Please enable JavaScript.
Coggle requires JavaScript to display documents.
Revision yr10 - Coggle Diagram
Revision yr10
-
Internet
What is the internet?
The internet started in the 1960s as a way for US government researchers to share information. In the 60s computers were large and immovable and the storage that was used was little better with huge magnetic tapes being used to store data.
As a result of this if the researchers wanted to look at each other's work they had to travel to different sites or have the large, magnetic tapes shipped around the country- it was too inefficient. Another driving factor to the development of the internet was the Cold War with the Soviet Union as governments looked for ways to share information in the event of a nuclear attack.
This led to the development of ARPANET (Advanced Research Projects Agency Network) which evolves into the Internet. At the time it was limited for use by academic and research agencies that were employed by the defence department.
January 1 1983 is considered to be the official birthday of the internet. It was at this point that protocols were established for the communication of data between systems. The protocol that had been developed was the Transfer Control Protocol/ Internet Protocol- this is now referred to as TCP/IP. This universal language now allowed networks to talk to each other.
The internet is often confused with the World Wide Web. This was developed by the British scientist Tim Berners-Lee when he was working the CERN laboratory in Switzerland. It's original purpose was to allow for the sharing of documents around universities and research facilities
MAC addressing
.
Each device that connects to a network has a Network Interface Card (NIC). Each NIC has it's own Media Access Control address (MAC address). This is give to the device by the manufacturer. A MAC address cannot be changed, it is unique to that device.
A MAC address is a 48 bit address written in Hexadecimal. This makes it easier for humans to identify and communicate the devices addressing than a binary value. Each MAC address can identify the manufacturer and then the individual device.
Try finding the MAC addresses on your mobile phone. You will probably find more than one. This is because there is likely to be a WiFi adapter and a Bluetooth adapter and both have different MAC addresses.
-
IP addressing
.
Every computer in the world has a unique IP address. This IP can be changed be the user or automatically depending on the situation in which it is being used; mobile devices tend to have dynamic IP addressing meaning that it can change.
The current system is known as IPv4. It takes an address that is made up of 4 values up to 255 (8 bits).
Example of an IPv4 address- 65.123.54.254
-
It is anticipated that we will run out of possible combinations for IPv4 as there may be as many as 30 billion devices in the world. To deal with more devices a new system called IPv6 has been developed. IPv6 128 bits long which are arranged in eight groups of sixteen bits. Each group is four hexadecimal values.
Network Hardware
Too create a network certain pieces of hardware are required for the devices to be connected and for these to be able to access the internet. You do not need to know all of these devices for your GCSE but you should be aware of them.
router
A router is the device that we may most often recognise as most people have broadband. As mentioned before it is the connection between a Local Area Network and a Wide Area Network and is often has other components built into it. It is responsible for forwarding data packets (more on this later) between different computer networks.
The packets are forwarded between routers using various protocols including the Internet Protocol (IP) which provides an address for each of the routers so that it can be found.
Most likely in your home network the only device that has a static IP address is the router- this is so that it can be found by other routers on the internet. Each of the devices connected to your router will most likely have a dynamic IP address that changes, your devices will be assigned these by your router which recognises the device by it's MAC address.
Hub
You will have come across the term hub when we looked at network topologies. It is often used as part of a star network. A hub acts as a point that can connect all devices on a network together, in much the same way as a bike wheel has a hub to hold all the spokes in place.
Hubs are similar to another device that is now more commonly found on a network, a switch. A hub receives data from computers connected to it. Data on a Local Area Network is carried by a data type known as a frame (once ready for transmission on the internet this is transferred to packets). When a hub receives a frame it amplifies it and then transfers it to a destination PC by broadcasting it to all other devices on the network.
This is the key difference between a hub and Switch. This broadcasting of data to all connections has the added problem of slowing a network down as there is so much traffic on the network.
Switch
As described above a switch performs a similar role as a hub. However switches tend to be more expensive as they perform an additional task. In a hub the data frames are broadcast to all devices. A switch 'learns' the MAC addresses of the devices attached to it and creates a routing table. Once it has learnt the addresses it only sends data to the device that it needs to; this means that there is less data on a network meaning that transfer of data is significantly faster.
Network Interface Card
All devices that connect to a network require a Network Interface Card (NIC). The NIC stores the information that identifies an individual device on a network, the MAC address. Each NIC has it's own unique, and unchangeable MAC address (it is however possible to spoof a MAC address). NIC can be wired or wireless.
-
Wireless Networking
.
Wi-Fi is a family of protocols or rules.
In order to use a Wireless network a Wireless Access Point (WAP) is needed. This receives the data via a physical wired connection. The data is then converted into radio signals. Any device that has a Wireless Network Card can then access this data. The reverse happens to send data back over the internet.
-
Wireless security should be considered are there a number of measures that are used on wireless networks to prevent data loss. These include:
.
Disabling the broadcast of the Service Set identifier (SSID). This hides the network from other potential users.
-
-
To manage the connections to WiFi installations there are two different band of frequencies that are used. These are 2.4Ghz and 5GHz bands. These frequencies are subdivided into channels. These channels overlap each of which has a central frequency and bandwidth. Most broadband providers send their routers out with the channel settings as Auto but it is possible to change the channel especially if you are experiencing issues with connections; this can happen if a neighbour is using the same channel on their router.
Wide Area Networks
.
Wide Area Networks (WAN) cover a large geographical area, the most famous being the internet. Some large organisations will also make use of WANs. A WAN is a collection of computers and networks connected by a third party. This third party will be a company that owns the infrastructure such as BT. A WAN will make use of this companies cables, telephones lines, satellites and radio waves to transfer the data from one site to another.
Using a Wide Area network makes it possible for resources to be shared across a large area. These resources might be something like storage and it would enable employees working at different sites to access the same files or programs.
Local Area Networks
Local Area networks usually cover a relatively small geographic area. They consist of a single site such as a school or home. The infrastructure of a Local Area Network is owned by the company or individual, they are responsible for the issues that occur on the network.