data communications & networking
DESCRIPTION
Data Communications & Networking. Chapter 1 - Introduction. Data Communication. Data communication – exchange of data between two devices via a transmission medium. Communication System Components. Data Representation. Text – represented as a bit pattern; codes often used: - PowerPoint PPT PresentationTRANSCRIPT
DATA COMMUNICATIONS & NETWORKING
CHAPTER 1 - INTRODUCTION
DATA COMMUNICATION
Data communication – exchange of data between two devices via a transmission medium
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COMMUNICATION SYSTEM COMPONENTS
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DATA REPRESENTATION
Text – represented as a bit pattern; codes often used:
• ASCII; Extended ASCII; Unicode; ISO
Numbers – represented by binary equivalent
Images – bit patterns representing pixels
Audio – recording sound or music
Video – movie , motion picture
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DIRECTION OF DATA FLOW
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Simplex – unidirectional; one transmits, other receives
Half-duplex – each can transmit/receive; communication must alternate
Full-duplex – both can transmit/receive simultaneously
NETWORKS
• Set of devices (nodes) connected by media
• A node can be a computer, printer
• or any device capable device capable of sending and/or receiving data
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NETWORK CRITERIA
• Performance
• affected by # users, • type of medium, • Hardware , software• often evaluate by throughput and delay
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NETWORK CRITERIA
• Reliability
• measured by frequency of failure, • recovery time, • catastrophe vulnerability
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NETWORK CRITERIA
• Security
• protection from unauthorized access, • protecting data from damage
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TYPES OF CONNECTIONS
Point-to-point – dedicated
Multipoint – shared
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PHYSICAL TOPOLOGY
• Physical or logical arrangement
• 4 basic types:
• mesh• star
• bus
• ring
• May often see hybrid
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MESH TOPOLOGY
• Dedicated point-to-point
• links to every other device
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STAR TOPOLOGY
• Dedicated point-to-point links to central controller (hub)
• Controller acts as exchange
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BUS TOPOLOGY
• Multipoint configuration
• One cable acts as a backbone to link all devices
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RING TOPOLOGYDedicated point-to-point configuration to neighbors
Signal is passed from device to device until it reaches destination
Each device functions as a repeater
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CATEGORIES OF NETWORKS
Local Area Network (LAN) – smaller geographical area
Metropolitan Area Network (MAN) – network extended over an entire city
Wide Area Network (WAN) – large geographical area
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INTERNETWORKS
Connection of two or more networks
Internet vs. internet
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THE INTERNET
Collaboration of more than hundreds of thousands interconnected networks
1969 – started as ARPAnet, a small network of connected computers
1972 - Cerf and Khan – packet delivery and Transmission Control Protocol (TCP)
Shortly thereafter – evolution of TCP/IP
A brief history of the Internet
Internet Timeline
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PROTOCOLS AND STANDARDS
Why do we need them?
Protocol – set of rules that govern data communication; defines what, how, and when
• Key elements – syntax, semantics, timing
Standard – provides a model for development; allows for interoperability
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STANDARDSTypes –
• De jure/Formal – legislated by an officially recognized body• De facto – by convention or widespread use
Standards Organizations – committees, forums, regulatory agencies
Internet Standards
• Drafts• RFC Process
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SUMMARY
Introduction to data communication, networking, and protocol standards
Next chapter…
• Network models
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CREDITS
All figures obtained from publisher-provided instructor downloads
Data Communications and Networking, 3rd edition by Behrouz A. Forouzan. McGraw Hill Publishing, 2004
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