Fiber-optic cable transmits data as pulses of light through tiny tubes of glass.

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Chapter Outline

 Communications o The process of sharing data, programs, and information between two or more

computers including:

 E-mail

 Provides a fast, efficient alternative to traditional mail by sending and receiving electronic documents.

 Texting

 Provides very efficient direct text communication between individuals using short electronic messages.

 Video Conferencing

 Provides a very low-cost alternative to long-distance telephone calls using electronic voice and video delivery.

 Electronic commerce

 Buying and selling goods electronically. o Connectivity - using computer networks to link people and resources.

 Connecting personal computers to other computers and information sources almost anywhere.

 To be able to efficiently and effectively use computers becomes a matter of knowing about connectivity through networks to personal

computers and also about larger computer systems and information

resources

o The Wireless Revolution -  The single most dramatic change in connectivity and communications

in a decade has been the widespread use of mobile devices like

smartphones and tablets with wireless Internet connectivity.

 Allows individuals to stay connected with one another from almost anywhere at any time.

 It is estimated that over 1.5 billion smartphones are in use worldwide  While wireless technology was originally used primarily for voice

communications, many of today’s cell phones support e-mail, web

access, social networking, and a variety of Internet applications.

 Allows a wide variety of nearby devices to communicate with one another without any physical connection

 High speed Internet wireless technology allows individuals to connect to the Internet and share information from almost anywhere in the

world.

o Communications systems - electronic systems that transmit data from one location to another.

o Four basic elements of a communication system include:  Sending and receiving devices –

 often a computer or specialized communication device

 originates (send) as well as accept (receive) messages in the form of data, information, and/or instructions

 Connection devices –

 act as an interface between the sending and the receiving devices and communication channel

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 convert outgoing messages into packets that can travel across the communication channel and reverse the process for

incoming messages

 Data transmission specifications - rules and procedures that coordinate the sending and receiving devices by physically defining

how the message will be sent across the communication channel.

 Communication channel –

 transmission medium that carries the message

 medium can be a physical wire or cable, or it can be wireless

 Communications Channels o Essential element of every communication system o Carry the data from one computer to another. o Two categories of communication channels that connect sending and receiving

devices include physical and wireless connection

o Physical Connections- a solid medium to connect sending and receiving devices. These connections include:

 Twisted pair cable– pairs of copper wires twisted together

 Both standard telephone lines and Ethernet cables use twisted pair, See Figure 8-3

o Ethernet cables are often used in networks and to connect a variety of components to the system unit.

 Coaxial cable - a high-frequency transmission cable consisting of a single, solid copper core. See Figure 8-4.

 Used to deliver television signals as well as to connect computers in a network

 Fiber-optic cable - transmits data as pulses of light through tiny tubes of glass.

 Lighter, faster, and more reliable than coaxial cable

 Rapidly replacing twisted-pair cable telephone lines. o Wireless Connections o Do not use a solid substance to connect sending and receiving devices. o Data is moved through the air. o Primary technologies used for wireless connections are Bluetooth, Wi-Fi,

microwave, WiMax, cellular, and satellite connections.

 Bluetooth is a short-range radio communication standard that transmits data over short distances of up to approximately 33 feet.

Bluetooth is widely used for wireless headsets, printer connections,

and handheld devices.

 Wi-Fi (wireless fidelity) uses high frequency radio signals to transmit data. A number of standards for Wi-Fi exist, and each can send and

receive data at a different speed. Most home and business wireless

networks use Wi-Fi, See Figure 8-6

 Microwave - communication uses high-frequency radio waves. It is sometimes referred to as line-of-sight communication because

microwaves can only travel in a straight line.

 Because waves cannot bend with the curvature of the earth they can only be transmitted over relatively short distances.

 For longer distances, the waves must be relayed by means of microwave stations with microwave dishes or antennas.

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 WiMax (Worldwide Interoperability for Microwave Access) is a new standard that extends the range of Wi-Fi networks using microwave

connections. WiMax is commonly used by universities and others to

extend the capability of existing Wi-Fi networks.

 Cellular communication uses multiple antennae (cell towers) to send and receive data within relatively small geographic regions (cells);

most cell phones and mobile devices use cellular networks.

 Satellite - amplified microwaves that use point-to-point communication to relay devices (satellites) orbiting 22,000 miles

above the earth.

 Orbit at a precise point and speed above the earth.

 Many are offered by Interlsat, the International Telecommunications Satellite Consortium

 Amplify and relay microwave signals from one transmitter on the ground to another.

 Used to send and receive large volumes of data.

