Understanding Computers Today and Tomorrow 12 th Edition

Understanding Computers Today and Tomorrow 12 th Edition Chapter 7: Computer Networks

Learning Objectives • Define a network and its purpose. • Describe several uses for communications technology. • Understand the various topologies and architectures a computer network might use. • Explain the difference between a LAN, a WAN, and a PAN, and between an intranet, an extranet, and a VPN. Chapter 7 Understanding Computers, 12 th Edition 2

Learning Objectives • Understand characteristics about data and how it travels over a network. • Name specific types of wired and wireless transmission media and explain how they transmit data. • Identify different protocols that can be used to connect the devices on a network. • List several types of networking hardware and explain the purpose of each. Chapter 7 Understanding Computers, 12 th Edition 3

Overview • This chapter covers: – Networking concepts and terminology – Common networking and communications applications – Technical issues related to networks, including the major types of networks, how data is transmitted over a network, and types of transmission media involved – Explanation of the various ways networked devices communicate with one another – Various types of hardware used in conjunction with a computer network Chapter 7 Understanding Computers, 12 th Edition 4

What Is a Network? • Network: A connected system of objects or people • Computer network: A collection of computers and other hardware devices connected together so that users can share hardware, software, and data, as well as electronically communicate with each other • Internet: Largest computer network in the world • Types of networks – Business networks – Phone networks – Home and multimedia networks Chapter 7 Understanding Computers, 12 th Edition 5

Networking and Communications Applications • Mobile phones (wireless phones) – Cellular (cell) phones • Must be within range of cell tower to function – Satellite phones • Used where cell service isn’t available – Dual-mode phones • Allows users to make telephone calls on more than one network • Cellular / Wi-Fi dual mode phone are most popular Chapter 7 Understanding Computers, 12 th Edition 6

Networking and Communications Applications Chapter 7 Understanding Computers, 12 th Edition 7

Networking and Communications Applications • Paging – Sending short numeric or text messages to a person’s pager – Most often used for onsite paging applications • Messaging – Two-way paging – Most often takes place today via a mobile phone Chapter 7 Understanding Computers, 12 th Edition 8

Networking and Communications Applications • Global positioning system (GPS): Uses satellites and a receiver to determine the exact geographic location of the receiver – Commonly found in cars today – Available as handheld units – Used by the military, hikers, travelers, and others who need to know their precise location Chapter 7 Understanding Computers, 12 th Edition 9

Networking and Communications Applications • Monitoring systems: Monitor status or location of individuals, vehicles, assets, etc. – RFID-based systems – GPS-based monitoring systems – Electronic medical monitors and other types of home health monitoring • Digital entertainment – High-definition television/radio: HDTV is replacing analog broadcasts – Satellite radio: Delivers digital radio content to satellite receivers – Multimedia networking and digital data distribution Chapter 7 Understanding Computers, 12 th Edition 10

Networking and Communications Applications • Videoconferencing: Use of communications technology for real-time, face-to-face meetings between individuals located in different places – Technology continues to improve and mimic reallife meeting environments – Telepresence videoconferenceing – Online conferencing (via the Internet) – Video phone calls Chapter 7 Understanding Computers, 12 th Edition 11

Networking and Communications Applications • Collaborative computing (workgroup computing): Using a computer and communications technology to work together on documents and other project – Tools include Microsoft Office markup tools and collaboration software • Telecommuting: Individuals work at home and communicate with their place of business and clients via communications technologies – Possible because of the Internet and other communications technologies Chapter 7 Understanding Computers, 12 th Edition 12

Networking and Communications Applications • Telemedicine: Use of communications technology to provide medical information and services – Remote monitoring and consultations – Remote diagnosis – Telesurgery Chapter 7 Understanding Computers, 12 th Edition 13

Types of Networks • Topology: How the devices in the network (called nodes) are arranged – Star networks: All devices connect to a central device or hub) – Bus networks: All devices connect to a central cable – Ring networks: Devices connect to one another in a ring – Mesh networks: Multiple connections between devices – Some networks use a combination of topologies Chapter 7 Understanding Computers, 12 th Edition 14

Network Topologies Chapter 7 Understanding Computers, 12 th Edition 15

Types of Networks • Architecture : The way networks are designed to communicate • Client-server networks – Client: PC or other device on the network that requests and utilizes network resources – Server: Computer dedicated to processing client requests Chapter 7 Understanding Computers, 12 th Edition 16

