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EXTENDED LEARNING MODULE D NETWORK BASICS THE MODULE IN SHORT FORM… This module is a basic introduction to networks and their components. You’ll start out with the most simple types of networks and go on to the Internet, client/server systems, and then cover some network technologies. The first section describes peer-to-peer networks and what would be needed to set up a small network at home or in a dorm room. There are two possibilities for building a home network: (1) with Ethernet cards and network cabling or (2) using existing phone wiring. This section also covers adding wireless access to the home network. This section includes key terms such as peer-to-peer networks, network interface card, Ethernet card, router, Bluetooth, WiFi, and router. The second section discusses the five ways of accessing the Internet 1. Telephone or dial-up connection (key terms such as telephone modem) 2. Digital Subscriber Line (DSL) 3. Cable modem (key terms such as cable modem) 4. Internet over satellite 5. Wireless Internet connection (key terms such as Palm OS, Pocket PC OS, Wireless Internet service provider, and personal digital assistant) The third section deals with client/server networks, first from a business viewpoint and then briefly from the point of view of physical components including key terms such as client/server network and communications protocol. The next section covers the classification of networks by geographical distance (key terms such as local area network, municipal area network and wide area network) wired telecommunications media (key terms such as coax and optical fibre) wireless telecommunications media (key terms such as infrared, microwave, repeater, and communications satellite). The last section discusses communications service providers and the ownership options that are available. STUDENT LEARNING OUTCOMES 1. 2. 3. 4. 5. 6. Identify and describe the four basic concepts on which networks are built. List the components you need to set up a small peer-to-peer network at home. Compare and contrast the various Internet connection possibilities. Describe client/server business networks from a business and physical point of view. Define local area networks (LANs), municipal area networks (MANs), and wide area networks (WANs). Compare and contrast the types of communications media. D-1 EXTENDED LEARNING MODULE D LECTURE OUTLINE INTRODUCTION (p. 426) 1. Basic Principles of Networks PEER-TO-PEER HOME NETWORK (p. 427) 1. Home Network Components 2. Wireless Access to Your Home Network 3. Home Network with Existing Home Wiring INTERNET ACCESS (p. 431) 1. Telephone or Dial-Up Connection 2. Digital Subscriber Line (DSL) 3. Cable Modem 4. Internet over Satellite 5. Internet Access on Multiple Computers 6. Wireless Internet Connection BUSINESS NETWORKS (p. 435) 1. Client/Server: A Business View 2. Client/Server: A Physical View LANs, MANs, WANs, AND COMMUNICATIONS MEDIA (p. 441) 1. Classification of Networks by Geographic Distance 2. Telecommunications Media: The Paths That Carry Information 3. Bandwidth 4. Wired Communications Media 5. Wireless Communications Media 6. Infrared and Omnidirectional Microwave for Short Distances 7. Directional Microwave for Medium Distances 8. Satellites for Long Distances COMMUNICATIONS SERVICE PROVIDERS (p. 445) 1. Key Considerations for Communications Media END OF MODULE (p. 448) 1. Summary: Student Learning Outcomes Revisited 2. Key Terms and Concepts 3. Short-Answer Questions 4. Assignments and Exercises D-2 EXTENDED LEARNING MODULE D KEY TERMS AND CONCEPTS KEY TERMS AND CONCEPTS Bandwidth Bluetooth Broadband Cable modem Cat 5 (Category 5) Client/server network Coaxial cable (coax) Communications medium Communications protocol (protocol) Communications satellite Communications service provider Computer network Digital Subscriber Line (DSL) Ethernet card Firewall Handspring Home PNA (Phoneline Networking Alliance) Infrared International virtual private network (International VPN) Local area network (LAN) Microwave Municipal area network (MAN) Network hub Network interface card (NIC) Optical fibre Palm Palm Operating System (Palm OS) Peer-to-peer-network Personal digital assistant (PDA) PNA adapter Card Pocket PC Pocket PC OS (Windows CE) Private network Public network Repeater Router Satellite modem Switch Telephone modem (modem) Value-added network (VAN) Virtual private network (VPN) Wide area network (WAN) D-3 TEXT PAGE 442 430 431 433 428 435 443 442 440 445 445 426 432 427 428 435 430 444 447 442 444 442 427 427 443 435 435 427 434 430 435 435 446 445 444 428 433 428 431 446 446 442 EXTENDED LEARNING MODULE D WiFi (Wireless Fidelity or IEEE 802.11b) Wired communications medium Wireless network access point (wireless access point) Wireless communications media Wireless Internet service provider (wireless ISP) D-4 429 442 429 442 434 EXTENDED LEARNING MODULE D SUPPORT Extended Learning Modules XLM/C – this is a good module to cover if your students need an introduction to computer hardware and software, essential for understanding networks. XLM/B – which discusses computer crime and forensics and would be good to cover in conjunction with this one since it discusses how networks can be abused. Web Support (www.mcgrawhill.ca/college/haag) Wireless technologies Web access Network technologies D-5 EXTENDED LEARNING MODULE D Introduction INTRODUCTION This module covers networks, including the basic components common to all networks. It includes discussions of small home or dorm networks, different types of Internet access, business networks, classifications of networks, telecommunications media, and communications service providers. Key Term: Computer network - two or more computers connected so that they can communicate with each