 Uplink is a term relating to sending data to a satellite

 Downlink refers to receiving data from a satellite

 Communication interferences can occur in bad weather.

 A network of satellites are owned and managed by the Department of Defense that continuously send location

information to earth

 Used by global positioning system (GPS) devices.

 Used by many smartphones and tablets

 Infrared uses infrared light waves to communicate over short distances

o Can only travel in a straight line and for short distances without obstructions

 Connection Devices o At one time nearly all computer communication systems used telephone lines

and analog signals. Computers use digital signals. A modem is required to

convert the digital signals to analog signals and vice versa.

o Modems (modulator-demodulator) -  Modulation is the name of the process of converting from digital to

analog

 Demodulation is the process of converting from analog to digital  Transfer rate is in bits-per-second; typically measured in millions of

megabits per second (Mbps)

 Three commonly used types of modems include:

 DSL (digital subscriber line) – uses standard phone lines to create a high-speed connection directly to the phone company’s

offices; external and usually use USB or Ethernet port to

connect to system.

 Cable – uses the same coaxial cable as a television to create a high-speed connection. Connect using USB or Ethernet port.

 Wireless (also known as a WWAN- wireless wide area network modem). Commonly a USB or special card ports that

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provides very portable high-speed connectivity from virtually

anywhere.

o Connection Service  T1– special high speed lines from telephone companies that support all

digital communications.

 T3 or DS3 provide higher capacity options

 Used by large companies.

 Too costly for most individuals.

 Have largely been replaced with optical carrier (OC) lines which are much faster.

 Dial-up - uses existing telephones and telephone modems to connect to the Internet. Very slow and has been replaced by other higher-speed

connection services.

 Digital subscriber line (DSL) - uses existing telephone lines to provide high-speed connections. Much faster than dial-up.

 ADSL (asymmetric digital subscriber line) is one of the most widely used types of DSL

 Cable service - use existing television cables to provide high-speed connections. Usually faster than DSL.

 Fiber Optic Service (FiOS) is a new technology in some areas but not widely available. Current providers of FiOS include Google and

Verizon with speeds faster than cable or DSL.

 Satellite connection services - use satellites to provide wireless connections. Slower than DSL and cable modem but higher availability

 Cellular services - Cellular service providers including Verizon, AT&T, Sprint, and T-Mobile support voice and data transmission to

wireless devices. Cellular services have gone through different

generations.

 1G (first generation mobile telecommunications) started in the 1980s using analog radio signals to provide analog voice

transmission service.

 2G (second generation mobile telecommunications) stared in the 1990s using digital radio signals. This generation focused

on voice transmission and was too slow for effective Internet

connectivity.

 3G (third generation mobile telecommunications) started in the 2000s providing services capable of effective connectivity

to the Internet and marked the beginning of smartphones.

 4G (fourth generation mobile telecommunications) have begun to replace 3G with providers using WiMax LTE (Long

Term Evolution) connections to provide faster transmission

speeds. A user’s experience with 4G will depend on several

factors including carrier, geography, and proximity to cell

towers. 4G technologies can provide speeds up to 10 times

faster than 3G.

 Data transmission

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o Bandwidth – is a measurement of the width or capacity of the communication channel. How much information can move across the communication channel

in a given amount of time.

o Four categories of bandwidth include:  Voiceband (low bandwidth) - used for standard telephone

communication by personal computers with telephone modems and

dial-up service. Can transmit text documents but is too slow for many

types of transmitting high-quality audio and video.

 Medium band - used in special leased lines to connect midrange computers and mainframes as well as to transmit data over long

distances. Capable of very high-speed data transfer.

 Broadband – widely used by DSL, cable, and satellite connections; several users can simultaneously use a single broadband connection for

high-speed data transfer.

 Baseband - widely used to connect individual computers that are located close to one another.

 Like broadband, it is able to support high-speed transmission.

 Unlike broadband, however, baseband can only carry a single signal at one time.

o Protocols for data transmission to be successful, sending and receiving devices must follow a set of communications rules for exchange of

information. Protocols are the rules for exchanging data between computers.

 https or hypertext transfer protocol secure is a widely used protocol to protect and transfer sensitive information.

 TCP/IP – Transmission Control Protocol/Internet Protocol is the standard protocol for the Internet. Essential features involve – sending

and receiving devices and breaking information into small parts for

transmission across the Internet

 Identification: Every computer on the Internet has a unique numeric address called an IP address (Internet protocol

address). Used to deliver –email and to locate websites

o Uses a domain name server (DNS) that automatically converts text-based addresses to numeric IP addresses

o Enter a URL and a DNS converts it to an IP address before a connection can be made

 Packetization: Information sent or transmitted across the Internet usually travels through numerous interconnected

networks. Before a message is sent, it is reformatted or broken

down into small parts called packets. Each packet is then sent

separately over the Internet, possible traveling different routes

to one common destination. At the receiving end, the packets

are reassembled into the correct order.

