1 CP586 © Peter Lo 2003 Multimedia Communication Bandwidth & Basic Web Terminology

CP586 © Peter Lo Internet History The Internet began in1969 as the Advanced Research Projects Agency Network, better known as ARPANET. The project was developed by the US Department of Defense and was later made available to universities and other organizations. The WWW started in 1989 at CERN, a European laboratory for particle physics in Geneva. CERN researchers developed the protocol for the free exchange of information and ideas related to physics and science. The system was text based and there was no intention of adding sound and video, let alone images. Once HTTP was developed, client server software was written.

CP586 © Peter Lo WWW Terminology The WWW stands for the World Wide Web. HTTP stands for Hypertext Transfer Protocol. URL stands for Universal Resource Locator and can denote http, ftp and Telnet recourses.

CP586 © Peter Lo HTTP HTTP is Short for Hyper Text Transfer Protocol, the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. HTTP is called a stateless protocol, because each command is executed independently, without any knowledge of the commands that came before it.

CP586 © Peter Lo Bandwidth The amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second(bps) or bytes per second. For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).

CP586 © Peter Lo Fiber Optic Cable Uses glass (or plastic) threads (fibers) to transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves. Fiber optic cables have a much greater bandwidth than metal cables. Fiber optic cables are less susceptible than metal cables to interference (e.g. magnetic). Fiber optic cables are much thinner and lighter than metal wires. Data can be transmitted in a digital format. When you multiplex a signal it allows you To combine multiple signals (analog or digital) for transmission over a single line or media.

CP586 © Peter Lo HTML Issues HTML stands for Hyper Text Markup Language. HTML lack WYSIWYG capabilities. Different HTML versions in conjunction with poor co-operation between the leading browsers make truly cross platform web pages very difficult to achieve.

CP586 © Peter Lo ISDN ISDN stands for integrated services digital network. ISDN is designed to carry large amounts of information at a fast rate of speed. ISDN is especially suited for the transmission of high quality audio and video.

CP586 © Peter Lo ISO Short for International Organization for Standardization. Note that ISO is not an acronym; instead, the name derives from the Greek word iso, which means equal. For example, ANSI (American National Standards Institute) is a member of ISO.

CP586 © Peter Lo Communication Terminology The Internet uses TCP/IP (Transport Control Protocol / Internet Protocol). A packet is the basic unit of communication within TCP/IP. Asynchronous data flow is typically made up of a number of different packets.

CP586 © Peter Lo OSI Reference Model OSI stands for Open System Interconnection, an ISO standard for worldwide communications that defines a networking framework for implementing protocols in seven layers. What was once thought to become the universal communications standard now serves as the teaching model for all other protocols.

CP586 © Peter Lo OSI Reference Model

CP586 © Peter Lo Networks Local Area Network (LAN) Connects computers in a single office/building. Wide Area Network (WAN) Connects networks over a large area. Metropolitan Area Network (MAN) Connects networks around a town or city.

CP586 © Peter Lo Local area network (LAN) Network in limited geographical area such as home, school computer laboratory, or office building nodes in network

CP586 © Peter Lo Peer-to-peer LAN Small network that shares hardware, data, or information located on any other computer in network Each computer stores files on its own storage devices printer may be used by all computers on network network operating system and application software installed on each computer

CP586 © Peter Lo Client/server LAN Network in which one or more computers act as a server and other computers on the network can request services from server client serverlaser printer

CP586 © Peter Lo Wide area network (WAN) Network that covers large geographic area Internet is world’s largest WAN communications satellite

CP586 © Peter Lo Internet use of peer-to-peer (P2P) Enables users with same networking software to connect to each other’s hard disks and exchange files directly

CP586 © Peter Lo Metropolitan area network (MAN) Backbone network that connects local area networks in a metropolitan area such as a city or town

CP586 © Peter Lo Types of Networks 100 Base-T. 100 Base-VG. Token Ring. Ethernet. Integrated Services Digital Network (ISDN)

CP586 © Peter Lo Transmission Alternatives. Telecommunications Network. Cable TV. Terrestrial Broadcast. Satellite Broadcast. ISDN. Fibre Optic Cable.

CP586 © Peter Lo Internet Addressing Domain Name Server (DNS) Top level domains Describe the category of use. (Eg. COM, GOV, EDU, NET, AU) Second level domains Describe specific users or organizations within first level domains (Eg. Ballarat, IBM, Star Wars) Third or subsequent levels Specify a particular user or computer.

CP586 © Peter Lo Reference Discovering Computers World 2003 (Ch. 6)