other and share information, software, peripheral devices, and/or processing power. Basic Principles of Networks (p. 426) Key Points: An important point to stress is that networks come in all sizes from two computers connected to share a printer, to the Internet, which joins millions of computers. Some basic principles apply to all networks no matter what size they are: Each computer on the network must have a network card. The network usually has a connecting device like a hub or a router that ties the computers together. The network must have some sort of communications channel to allow information to move between devices. Each computer must have network operating system software. Concept Reinforcement: Adding Value – Class Participation Start by asking your students what sort of tasks they use computer networks for. For example, if they access journal article databases, they most likely use a network. If they enroll in classes online or use a course delivery tool like Blackboard, they use a network. And, of course, if they use e-mail or the Web, they’re using a network. PEER-TO-PEER HOME NETWORK This section provides an introduction to peer-to-peer networks, the simplest kind of networks that share information, software, and peripheral devices. Key Points: A peer-to-peer network, at its most basic, would connect two computers or two computers and a printer so that the two computers could use the same printer. You can set up a simple home network in one of two ways: (1) with Ethernet cards, network cabling, and a hub; or (2) with existing phone wiring. Key Term: Peer-to-peer network – a network in which a small number of computers share hardware (such as a printer), software and/or information. Home Network Components (p. 427) Key Points: For a small number of computers, you can set up a network with four basic components D-6 EXTENDED LEARNING MODULE D Peer-to-Peer Home Network The components are Ethernet cards – one for each computer. Direct your students’ attention of the photo of an Ethernet expansion card for desktop computers and the PC Card Ethernet adapter for notebooks. a home router – to connect the computers together cables – as channels between devices on which information will travel operating system software that supports information transfer between computers – any of the newer versions of Windows Key Term: Network interface card (NIC) – an expansion card or a PC Card (for a notebook computer) that connects your computer to a network and provides the doorway for information to flow in and out. Key Term: Ethernet card – the most common type of network interface card. Key Points: Network connecting devices tie computers together so that information and messages can pass between them. Network connecting devices include network hubs, switches, and routers. See Figure D.1 on page 428 for a graphical representation of the differences between these devices. A network hub allows only one connection at a time. It’s similar to a four-way stop in which only one car can cross the intersection at a time. A switch allows multiple communications links simultaneously, like a four-leaf clover that allows cars to move in several different directions at once. A router is a switch with the capability of keeping traffic traveling between computers in a network from being transmitted outside that network, and checking incoming traffic before letting it through. For home networks, routers are probably the best, since a router, because it keeps local network traffic in and monitors traffic from the outside, also acts as a firewall and will bring a measure of protection to a home network. Key Term: Network hub – a device that connects multiple computers into a network. Key Term: Switch – a device that connects multiple computers into a network in which multiple communications links can be in operation simultaneously . Key Term: Router – a device that acts as a smart hub connecting computers into a network, and it also separates your network from any other network it’s connected to. Key Term: Firewall – software and/or hardware that protects a computer or network from intruders. Key Points: The most common transmission medium for a home network is Cat 5 cable. Cat 5 cable has RJ-45 connectors on each end. One end plugs into a computer and the other end goes into the home router. RF-45 connectors look just like regular phone cable connectors, except that they’re bigger. See Figure D.2 on page 429 for a typical home network configuration. D-7 EXTENDED LEARNING MODULE D Peer-to-Peer Home Network Key Term: Cat 5 or Category 5 cable – a better constructed version of the phone twisted-pair cable. Concept Reinforcement: Extended Learning Module B – Computer Crime and Forensics Since a lot of computer crime is perpetrated using networks, this would be a good place to include material from module B. Firewalls and other protective measures are discussed in module B. Chapter 8 is also relevant here since, in that chapter, we discuss ethics and the use and value of information that is usually stored in networks Wireless Access to Your Home Network (p. 429) Key Points: Many networks now allow wireless access. For wireless information transmission to work, you need a wireless access point on the network. A wireless access point has a receiver and a transmitter to move information in and out of the network. The notebook computer must have a wireless PC card, which also has a receiver and a transmitter. WiFi and Bluetooth are two types of wireless technology that are popular at the moment. Key Term: Wireless network access point or wireless access point – a device that allows computers to access a network using radio waves. Key Term: WiFi or Wireless Fidelity or IEEE 802.11b – a way of transmitting information in wave form that is reasonably fast