 Networks o A computer network is a communication system that connects two or more

computers so they can exchange information and share resources.

o Networks can be set up in different arrangements to suit users’ needs (See Figure 8-13) and may consist of only personal computer or it may integrate

personal computer or other devices with larger computers

o Number of specialized terms that describe computer networks include:  Node—any device that is connected to a network.

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 Client —a node that requests and uses resources available from other nodes. Typically, a client is a user’s personal computer.

 Server—a node that shares resources with other nodes. Dedicated servers specialize in performing specific tasks.

 Directory server—specialized server that manages resources such as user accounts for an entire network.

 Host—any computer system that can be accessed over a network.  Router —a node that forwards or routes data packets from one

network to their destination in another network

 Switch—central node that coordinates the flow of data by sending messages directly between sender and receiver nodes. A hub

previously filled this purpose by sending a received message to all

connected nodes, rather than just the intended node.

 Network interface cards (NIC)—expansion cards located within the system unit that connect the computer to a network. Sometimes

referred to as a LAN adapter.

 Network operating systems (NOS)—control and coordinate the activities of all computers and other devices on a network.

 Network administrator—a computer specialist responsible for efficient network operations and implementation of new networks.

 Network Types o Local Area Networks (LANs)- Networks with nodes that are in close

physical proximity, typically spanning less than a mile and are owned and

operated by individual organizations.

 Network gateway - device that allows one LAN to be linked to other LANs or to larger networks.

 The most common standard in which nodes in a LAN can be connected to one another is known as Ethernet.

o Home Networks - networks being used by individuals in their homes and apartments. Allow different computers to share resources, including a

common Internet connection

 Connections in a variety of ways, including electrical wiring, telephone wiring, and special cables

o Wireless LAN (WLAN) - uses radio frequencies to connect computers and other devices. All communications pass through the network’s centrally

located wireless access point or base station. This access point interprets

incoming radio frequencies and routes communications to the appropriate

devices. In public places wireless access points are known as hotspots and

typically use Wi-Fi technology. Most mobile computing devices have an

internal wireless network card to connect to hotspots.

o Personal area network (PAN) - type of wireless network that works within a very small area—your immediate surroundings. PANs connect cell phones to

headsets, PDAs to other PDAs, keyboards to cell phones, and so on. Most

popular PAN technology is Bluetooth, with a maximum range of around 33

feet.

o Metropolitan Area Networks (MANs)- span distances up to 100 miles. Frequently used links between office buildings that are located throughout a

city. MANs are typically owned by a group of organizations who jointly own

and operate the network or by a single network service provider that provides

network services for a fee.

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o Wide Area Networks (WANs) - countrywide and worldwide networks. Provide access to regional service (MAN) providers and typically span

distances greater than 100 miles. They use microwave relays and satellites to

reach users over long distances. The widest of all WANs in the Internet, which

spans the entire globe.

 The primary difference between a PAN, LAN, MAN, and WAN is the geographic range.

 Network Architecture o Describes how a network is arranged and how resources are coordinated and

shared.

o Topology – Describes the physical arrangement of a network and how resources are coordinated and shared.

 Bus network

 Each device is connected to a common cable called a bus or backbone and all communications travel along this bus.

 Ring network

 Each device is connected to two other devices, forming a ring See Figure 8-17;

o When a message is sent, it is passed around the right until it reaches the intended destination.

 Star

 Each device is connected directly to a central network switch See Figure 8-18

 Whenever a node sends a message, it is routed to the switch, which then passes the message along to the intended recipient.

 Most widely used network topology today.

 Range of applications includes small networks in the home to very large networks in major corporations.

 Tree

 Each device is connected to a central node, either directly or through one or more other devices.

 Central node is connected to two or more subordinate nodes that in turn are connected to other subordinate nodes, and so

forth, forming a treelike structure See Figure 8-19

 Also known as a hierarchical network.  Mesh

 Newest type of topology and does not use a specific physical layout.

 Requires that each node have more than one connection to the other nodes. The resulting pattern forms the appearance of a

mesh.

 If a path between two nodes is somehow disrupted, data can be automatically rerouted.

 Wireless technologies are frequently used to build mesh networks.

