~ Wired and Wireless networks


Take an interactive quiz!

Teachers - use this quiz on this particular topic to test students or adapt it with your own questions. Students can play individually or in teams against each other! It's free!

https://play.kahoot.it/#/k/d1e83816-1bd3-4f9e-b49a-5edf5fc868e0

 

 

PowerPoint theory

PowerPoint loading ...

Starter - Be Inspired

Have you ever wondered what the internet really is? You use it all the time - in fact you are using it now! But what is it? Well, the word "internet" is comprised of two words: "international" and "network", combining to form "inter-net". Did you know that the internet is basically just a massive network! Your next question should be - what on earth is a network? There are different types of networks and as you can imagine networks are absolutely crucial to technology today! So let's get stuck in with some theory on this exciting topic.

Let's start with a video

This video looks at the history of arguably the greatest network of all time - the internet!

Discussion questions

1. If you're sitting in a classroom (school or college) you are using a network. Try and explain to someone how it is possible for you to log on to any machine in the building and retrieve your files. Your files (documents, images etc) are obviously NOT stored on every machine on your site! So how does it work?

2. Do you have a home network? How does it work?

 

 


One of the key aspects of computing is communication. For example, input and output devices need to communicate with the processor, the hard disk needs to communicate with memory and so on.

Communication in this sense takes place through the transmission of data and instructions. We have already looked at many examples of data transmission inside the computer. In this section, we are more concerned with communication between computers and peripheral devices and also between one computer and another across local and global networks. This section will also include a detailed analysis of the infrastructure that makes up the Internet

Network - devices that are connected together to share data and resources.

A network is any number of computers connected together for communication, sharing processing power, storage capacity and other resources. In order to connect to a network, a computer must have a network adapter, more commonly know as a Network Interface Card (NIC).

Network adapter / Network Interface Card (NIC) - a card that enables devices to connect to a network.

 

 
A network interface card

The NIC is a printed circuit board which is contained inside the computer like any other card (graphics and sound cards, for example). The NIC will be specifically designed to allow the computer to connect either via cable or wirelessly to the particular network topology being used. The type of card also dictates the speed of data transmission that will be available between devices and the network. These are typically already integrated into modern motherboards.

Networks are usually described in terms of geographical area that they cover and the way in which the connections are configured, known as network topology.

Network topology - the layout of a network, usually in terms of its conceptual layout rather than physical layout.

Local Area Network (LAN)

- a network over a small geographical distance - usually on one site and typically used by one organisation.

A Local Area Network (LAN) is a number of computer and peripherals connected over a small geographical distance, covering one building or site. Most LANs are made up of one or more servers and clients. A server is a high specification computer with sufficient processing power and storage capacity to service a number of users. A client is any computer attached to the network.

Wide Area Network (WAN) - a network spread over a large geographical distance.

A Wide Area Network (WAN) is a number of computers and peripherals connected together over a large geographical distance. This could mean any network that extends beyond a single site right up to global networks such as the Internet. WANs make use of a wider variety of communication media including telephone wires, microwaveable links, satellite connections and fibre optic cables.

 

In addition to the server and client the other critical device within a network is a router. Modern routers are actually a number of devices merged together into a single device. The typical router for a home network:

  • receives every packet of data being transmitted, reads the header of the packet and then forwards it to its destination
  • acts as a firewall, preventing certain packets from being forwarded
  • acts as a switch, creating a connection between two devices on a network
  • provides a wireless access point transmitting a WiFi signal
  • acts as a modern to convert digital signals to analogue so that they can be transmitted down standard telephone cables.

Wireless networks

Wireless Wide Area Network (WWAN) - a WAN that does not use cables, but sends data using radio waves.

 

A wireless network varies from a wired network in that it does not use cables to make the physical connections between devices. Instead the data is sent using radio waves. Wireless networks can be implemented over small or large geographical distances so it is possible to have a wireless LANs (WLAN) and wireless WANs (WWAN). Many business and home networks are set up wirelessly, doing away with the need for costly cabling and enabling easy access to the network from any device with a wireless network adapter (NIC).

