Networks

ÐŽ§Networks have had an impact on the way people live over the last twenty years.ЎЁ

M.Cassim

Computer networking is concerned with communication between computer systems. Such networks involves at least two computers, which can be separated by a few centimeters (e.g. via Bluetooth) or thousands of kilometers (e.g. via the Internet). Over the past two decades computers and computer networking have changed drastically. A few areas of these networking advances will be discussed.

Telephone networks have been so far the primary bearer of data and voice communications. In 1984 fully digital, circuit-switched telephone systems, known as Integrated Services Digital Network (ISDN) for voice and non-voice data communications were introduced. The following year BellCore began working on the standard for the Synchronous Optical Network (SONET). In the late 1980ÐŽ¦s Local Area Networks (LANs) emerge as an effective way to transfer data between a group of local computers, and telephone companies replaces all its analog multiplexing with digital multiplexing.

By 1998 advanced packet-switching networks allowed simultaneously sending voice, data, and video down a single phone line. These advances have let to high speed network connectivity over a single line using Asymmetric Digital Subscriber Lines (ADSL), which standardized using the discrete multi-tone techniques to allow greater services to be provided.

The World Wide Web was born in 1990., Tim Berners-Lee created HyperText Markup Language, or HTML. Using ideas like HTML, URL (Uniform Resource Locater), and HTTP (HyperText Transfer Protocol), the Internet was able to expand into the World Wide Web. Web sites could be built and hosted on servers. Links connected thousands of web sites, making them available to the public. Tim Berners-Lee, the creator of HTML, also created the first Internet browser and the first web server in 1991. By 1992 the Internet recorded itÐŽ¦s one-millionth host connected, with itÐŽ¦s size doubling every year.

In 1979, the first commercial operational cellular phone service was implemented in Tokyo, Japan. The advanced mobile phone service, or AMPS for short, which dominates the cellular telephony industry today, makes use of two very important principles, these are cell splitting and frequency reuse. This allowed a drastic increase in the number of users a cellphone network could connect. Since the early nineteen-eighties, cellular telephony has been not just a breakthrough, but also a fad. This technology has allowed voice and data networks to be established using telephone signals wirelessly. At the beginning of the 21ÐŽ¦s centaury third generation cellphone networking has allowed live streaming of radio and television, as well as high speed data connectivity.

Latest networking technology include wireless networking such as Bluetooth, which started development in 1998 and is used for wireless data exchange between handheld computers and cellphones. WiFi (Wireless Fidility) describes the underlying technology of wireless local area networking(WLAN). This networking technology was originally intended to be used for mobile computing devices, such as laptops, in LANs, but is now often used for increasingly more applications, including Internet and VoIP phone access, gaming, and basic connectivity of consumer electronics.

Wifi devices are connected together by a wireless access point(WAP), and a wireless router allows connection to adjacent wired networks. A user can access these connections by being in the range of the network. This range is referred

to as a hotspot. These connections allows users to have wireless access to an internet connection, shared printer,