Chapter 10 The Internet
 
 

internet - the interconnection of two or more networks
Internet - a specific wide area network made up of many interconnected networks around the globe, including local and long-distance connections, routers, servers, and a variety of protocols.

Internet - fastest growing segment of the computer industry
            - oldest WAN in existence
            - millions of users have access
            - file transfer and email
            - corporations and consumers use
            - electronic commerce
            - first step towards building a National Information Infrastructure (NII)
 

History of the Internet

By definition, the Internet is a global-linked network of computers. It provides people, business & corporations, educational institutions, governmental agencies and even countries with the ability to electronically communicate over long-distances. It came into existence during the Cold War Era when the U.S. Department of Defense became concerned with the question of how different governmental services would be able to communicate in the event of nuclear war.

The Rand Corporation , under search sponsored by the United States Air Force and known as Project RAND, grappled with this problem and eventually conceived of a network of computers designed to function despite the loss of a substantial part of
the system.

In short, each computer or node would be capable of sending, routing and receiving information by taking messages and breaking them into different parts--packet switching-- and sending them along separate routes to their eventual destination. Each node was treated equally without a single computer being the hub; if large parts of the system were destroyed, it's
self-sufficient nature allowed information to get through.

In 1969, this concept was tested and funded by the Advanced Research Projects Agency (ARPANET), primarily so that researchers and scientists could communicate and transfer data. Initially, UCLA, Stanford Research Institute, University of California, Santa Barbara, and the University of Utah were the first to be connected to this network .

Within two years, however, a strange twist developed. Instead of long-distance research and development , the Internet was being used for personal communication. Eventually, ARPANET gave way to what we today know as the Internet. This was brought on by TCP/IP, a standard of communication which replaced ARPA's original "Network Control Protocol" or NCP. "Transmission Control Protocol" or TCP breaks information into different packets at its source and then puts them together
at its final destination. "Internet Protocol" or IP does the addressing of the information ensuring that the packets are sent across multiple nodes and networks using different standards. Whole networks began using TCP/IP to communicate with ARPANET and TCP/IP became more commonly used. In 1983, ARPANET switched to TCP/IP and some consider that to be the official beginning of the Internet because with TCP/IP many differenct computers using different operating computers using different operating systems could communicate over the same network.
 

Other networks were being developed at various universities:
1. Computer Science Network (CSNet) - 1980, devoted to providing connections between universities and industry
2. Because It's Time Network (BITNET) - designed to provide general computer networking capability to universities; access thru most university computing centers
3. National Science Foundation Network (NFSNET) - funded by National Science Foundation in 1987; was actually a backbone network, meaning that it provided connections for regional networks to connect to the Internet; discontinued in 95

Internet service providers (ISPs) - companies that provide access and connections to the Internet. Also long distance co.
 

Internet Addressing

Each computer attached to the Internet falls in one of two categories:
1. host node - computers that are used to attach a network to the Internet (ISPs)
2. nonhost nodes - computer that have access to the Internet but are not connected directly. (home computer)

IP Addresses - host or nonhost, a unique number that are 32 bits long and called dotted-quads.

Subnetting - allows organizations to assign a distinct subnetwork number to each private, internal networks, calle subnets.

Internet Information Center (InterNIC) - organization that assigns Internet addresses to organizations and individuals that request an Internet site.

Classless Internet Domain Routing (CIDR) - # of unassigned IP addresses are running ot so a new scheme is in effect. P. 10-6

Domain Name System (DNS) - since IP addresses are hard to remember the use of a text name can be substituted for the IP address. Text verision is called a domain name. To translate and track domain names, InterNIC uses the Domain Name System (DNS) which is a set of distributed databases containing IP addresses and their corresponding domain names.
 

Several layers of naming conventions, each of which is called a domain. A domain refers to a group of computers and devices on a network that is administered as a unit with common rules and procedures.
1. top-level domain - class of institution to which the organization belongs on the Internet
2. hostname
3. second-level domain
4. subdomains - between the second-level and hostname

Every time you use a domain name a Domain Name System server must translate the domain name into the corresponding IP address.
 

Electronic Mail Addresses

Electronic mail (e-mail) addresses are made up of two parts: a person's individual address and a domain name address. Mail server - a computer that runs software to manage and store messages.
 

Different Ways to Connect to the Internet :

1. connect from home via a modem to dial in to an ISP over regular telephone lines
2. home users can have Intergrated Services Digital Network (ISDN) can have higher-speed connection ranging from 64 to 128 Kbps
3. digital subscriber line (DSL) - provided Internet access at speeds ranging from 7 Mbps downloading data to 640 Kbps for uploading data
4. computers connected to the Internet thru a business or school are usually part of a LAN that is connected to an ISP through a higher-speed connection line leased for the local telephone company.
5. via a cable television connection, 500 Kbps to 30 Mbps
6. cellular wireless network and satellite delivery system also in operation
 
 

Internet Backbone

ISPs are connected to the Internet by a group of larger networking companies called network service providers (NSPs) which operate and maintain the Internet backbone networks. ISPs connect to NSPs by lines leased from local telephone companies. NSP backbone networks connect to one another at a variety of location across the US.

Routers - p 11

Servers - p 11-12

Protocols - Internet Engineering Task Force (IETF) respnosible for determining new protocols and application requirements for the Internet.

World Wide Web (WWW)

Web page has built-in links to other related documents call hyperlinks. Web pages are created using hypertext markup language (HTML). It is a special set of instructions, called tags or markups, that specifylnks to other documents and how the page is displayed. Collection of hyperlinked documents accessible on the Internet has become known as the World Wide Web, WWW, W3, or simply the web.

Browsers - p 13
 

Other Internet Services

Telnet - user command used to access a remote computer.

File Transfer Protocol (FTP) - is a utility that allows file to be downloaded or uploaded to a remote computer.

Gopher - a program that provides a menu of services available on a computer

Archie - allows users to search indexes of the files that are available on public information servers on the Internet

Veronica - used to search Gopher menus to find information about a specific topic

Usenet Newgroups

Listservs
 

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