All devices on a network have a Media Access Control (MAC) address. This is a unique identifier encoded into the network interface card (NIC) in the format of six groups of two hex digits separated by colons, e.g. 02:32:45:77:89:ab. Any device that connects to a network using WiFi will connect through a wireless access point and must have its own unique MAC address. Every NIC ever manufactured has a unique address meaning that they can be used to identify every device uniquely. The first half of the MAC address is the manufactured code and the second half is the unique device code allocated network adapter (NIC).

Media Access Control (MAC) - a unique code that identifies a particular device on a network.

 

WiFi is the generic term for a Wireless Local Area Network (WLAN) where devices can connect wirelessly to each other and where a connection can be made to the Internet providing one of the devices in the network is online. WiFi operates to a generic standard called IEEE 802.11, ensuring that all devices are compliant and can connect and transmit data around the network.

Wireless Local Area Network (WLAN) - a LAN that does not use cables but connects using radio waves.

 

Advantages and Disadvantages of Wireless Networks

Advantages disadvantages
low set-up costs interference can occur and is slower than wired networks
not tied down to a specific location the connection is not as stable as wired networks and can 'drop off'
can connect multiple devices without the need for extra hardware more open to hacking
less disruption to the building due to no wires being installed it will lose quality through walls or obstructions

 

The purpose of Service Set Identifier (SSID)

SSID is simply the technical term for a network name.

When you set up a wireless home network, you give it a name to distinguish it from other networks in your neighbourhood.

You'll see this name when you connect your computer to your wireless network.

An SSID is the primary name associated with a 802.11 wireless local area network (WLAN) including home networks and public hotspots.

On home Wi-Fi networks, a broadband router or broadband modem stores the SSID and allows administrators to change it.

 
Eltek V7921-A2 contains a Dual-Band (2.4 GHz / 5 GHz) Wireless access point with 802.11b/g/n (2.4 GHz) and 802.11n/ac (5 GHz) radio (common in the year 2015) and two antennas.

Routers can broadcast this name to help wireless clients find the network

How wireless networks are secured

Strong encryption of transmitted data can be done using WPA /WPA2, SSID (Service Set Identifier) broadcast disabled, MAC (Media Access Control) address white list:

  • WPA - wireless protected access

Wi-Fi Protected Access (WPA) is a security standard for users of computers equipped with a wireless connection. It is an improvement on and is expected to replace the original Wi-Fi security standard, Wired Equivalent Privacy (WEP). WPA provides more sophisticated data encryption than WEP and also provides user authentication. WEP is still considered useful for the home user, but insufficient for the corporate environment where the large flow of messages can enable hackers to discover encryption keys more quickly.

 
An example of a Wi-Fi Protected Access label found on a consumer device
  • WPA2

Stands for Wi-Fi Protected Access 2, the follow-on security method to WPA for wireless networks that provides stronger data protection and network access control. It provides enterprise and consumer Wi-Fi users with a high level of assurance that only authorised users can access their wireless networks. Based on the IEEE 802.11i standard, WPA2 provides government grade security

  • SSID Broadcast disabled

Most routers and other wireless access points automatically transmit their network name (SSID) at regular intervals (every few seconds). This SSID broadcasting feature of Wi-Fi network protocols is intended to allow clients to dynamically discover and roam among wireless networks (WLANs). For security, this feature can be disabled. The tradeoff is between security and the convenience of setting up new networking clients.

  • MAC Address white list

A media access control address (MAC address), also called physical address, is a unique identifier assigned to network interfaces cards (NICs) for communications on the physical network. Many network admins set up MAC address whitelists, or a MAC address filter, to control who is allowed on their networks. This is used when encryption is not a practical solution or in tandem with encryption.

 

 
Label of an UMTS router with MAC addresses for LAN and WLAN modules

Source: CC Licensed: https://en.wikibooks.org/wiki/A-level_Computing

Network performance refers to measures of service quality of a network as seen by the customer.

