Download - Open Socrative – Room 970781
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