Types of Networks • Peer-to-peer networks: All computers at the same level) – Internet peer-to-peer (P 2 P) computing: Performed via the Internet Chapter 7 Understanding Computers, 12 th Edition 17

Types of Networks • Local area network (LAN): Small geographical area (office, campus, etc. ) • Wide area network (WAN): Large geographical area (Internet) • Metropolitan area network (MAN): Serves a metropolitan area – Municipal Wi-Fi projects • Personal area network (PAN): Connects personal devices for one individual, such as his or her portable PC, mobile phone, and portable printer Chapter 7 Understanding Computers, 12 th Edition 18

Types of Networks • Wireless sensor networks (WSNs): Contain sensors (devices that respond to a stimulus and generate an electrical signal that can be measured or interpreted) • Intranet: Private network set up by an organization for use by its employees • Extranet: Intranet that is at least partially accessible to authorized outsiders • Virtual private network (VPN): Secure path over the Internet that provide authorized users a secure means of accessing a private network via the Internet Chapter 7 Understanding Computers, 12 th Edition 19

Data Transmission Characteristics • Analog vs. digital (waves vs. discrete) • Bandwidth: The amount of data that can be sent at during a given period of time – Measured in bits per second (bps) • Serial vs. parallel transmission – Serial = 1 bit – Parallel = at least 1 byte at a time Chapter 7 Understanding Computers, 12 th Edition 20

Data Transmission Characteristics • Transmission timing – Synchronous transmission (at regular, specified intervals) – Asynchronous transmission (sent when ready) – Isochronous transmission (sent at the same time as other, related, data) Chapter 7 Understanding Computers, 12 th Edition 21

Data Transmission Characteristics • Transmission directions – Simplex transmission (one way only) – Half-duplex transmission (one way at a time) – Full-duplex transmission (both ways at the same time) Chapter 7 Understanding Computers, 12 th Edition 22

Data Transmission Characteristics • Type of connections – Circuit-switched: Dedicated path over a network is established and all data follows that path – Packet-switched: Messages are separated into small units called packets and travel along the network separately • Used to send data over the Internet – Broadcast: Data is sent out to all other nodes on the network • Primarily used with LANs Chapter 7 Understanding Computers, 12 th Edition 23

Type of Connections Chapter 7 Understanding Computers, 12 th Edition 24

Data Transmission Characteristics • Wired connections: The PC is physically cabled to the network – Common in schools, business, and government facilities • Wireless connections: Typically use radio waves to send data through the air – Rapidly becoming more popular in homes and businesses – Wireless hotspots are commonly available in public locations Chapter 7 Understanding Computers, 12 th Edition 25

Wired Network Transmission Media • Twisted-pair cable – Pairs of wires twisted together – Used for telephone and network connections • Coaxial cable – Thick center wire – Used for computer networks, short-run telephone transmissions, cable television delivery • Fiber-optic cable – Glass or fiber strands through which light can pass – Used for high-speed communications Chapter 7 Understanding Computers, 12 th Edition 26

Wired Network Transmission Media Chapter 7 Understanding Computers, 12 th Edition 27

Wireless Network Transmission Media • Use radio signals – Short-range (such as Bluetooth) can connect a wireless keyboard or mouse to a PC – Medium-range (such as Wi-Fi) are used for wireless LANs and to connect portable PC users to the Internet at public hotspots – Longer-range (Wi. MAX) can be used to provide Internet access to wide geographic areas • Radio frequencies are assigned by the FCC and are measured in hertz (Hz) • The electromagnetic spectrum is the range of common electromagnetic radiation (energy) that travels in waves Chapter 7 Understanding Computers, 12 th Edition 28

Wireless Network Transmission Media Chapter 7 Understanding Computers, 12 th Edition 29

Cellular Radio Transmissions • Use cellular towers within cells • Calls are transferred from cell tower to cell tower as the individual moves • Different transmission frequencies are used to avoid interference and allow multiple conversations to take place via a single tower at one time • Widely used, but cell service not available everywhere • Cell phone technology is referred to in generations – Today’s phones are third-generation – 4 G service is beginning to become available Chapter 7 Understanding Computers, 12 th Edition 30