 Strategies o Every network has a strategy, or way of coordinating the sharing of

information and resources. Two of the most common network strategies are

client/server and peer-to-peer.

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 Client/server networks - are widely used on the Internet

 Each time a web browser is opened the computer (client) sends out a request for a specific web page; the request is routed over

the Internet to a server and then the server locates and send the

requested material back to the computer

 Client/server networks are widely used on the Internet.

 Advantage of the client/server network strategy include:  Ability to handle very large networks efficiently.  Availability of powerful network management

software to monitor and control network

activities.

 The major disadvantages of the client/server network strategy are the cost of installation and maintenance

 Peer-to-peer (P2P) network - nodes have equal authority and can act as both clients and servers. Many current popular games, movies, and

music sharing services use this network strategy.

 Special file-sharing, software such as BitTorrent can be used to obtain files located on another personal computer.

 Advantage of P2P:  Easy and inexpensive (often free) to set up and

use.

 Disadvantage of P2P:  Lack of security controls or other common

management functions.

 Organizational Networks o Intranet Technologies

 A private network within an organization that resembles the Internet.  Uses browsers, web sites, and web pages.  Organizations use intranets to provide information to their employees

such as electronic telephone directories, e-mail addresses, internal job

openings, and more.

 Accessible only to those within the organization.  Easy and intuitive for employees to use.

o Extranet  A private network that connects more than one organization.  Many organizations use Internet technologies to allow suppliers and

others limited access to their networks.

 Main purpose is to increase efficiency and reduce costs. o Network Security o Securing large corporate networks requires specialized technology. Three

technologies commonly used to ensure network security include:

 Firewalls

 A security system designed to protect an organization’s network against external threats.

 Consists of hardware and software that control access to a company’s intranet or other internal networks.

 Sometimes organizational firewalls include a special computer or software called a proxy server. This system is a gatekeeper.

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All communications between the company’s internal networks

and the outside world must pass through it. See Figure 8-22

 Intrusion detection systems (IDS)

 Works with firewalls to protect an organization’s network.

 Uses sophisticated statistical techniques to analyze all incoming and outgoing network traffic.

 Uses advanced pattern matching and heuristics to recognize signs of a network attack and disable access before an intruder

can do damage.

 Virtual private networks (VPN)

 Create a secure private connection between a remote user and an organization’s internal network.

 Connection is heavily encrypted

 Special VPN protocols create the equivalent of a dedicated line between a user’s home or laptop computer and a company

server.

 Careers In IT o Network administrators manage a company’s LAN and WAN networks. o Duties

 Design, implementation, and maintenance of networks.  Maintenance of both hardware and software related to a company’s

intranet and Internet networks.

 Diagnosing and repairing problems with these networks.  Planning and implementations of network security

o Bachelor’s degree or an advanced associate’s degree in computer science, computer technology, or information systems as well as practical networking

experience or technical certification.

o Annual salary of $47,000 to $64,000. o Expected to be among the fastest-growing jobs in the near future.

 A Look to the Future o Telepresence Lets You Be There without Actually Being There o Telepresence seeks to create the illusion that you are actually at a remote

location, seeing, hearing, and someday maybe even feeling as though you

were really there.

o Today’s early telepresence implementations mainly focus on an extension of videoconferencing.

o Might be used to allow people to work in hazardous areas from a safe remote location. Doctors and medical specialists might be able to perform surgeries

on people unable to travel.

Teaching Tips

 Communications o Emphasize in discussion that connectivity is the fastest growing sector of the

computer industry and that The Wireless Revolution is the single most

dramatic change in connectivity and communications in the past five years.

o Discuss why it is called a revolution. o Give an overview of the different parts of a communication system that will be

covered.

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o You can refer to the basic communications model that is discussed in public speaking classes and how computers work in the same fashion. See Figure

 Sending and receiving devices  Communication channel = medium  Connection devices  Data transmission specifications = message

o Have students recap how communication has changed during their lives (if you have different generations attending class students will see how

communication has changed very easily and how it affects their lives)

 Communications Channels o Emphasize that there are two types of channels: o Physical (wired) - a solid medium to connect sending and receiving devices.

 Mention that twisted pair – uses copper wires to conduct electricity, covers the least distance and is the slowest of the wired channels

 Coaxial cable - a high-frequency transmission cable, uses copper wire to conduct electricity, has a medium-range distance capability and

speed.

 Fiber-optic cable - transmits data as pulses of light through tiny tubes of glass or plastic, covers the farthest distance and has the fastest

transmission speed

o Bring samples of the physical (wired) channels to class. It gives the students a clear visual and makes it easier to open a discussion on the various types.

