CSCI 1200Introduction to Computing for

Non Majors

CHAPTER 8

Tami Meredith, Ph.D.tami.meredith@live.com

Objectives

Describe the basic types of telecommunication technology, both wired and wireless

Understand the role and purpose of local and wide area networks

Describe the convergence of data, telephone, video (cable), and other networks to a unified digital model

Describe several ways to maximize effectiveness of online communication

Describe current and future trends in telecommunications and networking

2

Arthur C. Clarke’s Magical Prophecy Arthur C. Clarke: predicted

the use of geostationary communications satellites

Considered to be the father of satellite communications

Nice idea, but a few problems:› Needs more power to go

farther (like into space)› Takes longer to go farther› Maintenance, upgrade,

installation is expensive

3

Basic Network Anatomy A computer network is any system of two

or more computers that are linked together

Three essential components of every computer system:› Hardware› System Software› Applications (and their users)

4

Local Networks

LAN (local area network): computers are physically close to each other› Nodes: connected to hubs or switches, which

allow any node on the network to communicate with any other

› E.g., an office building, a university campus› Often viewed as a single place on the Internet

Ethernet: popular networking architecture developed in the 1970s; now an industry standard (Cat 5 Cable, 6 wire larger phone plug)

5

Long Distance Networks

WAN (wide area network): extends over a long distance› Each networked LAN site is a node on the

WAN Routers: hardware devices or software

programs that route messages between networks

6

The Importance of Bandwidth

Bandwidth: refers to the quantity of data that can be transmitted through a communication medium in a given amount of time

Typically measured in kilobits or megabits per second

More is always better Think of it as the size of a network

"pipe" – a bigger bandwidth means a bigger pipe that lets more data flow

7

Bandwidth

A network is as strong as it's weakest link (it's bottleneck)

Bandwidth can be affected by:› Physical media of the network› Amount of traffic on the network› Type of network connection

Fast Ethernet: carries traffic at 100 megabits per second

Gigabit Ethernet: standard is capable of transferring 1 gigabit of data per second

8

Communication Software Protocol: set of rules for the exchange of data between

devices› Computers must follow the same protocols to understand each

other. TCP/IP: protocols that form the basis of the Internet

› TCP/IP controls the exchange of data› IP = Internet protocol; controls how to get a single "packet" of data

from one computer on the Internet to another› TCP = Transmission control protocol; sequences the flow of packets

so that none are lost and all are assembled in the right order› Other protocols (e.g., http) describe what goes in the packets› Ethernet is the protocol used by the hardware to move the bits of a

packet

9

Communication Software Communication software takes many forms:

› Operating system handles communications by linking all the protocols and hardware for you

› Applications (e.g., Firefox, Chrome) use the Operating System to do network communication

› Client/server model: one or more computers act as dedicated servers and all the remaining computers act as clients – e.g., WWW, WoW

› Peer-to-peer model: every computer on the network is both client and server – e.g., torrents, Skype

10

Internet Connection Technologies

Everything is sent as TCP/IP today New protocols replacing Ethernet for

Fibre Optic connections Phone, HDTV, Email, Gaming, etc. is all

sent the same way now Aliant and Eastlink both provide,

phone, TV, and Internet over fibre optic connections – no major difference anymore, and growing more the same

11

Connection Technologies Most common broadband alternatives:

› Fibre Optic: Flexible glass cables that send signals via light› DSL (digital subscriber line): uses copper telephone lines

that carry voice calls -- mostly rural until fibre optic replaces the old phone wires

› Cable modems: use same network of coaxial cable as television signals -- old urban areas until replaced by fibre optic

› Cellular connections: use the cell phone system (e.g., smartphones, Rogers rocket stick)

› Satellite connections: use dishes to talk to satellites -- remote areas where no other infrastructure exists or is cost effective

› Wireless connections: WiFi, short range connection (e.g., at Dalhousie, SMU)

12

Wireless Network Technology

13

Wi-Fi and WiMax Technology Wireless access

point (WAP): central connection point wireless devices

802.11n: standard IEEE 802.11 (Wi-Fi) specifications for wireless local area networks

14

Network Vulnerability

Anything sent over wireless can be picked up by any receiver within range of the transmitter

Anything sent on a LAN can potentially be picked up by any other computer on the LAN

Anything sent over the Internet can be seen by every router and system between the source and the destination

The only way to achieve privacy is to encode/encrypt the data

15

Wi-Fi and WiMax Technology WiMAX: new radio-based wireless standard

in which a single tower can provide access to a 25-square-mile area

WEP (wired equivalent privacy): encryption scheme improves the security of wireless networks

Note: Wired is only marginally more "private" than wireless (but at least you know who is listening on a wired network)

VPN (virtual private network): electronic "tunnel” through the Internet that helps to prevent eavesdropping

16

Bluetooth Technology Bluetooth technology: named for Danish

king who overcame his country’s religious differences› Overcomes differences between mobile phones,

handheld computers, and PCs, allowing communication between different operating systems

