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Overview ofOverview of
Data CommunicationsData Communications
andand
NetworkingNetworking
PART IPART I

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Overview

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Chapters
Chapter 1 Introduction
Chapter 2 Network Models

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Chapter 1
Introduction

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1.1 Data Communication
Components
Data Representation
Direction of Data Flow

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Figure 1.1 Five components of data communication

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Figure 1.2 Simplex

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Figure 1.3 Half-duplex

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Figure 1.4 Full-duplex

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1.2 Networks
Distributed Processing
Network Criteria
Physical Structures
Categories of Networks

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Figure 1.5 Point-to-point connection

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Figure 1.6 Multipoint connection

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Figure 1.7 Categories of topology

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Figure 1.8 Fully connected mesh topology (for five devices)

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Figure 1.9 Star topology

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Figure 1.10 Bus topology

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Figure 1.11 Ring topology

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Figure 1.12 Categories of networks

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Figure 1.13 LAN

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Figure 1.13 LAN (Continued)

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Figure 1.14 MAN

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Figure 1.15 WAN

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1.3 The Internet1.3 The Internet
A Brief History
The Internet Today

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Figure 1.16 Internet today

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1.4 Protocols and Standards1.4 Protocols and Standards
Protocols
Standards
Standards Organizations
Internet Standards

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Computer communications and
standards
 Why standards?
 Required to allow for interoperability between
equipment
 Advantages
 Ensures a large market for equipment and software
 Allows products from different vendors to communicate
 Disadvantages
 Freeze technology
 May be multiple standards for the same thing
 Defacto and Dejure standards

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Key Organizations
 Standards organizations provide forums for
discussion, help turn discussion into formal
specifications
 Most standards organizations have specific
processes for turning ideas into formal standards.
 They all iterate through several rounds of
organizing ideas, discussing the ideas, developing
draft standards, voting on all or certain aspects of
the standards, and finally formally releasing the
completed standard to the public.

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Key Organizations (con’t)
 Some of the better-known standards
organizations follow:
 International Organization for Standardization
(ISO)—An international standards organization
responsible for a wide range of standards,
including those relevant to networking. This
organization is responsible for the OSI
reference model and the OSI protocol suite.

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Key Organizations (con’t)
 American National Standards Institute (ANSI)—
The coordinating body for voluntary standards
groups within the United States. ANSI is a member
of ISO. ANSI’s best-known communications
standard is FDDI.
 Electronic Industries Association (EIA)—A
group that specifies electrical transmission
standards. EIA’s best-known standard is
EIA/TIA-232 (formerly RS-232).

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Key Organizations (con’t)
 Institute of Electrical and Electronic Engineers
(IEEE)—A professional organization that defines
network standards. IEEE LAN standards (including
IEEE 802.3 and IEEE 802.5) are the best-known
IEEE communications standards and are the
predominant LAN standards in the world today.

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Key Organizations (con’t)
 International Telecommunication Union
Telecommunication Standardization Sector (ITU-T)
(formerly the Committee for International Telegraph
and Telephone [CCITT])—An international
organization that develops communication
standards. The best-known ITU-T standard is X.25.

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Key Organizations (con’t)
Internet Activities Board (IAB)—A group of
internetwork researchers who meet regularly to
discuss issues pertinent to the Internet. This board
sets much of the policy for the Internet through
decisions and assignment of task forces to various
issues.
Some Request for Comments (RFC) documents are
designated by the IAB as Internet standards, including
Transmission Control Protocol/Internet Protocol
(TCP/IP) and the Simple Network Management
Protocol (SNMP).