[Word of caution – do not let students handle the piece of fiber-optic cable

– it has tiny strands of glass that may stick into their skin. Passing it around is

easier if it is sealed in a plastic freezer bag.]

o Wireless-Give specific examples for each category or have students discuss which ones work best for them

 Bluetooth is a short-range radio communication standard that transmits data over short distances of up to approximately 33 feet.

Bluetooth is widely used for wireless headsets, printer connections,

and handheld devices.

 WiFi - (wireless fidelity) uses high frequency radio signals to transmit data. A number of standards for Wi-Fi exist, and each can send and

receive data at a different speed. Most home and business wireless

networks use Wi-Fi.

 Microwave - communication through high-frequency radio waves and provides line-of-sight communication but over short distances.

Bluetooth is a form of microwave transmission

 LTE (Long Term Evolution) is one of the newest wireless standards. Currently, LTE and WiMax connections provide similar performance.

LTE, however, promises to provide greater speed and quality

transmissions in the near future.

 Satellite - amplified microwaves that use point-to-point communication to relay devices (satellites) orbiting the earth.

Communication interferences can occur in bad weather.

 GPS (global positioning system); Discuss many applications of GPS and how it is now used in legal events

 Infrared uses infrared light waves to communicate over short distances. Line of sight, remotes

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o As a lab exercise task students with interviewing and identifying which (if any) of the wireless communication channels are used at their school, work, or

home

 Connection Devices See o Signals

 Analog – continuous electronic waves  Digital – represents the presence or absence of an electronic pulse

o You can emphasize the difference between modems and higher speed devices. o Most students are familiar with both and are interested in how you can connect

using the higher speed devices.

o Discuss how DSL uses standard phone lines o Have students identify how each of the basic types of modems are used o Discuss the pros and cons are each type of connection device

 Connections Services o Describe the following services and give examples of each: o DSL, Cable, Satellite, Cellular o Discuss the cellular service generations of mobile communications 1G, 2G,

3G and 4G.

o Have students research and prepare graphs for 1G-4G rates

 Data transmission o Bandwidth can be difficult for students to understand. You can use an analogy

of a highway and the wider the road the more cars can travel on it in a given

amount of time.

o Protocols can be compared to foreign services and how different countries have different ways to communicate. Mention Internet protocol TCP/IP

o You can discuss with students how it is possible to determine which computer on the Internet was used to send an e-mail or to access a certain web site.

Discussing the concept of the “digital footprint” with students is often

enlightening.

 Making IT Work – the Mobile Internet should be really interesting to your students; you can have student develop questions for a jeopardy game for this chapter; working

in pairs

 Networks o You can emphasize the basic parts that comprise a network. o Look at all of the parts of a network as it makes it easier for the students to

grasp the terminology that is used to describe computer networks (node, client,

server, directory server, host, router, switch, network interface card, network

operating system, and network administrator)

 Network Types o The divisions between the types of networks are not as clear cut from a

technical perspective because some types of devices that used to be solely

used for a WAN can be used in LAN environments. Some students can point

this fact out. It is best to state that you are taking this from a geographical

perspective.

o Many students have installed or want to install a home network

 Network Architecture o How a network is arranged and how resources are coordinated and shared. o Look at the corresponding figures in the book to identify network architecture.

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o Stress to students that the star network is the most widely used network topology today. It is used in small networks in the home and very large

networks in major corporations.

 Strategies o Most of the students have had experiences with BitTorrent, and other types of

downloading programs. You can use these as an example of how client/server

and peer-to-peer work.

o Open a discussion with students and explore their experiences with the use of this type of downloading programs. Why pay for it – when you can get it for

free? Problem with downloading viruses from these unsecured sites.

Copyright infringements. All of this is further explored in Chapter 9.

 Organizational internets o Intranet

 Emphasize that it is a private network within an organization that resembles the Internet and it provides services accessible only to those

within the organization.

o Extranet  Emphasize that it is a private network that connects more than one

organization to allow suppliers and others limited access to their

networks.

 Good examples are organizations that use Just In Time inventory.  Good discussion on this would be how Wal-Mart uses this type of

network and why they are so successful by doing so.

o Network Security  Firewalls

 Both hardware and software

 Good for home use as well

 Have students identify what type of firewall they are using on their personal computers.

 Intrusion detection systems (NIDS)

 Ask students to search the Internet for more information on how this system can recognize network attacks and disable

access

 Virtual Private Network (VPN) – This technology is widely used by many people who work from home.

 Ask students to do research to find out what is needed to use VPN