Information Networks
Author: mety Labels:: Extranet, Intranetm, LAN, WAN, WorkgroupA LAN (Local Area Network) is a system where individual PCs are connected together within a company or organization. For instance if ten people are working together within an office to connect them to have a single printer and all ten people can print to it In a similar way, other devices such as modems or scanners can Even more useful is the ability to share information when connected to a network A WAN (Wide Area Network) allows you to connect to other computers over a wider area (i.e. the whole world) Client/server This term mean to the type of network where resources are kept centrally on the server and used locally by the client. The server tends to be a very powerful PC (or group of PCs), while each client workstation, which the users have, is less powerful Workgroup Groups of people working together can share their resources with each other. People within the workgroup can share information on their hard disks as well as sharing printers, modems and scanners. The workgroup is connected via a computer network. This network can simply consist of a few computers at a single location physically connected to each other via a network cable, or it may be a workgroup of computers connected globally via the Internet. The networked nature of computers means that the physical distance between workgroups members is fast becoming irrelevant Intranet and Extranet An Intranet It is a smaller, closed version of the Internet, which can only be accessed by authorized members of an organization. Intranets are becoming an increasingly popular way to share information within a company or other organization. An Intranet uses Internet technologies to allow users to access company documents, search databases, schedule meetings and of course send emails. Once a company has installed a comprehensive Intranet many users need only one piece of software on their PC, a web browser An Extranet is an Intranet which is partially accessible to authorized outsiders. An Intranet is normally only accessible by members of the same company or organization; an extranet also allows outsiders who have been issued with a password to gain limited access to information held on a company network. Extranets are being used as a way for business partners to share information. The Internet A collection of networks started by and for the US military to enable them to 'survive' a nuclear war. Later adopted by the educational system, and now exploited by the commercial world The Internet is a global network of interconnected networks The unique thing about the Internet is the sheer amount of information which you can access from it the Internet enables all of the following to take place: Sharing information on Web sites Moving files between computers at different locations Sending email to recipients around the world Holding private video and audio conferences Working collaboratively with people at other locations The difference between the World Wide Web (WWW) and the Internet The World Wide Web (WWW) is just a small part of the Internet as a whole. The Internet relates to all the hardware and software involved, as well as the WWW, it also includes FTP (File Transfer Protocol), email and newsgroups. The WWW is basically the text and pictures which you can view using your web browser, such as Microsoft Internet Explorer, or Netscape Navigator The Telephone Network in Computing If you use a modem to connect to the Internet, then this connection is made by the telephone network. PSTN (Or Public Switched Telephone Network) is the technical name for the public telephone system It is based on traditional 'copper wire' technology and can transmit analogue voice data PSDN (Or Public Switched Data Network) is simply the technical name for the telephone system in use today ISDN Stands for "Integrated Services Digital Network" ISDN dates back to 1984, and allow much faster transfer rates than when using modems. Using ISDN, you can transfer 64 Kbit or 128 Kbit of data per second ADSL Short for 'Asymmetric Digital Subscriber Line' A more recent technology which allows more data to be sent over existing copper telephone lines, but requires a special ADSL modem ADSL allows data transfer rates of ranging from to 8 Mbps when receiving data (called the downstream rate) and from 16 to 640 Kbps when sending data (called the upstream rate) DSL Refers collectively to all types of 'Digital Subscriber Lines', the two main categories being ADSL and SDSLDSL technology allows faster data transfer while still using copper wires (as opposed to optic fiber cables) Modem Modem stands for "MODulate/DEModulate". The modem sends information from your computer across the telephone system. The modem at the other end of the phone line, converts the signal back into a format which can be used by the receiving computer Digital modem and analogue modem A digital system uses 1 or 0 to transmit data or to represent data. Thus, a digital clock will display whole seconds, whole minutes and whole hours. An analogue system, such as a traditional clock, does not use multiples of 1 or 0, but rather uses the full range of numbers, including fractions. In this way, an analogue clock can display fractions of a second Baud rate The baud rate tells you how fast a modem can send/receive data. Most modern modems have a maximum baud rate of 56 Kilobits per second (Kb/sec)
