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CIS 321 – Fall 2004
Data Communications &
Networking
Chapter 1 - Introduction
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321 Topics to be Covered
Network Topologies &Categories
Transmission Modes
Network Models Signaling and Media
Encoding and Modulating
High Speed Digital Access
Multiplexing Error Detection and
Correction
Data Link Control andProtocols
LANs/WANs,
VLANs/VPNs Frame Relay, ATM
Internetworking
Security
Compression TCP/IP
Application Services
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Part 1 Overview of Data
Communications and NetworkingChapter 1
Brief description of data communication, networking,
and protocol standardsChapter 2
Network models
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Data Communication
Why study data communications?
Data communication – exchange of data between
two devices via a transmission mediumEffectiveness depends on:
Delivery, Accuracy, Timeliness
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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; ISONumbers – represented by binary equivalent
Images – bit patterns representing pixels
AudioVideo
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Direction of Data Flow
Simplex – unidirectional; one transmits, other
receives
Half-duplex – each can transmit/receive;
communication must alternate Full-duplex – both can transmit/receive
simultaneously
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Networks
Set of devices (nodes) connected by media
Distributed processing
Advantages
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Network Criteria
Performance – affected by # users, type of
medium, HW/SW
Reliability – measured by freq of failure, recoverytime, catastrophe vulnerability
Security – protection from unauthorized access,
viruses/worms
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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
Advantages
Disadvantages
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Star Topology
Dedicated point-to-point
links to central controller
(hub)
Controller acts as
exchange
Advantages
Disadvantages
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Bus Topology
Multipoint configuration
One cable acts as a
backbone to link all
devices
Advantages
Disadvantages
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Ring Topology
Dedicated point-to-pointconfiguration to neighbors
Signal is passed from device todevice until it reaches destination
Each device functions as arepeater
Advantages
Disadvantages
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Categories of Networks
Local Area Network (LAN) – smaller geographical
area
Metropolitan Area Network (MAN) – networkextended 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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Standards
Types – 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, 3rdedition by Behrouz A. Forouzan. McGraw Hill
Publishing, 2004