Cellular Radio Transmissions Chapter 7 Understanding Computers, 12 th Edition 31

Microwave and Satellite Transmissions • Microwaves: High-frequency radio signals – Sent and received using microwave stations or satellites – Microwave stations are earth-based and can transmit signals to each other over distances of about 30 miles – Signals are line of sight, so stations are usually built on tall buildings, towers, mountaintops • Communication satellites: Space-based devices launched into orbit to send and receive microwave signals from earth – Traditional satellites use geosynchronous orbit – Low earth orbit (LEO) satellites were developed to combat delay – Medium earth orbit (MEO) satellites are most often used for GPS systems • Can send large quantities of data at high speed over long distances Chapter 7 Understanding Computers, 12 th Edition 32

Microwave and Satellite Transmissions Chapter 7 Understanding Computers, 12 th Edition 33

Infrared (IR) Transmissions • Sends data as infrared light • Like an infrared television remote, IR requires line of sight • Because of this limitation, many formerly IR devices (wireless mice, keyboards) now use RF technology • IR is still sometimes used to beam data between handheld PCs or gaming systems, or send documents from portable PCs to printers Chapter 7 Understanding Computers, 12 th Edition 34

Networking Standards and Communications Protocols • Standards: A set of criteria or requirements considered to be the approved model for something • Networking standards: Address how networked computers communicate and connect • Communications protocol: An agreed-upon standard for transmitting data between two devices on a network • In networking, standards and protocols specify how: – Devices physically connect to a network – Data is packaged for transmission – Receiving devices acknowledge signals – Errors are handled – Also ensure products can work together Chapter 7 Understanding Computers, 12 th Edition 35

Ethernet • Ethernet: Most widely used communications protocol for wired LANs – Typically used a bus or star topology and twistedpair, coaxial, or fiber-optic cables – Original (10 Base-T) Ethernet networks run at 10 Mbps – Newer 100 Mbps, 1 Gbps, and 10 Gbps versions are common – 100 Gbps is in development • Power over Ethernet: Allows electrical power to be sent along with data on an Ethernet network – Most often used by businesses Chapter 7 Understanding Computers, 12 th Edition 36

Ethernet Chapter 7 Understanding Computers, 12 th Edition 37

TCP/IP and Wireless Application Protocol (WAP) • TCP/IP (Transmission Control Protocol/Internet Protocol): Used for transferring data over the Internet – Uses packet switching – TCP/IP support built into virtually all Oss – IPv 4 uses 32 -bit addresses – IPv 6 uses 128 -bit addresses and expected to eventually replace IPv 4 • Wireless Application Protocol (WAP): A standard for delivering Internet content to mobile devices – Microbrowser: Used to access WAP content Chapter 7 Understanding Computers, 12 th Edition 38

TCP/IP Chapter 7 Understanding Computers, 12 th Edition 39

Wi-Fi (802. 11) • Wi-Fi (Wireless Fidelity): A family of wireless networking standards using the IEEE standard 802. 11 – Also called wireless Ethernet – Current standard for wireless networks in home and office – Designed for medium-range transmission – Wi-Fi hardware built into most notebook PCs and many consumer devices today – Hotspots rapidly multiplying – Speed and distance of Wi-Fi networks depends on • Standard and hardware being used • Number of solid objects between the access point and the PC or wireless device • Possible interference Chapter 7 Understanding Computers, 12 th Edition 40

Wi-Fi (802. 11) Chapter 7 Understanding Computers, 12 th Edition 41

Wi-Fi (802. 11) • Various standards – Current standard is 802. 11 g – Emerging standard is 802. 11 n Chapter 7 Understanding Computers, 12 th Edition 42

Wi. MAX, Mobile Wi. MAX, and Mobile-Fi • Wi. MAX (Worldwide Interoperability for Microwave Access or 802. 16): Fairly new wireless standard for longer range wireless networking connections – Designed to deliver broadband to homes, businesses, other fixed locations – Mobile Wi. MAX is the mobile version of the standard – 4 G mobile phones may be Wi. MAX-based • Mobile-Fi (802. 20): Currently in development for providing high-speed mobile Internet access in cars, trains, and other moving vehicles Chapter 7 Understanding Computers, 12 th Edition 43

Wi. MAX, Mobile Wi. MAX, and Mobile-Fi Chapter 7 Understanding Computers, 12 th Edition 44

