Open Socrative – Room 970781

List as many network

components as possible

• compare the role of the following network components: • switches, • hubs, •wireless access points, • network interface cards, •wireless network interface cards, • routers, • repeaters, • Bridges • servers (file, applications, mail, proxy, print, backup)

• identify where their use would be appropriate;

Objectives

Hub• Hub is the same as a switch but not

as intelligent• Does not examine the packets but

sends them to every port.• Data is filtered by recipient devices.• Data collisions slow network

• The following diagram shows two hubs segmented using a bridge (see bridge). Four computers have direct access to the network, although only one hub has direct access to the server.

The hub is used to allow 4 computers to physically connect to the network. The hub is then connected to the server.

Client

ClientHub

Client

Client

Server

Client

Client

Hub Bridge Hub

Server

Client

Client

Hub

Switch• Connect several devices• Data packets are received and examined

by the switch that then sends them to the correct port• Managed switches can be configured to

control the flow of data (priority etc)• Technical to setup

Switch

Four web designers share both large and small files. Sometimes they send and receive emails with videos attached, download animations, upload large web pages, save and retrieve large files and print various files.

A star topology was used because of its speed and security.

A switch was used as it can direct files efficiently by choosing the connections needed to make. This is especially useful when all four designers are accessing the network at the same time.◦ As the switch can make simultaneous connections.

Client

ClientSwitch

Client

Client

Server

Print Server

Web Server

File Server

Mail Server

Printer

Router• Advanced version of a switch. It

stores the address of devices connected to it and sends data to recipient devices on an efficient route• Normally connects LAN to WAN

NIC• Enables a computer to connect

to a network• Integrated into motherboard• Each NIC has a MAC address

Wireless NIC• To communicate with a WAP you

need a wireless NIC• Can be in the motherboard,

external dongle, or adapter card• Different communication standards

WAP• This is a hub that

communicates wirelessly• These then connect to a switch

more commonly• Problems with hackers

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

A signal is broadcast out

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

The wireless device broadcasts back!

Any device in broadcast range could intercept it!

Baddy Client!

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Baddy Client!

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Baddy Client!

Baddy Client!

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Baddy Client!

Wireless Access PointsClient

Client

WAP

Client

Client

Switch

Repeater• Strengthens signals• Receives the signal cleans it

and re-amplifies.• Think at home about the

wireless connection

Repeater

• Quicky What type of hardware could go where the question mark is? Discuss.

Client ClientClient Client

Client ?Client Server

Repeater

Room 1

Room 2

Bridge• Connects to LANS together• Different to router as does n ot

store addresses of devices connected to it.

Bridge

Segments are simple parts of a whole network.

Networks often split into smaller segments to maximise network efficiency.◦ Computers that usually talk to each other are kept in the same network. This minimises the risk of packet

collisions.◦ This is common place when businesses are split into departments. Computers in the sales department will be

on one segment, where as the finance department will have computers in a different segment. But, they are still part of the same network.

◦ The bridge will have ports so that it can forward any traffic to another segment if needed. The bridge also blocks communications. It will know which computers are in which segment. If a packet is sent to a computer in the same segment as its originator, it will be blocked from going to the other segments on the network.

Client

Client Client

ClientClient

Client

BridgePort A Port B

Segment 1 Segment 2

Servers• Lots of different servers

completing different jobs.

File server• Stores user data files.

• Network Operating System (NOS) allows accounts to be set up.

• Requires username and password.

• Can only access your own files.

• Stores applications for use across networks.

• The application server can be used in two ways:– For storing installation files which can easily be deployed across

client machines.• Low network traffic but increase in required processing power at client

side.

– Allows applications that are installed on the server to be run by client from the server side.• High network traffic but less demand on processing at client side.

Application Server

Mail server• Manages mail in and out of a network.

– Checks income emails for viruses– Filters out SPAM emails– Provides central address book for the organisation– Sets email and inbox sizes

• Useful for both internal and external email.

Proxy server• Used to cache web pages.

• When a request is made to a web server, a web page is downloaded and displayed on the client’s computer. It is also stored or ‘cached’ on the proxy server.

• Requests for the same page are then downloaded from a proxy server which is much quicker than downloading from the internet.

Proxy server (cont.)Also act as a security buffer.

Clients make a request for a file on a file server.

The proxy intercepts the request and checks the client’s authenticity.◦ Checks validity of user and they have authorisation to receive a file.

Proxy then requests the file from the file server and forwards it back to the client.

The client never has direct access to the file server.

Print server• Allows access to a shared printer.

• Usually come with spooler software.– Spoolers collect jobs that have been sent to a printer, puts them

in a queue, and then forwards the print queue to the printer.

• Printers work much slower than a computer. This is why we use a spool.– Computers would slow down if each file was sent to a printer as

the computer would have to wait for the printer to catch up with it.

• The backup server backs up all data on the network.

• If all users save data on the server, the server can automatically back-up files over night.

• This means that if data is lost it can be recovered.– It may not be the most up to date version but it is better than

having to start again.

• It will usually make use of tape drives.

Backup Server