Lecture 10

Introduction to Computer Networks and Data

Communications

Summary of Previous

In the previous lecture we have learnt, Managing business data MS Access 2007

Purpose and Data OrganizationCreating a Database

Table Form Query Report

Summary of Previous Data Presentation

Purpose and Types of presentations Microsoft Power Point A New presentation Design Templates Animation Slide Master Adding Pictures Working With Text Graphs and Charts

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Today’s Topics Introduction to Telecommunications

Basic Components of Communications Telecommunications Media 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 networkMicrocomputer-to-InternetLocal area network-to-local area networkPersonal area network-to-workstationLocal area network-to-metropolitan area

networkLocal area network-to-wide area network

Today’s TopicsSensor-to-local area networkSatellite and microwaveCell phonesComputer terminal / microcomputer-to-

mainframe Summary

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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

message

Receiver: Person or device receiving the

message

Medium: What carries the message from

sender to receiver

Sender

Person

Receiver Person

Channel/Medium

A short distance of air

Message

Voice

Face-to-face Communication

Sender Telephone, Computer,

Video Conferencin

g

Channel/Medium Various

Types of Electronic Media

Message Voice, Data Video, etc.

Receiver Telephone, Computer,

Video Conferencin

g

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: 5-30voice bands: 1,000-9,600broad bands: 100,000

Computer Networks

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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

Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable.

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 TopologyThe 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

Types Metropolitan area network

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

MAN 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.

Types Wide area network

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

Types Personal area network

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

Types Voice network

a network that transmits only telephone signals (almost extinct)

Data network a network that transmits voice and computer

data (replacing voice networks)

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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

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The Big Picture of Networks Networks are composed of many devices,

including:Workstations (computers, tablets, wireless

phones, etc)ServersNetwork hubs and switches Routers (LAN to WAN and WAN to WAN)Telephone switching gear

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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

Network Devices Switches,

They are the collection points for the wires that interconnect the workstations

Routers, They are the connecting devices between

local area networks and wide area networks

A Switch

A Switch with Network Ports

RJ-45 and Network Cables

A Network Router

Computer Network Layouts

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Basic Layouts of Communication networks 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

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Local area network-to-wide area network Sensor-to-local area network Satellite and microwave Cell phones Computer terminal / microcomputer-to-

mainframe

Basic Layouts of Communication networks

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Highly common throughout business and academic environments, and now homes

Typically a medium- to high-speed connection

Computer (device) requires a NIC (network interface card)

NIC connects to a hub-like device (switch)

Micro Computer to Local Area Network Layout

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Microcomputer-to-Local Area Network Layout (continued)

Micro computer to LAN

Gaming Competition

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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

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Microcomputer-to-Internet Layout (continued)

Dialup Connections

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Local Area Network-to-Local Area Network Layout

Found in systems that have two or more LANs and a need for them to intercommunicate

A bridge-like device (such as a switch) is typically used to interconnect LANs

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Local Area Network-to-Local Area Network Layout (continued)

Hardware that connects

computers to one another on a local network.

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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

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Personal Area Network-to-Workstation Layout (continued)

Example

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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 fiber-

optic links

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Local Area Network-to-Metropolitan Area Network Layout (continued)

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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)

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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

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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

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Sensor-to-Local Area Network Layout (continued)

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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

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Satellite and Microwave Layout (continued)

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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)

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Cell Phone Layout (continued)

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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

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Terminal/Microcomputer-to-Mainframe Computer Layout (continued)

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One More Layout An Additional Basic layout – telephone-to-

networkTelephone systems are ubiquitous and now

carry more data than voiceVoice over IP – telephone-to-LAN via gateway

or telephone to gateway via DSL/cable

Summary We have been discussed about

Telecommunication essentials Computer Networks

Definition Topology Classification Layouts

We have understood that using network we can perform day to day business functions. Depending upon the types and nature of business we

want to set up our computer network.