University of Palestine CollegeofBusiness business computer application Instructor: Mr. Ahmed Abumosameh
Lecture 5 Communications and Networks
Communications notebookcomputers Web-enabledPDAs smartphones servers GPS receivers desktopcomputers mainframecomputers set-top boxes Tablet PCs What are computercommunications? • Process in which two or more computers or devices transfer data, instructions, and information via cables and wires or wirelessly mainframe computers • Data is transferred from one place to another in the form of signals, which may be in analog or digital form, therefore data transmission is divided into: • - Analog data transmission- Digital data transmission
Communications Sending device — initiates instruction to transmit data, instructions, or information Communications device — connects the sending device to the communications channel Communications channel — media on which data, instructions, or information travel Communications device — connects the communications channel to the receiving device Receiving device — accepts transmission of data, instructions, or information What is needed for successful communications?
Communication Channels The path through which data is transmitted from one place to another is called channel or communication media or transmission media. There are different type of transmission media: • Bounded Media • Unbounded Media
Bounded Transmission Media • Also known as guided or physical Transmission media. • In this media the devices are directly connected with each other by using some physical media like wires. • The examples of bounded media are twisted Pair Wire, Coaxial Cable and Fiber optics.
Unbounded Media • Also known as wireless or unguided transmission media. • The devices communicate with each other through air or space using broadcast radio signals, microwave signals and infrared signals. • Some examples of unbounded media are: • Communication Satellite • Broadcast Radio • Cellular Radio
Data Transmission Mode • The way in which data is transmitted from one place to another is called data transmission mode. • There are three types of transmission mode • Simplex Mode • Half duplex Mode • Full duplex Mode
Uses of Computer Communications What are some uses of communications technology? Internet Web E-Mail InstantMessaging Chat Rooms Newsgroups FTP WebFolders VideoConferencing Fax Machine or Computer Fax/Modem
Networks What is a network? • Collection of computers and devices connected via communications devices and transmissionmedia
Computer Network • Types of Computers in Network • ServerComputer • ClientComputer • Types of Computer Networks • LAN (Local Area Network) • MAN (Metropolitan Area Network) • WAN (Wide Area Network)
Networks What is a local area network (LAN)? • Network in limited geographical area such as home or office building • Metropolitan area network (MAN) connects LANs in city or town
Networks What is a wide area network (WAN)? • Network that covers large geographic area using many types of media • Internet is world’s largest WAN
Networks What is a client/server network? • One or more computers act as server and other computers, or clients, access server
Networks What is a peer-to-peer network? • Simple network that connects fewer than 10 computers • Each computer, or peer, has equal capabilities
Network Topologies • The physical layout of connected devices in a network is called topology. • Bus Topology • Ring Topology • Star Topology • Tree Topology • Mesh Topology
Networks What is Internet peer-to-peer (P2P)? • Enables users to connect to each other’s hard disks and exchange files directly
Networks What is a bus network? • All computers and devices connect to central cable,or bus • Advantage: Easy to implement • Disadvantage: Bus traffic, Bus failure
Networks What is a ring network? • Cable forms closed ring, or loop, with all computers and devices arranged along ring • Data travels from device to device around entire ring, in one direction • Advantage: Span a long distance. • Disadvantage: One node fail, all network down.
Networks What is a star network? • All devices connect to a central device, called hub • All data transferred from one computer to another passes through hub • Advantage: Easy to install • Disadvantage: If the hub fail, the network became inoperable
Intranet • An intranet is a private computer network that uses Internet Protocol technologies to securely share any part of an organization's information or operational systems within that organization. Sometimes the term refers only to the organization's internal website, but may be a more extensive part of the organization's information technology infrastructure.
Extranet • An extranet is a private network that uses Internet protocols, network connectivity. An extranet can be viewed as part of a company's intranet that is extended to users outside the company, usually via the Internet.