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Lesson 7 Networks Computer Concepts BASICS 4th Edition 1 Wells Objectives Lesson 7 2 Describe the benefits and disadvantages of networks List and describe the types of networks List and describe communications hardware List and describe communications media Describe the different network topologies Describe network architecture and protocols Wells Computer Concepts BASICS Vocabulary Lesson 7 3 baseband broadband bus topology client/server network client Wells communications channel data communications Ethernet local area network (LAN) Computer Concepts BASICS Vocabulary (continued) Lesson 7 4 modem peer-to-peer network ring topology router server Wells star topology token ring topology transmission media wide area network (WAN) Computer Concepts BASICS Network Building Blocks Lesson 7 5 A network is a group of two or more computers linked together Data communications is the transmission of data from one location to another. The five components of data communications are: – Wells sending device, signal conversion device, communication path, receiving device, and communications software Computer Concepts BASICS Network Building Blocks (continued) Advantages of a Network: – Lesson 7 6 Information Sharing, Hardware Sharing, Software Sharing, and Collaborative environment Disadvantages of a Network: – Wells Vulnerable to malicious code, Equipment problems, Investment in hardware and software, and Need for maintenance Computer Concepts BASICS Network Types The two most common types of networks: – – Lesson 7 Other types of networks: – – – – 7 local area networks (LANs) wide area networks (WANs) Wells metropolitan area networks (MANs) personal area networks (PANs) home area networks (HANs) campus area networks (CANs) Computer Concepts BASICS Network Types (continued) Lesson 7 Most local area networks (LANs) connect personal computers and devices in a limited geographical area Each device on the network is called a node and shares resources such as a printer, programs, or other hardware A wireless LAN (WLAN) is similar to a LAN, but uses no physical wires 8 Wells Computer Concepts BASICS Network Types (continued) Client/server local area network Lesson 7 9 Wells Computer Concepts BASICS Network Types (continued) Lesson 7 10 A wide area network (WAN) covers a large geographical area. The largest WAN is the Internet. Most WANs are two or more LANs connected by routers. Two variations on a WAN are intranets and extranets. – – Wells An intranet is designed for the exclusive use of people within an organization An extranet allows specified users outside the organization to access internal information systems Computer Concepts BASICS Network Types (continued) Lesson 7 11 MANs, PANs, HANs, and CANs: Metropolitan area network (MAN): Connects users in a geographic area bigger than a LAN, but smaller than a WAN Personal area network (PAN): Connects personal digital devices within a range of about 30 feet Home area network (HAN): Contained within a user’s home Campus area network (CAN): Collection of LANs within a limited geographical space, such as a university campus Wells Computer Concepts BASICS Network Types (continued) Lesson 7 12 Network Architectures: Popular LANs: client/server and peer-to-peer Client/server network: One or more computers act as a server. Network operating system software and software applications are stored on the server. All other computers on the network are called clients. Peer-to-peer network: All computers are equals Internet peer-to-peer: Also called P2P, users connect directly to each other over the Internet Wells Computer Concepts BASICS Network Hardware Lesson 7 13 Communications Devices: Communications devices facilitate the transmitting and receiving of data. A list of common communications devices follows over the next slides: Dial-up modem: Enables data transmission over analog telephone lines DSL and ISDN modems: DSL (digital subscriber line) and ISDN (integrated services digital network) modems allow digital transmission over telephone copper wires Wells Computer Concepts BASICS Network Hardware (continued) Lesson 7 14 Communications Devices (continued): Cable modem: Uses coaxial cable to send and receive data Wireless modem: Many mobile devices, such as a PDA, contain a wireless modem Network interface card (NIC): Each computer on a network must have a NIC. Most computers have a built-in NIC. Gateway: Software and hardware linking two different types of networks that use different protocols Wells Computer Concepts BASICS Network Hardware (continued) Communications Devices (continued): Router: An intelligent device that directs network traffic Wireless access point: Connects wireless communications devices together to create a wireless network Hub: A place of convergence where data arrives from one or more directions and is forwarded in one or more other directions Wireless Access Point Lesson 7 15 Wells Computer Concepts BASICS Communications Media Lesson 7 16 A communications channel is the link that allows data be transferred from one computer to another Bandwidth is the transmission capacity of a communications channel High bandwidth media, such as cable, fiber, and DSL, are generally referred to as broadband, whereas a standard telephone line is referred to as baseband Wells Computer Concepts BASICS Communications Media (continued) Lesson 7 17 At one end of the communications channel, you have a sending device A communications device, such as a modem, converts the signal to a form that transmits over a standard dial-up telephone line or a dedicated line A switch, located at the