NetworksChapter 3

LANs, WANs, Virtual networks Advantages of a client-server network Network components – describing their

purpose and justifying their use Importance of Standards & The Use of

Protocols

Revision today – chapter 3

The characteristics of:◦ Local Area Networks◦ Wide Area Networks◦ Virtual Networks

This presentation covers:

A network is two or more computers which are connected together.

By connecting computers together, they are able to talk to each other and share resources like files and hardware (printers, scanners etc).

Introduction

Computers which are connected in a local geographical area.

You usually find them in:◦ Schools◦ Libraries◦ Doctor and Dentist surgeries◦ Hospitals◦ Police Stations◦ And increasingly more at home.

Local Area Network (LAN)

Computers are connected in a local geographical location. Eg up to ½ sq miles

Workstations have either physical or wireless network connections

Organisation owns the cabling.

Peripherals are often shared.

Software and data can be shared.

Characteristics of a LAN

Increasingly, more and more households how have more than one computer or laptop.

Data is now being shared across these devices including music and video streaming.

Printers are shared across the network also.

Media can also be streamed to devices like Xbox 360 and PS3 consoles.◦ This allows people to stream music from their

PC and play it through their console while playing a game!

LAN at home...

LAN

Switch/Router connected to Internet

Wireless Access Point (WAP)

Computers are connected across a wider area compared to LAN.◦ The geographical locations are far apart.

The internet is a fantastic example of a WAN.

Computers are able to connect to one another through the internet.

Wide Area Network (WAN)

Some systems might need WAN connections as well as LAN connections.

Examples include:◦ University campuses spread over large areas

◦ The medical network (allows medical records to be accessed from all over the country)

◦ ATM machines, Lottery machines

◦ Large global businesses

Wide Area Network (WAN)

Computers are not close together.

External equipment may be needed to connect computers together:◦ Telephone lines◦ Satellite◦ Mobile Phones

Specialist equipment is needed to connect to the WAN e.g. Router or modem.

Characteristics of a WAN

WAN

Router

The InternetIs a WAN network...

But is made up of lots of single computers and LAN networks.

LAN 1

LAN 2

There may be many computers connected in a LAN but they can be fooled into thinking that their network is much smaller.

This is accomplished by using virtual networks to limit what computers another computer can see on the network.

Virtual Network

Virtual Network in a LAN

The computers surrounded with red do not know the blue computers exist.

The switch ‘hides’ the blue computers from the red computers.

Virtual Network across a WAN

This example shows how computers might be connected using a virtual network across a WAN.

The red computers communicate with each other and are unaware of the blue computers.

Identify three characteristics of a LAN

Identify two characteristics of a WAN

Describe the purpose of a Virtual Network

Identify four services offered by an ISP

Questions

Identify three characteristics of a LAN -within a local geo area, owns its cables, shared peripherals

Identify two characteristics of a WAN – covers large geo area, uses external cabling eg tel lines, leased lines, mobiles

Describe the purpose of a Virtual Network – to create a network of computers which operate like a single LAN even though computers maybe from different LANs or WANs,

Identify four services offered by an ISP

Answers