computers and millions of users throughout the world. Systems (nodes) on the Internet are connected to each other through routers (sometimes called "gateways"), and share a common name and address space. The Internet is the successor to ARPAnet.

All computers on the Internet must have a way to uniquely identify each other -- just like all telephones need a unique identifier, the phone number. Computers on the Internet have two such methods:


1; gopher to; anonymous FTP to; or telnet to and login as gopher or www.

2 See NSF, May 6, 1993 Solicitation for Network Access Point Manager, Routing Arbiter, Regional Network Providers, and Very High Speed Backbone Network Services Provider for NSFNET and NREN Program (soliciting proposals for five-year contracts).

3 Most conceptions of the NII view it as switched broadband network. Under this view, the Internet is a precursor of the NII because it is a fully switched public network - although it is not yet broadband.

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