Data Communications & Networking

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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