Lecture Computing for management - Chapter 10

Lecture 10 - Introduction to computer networks and data communications. After studying this chapter you will be able to understand: Introduction to telecommunications, basic components of communications, telecommunications media, rate of data transfer, define the basic terminology of computer networks,...

Lecture 10

Introduction to Computer

Networks and Data Communications

Summary of Previous

In the previous lecture we have learnt,

 Managing business data

Summary of Previous

 Data Presentation

 Purpose and Types of presentations

 Microsoft Power Point

 Working With Text

 Graphs and Charts

 Rate of data transfer

 Define the basic terminology of computer

networks

 Network Topology

 Classification of Computer Networks

 Network Devices

 Recognize the individual components of the big

picture of computer networks

Today’s Topics

 Computer Network Layouts

 Microcomputer-to-local area network

 Microcomputer-to-Internet

 Local area network-to-local area network

 Personal area network-to-workstation

 Local area network-to-metropolitan area network

 Local area network-to-wide area network

Today’s Topics

 Sensor-to-local area network

 Satellite and microwave

 Cell phones

 Computer terminal / mainframe

microcomputer-to- Summary

Introduction

 Everyone is using a computer network today.

 Mass transit, interstate highways, 24-hour

bankers, grocery stores, cable television, cell

phones, businesses and schools, and retail

outlets support some form of computer network

What is Telecommunication?

 Transmission of different forms of data

 such as text, audio, video, images, graphics

 It occurs between one set of electronic devices over media to another set of geographically separated electronic devices.

Basic Components of Communications

 Sender: Person or device sending the

Sender  

Telephone, 

Computer, 

Video  Conferencing

Channel/Medium  

Various Types of  Electronic Media

Message 

Voice, Data  Video, etc.

Receiver  

Telephone,  Computer,  Video  Conferencing

Telecommunications

Telecommunications Media

 Communications media - the paths, or physical

channels, in a network over which information travels.

 Wired communications media - transmit information

over a closed, connected path

 Wireless communications media - transmit

information through the air.

Telecommunications Media

Telecommunication – Rate of data transfer

 Data transmission channels (bps)

 narrow bands: 5-30

 voice bands: 1,000-9,600

 broad bands: 100,000

Computer Networks

What is Computer Network?

 Computer network is an interconnection of computers and computing equipment using either wires or radio waves over small or large geographic areas

Network Topology – Connecting

Computers

The network topology defines the way in which computers, printers, and other devices are connected

A network topology describes the layout of the wire and devices as well as the paths used by data transmissions

Bus Topology

Ring Topology

 A network configuration in which

computers are arranged in the form of a ring using twisted-wire, coaxial cable, or fiber optics

 Messages are transmitted in one

direction to all devices between the sending node and the receiving node

Ring Topology

Star Topology

 A topology in which a central host computer receives all messages and then forwards the message to the appropriate computer on the network

Star Topology

Mesh Topology

The mesh topology

connects all devices

(nodes) to each other for redundancy and fault

tolerance

It is used in WANs to interconnect LANs and for mission critical networks like those used

by banks and financial institutions

Implementing the mesh topology is expensive and difficult

Classification of Computer

Networks

Different Types of Network Exists

 Local area network

 Networks that are small in geographic size spanning a room, floor, building, or campus

 Metropolitan area network

 Networks that serve an area of 1 to 30 miles, approximately the size of a typical city

 MAN networks are generally good for businesses and organizations that have multiple locations around a city A bank may also take advantage of a MAN

 Wide area network

 a large network that encompasses parts of states, multiple states, countries, and the world

 Personal area network

 a network of a few meters, between wireless devices such as PDAs, laptops, and similar devices

 Voice network

 a network that transmits only telephone

signals (almost extinct)

 Data network

 a network that transmits voice and computer data (replacing voice networks)

Computer Network Popular Terms

 Data communications – the transfer of

digital or analog data using digital or

analog signals

 Telecommunications – the study of

telephones and the systems that transmit telephone signals (becoming simply data communications)