and is often used for notebooks. Key Term: Bluetooth – technology that provides entirely wireless connections for all kinds of communications devices. Key Points: Hardware alone is never enough, you always need software for the hardware do its job. For peer-to-peer home networks, the Windows operating system is all you need. Home Network with Existing Phone Wiring (p. 430) Key Points: Another way to get a home network is to use existing phone wiring. See Figure D.3 on page 430 for a graphical representation of how PNA works. You won’t need cabling or a router All you need are PNA adapter cards for each computer. Key Term: Home PNA – allows you to network your computers using telephone wiring. Key Term: PNA adapter card – an expansion card that you put into your computer to act as a doorway for information flowing in and out. D-8 EXTENDED LEARNING MODULE D Peer-to-Peer Home Network Concept Reinforcement: Adding Value – Class Participation You can find out more about creating a small network with existing phone wiring at www.homepna.org The site has lots of information that would be useful if your students want to set up a small network. INTERNET ACCESS This section discusses the five ways you can access the Internet. Key Points: Your choices for Internet connections are telephone or dial-up modem DSL cable modem satellite modem wireless ISP connection DSL, cable, satellite and wireless are all broadband Key Term: Broadband – a high-capacity telecommunications pipeline capable of providing high-speed Internet service. Telephone or Dial-Up Connection (p. 431) Key Points: For a telephone or dial-up modem you need a phone line, a modem, and an ISP. A modem converts the digital signal from your computer to the analog signal of the phone line, i.e. it modulates the signal for outgoing messages. For incoming messages, the modem demodulates the signal (see Figure D.4 on page 431). Telephone modems are often part of more modern motherboards in both desktop and notebook computers. A telephone modem is the slowest type of Internet connection. Key Term: Telephone modem or modem – a device that connects your computer to your phone line so that you can access another computer or network. Concept Reinforcement: Adding Value – Class Participation Sometimes people are bothered by the dialing and screeching sounds when using a dial-up modem If your students ask you how to silence this process, tell them the following Your modem's speaker is controllable through the Windows Control Panel. Select Start, then Settings, and highlight Control Panel. Double-click on the Modems icon. Highlight the modem you are using, click the Properties button and go to the General tab. Move the volume slide bar down or off and click OK. D-9 EXTENDED LEARNING MODULE D Internet Access Digital Subscriber Line (DSL) (p. 432) Key Points: A DSL Internet connect uses phone lines as the transmission medium, but it’s much faster than a dial-up modem, and uses only part of the phone line so that the line is still available for phone calls (see Figure D.5 on page 432). The big disadvantage is that, to get a DSL connection, you have to live within 4.8 km or so of the phone company building or one of its COs (Central Offices) which are located throughout metropolitan areas. Your speed, which depends on the type of DSL you have and how far from the phone company your computer is, is guaranteed, i.e. it will not slow down with more users on the system. Key Term: Digital Subscriber Line (DSL) – a high-speed Internet connection using phone lines, which allows you to use your phone for voice communications at the same time. Cable Modem (p. 432) Key Points: A cable modem allows you to get access to the Internet through the same cable that brings you cable TV. A splitter in your home divides the signal between your cable modem and the TV (see D.6 on page 433). Your service will slow down as more people in your neighbourhood get onto the Internet with their cable modems. Key Term: Cable modem – a device that uses your TV cable to deliver an Internet connection. Concept Reinforcement: Adding Value – Class Participation Students may ask your advice on whether a cable modem is better than DSL or vice versa. The answer to this question is a hotly debated issue. On major advantage of DSL modems is that their speed is constant because you have your own “pipeline” to the Internet, and you’re not affected by the number of people concurrently using the ISP’s service. All cable modems from one provider share a single “pipeline” to the Internet. The speed of your transmission will depend partly on how many other people are using the pipeline. The more people, the slower the traffic for all users. Internet over Satellite (p. 433) Key Points: A newer mode of Internet access is Internet over satellite (IoS) which uses a satellite dish similar to the satellite dish that delivers TV service (see Figure D.7 on page 434). Satellite Internet access requires: an appropriate satellite dish a satellite modem D-10 EXTENDED LEARNING MODULE D Internet Access cable between the satellite modem and the dish an unobstructed view to the sky in the direction of the equator, above which the satellite floats. Key Term: Satellite modem – a modem that allows you to get Internet access from a satellite dish. Internet Access on Multiple Computers (p. 434) Key Points: DSL, cable, or satellite Internet connections will allow you to use a single Internet connection for all the computers on your home network. Simply connect the router to the appropriate modem. The router has private IP addresses which it will assign to the computers on the network and route traffic accordingly. Concept Reinforcement: Adding Value – Class Participation If you have, or can get, an old router, modem card, Ethernet card, or any other network