telephone, establishes a link between the sender and receiver At the receiving end, another modem converts the signal back into a format that the receiving device can understand To send the data through the channel requires some type of transmission media, physical or wireless Wells Computer Concepts BASICS Lesson 7 Communications Media (continued) 18 Physical Media: Twisted-pair cable is used in telephone systems. There are two wires: one carries the signal and the other absorbs signal interference. Coaxial cable is used for cable television. The heavily shielded cable is less prone to interference than twisted-pair cable. Fiber-optic cable is made from thin, flexible glass tubing. They have higher bandwidth than metal wires, and are less susceptible to interference. Wells Computer Concepts BASICS Communications Media (continued) Lesson 7 19 Wireless Media: Microwave signals are sent in the form of electromagnetic waves in straight lines between microwave stations Communication satellites are placed in orbit and maintain a constant position above one point of the Earth’s surface IrDA media (also called infrared transmission) send signals using infrared light waves. Wells Satellites Computer Concepts BASICS Communications Media (continued) Wireless Media (continued): Bluetooth technology uses radio waves to connect mobile devices such as cell phones, PDAs, and notebook computers within 30 feet of each other. Wi-Fi, or wireless fidelity, identifies any network based on the 802.11 family of standards governing wireless transmissions. WAP is short for Wireless Application Protocol. This protocol specifies how users access information instantly through mobile devices such as smartphones and pagers. Lesson 7 20 Wells Computer Concepts BASICS Network Topologies Network configurations are referred to as topologies. – Lesson 7 – 21 – Wells Within the bus topology, all devices are connected to and share a master cable called the bus or backbone. There is no single host computer, and data can be transmitted in both directions. With a ring topology the devices are connected in a circle. Data travels from device to device around the ring. Star topology: Within a star topology, all devices are connected to a central hub or computer. All data that transfers from one computer to another must pass through the hub. Computer Concepts BASICS Communications Protocols A protocol is an agreed-upon set of rules and procedures for transmitting data between two or more devices. Within networking and LANs, the two most widely used protocols are: Lesson 7 – 22 – The Ethernet protocol which is based on the bus topology, but can work with the star topology as well With a token ring all of the computers are arranged in a circle and a token, a special signal, travels around the ring On the Internet, the major protocol is TCP/IP which is the acronym for Transmission Control Protocol/Internet Protocol Wells Computer Concepts BASICS Network Operating Systems Software Lesson 7 – – 23 All computers, including network servers, require an operating system. Network operating systems provide features such as administration, file management, print, communications and security. Two types of operating systems are necessary in computer networking: the desktop operating system, such as Windows or Mac OS the network operating system Some desktop operating systems have built-in networking functions. Wells Computer Concepts BASICS Lesson 7 Summary 24 In this lesson, you learned: Data communication is the transmission of data from one location to another. A network is a group of two or more computers linked together. The Internet is the biggest network of all. Networks have advantages and disadvantages. A local area network generally is confined to a limited geographical area. A wide area network is made up of several connected local area networks. The two popular types of LANs are the client/server network and peer-to-peer network. Wells Computer Concepts BASICS Summary (continued) Lesson 7 25 Other types of specialized networks include metropolitan area networks (MANs), personal area networks (PANs), home area networks (HANs), and campus area networks (CANs). You can use a network for information sharing, hardware sharing, software sharing, and as a collaborative environment. The link through which data is transmitted is the communications channel. Transmission media can be either physical or wireless. Physical media include twisted-pair cable, coaxial cable, and fiber-optic cable. Wells Computer Concepts BASICS Summary (continued) Lesson 7 26 Most networks consist of a network server and computer clients. Communications devices facilitate the transmitting and receiving of data, instructions, and information. Communications devices include dial-up and cable modems, DSL and ISDN modems, network interface cards, gateways, routers, wireless access points, and hubs. Network interface cards enable the sending and receiving of data between the PCs in a network. A router directs the Internet or network traffic. Wells Computer Concepts BASICS Summary (continued) Lesson 7 27 Wireless media includes microwaves, satellites, IrDA, Bluetooth, and Wi-Fi. Network topologies include bus, ring, and star. A protocol is an agreed-upon set of rules and procedures for transmitting data between two or more devices. The Ethernet protocol is one of the most popular LAN protocols. Token ring is the second most widely used LAN protocol. TCP/IP is a protocol used by both LANs and WANs to connect to the Internet. All computers on a network require an operating system, and networks require network operating systems. Wells Computer Concepts BASICS