› Super short range so that it can be very low power and not drain small batteries

› Not designed to replace WiFi › PAN (personal area network): links a variety of

electronic devices using Bluetooth technology

17

3G and 4G Technology 3G and 4G technology: 3G (3rd Generation

Cellular) networks carry multimedia data and voice communications simultaneously› Lack true broadband speeds› 4G networks have gigabit broadband speeds› Just terms for various Cellular technology› Tethering: cabling a laptop to a mobile phone

(nobody does this now) so it can send and receive Internet data through the phone’s wireless Internet connection

› Use a USB device that broadcasts on the cell network (e.g., Rogers rocket stick)

18

Specialized Networks

GPS (Global Positioning System): specialized network of the U.S. Department of Defense

GPS receiver uses signals broadcast by satellites to determine its position

19

Network Uses

Networks enable people to:› Share computer hardware resources

Print servers accept, prioritize, and process print jobs

› Share data and software programs Site licenses reduce costs for multiple copies

of software› Work, play, and communicate together

Groupware enables several users to work on the same document at the same time.

20

Home Networks ...

21

Home Networks

Modem: Modulator-Demodulator – device that connects to the wire/fibre that comes into your house

Router: Device that lets you put more than one computer on your network

Wireless Router: Router with a Wireless Access Point built into it

Note: Cables to the router (e.g., ethernet) are FASTER by a lot than wireless

Printers may be connected to a computer or "network printers" directly connected to the network (usually by plugging them into the router with a cable)

22

The Many Faces of Email Email is built on protocols SMTP (Simple Mail Transfer Protocol):

sending mail POP (Post Office Protocol) or IMAP (Internet

Message Access Protocol): receiving mail Webmail: Web-based email, such as Gmail

or Hotmail Mail is not sent to you and instead you get a

web page containing the contents of the email You type into the browser, use HTTP to send it

to the web server and it sends it out with SMTP Someone else stores and controls your email

23

Email Issues Spam: unsolicited, junk email Phishing: luring people into fake Web sites

to capture sensitive information Mailing lists: enable you to participate in

email discussion groups› Moderated groups try to control the quality of

the discussions› Many email servers won't send large numbers of

messages as it overloads the bandwidth – may need a special mail service (e.g., chimpmail) to send to a large list of customers etc.

24

Online Terms Newsgroups: public discussion on a

particular subject – generally out of date now

Web forums: accessed through a Web browser (Chat sites, Wikis, other interactive sites)

Blogs: (Web Logs) - frequently updated websites, often just "journals" and not interactive

25

Messaging Asynchronous communication

("offline"): sender and receiver don’t have to be logged in simultaneously

IM (instant messaging): real-time communication between to computers (e.g., Skype, Google Chat)

Text messaging: uses SMS technology (via cell system); more limited than IM

Chat room: public or private virtual conference room

26

Computer Telephony Voice mail: voice messaging via

phone system Internet telephony: also called

Voice-over IP (VOIP) – now the norm in most places

Many smart phones can connect to the Internet via the cell system

Skype uses VOIP with Real-time Video (can call phones or other Skype users)

27

Online Privacy Protection

Let your system do as much work as possible

Minimise what you do online

Avoid computer address books

Don’t share passwords Don't store passwords Don't forward email Don’t open suspicious

attachments

Don’t get hooked by a phishing expedition – Learn to read actual URLs

Keep your security systems up to date

Cross-check online information sources

Beware of urban legends – much of what you hear isn't true

Avoid information overload.

28

Social Networking

Websites designed to facilitate social interaction: Facebook, LinkedIn, Pinterest, Twitter

Your privacy is controlled by the website owner – be aware of their goals

MMORPGs/MMOGs - massively multiplayer online (role-playing) games: Games with real-time player interaction

Wiki: web site designed to enable anyone who accesses it to contribute to it

29

Say what you mean; say it with care

Proofread your messages

Don’t assume you are anonymous

Learn the “nonverbal” language and it's localisation

Know your abbreviations

Keep your cool Don’t be a source of

spam Say no—and say

nothing—to spam

30

Netiquette

Sharing Resources

Peer-to-peer: file sharing allows users to share files by making their hard drives available to other users rather than posting them on a central server

Grid computing: sharing processing power rather than sharing data

Cloud computing: form of grid computing where the resources come from the Internet rather than a specific source

31

Digital Communication in Perspective

New technologies emerge all the time Social networking is relatively new, but

it has greatly impacted communication Most new technologies don't really

change how we communicate and instead change the speed at which we communicate and increase our access to that communication

32

Summary Networking is an important trend in

computing today LANs are made up of computers that

are in close proximity Most networks use the Ethernet

architecture More bandwidth is better Many different wireless options exist

33

Summary (cont.) Issues of privacy, security and

censorship have always existed and continue to exist with electronic communication

Large number of communication technologies exist: email, instant messaging, teleconferencing

34