parts, it will help reinforce your presentation to pass the part around the classroom and let students examine it for themselves. Even if you only have a piece of phone wire, you can bring it in and say that an RJ-45 connector is just like the phone connector, but bigger. Wireless Internet Connection (p. 434) Key Points: ISPs are increasingly offering wireless Internet connections. Usually you access the wireless ISP with a notebook computer or PDA. To get access, you have to be within range of a wireless access point of the ISP. Cell phones are now being sold that allow Internet access. Key Term: Wireless Internet service provider or wireless ISP – does the same job as standard Internet service providers except that you don’t need a wired connection for access. Key Term: Personal digital assistant (PDA) – a small hand-held computer that helps you surf the Web and perform simple tasks such as note taking, calendaring, appointment scheduling, and maintaining an address book. Key Term: Palm – a type of PDA that runs on Palm Operating System (Palm OS). Key Term: Handspring– a type of PDA that runs on Palm Operating System (Palm OS). Key Term: Pocket PC – a type PDA that runs on Pocket PC OS (Windows CE). Key Term: Palm Operating System (Palm OS) – the operating system for Palm and Handspring PDAs. Key Term: Pocket PC OS – the operating system for Pocket PCs. D-11 EXTENDED LEARNING MODULE D Internet Access BUSINESS NETWORKS Business networks are usually client/server networks rather than peer-to-peer. The server or servers are usually high-end PCs or minicomputers. The advantages of client/server networks include decreased cost in software since a network license is often cheaper than separate software packages for each computer easier and faster updates of software packages better control and security when shared information is on the server Client/Server: A Business View (p. 435) Key points: The term “client/server network” can mean either the physical structure of a network or the way in which tasks are allocated among server and clients. There are five basic client/server models and they differ according to three factors (see Figure D.9 on page 438). 1. where presentation of information is formatted 2. where processing of the logic or business rules takes place 3. where the database and database management system are located Model 1 – Distributed Presentation: server handles database management, logic, and part of the presentation function Model 2 – Remote Presentation: client handles all presentation functions. Model 3 – Distributed Logic: server handles all data management and client handles presentation function, but logic processing is shared. Figure D.10 on page 440 shows a graphic representation of Model 3. Model 4 – Remote Data Management: server handles data management only and client processes logic and presentation formatting. Model 5 – Distributed Data Management: client handles all presentation formatting and logic processing but server and client share data management duties. See Figure D.8 on page 436 for a graphical representation of this implementation. Note that “distributed” in the model type means “shared” and remote means “all of it on one side or the other.” Key Term: Client/server network – a network in which one or more computers are servers and provide services to the other computers which are called clients. Concept Reinforcement: Team Work – What Sort of Computer Network Does Your School Have (p. 436) This assignment is intended to get your students to relate the network discussion to the network they use at school. This will only be a helpful exercise if the computer technicians at your school don’t object to getting lots of questions from students. D-12 EXTENDED LEARNING MODULE D Business Networks As an alternative, you could ask one of your institution’s technical people to come to the class and talk about your network. Client/Server: A Physical View (p. 439-441) Key Points: Physical implementations of networks are many and varied. The same basic principles apply to large networks as well as small, but large networks are much more complicated. There are many more hardware and software considerations in a large client/server network than in a small peer-to-peer. In a large network, there are many types of connecting devices, and other devices like multiplexors, and so on. A client/server network requires server operating system software. Figure D.11 on page 441 shows a client/server network for a typical network in a medium-sized business. Key Term: Communications protocol or protocol – a set of rules that every computer follows to transfer information Concept Reinforcement: On Your Own – How Is a Server Different from a Client Computer? (p. 443) This assignment will help your students better understand the concept of a server. Any of the major computer-sales Web sites have servers. Generally, a server has more memory than a regular PC. A server usually has large hard disk capacity, and perhaps multiple disks. Often servers have RAID systems to mirror everything saved to the hard disk. LANs, MANs, WANs, AND COMMUNICATIONS MEDIA Networks can be classified by geographic distance and network computers can be connected by many types of communications media. Classification of Networks by Geographic Distance (p. 442) Key Points: There are three basic types of networks that are classified by geographic distance Local area network (LAN) Municipal area network (MAN) Wide area network (WAN) Key Term: Local area network (LAN) – covers a limited geographic distance, such as an office, building, or a group of buildings. Key Term: Municipal area network (MAN) – covers a metropolitan area. D-13 EXTENDED LEARNING MODULE D LANs, MANs, WANs, and Communications Media Key Term: Wide area network (WAN) – covers