8/8/2019 01i Introduction

1/26

1.1

Chapter 1Introduction

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

8/8/2019 01i Introduction

2/26

1.2

8/8/2019 01i Introduction

3/26

1.3

Communication Services &

Applications A communication service enables the exchange

of information between users at differentlocations.

Communication services & applications areeverywhere. E-mail

E-mail

server

Exchange of text messages via servers

8/8/2019 01i Introduction

4/26

1.4

Communication Services &

Applications A communication service enables the exchange

of information between users at differentlocations.

Communication services & applications areeverywhere. Web Browsing

Web server

Retrieval of information from web servers

8/8/2019 01i Introduction

5/26

1.5

Communication Services &

Applications

Instant Messaging

Direct exchange of text messages

A communication service enables the exchangeof information between users at differentlocations.

Communication services & applications areeverywhere.

8/8/2019 01i Introduction

6/26

1.6

Communication Services &

Applications

Telephone

Real-time bidirectional voice exchange

A communication service enables the exchangeof information between users at differentlocations.

Communication services & applications areeverywhere.

8/8/2019 01i Introduction

7/26

1.7

Communication Services &

Applications

Cell phone

Real-time voice exchange with mobile users

A communication service enables the exchangeof information between users at differentlocations.

Communication services & applications areeverywhere.

8/8/2019 01i Introduction

8/26

1.8

Communication Services &

Applications

Short Message Service

Fast delivery of short text messages

A communication service enables the exchangeof information between users at differentlocations.

Communication services & applications areeverywhere.

8/8/2019 01i Introduction

9/26

1.9

8/8/2019 01i Introduction

10/26

1.10

Many other examples!

Peer-to-peer applications

Napster, Gnutella, Kazaa file exchange

Searching for ExtraTerrestrial Intelligence(SETI)

Audio & video streaming

Network games

On-line purchasing

Text messaging in PDAs, cell phones (SMS)

Voice-over-Internet

8/8/2019 01i Introduction

11/26

1.11

Services & Applications

Service: Basic information transfer capability

Internet transfer of individual block of information

Internet reliable transfer of a stream of bytes

Real-time transfer of a voice signal Applications build on communication services

E-mail & web build on reliable stream service

Fax and modems build on basic telephone service

New applications build on multiple networks SMS builds on Internet reliable stream service and

cellular telephone text messaging

8/8/2019 01i Introduction

12/26

1.12

What is a communication network?

The equipment (hardware & software) and facilities that

provide the basic communication service Virtually invisible to the user; Usually represented by a

cloud

Communication

Network

Equipment

Routers, servers,switches,multiplexers, hubs,modems,

Facilities

Copper wires, coaxialcables, optical fiber

Ducts, conduits,telephone poles

How are communication networks designed and operated?

8/8/2019 01i Introduction

13/26

1.13

Communication Network

Architecture Network architecture: the plan that specifieshow the network is built and operated

Architecture is driven by the network services

Overall communication process is complex Network architecture partitions overall

communication process into separate functionalareas called layers

8/8/2019 01i Introduction

14/26

1.14

11--1 DATA COMMUNICATIONS1 DATA COMMUNICATIONS

TheThe termterm telecommunicationtelecommunication meansmeans communicationcommunication atat aadistancedistance.. TheThe wordworddatadata refersrefers toto informationinformation presentedpresented

inin whateverwhatever formform isis agreedagreed uponupon byby thethe partiesparties creatingcreating

andand usingusing thethe datadata.. Data Data communicationscommunications areare thethe

exchangeexchange ofof datadata betweenbetween twotwo devicesdevices viavia somesome formform ofoftransmissiontransmission mediummedium suchsuch asas aa wirewire cablecable..

Components

Data Representation

Data Flow

Topics discussed in this section:Topics discussed in this section:

8/8/2019 01i Introduction

15/26

1.15

Figure 1.1 Five components of data communication

*some books use term source destination,

transmitter, receiver, transmission system

8/8/2019 01i Introduction

16/26

1.16

Figure 1.2 Data flow (simplex, half-duplex, and full-duplex)

8/8/2019 01i Introduction

17/26

1.17

11--2 NETWORKS2 NETWORKS

AA networknetworkisis aa setset ofof devicesdevices (often(often referredreferred toto asas nodesnodes))connectedconnected byby communicationcommunication linkslinks.. AA nodenode cancan bebe aa

computer,computer, printer,printer, oror anyany otherother devicedevice capablecapable ofof sendingsending

and/orand/or receivingreceiving datadata generatedgenerated byby otherother nodesnodes onon thethe

networknetwork..

8/8/2019 01i Introduction

18/26

1.18

Figure 1.3 Types of connections: point-to-point and multipoint

8/8/2019 01i Introduction

19/26

1.19

Figure 1.4 Categories of topology

8/8/2019 01i Introduction

20/26

1.20

Figure 1.5 A fully connected Mesh topology (five devices)

8/8/2019 01i Introduction

21/26

1.21

Figure 1.6 A Star topology connecting four stations

8/8/2019 01i Introduction

22/26

1.22

Figure 1.7 ABus topology connecting three stations

8/8/2019 01i Introduction

23/26

1.23

Figure 1.8 ARing topology connecting six stations

8/8/2019 01i Introduction

24/26

1.24

Figure 1.9 AHybrid topology: a star backbone with three bus networks

8/8/2019 01i Introduction

25/26

1.25

Figure 1.10 An isolated LANconnecting 12 computers to a hub in a closet

8/8/2019 01i Introduction

26/26

1.26

Exercises

Draw a hybrid topology with a starbackbone and 3 ring topology

Draw a hybrid topology with a ringbackbone and 3 bus topology