Chapter 8

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Chapter 8

Communications & Networks

Professor Michael J. Losacco

CIS 1110 – Using Computers

Chapter

8

Overview

Identify Various Communication Uses

List Network Advantages

Differentiate Network Types

Describe Communications Standards

Describe Communications Devices

Identify Different Transmission Media

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Chapter

8

Communications

Two or More Devices

Transfer Data or Instructions

Requirements

Sending Device

Communications Device

Connects Sending Device to Channel

Connects Channel to Receiving Device

Communications Channel

Media on Which Data Travels

Receiving Device

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Chapter

8

Uses

Wireless Messaging

Text Messaging

Send / Receive Text Messages Using Phone

14-17: 60 v. 5

Picture Messaging

Pew Internet 5/10

Send / Receive Graphics, Pictures, Video

Sexting: 30% of 17-year-olds

Pew Internet 12/09

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Chapter

8

Uses

GPS (Global Positioning System)

Signals Sent by Satellites Orbiting Earth

Signal Sent Every 1/1000 of a Second

Earth-based Receivers Analyze Signals

Determine Receiver’s Geographic Location

Groupware

Assists Groups in Working Together

Share Data Over Network e.g., Schedule Meetings

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Chapter

8

Uses

Web Services

Software Applications

Communicate with Other Remote Computers

Use Internet or Internal Business Network

Mashup

Combines Services from Multiple Sources

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Chapter

8

Uses

Very Hard to Give Up

75%

50%

38%

51%

38%

45% 47% 43%

63%

40%

25%

0%

Cell Phone Internet TV

36%

6%

Phone Wireless

Email

2002 2007

Pew Internet 3/08

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Chapter

8

Networks

Collection of Computers & Devices

Connected via

Communications Devices

Transmission Media

Advantages

Facilitating Communications

Sharing Hardware

Sharing Software

Sharing Data And Information

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Chapter

8

Network Types

LAN (Local Area Network)

Network in Limited Geographical Area

Typically Within a Building

WLAN

Wireless LAN

WAN (Wide Area Network)

Large Geographic Area

Uses Many Types of Media

Internet

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Chapter

8

Network Architectures

Client/Server

Client

Requests Resource Accessed from Server

Server

One or More Computers Controlling Resource

P2P (Peer-to-Peer)

Access Any Other Computer in Network

Internet File Sharing

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Chapter

8

Network Topology

Configuration of Devices in a Network

Bus

Consists of Single Central Cable

All Devices Connect to it

Inexpensive & Easy to Install

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Chapter

8

Network Topology

Ring

Cable Forms Closed Ring

Data Travels In One Direction

Expensive & Difficult to Install

Star

All Devices Connect to Hub

All Data Passes Through Hub

Bottlenecks Can Occur

Easy to Install

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Chapter

8

Intranet & Extranet

Intranet

Internal Corporate Network

Uses Internet

Accessible to Corporate Employees

Facilitates Working in Groups

Extranet

Allows Access to Parts of a Intranet

Customers / Suppliers

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Chapter

8

Protocol

Protocol

Collection of Procedures

Establish, Maintain, & Terminate Transmissions

Type of Error Checking Used

Data Compression Method, If Any

Indicate Finished Sending Message

Indicate Message Has Been Received

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Chapter

8

Standards

Ethernet

For LANs

Uses Bus or Star Topology

Widely Implemented

TCP/IP

Used for Internet Transmissions

Packet Switching

Transmits Data by Breaking it Into Packets

Reassembles Data at Destination

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Chapter

8

Standards

802.11 (Wi-Fi)

Family of Standards for Wireless LANs

802.16 (WiMAX)

Towers Cover 30-mile Radius

Provides Wireless Broadband Internet

Bluetooth

Short-range Radio Technology

WAP

Wireless Mobile Devices Connect to Internet

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Chapter

8

Standards

IrDA

Data Transferred via Infrared Light Waves

RFID

Radio Signals Communicate with Tags

Failed Legislation

Nevada

Require Retailers to Inform Customers

Rhode Island

Government Agency Cannot Track Individuals

Texas

Prohibit Schools from Using RFID on Students

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Chapter

8

Types & Speeds

Measured in bps (Bits per Second)

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Chapter

8

Devices

Modem

Converts Analog to Digital & Vice Versa

Required for Telephone Line Communication

DSL Modem

Cable Modem

Uses Cable TV Network

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Chapter

8

Devices

Wireless Modem

Internet Access

Network Card

Connects PC to Network

Wireless Access Point

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Chapter

8

Devices

Router

Connects Multiple Computers / Routers

Transmits Data to Network Destination

Uses Fastest Available Path

Many Protected by Hardware Firewall

Hub / Switch

Provides Central Point for Network Cables

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Chapter

8

Channel

Communication Path Between Devices

Bandwidth

Difference Between Frequencies

Amount of Data that Travel Over Channel

Latency

Time for Signal to Travel

From One Network Location to Another

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Chapter

8

Broadband

Channel

Transmit Multiple Signals over Channel

Transmission Media

Materials or Techniques

Capable of Carrying Signals

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Chapter

8

Physical Transmission Media

Twisted-pair

Telephone System

Coaxial Cable

Cable Television

Fiber-optic

Thin Strands of Glass or Plastic

Uses Light to Transmit Signals

Less Susceptible to Interference

More Secure

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Chapter

8

Wireless Transmission Media

Broadcast Radio

Distributes Radio Signals

Long & Short Distances

Cellular Radio

Widely Used for Mobile Communications

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Chapter

8

Wireless Transmission Media

Microwave Station

Earth-based Reflective Dish

Contains Antenna, Transceivers

Uses Line-of-sight Transmission

Satellite

Space Station

Receives Microwave Signals

Amplifies Signals

Broadcasts Signals Back

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