large geographic distances, such as a state, a country, or even the entire world. Concept Reinforcement: Adding Value – Class Participation Be sure to stress to your students that building, maintaining, administering and managing networks is one of the hottest fields in computing today. Ask students to find job descriptions and salary ranges for network administrators. Telecommunications Media: The Paths That Carry Information (p. 442) Key Points: Networks transmit information from one place to another by means of communications media. Communications media can be wired or wireless. Wired communications media include Twisted-pair cable Coaxial cable Optical fibre Wireless communications media include Microwave Satellite Infrared Key Term: Communications medium - the path, or physical channel, in a network over which information travels. Key Term: Wired communications medium - transmits information over a closed, connected path. Key Term: Wireless communications medium – transmits information through the air. Bandwidth Key Points: Communications media capacity is measured in bits per second (bps), thousands of bits per second (Kbps), and millions of bits per second (Mbps), and gigabits per second (Gbps). Band width is comparable to the size of a drinking straw; the wider the straw, the more liquid you get per unit of time. Key Term: Bandwidth – capacity of the communications medium, refers to the amount of information that a communications medium can transfer in a given amount of time. Wired Communications Media (p. 443) Key Points: Twisted-pair cable comes in several varieties, from Cat 1 to Cat 5 (see photo on page 443). Most of the world’s phone system is twisted pair. D-14 EXTENDED LEARNING MODULE D LANs, MANs, WANs, and Communications Media Cat 1 twisted pair cable provides a slow but reasonable reliable conduit for phone service, but can cause errors in data transmission. Cat 5 is much more reliable. Coax is an alternative to twisted-pair cable (see photo on page 443). Coax is commonly used for leased-line private networks . Key Term: Coaxial cable or coax – is one central wire surrounded by insulation, a metallic shield, and a final case of insulating material. Key Points: Optical fibre cable has many advantages over twisted-pair and coax. It has the diameter of a human hair with a capacity of over 1,400 Mbps and much better security. Fibre optic cable is expensive and more difficult to install and maintain than twisted-pair and coax. Key Term: Optical fibre – uses a very thin glass or plastic fibre through which pulses of light travel (see photo on page 443). Concept Reinforcement: Adding Value – Class Participation Optical fibre cable is very expensive to install, so it’s usually used as the main cable, or backbone, of a network only. If you bring fibre optical fibre to each computer, you’ll spend a lot more in installation and will also have to buy special network cards that can cost up to 10 times the cost of regular network cards. Wireless Communications Media (p. 444) Key Points: Wireless communications media are good for rugged terrain, large distances, and situations where people are in motion. Wireless communications media radiate information through the air. Data security is one of the problems with wireless communications, and encryption methods are improving. Infrared and Omnidirectional Microwave for Short Distances (p. 444) Key Points: Infrared transmission is good for short distances and is used to connect hand-held devices to other devices like printers. Wireless keyboards and mice are usually infrared. Apart from infrared, microwave can also be used for short distances. WiFi and Bluetooth are two types of microwave transmission for short distances. Key Term: Infrared – a wireless communications medium that uses light waves to transmit signals or information. Key Term: Microwave – a type of radio transmission. Concept Reinforcement: Adding Value – Class Participation D-15 EXTENDED LEARNING MODULE D LANs, MANs, WANs, and Communications Media Many wireless products use infrared. To expand this discussion you could mention devices other than wireless keyboards and mice. At www.irda.org/products/index.asp you can find a list that includes cell phones, digital cameras, toys, and wrist watches. Directional Microwave for Medium Distances (p.444-445) Key Points: Microwave can be used for medium distances. Since microwave waves radiate in a straight line and don’t follow the curvature of the earth, repeaters are used to bring the signal back down and strengthen it before sending it on. See Figure D.12 on page 444 for an illustration of medium distance microwave data transmission Key Term: Repeater – a device that receives a radio signal, strengthens it and sends it on. Satellites for Long Distances (p. 445) Key Points: For very long distances, like from one continent to another, you can also use microwave data transmission. These microwave transmissions are captured by satellites in space, 22,500 miles up and then bounced back down to earth. Many businesses use satellite data transmission because it’s a cost-effective way of moving a lot of information. See Figure D.13 on page 445 for an illustration of how it works. Key Term: Communications satellite – microwave repeater in space. Concept Reinforcement: Adding Value – Class Participation Students may ask about putting up satellite dishes in places where they are prohibited by zoning regulations, condominium rules, or other regulations. Legally speaking, as long as the dish is less than one metre across (about 39 inches) it’s protected by Congress in Section 207 of the Telecommunications Act of 1996, in the Federal Communications Commission’s Over-the-Air Reception Devices Rule. This rule “prohibits restrictions that impair a person's ability to install, maintain, or