Transcript Hardware & Communication

Networks: LANs
What hardware do you need for a LAN network?
•File Server : Runs software, stores
files.
•Terminals : Workstations that give
network access.
•Print Server : Queues up all print jobs
from users in network.
•Cables (wire/optic) : Sends data
•HUBS – joins computers in a network
•Router – enables network to be
connected to the internet (SKY Router)
Hardware – Buses
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Buses are the lines of communication between
the hardware devices within a computer system
All data that moves in a computer must use the
buses that are available
There are different types of buses each with a
different role
Address Bus: This identifies the memory
location that is to be either written to or read
from
Hardware – Buses
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Data Bus: This bus transfers the data to
and from the processor, to the identified
memory location
Interfacing
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Computing peripheral devices have different
operating characteristics
When a device is connected to a computer, an
interface is the hardware and software needed
for the processor to be able to communicate with
the device
Sometimes the interface hardware comes on an
interface board, which has to be fitted into the
computer
Interfacing
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Commonly the peripheral is just connected via a
socket
This is the port through which signals to and
from the device travel
Serial/parallel
USB
Firewire
HDMI
MIDI
VGA etc
Handshaking
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When two devices need to communicate, one
device sends a message to the other
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When the other is ready, it sends a signal back to
the first device
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“are you ready to receive data?”
“Yes I am ready to receive data”
Now the communication can begin
This exchange of preliminary signals is called
handshaking
Networks Protocols
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Protocol: A set of rules for transmitting data across a
networkable to 'talk' or 'communicate' with one another
and they do this by following a protocol.
Protocols have rules for
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Detecting a connection
Handshaking
How to start a message
How to format a message
What to do about errors
How to detect a loss of connection and what to do next
Terminating a connection
Networks Protocols
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HTTP: HyperText Transfer Protocol
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FTP: File Transfer Protocol
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Used for transferring files from one computer to
another – uploading a web page to a web server
SMTP: Simple Mail Transfer Protocol
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Used for transferring web pages between a client and a
server on the Internet
Used for sending an email over the Internet
VoIP: Voice over Internet Protocol
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Used for sending voiced messages over the Internet
Networks Protocols
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Wireless
– WAP
WAP stands for Wireless Application Protocol
and is a popular type of mobile internet service
which can be used on a handheld device, such
as a mobile phone or PDA. It enables you to go
online while out and about and is especially
handy if you want to get the latest news updates,
sports scores and travel updates. (Apple phones
communicate with Android)
3G and 4G taken over
Portable Devices
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Any device that can be carried around with you
Laptop Computer
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Battery powered computers that can be used anywhere
Most have network cards so that they can connect to a
network either via a cable or a wireless connection
PDA Personal Digital Assistant)
– A small hand-held portable computer
– A palmtop computer
Wireless Networks
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Radio waves can be used to transmit data from
one computer to another
Each computer in a wireless network requires a
wireless network card together with the software
drivers
A wireless hub is connected to the network and
transmits receives data from the computers
Wireless Networks - Advantages
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No need for cabling
Computers can be used anywhere within range
of the signal
Wireless Networks - Disadvantages
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Data transmission speeds can be slow
Data signals can only be received within a limited
range
Security maybe a problem as people may be able
to pick up the data signals outside of your
premises
Network Communications
GCSE ICT
Networks: WANs
What extra hardware do you need for a WAN
network?
• Modems : To connect up to a
telephone system (instead of cable).
How a modem
works…
The Telephone Network in Computing
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A modem is required for a computer to
communicate over telephone lines
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Data is converted from digital to analogue and then
back again
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The speed at which data is transmitted and/or
received is measured in bits per second
Network Communications
Bandwidth tells us the
rate at which data can
be transmitted down
the communications
line in a given period
of time.
The current standard
is 56,000 bits per
second
FAST BANDWIDTH
SLOW BANDWIDTH
Network Communications
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The higher the bandwidth, the quicker the
data will flow along the line…
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Web pages loaded quicker.
Multimedia is downloaded faster.
Internet connection is faster.
Less network traffic.
Quicker response time.
Network Communications
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There are a number of connection types
available to us when we want to access the
services from the Internet… Each one has a
different BANDWIDTH.
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PSTN : Public Switched Telephone Network.
ISDN : Integrated Services Digital Network.
ADSL : Asymmetric Digital Subscriber Line.
Public Switched Telephone Network
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PSTN for short.
Uses traditional telephone system to allow access to the
Internet. This is the telephone system used for making day-today telephone calls
It is the main reason why computers have become so popular
in recent years!
Low Bandwidth
Dial Up Connection.
Integrated Services Digital Network
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ISDN for short.
Has a greater range of frequencies than PSTN, at least as
twice as fast. Typical transfer rate of 128,000 bits per second
Data is transmitted simultaneously
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Special connection and modem required
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Supports Videoconferencing, faxes and voice applications.
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Asymmetric Digital Subscriber Line
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ADSL for short.
Usually referred to as ‘Broadband.’
Is permanently switched on, no need for dial up to get a
connection. Uses telephone lines to transmit data at very fast
speeds (512,000 bits per second)
ADSL modem and splitters required to separate telephone
signal from the ADSL signal
Has a high bandwidth.
You can still make telephone calls when surfing the web!
Connecting to The Internet
Single users can connect to the Internet.
Special Hardware and Software is required to
allow people to access the Internet. As well as
an electronic device (PC, Tablet etc.) you need:
 Internet Service Provider.
 Browser Software.
 Telecommunications line e.g. ISDN, ADSL.
 Modem/Broadband Modem/ISDN adapter.
Network Security
GCSE ICT
Learning Outcomes:
 Understand
how to secure a network.
 Understand Dangers posed to networks.
 Identify different types of security.
The Basics
There are many ways to secure a network ranging from complicated
around the clock security services to a simple lock and key.
Security is now a major item in every network it can mean the difference
between life and death for some businesses.
Example: The play station network, was taken down by hackers and some
of their customers credit card details stolen. This was all because the
security on this network was weak or unprotected.
Network Security
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Physical security means that the hardware
of the network is protected from theft and
kept safe.
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Access security means that there is a limit
to the amount of access a user has to the
information held on the network.
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Data security means that there are
Ways of protecting you and your
computer and network
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There are now many company's offering users different
packages to protect and prevent your computer and or network.
Most of theses packages detect, quarantine and delete
infected files And some monitor the websites accessed and
links to other servers and or networks.
Types of virus
There are many types of virus for example there are:
 Worm virus
 Trojan houses virus
 Boot sector virus
 Macro virus
 Root kit virus
 Time bomb virus
 Memory resistant virus
 Polymeric virus
Physical security for a network
As well as security software you will need to
protect your network in more conventional
ways i.e. lock and key.
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Fire protection- fire doors, smoke doors, fire proof safes est.
Alarms-rooms containing the server should be alarmed
Locks-all rooms with services inside and have limited recorded
access to them
Visibility-avoid putting computers on ground flour and where
they are visible to passes bye
Data security
There are many ways to prevent loss of your data:
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Password protecting your data.
You can also set the information as read only so it can not be
tampered with.
You can also back up data either as a hard copy of saved
digitally.
You will also need to keep a log on access to your server, so
that if the worst happens you can trace the perpetrator.