Networking and Digital Communication Objectives Objectives

TI2023 

Pengantar Komputer dan Internet 

TI2023 

Pengantar Komputer & Internet 

Restyandito 

© 2008 Prentice-Hall, Inc. 

Networking and 

Digital Communication 


Objectives 

Objectives 

Describe the basic types of technology that make 

telecommunication possible. 

Describe the nature and function of local area networks 

and wide area networks. 

Discuss the uses and implications of email, instant 

messaging, blogging, teleconferencing, and other forms 

of online communication. 

Explain how wireless network technology is 

transforming the ways people work and communicate. 

Describe current and future trends in 

telecommunications and networking. 



08- Networking and Digital Communication Restyandito - 1

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Magical Prophecy 

Magical Prophecy 

Arthur C. Clarke’s laws 

• If an elderly but distinguished scientist says that 

something is possible, he is almost certainly 

right, but if he says that it is impossible he is 

very probably wrong. 

• The only way to find the limits of the possible 

is to go beyond them into the impossible. 

• Any sufficiently advanced technology is 

indistinguishable from magic. 

Arthur C. Clarke’s most famous work was the 

monumental 1968 film 2001: A Space Odyssey, 

in which he collaborated with movie director 

Stanley Kubrick. 

Clarke’s most visionary work may be a paper 

published in 1945 in which he predicted the use 

of geostationary communications satellites— 

satellites that match the Earth’s rotation so they 

can hang in a stationary position relative to the 

spinning planet below, relaying wireless 

transmissions between locations on the planet. 



Basic Network Anatomy 

A computer network is any system of two or 

more computers that are linked together. 

How is networking important 

• People share computer hardware, thus reducing 

costs. 

• People share data and software programs, thus 

increasing efficiency and production. 

• People work together in ways that are otherwise 

difficult or impossible. 



Networks Near and Far 

In a local area network (LAN) computers are physically close to each other, 

usually in the same building. 

• Computers are linked within a building or 

cluster of buildings. 

• Each computer and peripheral is an individual 

node on the network. 

• Nodes are connected by cables, which may be 

either twisted pair (copper wires) or coaxial cable. 

In a wireless network each node has a tiny radio (or, less commonly, infrared) 

transmitter connected to its network port. 

• Computers send and receive data through the air rather than through cables. 




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A metropolitan area network (MAN) links two or more LANs within a city. 

A wide area network (WAN) extends over a long distance. 

• Each networked LAN site is a node on the WAN. 

• Data transmitted over common pathways called a backbone. 


Communication frequently happens between LANs and WANs 

• Routers: hardware devices or software programs that route messages as they travel 

between networks 

• Mesh networks: an alternative to today’s networks; rely on centralized routers 

• Used to set up small, temporary communication systems 

• Example: emergency personnel use at fire scenes to coordinate actions 

“Pretty soon you’ll have no more 

idea of what computer you’re using 

than you have an idea of where your 

electricity comes from.” 

—Danny Hillis, computer designer 




Specialized Networks 


Global Positioning System (GPS) 

• GPS is a specialized network developed by 

U.S. Department of Defense. 

• It includes 24 satellites that circle the Earth. 

• Each satellite contains a computer, an atomic 

clock, and a radio. 

• On the ground, a GPS receiver can use 

signals broadcast by three or four visible 

satellites to determine its position. 

Networks that keep our global financial systems running: 

• Automated Teller Machine (ATM): a specialized terminal linked to a bank’s main 

computer through a commercial banking network 




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The Network Interface 

A network interface card (NIC) permits 

direct network connection: 

• Adds an additional serial port to the computer 

• Controls the flow of data between the computer’s RAM 

and the network cable 

The most common types of networks today require some kind of Ethernet card 

or port in each computer. 

• Ethernet is a popular networking architecture developed in 1976 at Xerox. 

• Most newer PCs include an Ethernet port on the main circuit board, so they don’t 

require NICs to connect to Ethernet networks. 


Communication á la Modem 

Modem: a hardware device that connects a 

computer’s serial port to a telephone line 

(for remote access) 

May be internal on the system board or external, 

sitting in a box linked to a serial port 

Modem transmission speed measured in bits per second (bps) 

Transmit at 28,000 bps to 56.6K bps 





Computers send digital signals. 

The modem (modulator/demodulator) converts the digital signals to 

analog so that the message can be transmitted through telephone lines and 

converts it back on the other end. 

Broadband connection—a connection with much greater 

bandwidth than modems have 

• DSL uses standard phone lines and is provided by phone companies in 

many areas. 