use an antenna covered by the rule. It applies to state or local laws or regulations, including zoning, land-use or building regulations, private covenants, homeowners' association rules, condominium or cooperative association restrictions, lease restrictions, or similar restrictions on property within the exclusive use or control of the antenna user where the user has an ownership or leasehold interest in the property.” See the details of the rule at the FCC Web site at www.fcc.gov/mb/facts/otard.html#Q COMMUNICATIONS SERVICE PROVIDERS There are several different options available for network construction and use. D-16 EXTENDED LEARNING MODULE D Communications Service Providers Key Points: Network ownership determines your rights to the network and the level of cost, availability, services provided, speed, and security you get. Small networks are usually private. For wider reach, you can outsource network construction to one of many communications service providers. Your choices are public, private, value-added , and virtual private networks. See the table in Figure D14 on page 446 for a comparison of network ownership options. Key Term: Communications service providers – third parties who furnish the conduit for information. Key Term: Public network – a network on which your organization competes for time with others. Key Term: Private network – the communications media that your organization owns or exclusively leases to connect networks or network components. Key Term: Value-added network (VAN) – a semipublic network that provides services beyond the movement of information from one place to another. Key Term: Virtual private network – uses software to establish a secure channel on the Internet for transmitting data. Key Term: International virtual private network (International VPN)– a virtual private network that depends on services offered by phone companies of various nationalities. Key Considerations for Communications Media (p. 448) Key Points: To determine the most appropriate communications medium, the following factors need to be considered Capacity or bandwidth Reliability Cost Distance Mobility Concept Reinforcement: Team Work – What’s the Big Deal with Frequencies? (p. 447) Students sometimes have a difficult time understanding that wireless devices use a part of the radio frequency spectrum. This assignment helps to clarify this fact. The answers are: WiFi: 2.4 GHz GPS Devices: 1227 to 1575 MHz Microwave Ovens: 2.5 GHz D-17 EXTENDED LEARNING MODULE D Communications Service Providers Police Radar Guns: x-band guns 10.525 GHz and k-band guns 24.15 GHz TV Channels 2-6: 54-88 MHz Wildlife tracking Collars: 215-220 MHz CB Radio: 26.96 – 27.41 MHz Aviation Navigation: 960 – 1251 MHz Cordless Phones: 40 -50 MHz or newer models run at 900 MHz D-18 EXTENDED LEARNING MODULE D Summary: Student Learning Outcomes Revisited SUMMARY: STUDENT LEARNING OUTCOMES REVISITED In each chapter and module, we revisit the student learning outcomes as a mechanism and format for summarizing the chapter. You’ll find this content for Extended Learning Module D on pages 448-449. Following the adage “Tell them what you’re going to tell them, tell them, and then tell them what you told them,” you should walk through the summary with your students. You should also inform your students that the summary is great support for studying for exams. D-19 EXTENDED LEARNING MODULE D Short-Answer Questions SHORT-ANSWER QUESTIONS (p. 450) 1. What is a computer network? ANSWER: A computer network (or a network) is two or more computers connected so that they can communicate with each other and share information, software, peripheral devices, and/or processing power. p. 426 2. What is a peer-to-peer network? ANSWER: A peer-to-peer network is a network in which a small number of computers share hardware (such as a printer), software and/or information. p. 427 3. How is a peer-to-peer different from a client/server network? ANSWER: A client/server network is a network in which one or more computers are servers and provide services to the other computers which are called clients. On the other hand a peer-to-peer network is a network in which a small number of computers share hardware (such as a printer), software and/or information, and there is no server. p. 435 4. What is an Ethernet card? ANSWER: An Ethernet card is the most common type of network interface card. p. 427 5. What does a network hub do? ANSWER: A network hub is a device that connects multiple computers into a network. p. 427 6. How does an Ethernet network work? ANSWER: An Ethernet network works by broadcasting every message to all the computers on the network. All the computers check the recipient address, and the computer that is the recipient accepts the message. p. 428 7. What is Cat 5 cable used for? ANSWER: Cat 5 cable is used to connect computers and other devices into a network hub so that information can pass between the computers and devices. p. 428 8. What is Bluetooth? ANSWER: Bluetooth technology provides entirely wireless connections for all kinds of communications devices. p. 430 9. What do you need to have a dial-up connection to the Internet? ANSWER: You would need a phone line, a telephone or dial-up modem and an ISP. p. 431 10. How is a DSL Internet connection different from a telephone modem connection? ANSWER: Both use the phone line, but DSL is faster and doesn’t tie up the phone line when you’re on the Internet. p. 432 11. What is a satellite modem? ANSWER: A satellite modem is a modem that allows you to get Internet access from a satellite dish. p. 433 D-20 EXTENDED LEARNING MODULE D Short-Answer Questions 12. How is client/server model 1 different from client/server model 2? ANSWER: In client/server model 1 the presentation function is shared between the