Short-Range Wireless Networking • Bluetooth: Very short range (less than 10 feet) – For communication between computers or mobile devices and peripheral devices – Bluetooth devices are automatically networked with each other when they are in range (piconets) • Ultra Wideband (UWB or Wi. Media): Originally developed by the military for locating tanks, enemies, hidden objects – Designed for wireless multimedia networking – Range of 100 feet or less – Speed depends on distance between devices – New Bluetooth standards will use UWB to speed up transfers of large amounts of data – Wireless USB is UWB-based Chapter 7 Understanding Computers, 12 th Edition 45

Bluetooth Chapter 7 Understanding Computers, 12 th Edition 46

Short-Range Wireless Networking • Wireless HD (Wi. HD): In development, designed for networking home electronics devices • Zig. Bee: Emerging, designed for inexpensive, simple short-range networking like sensor networks – Intended for application that require low data transfer rates and several years of battery life – Can accommodate more than 65, 000 devices on a single network Chapter 7 Understanding Computers, 12 th Edition 47

Phoneline and Powerline • Phoneline (Home. PNA): Allows computers to be networked through regular phone lines and jacks – Geared for quick and easy networking – Home. PNA 3. 0 is fast (320 Mbps) and designed for both computers and multimedia networking • Powerline: Allows computers to be networked over power lines and conventional outlets – Also designed for quick and easy networks – Home. Plug AV is fast (200 Mbps) and designed for both computers and multimedia networking • Broadband over power lines (BPL): An emerging technology that allows Internet data to be sent over existing power-pole infrastructure Chapter 7 Understanding Computers, 12 th Edition 48

Cellular Standards • Second-generation wireless standards – GSM (Global System for Mobile communications) – CDMA (Code Division Multiple Access) • Third-generation standards – GPRS (General Packet Radio Service) – EDGE (Enhanced Data Rates for GSM Evolution) – UMTS (Universal Mobile Telecommunications System) – HSDPA (High Speed Downlink Packet Access)’ – EV-DO (Evolution Data Optimized) – SMS (Short Message Service) • Fourth generation standards are under development – Some are Wi. MAX-based Chapter 7 Understanding Computers, 12 th Edition 49

Networking Hardware • Network adapter: Used to connect a PC to a network or the Internet – Also called network interface card (NIC) when in the form of an expansion card – Available in a variety of formats • PCI and PCIe • USB • PC Card and Express. Card – Adapter must match the type of network being used (Ethernet, Wi-Fi, Bluetooth, etc. ) – Are often built into portable computers Chapter 7 Understanding Computers, 12 th Edition 50

Network Adapters Chapter 7 Understanding Computers, 12 th Edition 51

Networking Hardware • Modem: Device that connects a computer to the Internet or to another computer – Term used for Internet connection device, even if not connecting via a phone line – Type of modem needed depends on the type of Internet access being used • Conventional dial-up • Cable • Fixed wireless • DSL • These and other types of Internet access are discussed in Chapter 8 Chapter 7 Understanding Computers, 12 th Edition 52

Modems Chapter 7 Understanding Computers, 12 th Edition 53

Networking Hardware for Connecting Devices and Networks • Hub: Central device that connects all of the devices on the network • Switch: Connects devices and identifies the device on the network for which the data is intended and sends the data only to that node • Wireless access point: Used to connect devices to a network wirelessly • Gateway: A devices that connects two different networks – Bridge: Usually connects wired LANs – Router: Connects networks and plans path (routes traffic) • Can be wired or wireless Chapter 7 Understanding Computers, 12 th Edition 54

Other Networking Hardware • Repeater: Amplifies signals along a network • Range extender: Repeater for a wireless network • Antenna: Used when Wi-Fi networks need to go further than hardware normally allows – Higher-gain antennas can be used with routers – Some network adapters can use an external antenna • Multiplexer: Combines transmissions from several different devices to send them as one message • Concentrator: Combines messages and sends them via a single transmission medium in such a way that all of the messages are active Chapter 7 Understanding Computers, 12 th Edition 55

Networking Hardware Chapter 7 Understanding Computers, 12 th Edition 56

Summary • What Is a Network? • Networking and Communications Applications • Types of Networks • How Does Data Travel Over a Network? • Networking Standards and Communications Protocols • Networking Hardware Chapter 7 Understanding Computers, 12 th Edition 57