Communications & Networks
description
Transcript of Communications & Networks
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