server and client, whereas in client/server model 2, the presentation is all on the client side. p. 437 13. What does WiFi do? ANSWER: A WiFi or Wireless Fidelity or IEEE 802.11b is a way of transmitting information in wave form that is reasonably fast and is often used for notebooks. p. 429 14. What are communications service providers? ANSWER: A communications service provider is a third party who furnishes the conduit for information. p. 445 D-21 EXTENDED LEARNING MODULE D Short-Question Answers SHORT-QUESTION ANSWERS 1. A network card in each computer, a connecting device, a communications medium, and a network operating system. QUESTION: What are the basic components of a computer network? p. 426 2. A network in which one or more computers are servers and provide service to the other computers which are called clients. QUESTION: What is a client/server network? p. 435 3. A wireless communications medium that uses a red light that’s below what your eye can see. QUESTION: What is infrared? p. 444 4. The amount of information that communications medium can transfer in a given amount of time. QUESTION: What is bandwidth? p. 442 5. A semipublic network that provides services beyond the movement of information from one place to another. QUESTION: What is a value-added network (VAN)? p. 446 6. It is a better-constructed version of ordinary phone cable. QUESTION: What is Cat 5 cable? p. 428 7. It’s used as a communications medium for phone networks. QUESTION: What is twisted-pair cable? p. 443 8. It covers large geographic distances, such as a state, a country, or even the entire world QUESTION: What is a WAN? p. 442 9. A device that acts as a smart hub connection into a network and separates your network from any other network it’s connect to. QUESTION: What is a router? p. 428 10. A standard for wirelessly accessing a local area network. QUESTION: What is WiFi? p. 429 11. A device that uses your TV cable to deliver an Internet connection. QUESTION: What is a cable modem? p. 433 12. It uses a very thin glass or plastic tube through which pulses of light travel. QUESTION: What is optical fibre? p. 443 13. A network on which your organization competes for time with others. QUESTION: What is a public network? p. 445 D-22 EXTENDED LEARNING MODULE D Short-Question Answers 14. It takes a message, strengthens it, and passes it along. QUESTION: What is a repeater? p. 444 15. The paths, or physical channels, in a network over which information travels from one place to another. QUESTION: What are communications media? p. 444 D-23 EXTENDED LEARNING MODULE D Assignments and Exercises ASSIGNMENTS AND EXERCISES (p. 450-451) 1. Investigate Cell Phone Technology. A wireless device that you may have used, or perhaps use all the time, is a cell phone. A cell phone is actually a radio (with a transmitter and a receiver) and uses radio waves of certain frequencies. There are different systems (called cellular access technologies) for cell phones: TDMA, GSM, CDMA. Go to the Web and find the answers to the following questions (hint: a good place to look is www.howstuffworks.com ) A. What do the letters stand for? B. What’s the difference between them? C. Why are they called “cell” phones? D. Why was this “cellular” method used in the first place? DISCUSSION: A. The letters stand for the following CDMA: Code Division Multiple Access GSM: Global System for Mobile Communications TDMA: Time Division Multiple Access B. Following is a summary of the difference between them. TDMA fits three digital conversations into a FDMA channel, enabling compatibility with FDMA while enabling digital services and boosting capacity by a factor of three. This technology has no flexibility for varying digital data rates and has no accommodation for silence in a conversation. CDMA systems have no channels, but instead encode each call as a coded sequence across the entire frequency spectrum. Each conversion is modulated with a unique code that makes it distinguishable from other calls in the frequency spectrum. CDMA offers far greater capacity and variable data rates depending on the audio activity, many more users can be fit into a given frequency spectrum and higher audio quality can be provided. GSM uses a modified and far more efficient version of TDMA. GSM keeps the idea of timeslots and frequency channels, but the timeslots are smaller. However, when a call is inactive fewer timeslots are used. To facilitate filling in gaps left by unused timeslots, calls do “frequency hopping” in GSM. This means that calls will jump between channels and timeslots to maximize the system’s usage. A control channel is used to communicate the frequency hopping and other information between the cell tower ad the phone. C. The system is called “cellular” because it uses many base stations to divide a service area into multiple ‘cells’ or areas of service. Cellular calls are transferred from base station to base station as a user travels from cell to cell. D. The cellular method was used in the first place because researchers looked at early versions of mobile phones and realized that by using small cells with frequency reuse they could increase traffic capacity. However, at the time the technology to do this was not yet available. Later, the FCC later granted AT&T a number of radio-spectrum frequencies so that they could research the new technology. D-24 EXTENDED LEARNING MODULE D Assignments and Exercises 2. Find out about Personal Digital Assistants. Many people have personal digital assistants (PDAs) which are handheld computers that allow you to perform many computer tasks wirelessly. Some of the features of PDAs are calendar management, appointment management, mini spreadsheets and word processing capabilities, Web access, and sometimes even double as a cell phone. Do some research on PDAs and answer the following questions: A. What are three other features common in PDAs that were not listed above? B. What does the term “synching” mean? C. What are the two types of handwriting recognition systems used on PDAs. DISCUSSION: A. Your students could come up with a variety of features. A few examples would be e-mail, voice recorders, MP3 players, and digital cameras. B. “Synching” means passing information between PDA’s and desktop or notebook computers. It allows you to add or update programs as well as have a backup of all your PDA information. This term is also called synch or synchronizing. C. The two types of handwriting recognition systems used on PDA’s today are Graffiti and JOT. Calligrapher is also another very notable handwriting recognition system. 