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Network concepts

Internet information servers such as the Web run on computers connected to the Internet. This requires the computer to have network interface software as well as appropriate hardware. The Internet uses a suite of communications protocols commonly referred to as TCP/IP. This term actually refers to the two most common protocols: Transmission Control Protocol and the Internet Protocol. IP is the lowest-level protocol, creating the raw links between nodes. TCP is a higher-level protocol that provides a reliable virtual connection between two applications situated anywhere on the network using IP. There is another protocol that uses IP, User Datagram Protocol (UDP), which is used to send packets of data from one application to another, without ensuring reliability. Other Internet protocols are generally built on top of TCP and UDP. Most information system protocols, including HTTP, File Transfer Protocol (FTP), Gopher, Wide Area Information Service (WAIS), and Network News Transfer Protocol (NNTP, commonly referred to as USENET News), use TCP.

The TCP/IP protocols were developed on UNIX systems and most UNIX systems include them, except for some versions where they have been unbundled and are offered as an option at extra cost. TCP/IP implementations are also available for other operating systems. They have been available for systems such as VMS for some time, as have commercial add-on packages for Microsoft Windows, MS-DOS, and Apple Macintosh. With the increasing importance of the Internet, TCP/IP facilities are being added as standard components of the new versions of Windows, OS/2 and the Macintosh.

Computers on the Internet are referred to by names and addresses. Addresses are 32-bit numbers, usually expressed as a sequence of four decimal numbers separated by periods, for example: 192.168.0.1. Host names, such as www.ncsa.uiuc.edu, are used for human consumption, as people find them easier to remember than numbers. Host names are translated to addresses using the Domain Name System (DNS). This is a system of hierarchical names and name servers. Each name server has responsibility for allocating names in its domain, deriving its authority from the next higher level. See DNS and BIND by Cricket Liu and Paul Albitz[13]. BIND is the name of a particular DNS server, the Berkeley Internet Name Daemon.

Most computers can be connected to a network. The basic requirements are a network interface card and the software drivers for that card. Network interfaces are more or less standard on UNIX workstations. There are different types of physical network. Internal networks most commonly use Ethernet. Public networks use specialized communications equipment. The hardware requirements for connecting to public networks vary from a simple dial-up modem to dedicated router equipment.

Spinning the Web by Andrew Ford
© 1995 International Thomson Publishing
© 2002 Andrew Ford and Ford & Mason Ltd
Note: this HTML document was generated in December 1994 directly from the LaTeX source files using LaTeX2HTML. It was formatted into our standard page layout using the Template Toolkit. The document is mainly of historical interest as obviously many of the sites mentioned have long since disappeared.