Friday, May 31, 2019
Bandwidth :: essays research papers
Computers store all information as binary numbers. The binary number system uses two binary digits, 0 and 1, which are called bits. The follow of data that a computer network can transfer in a certain amount of time is called the bandwidth of the network and is measured in kilobits per entropy (kbps) or megabits per second (mbps). A kilobit is 1 thousand bits a megabit is 1 million bits. A dial-up telephone modem can transfer data at rates up to 56 kbps DSL and cable modem connections are much faster and can transfer at several mbps. The Internet connections used by businesses often operate at 155 mbps, and connections between routers in the heart of the Internet may operate at rates from 2,488 to 9,953 mbps (9.953 gigabits per second) The terms wideband or broadband are used to characterize networks with high capacity and to distinguish them from narrowband networks, which have low capacity. Research on dividing information into packets and switching them from computer to comput er began in the 1960s. The U.S. Department of Defense Advanced Research Projects Agency (ARPA) funded a research project that created a packet switching network known as the ARPANET. ARPA also funded research projects that produced two satellite networks. In the 1970s ARPA was faced with a dilemma Each of its networks had advantages for some situations, but each network was uncongenial with the others. ARPA focused research on ways that networks could be interconnected, and the Internet was envisioned and created to be an interconnection of networks that use transmission control protocol/IP protocols. In the early mid-eighties a group of academic computer scientists formed the Computer Science web, which used TCP/IP protocols. Other government agencies extended the role of TCP/IP by applying it to their networks The Department of Energys Magnetic Fusion Energy Network (MFENet), the High Energy Physics NETwork (HEPNET), and the National Science Foundation NETwork (NSFNET). In the 1980s, as large commercial companies began to use TCP/IP to build private internets, ARPA investigated transmission of multimediaaudio, video, and graphicsacross the Internet. Other groups investigated hypertext and created tools such as Gopher that allowed users to browse menus, which are lists of possible options. In 1989 many of these technologies were combined to create the World Wide Web.