• Cable modems provide fast network connections through cable 

television networks in many areas. 

• High-speed wireless connections can connect computers to networks 

using radio waves rather than wires. 

• Satellite dishes can deliver fast computer network connections as well 

as television programs. 




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Fiber Optic Connections 


Wireless Network Technology 

DSL and cable modems have nowhere near the bandwidth of the fiber optic 

cables that are replacing copper wires in the worldwide telephone network. 

A fiber optic network can rapidly and reliably transmit masses of multimedia 

data at the same time that it’s handling voice messages. 

A lightning-fast network connection to your desktop is of little use if you’re 

away from your desk most of the time; when bandwidth is less important than 

mobility and portability, wireless technology can provide practical solutions. 

• The fastest growing wireless LAN technology is known as Wi-Fi or 802.11b. 





Bluetooth: another type of wireless technology 

• Named for a Danish king who overcame his country’s religious differences 

• Overcomes differences between mobile phones, handheld computers, and PCs, making 

it possible for all of these devices to communicate with each other regardless of 

operating system 

With Bluetooth it’s possible to create a 

personal area network (PAN)—a network that 

links a variety of personal electronic devices so they can 

communicate with each other. 

Bluetooth technology is currently limited to simple device 

connectivity, but in the future it will open up all kinds of 

possibilities: 

• A pacemaker senses a heart attack and notifies the victim’s 

mobile phone to dial 911. 

• A car radio communicates with parking-lot video cameras 

to find out where spaces are available. 




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More examples of Bluetooth possibilities: 

• A pen scans business cards and sends the 

information to a PDA inside a briefcase. 

• A medical wristband transmits an accident 

victim’s vital information to a doctor’s 

handheld computer. 

• A cell phone tells you about specials on 

clothes that are available in your size as you 

walk past stores in a mall. 


Communication Software 

Protocol is a set of rules for the exchange of data between a 

terminal and a computer or between two computers. 

Communication software establishes a protocol that is followed 

by the computer’s hardware. 






The Network Advantage 

Communication software takes many forms: 

• Network operating system (NOS) 

• System handles communications among many 

workstations. 

• Client/server model 

• One or more computers act as dedicated servers and all the 

remaining computers act as clients. 

• Peer-to-peer model 

• Every computer on the network is both client and server. 

• Many networks are hybrids, using features of the 

client/server and peer-to-peer models. 

Why do people use networks 

• Networks enable people to share computer hardware resources, reducing 

costs and enabling people to take advantage of powerful computer 

equipment. 

• Networks enable people to share data and software programs, increasing 

efficiency and productivity. 

• Networks enable people to work together or collaborate in ways that are 

difficult or impossible without network technology. 




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A Home Computer Network 

Interpersonal Computing 

From Email to Social Networks 

Firewall/router 

USB cable 

DSL modem 

Wireless access 

point 

Wireless laptop 

The Many Faces of Email 

Email systems enable you to send and receive messages to others 

on the network. 

Web-based email systems and many older UNIX-based programs require 

that read and unread messages be stored in post office boxes or folders 

on the remote mail servers. 

Many email messages are plain ASCII text. 

Multiplayer games 







Even if their software can display HTML mail, not all email users want HTML 

emails: 

• HTML encoding can slow down an email program. 

• An HTML email message can also carry a Web bug. 

Most email programs can send and receive formatted word processor 

documents, pictures, and other multimedia files as attachments to messages. 

Mailing Lists 

Mailing lists enable you to participate in email discussion groups on 

special-interest topics. 

Subscribing to a busy list might mean receiving hundreds of messages 

each day. 

• To avoid being overwhelmed by incoming mail, many list members sign up to 

receive them in daily digest form. 

• Some lists are moderated to ensure that the quality of the discussion remains high. 




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Newsgroups 

Newsgroup: a public discussion on a particular subject 

• Notes are written to a central Internet site. 

• Notes are redistributed through a worldwide newsgroup network called USENET. 

• Listserv mail messages are delivered automatically to your mailbox, but you have 

to seek out information in newsgroups. 

• Mailing list messages are sent to a specific group of people, whereas newsgroup 

messages are available for anyone to see. 

Moderated newsgroups contain only messages that have been filtered by 

designated moderators. 

Rules of Thumb: Online Survival Tips 

Let your system do as much of the work as possible. 

Store names and addresses in computer-accessible 

addressbook. 

Don’t share your email address. 

Don’t open suspicious attachments. 

Protect your privacy. 

Cross-check on-line information sources. 

Be aware and awake. 

Avoid information overload. 





