Professor Michael J. LosaccoCIS 1110 – Using Computers

Communications & NetworksChapter 8

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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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Communications

Two or More DevicesTransfer Data or Instructions

RequirementsSending DeviceCommunications Device

Connects Sending Device to ChannelConnects Channel to Receiving Device

Communications ChannelMedia on Which Data Travels

Receiving Device

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Uses

Wireless Messaging

Text Messaging

Send / Receive Text Messages Using Phone

14-17: 60 v. 5

Picture Messaging

Send / Receive Graphics, Pictures, Video

Sexting: 30% of 17-year-olds

Pew Internet 5/10

Pew Internet 12/09

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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

GroupwareAssists Groups in Working Together

Share Data Over Networke.g., Schedule Meetings

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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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Uses

Very Hard to Give Up

38%

51%

38%45% 47%

43%

63%

40%

6%

36%

0%

25%

50%

75%

Cell Phone Internet TV Phone WirelessEmail

2002 2007

Pew Internet 3/08

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Networks

Collection of Computers & DevicesConnected via

Communications Devices

Transmission Media

AdvantagesFacilitating Communications

Sharing Hardware

Sharing Software

Sharing Data And Information

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Network Types

LAN (Local Area Network)Network in Limited Geographical Area

Typically Within a Building

WLANWireless LAN

WAN (Wide Area Network)Large Geographic Area

Uses Many Types of Media

Internet

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Network Architectures

Client/ServerClient

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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Network Topology

Configuration of Devices in a NetworkBus

Consists of Single Central CableAll Devices Connect to it

Inexpensive & Easy to Install

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Network Topology

RingCable Forms Closed RingData Travels In One DirectionExpensive & Difficult to Install

StarAll Devices Connect to HubAll Data Passes Through Hub

Bottlenecks Can Occur

Easy to Install

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Intranet & Extranet

IntranetInternal Corporate Network

Uses Internet

Accessible to Corporate Employees

Facilitates Working in Groups

ExtranetAllows Access to Parts of a Intranet

Customers / Suppliers

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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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Standards

EthernetFor LANsUses Bus or Star TopologyWidely Implemented

TCP/IPUsed for Internet TransmissionsPacket Switching

Transmits Data by Breaking it Into PacketsReassembles Data at Destination

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Standards

802.11 (Wi-Fi)Family of Standards for Wireless LANs

802.16 (WiMAX)Towers Cover 30-mile RadiusProvides Wireless Broadband Internet

BluetoothShort-range Radio Technology

WAPWireless Mobile Devices Connect to Internet

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Standards

IrDAData Transferred via Infrared Light Waves

RFIDRadio Signals Communicate with TagsFailed Legislation

NevadaRequire Retailers to Inform Customers

Rhode IslandGovernment Agency Cannot Track Individuals

TexasProhibit Schools from Using RFID on Students

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Types & Speeds

Measured in bps (Bits per Second)

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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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Devices

Wireless Modem

Internet Access

Network Card

Connects PC to Network

Wireless Access Point

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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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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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Channel

Broadband

Transmit Multiple Signals over Channel

Transmission Media

Materials or Techniques

Capable of Carrying Signals

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Physical Transmission Media

Twisted-pairTelephone System

Coaxial CableCable Television

Fiber-opticThin Strands of Glass or Plastic

Uses Light to Transmit Signals

Less Susceptible to InterferenceMore Secure

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Wireless Transmission Media

Broadcast Radio

Distributes Radio Signals

Long & Short Distances

Cellular Radio

Widely Used for Mobile Communications

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Wireless Transmission Media

Microwave StationEarth-based Reflective Dish

Contains Antenna, Transceivers

Uses Line-of-sight Transmission

SatelliteSpace Station

Receives Microwave Signals

Amplifies Signals

Broadcasts Signals Back