3. What Are the Internet Access Options in Your Area? Write a report on what sort of Internet connections are available close to you. How many ISPs offer telephone modem access? Is DSL available to you? Is it available to anyone in your area? Does your cable company offer a cable modem? Can you get wireless Internet access in your area? Compare each available service on price and extras like a help line, or people who will come out to your home and help you if you’re having difficulties. What type of Internet connection do you currently use? Do you plan to upgrade in the future? If so, to what type of connection? If not, why not? DISCUSSION: Answers from your students will depend, of course, on where you’re located. The point of this exercise it to make sure your students are aware of the options available to them As an added feature to this assignment, ask students to compare what’s available in their home town compared to their college town. D-25 EXTENDED LEARNING MODULE D Assignments and Exercises 4. Investigate Building Your Own Home Network. Build your own home network on paper. Assume you have the computers already and just need to link them together. Find prices for hubs and routers on the Web. Also research Ethernet cards and cables. If you were to get a high-speed Internet connection, like a cable modem or DSL modem, how much would they cost? Can you buy your own or would you have to rent the modems from the phone or cable company? DISCUSSION: Your students answers could vary based on the hardware specifics that they chose, but below is a range of prices for all hardware components mentioned. At the time of writing you can buy a range of hubs that vary in size and performance. 4-5 port hubs usually range in price from about US $30 to $50. At the moment you can buy a range of routers that vary in size and performance based on your needs. Four-port routers usually range in price from US $20 (after rebates) to $150 There are various makes of Ethernet cards on the market, but they generally cost somewhere in the region of US $40 or $50. Cables of various lengths are available at prices in the neighbourhood from US $3 for 3ft. cables to $5 for 7 ft cables. The cost of a high-speed Internet connection will vary depending on where you’re located. At the time of writing, cable modems range in price from about US $80 to $130. DSL modems range in price from US $200 to $700. 5. Investigate Satellite Radio. At the time of writing there are two satellite radio stations: Sirius and XM. Do a little surfing on the Web and find out if there are any others now. Also find out what you have to buy to install each type, how much the antenna costs, how the system would work in your car, and how much the monthly subscription is. DISCUSSION: At the time of writing, there are currently only two satellite radio systems, Sirius and XM. But, that situation could have changed by the time you assign this project. The cost of the satellite radio system right now typically includes a monthly charge of US $9.99 for XM and US $12.95 for Sirius. There are two options for what you need to receive satellite radio and the options are as follows: you can get a portable unit that sends a signal through your radio player or you could get a satellite ready receiver and a satellite ready radio. Typical cost for antennas range from US $50 to $80. 6. Find out about Firewalls. Go to the Web and find out about software and hardware that protects your computer and home network, respectively. A. If you only have one computer connected to the Internet, then a software firewall like Zone Alarm will most likely be enough protection from intruders. Find three different firewall software packages on the Web. A good place to start looking would be the sites that sell anti-virus software. Compare the firewall software on price and features. Some sites to try are as follows: Symantec at www.symantec.com D-26 EXTENDED LEARNING MODULE D Assignments and Exercises TREND Micro at www.trendmicro.com Virus List (a virus encyclopedia) at www.viruslist.com McAffee at www.mcaffee.com B. If you have a home network, then you’d be well advised to check into a hardware firewall. One place to look is at the LinkSys site (www.linksys.com) or any site that sells computer hardware. DISCUSSION: Some possible examples are as follows: McAffee: Personal Fire Wall Price US $49.95 (2 year subscription) Features include the following: Protection of personal Information Monitors Outbound Application Traffic Immediate Alerts Detailed Event Information Blocks or Allows Specified Internet Systems Hackerwatch.org Integration Automatic, 24x7 Online Updates Multi-Layered Security Symantec: Norton Personal Firewall Features include the following: Intrusion Detection Privacy Control Security Monitor Ad Blocking Inbound and Outbound Monitoring Network Notification Price US $49.95 Smith Micro: CheckIt Firewall Features include the following User friendly Identify Intruders Protect your data Always on Safety Price US $29.99 D-27