Instant Messaging and Teleconferencing: 

Real-Time Communication 

Mailing lists and newsgroups are delayed or asynchronous 

communication. 

• The sender and the recipients don’t have to be logged in at the same time. 

Instant messaging (IM) has been possible since the days of text-only 

Internet access. 

Newer, easier to use messaging systems from AOL, Microsoft, Yahoo, 

Apple, and others have turned instant messaging into one of the most 

popular Internet activities. 



Online services also offer chat rooms—public or private virtual conference 

rooms where people with similar interests or motivations can type messages 

to each other and receive near instant responses. 

Several IM programs make it possible to carry on two-way video 

teleconferences. 




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Computer Telephony 

Voice mail is a messaging system with the ability to store, organize, and 

forward messages. 

• An example of a growing trend toward computer telephony integration 

(CTI) is the linking of computers and telephones to gain productivity. 

It’s also possible to send voice signals through a LAN, a WAN, or the 

Internet, bypassing the phone companies (and their charges) altogether. 

Handheld PDA computers use software to integrate the functions of a 

PDA, a phone, and an Internet terminal. 


Internet Telephony has become a legitimate competitor to traditional 

phone companies. 

• Voice over IP (VoIP) requires a broadband connection to carry your 

call over the Internet. 

• You can place a calling using either a traditional phone with an adapter 

or an Internet-connected PC with a microphone headset and 

appropriate software. 








Advantages of VoIP 

• Calls are less expensive if you already have a broadband connection. 

• Calls are routed to you no matter where you are connected. 

• VoIP phones integrate more easily with online address books, video 

conference services, and other Internet services. 


Disadvantages of VoIP 

• Communication is impossible during a power outage (most networks 

are unusable). 

• There is no 911 or directory assistance service available. 

• Quality is suspect because there is no guarantee of packets being 

delivered in a timely manner. 




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Online Risks 

Social Networks and Information Sharing 

Online communities such as MySpace and Facebook 

Massively multiplayer role playing games (MMORPG) 

Common information resources such as Flickr and Wikipedia 

Email Issues 

Problems with Spam – more than 50% of e-mails are unsolicited. 

Email and teleconferencing are vulnerable to machine failures, network 

glitches, human errors, and security breaches. 

Email can be overwhelming. 

Email can pose a threat to privacy. 



Online Risks 

Online Risks 

Don’t Get Hooked—Advice on Phishing 

Examine the URL in the address bar. 

Re-examine the URL in the address bar. 

Look for the https prefix. 

Look for the padlock icon. 

Pay attention to pop-up warnings about fraudulent certificates. 

Make your own Web connection. 

Cookies – Can be used by snoopers to get information about you 

Wireless issues of access, security, and privacy 

Perils of posting too much information on blogs and websites 

Internet Addiction – Some game players spend 40-80 hrs a week online 

Virtual Sweatshops 




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Online Risks 

Digital Communication in Perspective 

Lesson Summary 

Many services we take for granted today—video rentals, cable TV, 

newspapers, and magazines, for example—will be transformed or 

replaced by digital high-bandwidth interactive delivery systems of the 

future. 

At the same time, entirely new forms of communication are likely to 

emerge. 

Telecommunications technology is rapidly changing our lives, and the 

changes will accelerate as the technology improves. 

Networking is one of the most important trends in computing today. 

LANs are made up of computers that are close enough to be directly 

connected with cables or wireless radio transmitters/receivers. 

• Most LANs include shared printers and file servers. 

WANs are made up of computers separated by considerable distance. 

Many computer networks are connected together through the Internet so 

messages and data can pass back and forth among them. 

Some specialized networks, including global positioning systems and 

financial systems serve unique functions. 



Lesson Summary 

Most computer networks today use the Ethernet architecture; an Ethernet 

port is a standard feature on most modern PCs. 

Communication software takes care of the details of communication 

between machines—details like protocols that determine how signals will 

be sent and received. 

Email, instant messaging, and teleconferencing are the most common 

forms of communication between people on computer networks. 

It’s not clear how all of these emerging technologies will converge; what is 

clear is that the wireless revolution is far from over. 



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Daftar Pustaka 

Williams, Brian K, 2007, Using Information Technology: 

Pengenalan Praktis Dunia Komputer dan Komunikasi 

Edisi 7, Penerbit Andi. (Bab 7) 

Beekman George, 2009, Tomorrows’s Technology and 

You 9th Edition, Prentice Hall. (Chapter 8) 

T E R I M A K A S I H

Networking and Digital Communication Objectives Objectives

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