Popular Terms

 Network management – the design, installation, and support of a network, including its hardware and software

 Network cloud – a network (local or

remote) that contains software,

applications, and/or data

The Big Picture of Networks

 Networks are composed of many devices, including:

 Workstations (computers, tablets, wireless

phones, etc)

 Servers

 Network hubs and switches

 Routers (LAN to WAN and WAN to WAN)

 Telephone switching gear

The Big Picture of Networks

(continued)

Network Devices

 Workstations

 They are personal computers/microcomputers (desktops, laptops, net books, hand held, etc.) where users reside

 Servers,

 They are the computers that store network

software and shared or private user files

A Switch

A Switch with 

Network Ports

RJ­45 and  Network  Cables

A Network Router

Computer Network Layouts

 Local area network-to-local area network

 Personal area network-to-workstation

 Local area network-to-metropolitan area network

 Local area network-to-wide area network

 Sensor-to-local area network

 Satellite and microwave

 Computer (device) requires a NIC

(network interface card)

 NIC connects to a hub-like device (switch)

Micro Computer to Local Area Network Layout

Microcomputer-to-Local Area Network

Layout (continued)

Micro computer to LAN

Gaming Competition

Microcomputer-to-Internet Layout

 Popular with home users and small

businesses

 For some, a dial-up modem is used to

connect user’s microcomputer to an

Internet service provider

 Technologies such as DSL and cable

modems are replacing modems

Microcomputer-to-Internet Layout

(continued)

Dialup Connections

Personal Area Network-to-Workstation Layout

 Interconnects wireless devices such as

PDAs, laptops and notebooks, and music playback devices

 Used over short distances such as a few meters

Personal Area Network-to-Workstation

Layout (continued)

Example

Local Area Network-to-Metropolitan

Area Network Layout

 Used to interconnect companies (usually their local area networks) to networks that encompass a city

 High-speed networks

 Typically, this interconnection uses only optic links

Local Area Network-to-Metropolitan Area Network

Layout (continued)

Local Area Network-to-Wide Area

Network Layout

 One of the most common ways to

interconnect a user on a LAN workstation

to the Internet (a wide area network)

 A router is the typical device that performs LAN to WAN connections

 Routers are more complex devices than switches

Data Communications and Computer Networks: A Business User's Approach, Sixth Edition 57

Local Area Network-to-Wide Area Network

Layout (continued)

Wide Area Network-to-Wide Area

Network Layout

 High-speed routers and switches are used

to connect one wide area network to

another

 Thousands of wide area networks across Pakistan, many interconnected via these routers and switches

Sensor-to-Local Area Network Layout

 Not all local area networks deal with

microcomputer workstations

 Often found in industrial and laboratory

environments

 Assembly lines and robotic controls

depend heavily on sensor-based local

area networks

Sensor-to-Local Area Network Layout

(continued)

Satellite and Microwave Layout

 Typically long distance wireless connections

 Many types of applications including long

distance telephone, television, radio, long-haul data transfers, and wireless data services

 Typically expensive services but many

companies offer competitive services and rates

 Newer shorter-distance services such as Wi-Max

Satellite and Microwave Layout (continued)

Cell Phone Layout

 Expanding market across the world specially

Pakistan.

 Third generation services available in many

areas and under many types of plans with fourth generation services starting to appear

 Latest generation includes higher speed data

transfers (100s to 1000s of kilobits per second)

Cell Phone Layout (continued)

Terminal/Microcomputer-to-Mainframe Computer Layout

 Predominant form in the 1960s and 1970s

 Still used in many types of businesses for data entry and data retrieval

 Few dumb terminals left today, e.g Telnet

Terminal/Microcomputer-to-Mainframe

Computer Layout (continued)

One More Layout

 An Additional Basic layout – network

telephone-to- Telephone systems are ubiquitous and now carry more data than voice

 Voice over IP – telephone-to-LAN via gateway

or telephone to gateway via DSL/cable