Networks and effects of using them Unit 4 Networks and effects of using them

What is a network? A network is a group of two or more computer systems linked together.

Hubs Hardware device Can have a number of devices connected to them Usually used to form a LAN Main task is to take any data packet - group of data being transmitted) Not very secure and/or efficient

Modems Short for “Modulator demodulator” Converts digital into analogue over an existing telephone line Reverse process Used to allow computer to connect to network

Switches Similar to hub but more efficient Connect computer together to form a LAN Checks data packet received and works out its destination and sends data to appropriate computer MAC(media access control)=address that identifies network

Bridge Connect one LAN to another LAN that uses the same protocol Connect different parts of a LAN so that they function as a single LAN

Router WAN (wide area network) Enable data packets to be routed between the different networks WAN (wide area network) One internet cable plugged in, and several cables connecting to computers and other devices on the LAN Main function is to transmit internet and transmission protocols between two networks IP= internet protocol

Gateway Network point or node that acts as an entrance to another network Key point for data on its way to or from other networks

Network interference card (NIC) Needed to allow device to connect to a network (ex. Internet) Contains MAC address

Network cables Instead of Wi-Fi Can be either copper or fiber optics ADVANTAGES Faster data transfer rates Can be more secure than wireless networks

IP adress ( internet protocol) Each device has one 32-bit number Home computer is given one when it connects to the internet Only ip adresses that remain uncharged are web servers Can be used instead of typing in the full URL

WIFI Offers wireless communication Wi-Fi network makes use of radio waves to transmit information across a network. The computer should include a wireless adapter that will translate data sent into a radio signal. This same signal will be transmitted, via an antenna, to a decoder known as the router. Once decoded, the data will be sent to the Internet through a wired Internet connection. As the wireless network will work as a two-way traffic, the data received from the Internet will also pass through the router to be coded into a radio signal that will be receipted by the computer's wireless adapter. 

Bluetooth The Bluetooth standard, like WiFi, uses the FHSS technique (Frequency-Hopping Spread Spectrum) which involves splitting the frequency band of 2.402-2.480 GHz into 79 channels (called hops) each 1MHz wide then transmitting the signal using a sequence of channels known to both the sending and receiving stations.  Thus, by switching channels as often as 1600 times a second, the Bluetooth standard can avoid interference with other radio signals. 

How to set up a small network You would need to buy some hardware: One or more switches / hubs - to link devices together Network cables to connect devices to the switch, etc. A separate wireless access point (or this could be part of the switch) - to allow wireless devices (e.g. laptops or smart-phones) to join the network A router to connect your LAN to the Internet (WAN) A firewall to protect your network from hackers Possibly a bridge if you already have a section of network and you want your new network to connect to it Server(s) to manage network functions such as networksecurity, network file storage, shared resources (such as printers)

How to set up a small network You would need to organise some other things: Set up an account with an Internet Service Provider (ISP) Get an Internet connection installed from the ISP to your location Configure various bits of hardware and software so that everything worked with the network

Local are networks (LAN) A local-area network (LAN) is a computer network that spans a relatively small area. Most often, a LAN is confined to a single room, building or group of buildings, however, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. ADVANTAGES DISADVANTAGES Sharing of resources Spread of viruses Ease of communication Slow access Easy to control Security risk

Wide area networks (WAN)  WAN is a collection of computers and network resources connected via a network over a geographic area. Wide-Area Networks are commonly connected either through the Internet or special arrangements made with phone companies or other service providers.

Wireless LANs (WLAN) WLAN is a type local network that utilizes radio waves, rather than wires, to transmit data. Today's computers have WLAN built onboard, which means no additional Wi-Fi card needs to be installed. Access points (AP) are connected into the wired network at fixed locations

Accessing the internet

Mobile phones and tablets ADVANTAGES DISADVANTAGES Very portable, network signal can be accessed Expensive if hot-spot is not available Persons are more likely to carry them Small display, more difficult to read web pages Easier to use while on the move Keboards are small Not all websites are mobile friendly Signal less likely to be as stable as wired systems

Laptops ADVANTAGES More mobile than desktops Touchpad is easier to use than phone touchpad Keyboards are much better than phone keyboards DISADVANTAGES Not as large as a desktop Expensive to access phone networks Processors are not as powerful as desktop Slow access speed

Desktops computers ADVANTAGES Fast processors Stable internet All websites are accessable Use of full-sized keyboard DISADVANTAGES Parts are all seperate Expensive to access phone networks heavy

Network issues and communication

Should the internet be policed? Help prevent illegal material being posted Prevent children from being subjected Stop incorrect infos Already available sources Expensive Difficult to enforce rules Laws already exist

Inappropriate sites and the accuracy of information Three main aspects to consider: Reliability Undesirablility Security issues

Reliability Up to date rather than books Easier to get infos Vast amount of infos Infos could be incorrect Risk of information overload

Undesirability Risk of finding inppropriate websites Risk of connecting to websites that are not genuine (real) Security risk

Security issues Passwords to access email account, online banking, social networks Protect your password! Anti-spyware software Change password regularly Hard to remember

Authentication Used to verify that data comes from a secure source

Viruses- Antivirus software Check software Compares possible virus against database of known viruses Carry out heuristic checking(checking behaviour that could indicate virus) Needs to be kept up to date Full system checks need to be carried out

Avoiding viruses Avoid unknown websites Look for padlock symbols Look out for odd behaviour in URL Don´t open emails from unknown sources

Data protection acts Don´t leave personal infos lying around Lock filing cabinets Use passwords and user Ids Do not leave data on a computer monitor

Network communication

Faxes Physical fax=machine connected to telephone line. Allows documents to be sent to another fax machine Electronic fax=network is required Saves paper, needs computer, transmissions are sent to an email account

Email Electronic mail Useful when sending attachments Available on any device Require an account More secure than faxes No need to print

Video conferencing Communication method that uses video and sound Hardware include: webcam, monitor, microphone, speakers Agree a time and date Check if all the hardware is connected and functionable

Audio conferencing Meeting via audio Organiser is given two PINs by phone company Organiser contacts all participants and inform them of their PIN Organiser dials conference number Participants call same conference number to join in, once they get through the have to put in their PIN Also possible with computer,, makes use of VoIp( Voice over Internet Protocol)