Image result for wikimedia commons bandwidth

There are many different ways to measure the performance of a network, as each network is different in nature and design. Performance can also be modeled and simulated instead of measured; one example of this is using state transition diagrams to model queuing performance or to use a Network Simulator

The following measures are often considered important:

  • Bandwidth commonly measured in bits/second is the maximum rate that information can be transferred
  • Throughput is the actual rate that information is transferred
  • Latency the delay between the sender and the receiver decoding it, this is mainly a function of the signals travel time, and processing time at any nodes the information traverses
  • Jitter variation in packet delay at the receiver of the information
  • Error rate the number of corrupted bits expressed as a percentage or fraction of the total sent

SUMMARY (for exams)

Factors affecting the performance of networks

  • -too many users on the network at the same time / heavy use without a sufficient amount of available bandwidth
  • -This would cause congestion and slow the network (above point)
  • -Wired connections usually improve the network performance compared to wired connections because generally speaking they are faster and more reliable
  • -Fibre optic cables have a greater performance capability than copper cables as the signal can travel over long distances and the signal does not degrade (it has higher bandwidth)
  • -Interference from other electronic or wireless devices can affect the performance of the network by decreasing the data speed – this would cause the network to slow down.

What is the below Wikimedia commons picture depicting?

Image result for wikimedia commons bandwidth

Client-server networks


Client-server
- a network methodology where one computer has the main processing power and storage and the other computers act as clients requesting services from the server.

In the star and bus topologies, the diagram shows a main server. Although the clients have local resources in terms of processing power and storage capacity, they are dependent upon the server. This is the most common way of constructing a LAN with a large number of users. The server will be a high-end computer with a large amount of processing power and storage capacity. It needs to be big enough and fast enough to cope with the demands placed upon the clients.

Client-server-model.svg
 
Source *applies to all the addtional theory pages in this section: CC licensed: https://en.wikipedia.org

Peer-to-peer networks

Peer-to-peer - a network methodology where all devices in a network share resources between them rather than having a server.

In a peer-to-peer network, no one computer is in overall control of the network. Instead the resources of each computer or workstation are available to all the computers in the network. Each workstation therefore can act either as a client or a server, depending on the current task. This more common among smaller networks on for certain applications such as file sharing.

P2P-network.svg
Characteristic Peer-to-peer Client-Server
Who's in charge? Where is the control? No one / Everyone Server
How are resources shared On a individual basis Centrally by the server to users/groups
Does it need a special OS? No Yes
Simple/hard to setup Simple Needs system admin
Cost Low High(er) (server can be expensive as can sys admin software)
Secure? Lower Higher (but needs expertise)

Look up and research the following terms:

  • WIFI
  • Coaxial Cable
  • CAT5e cable
  • Fibre optic cable
  • Network Interface Controller
  • Ethernet
  • USB Dongle
  • Switcgh
  • Router
  • Wireless Access point

 

The Internet!

Can you imagine life without the internet? What really is it?

The Internet is a worldwide collection of computer networks that began as a single network that was originally created in 1969 by ARPA (Advanced Research Projects Agency), a U.S. government agency that was far more interested in creating projects that would survive a nuclear war than in creating anything useful for the civilian population.

In its original form, ARPANET, the U.S. government hoped to create a network of computers that would allow communication between government agencies and certain educational centers that would be able to survive a nuclear explosion. It is doubtful that the original founders of ARPANET foresaw what we now know as "the Internet." From its humble beginnings as a military project, the ARPANET grew slowly throughout the 70's and 80's as a community of academics accomplished the truly monumental task of hammering out the building blocks of this new, open, modular conglomeration of networks.

In addition to the U.S. ARPANET, other countries also developed their own computer networks which quickly linked up to ARPANET, such as the UK's JANET (1983 onwards), and Australia's ACSnet (mid-1970s until replaced). Connecting these together would help develop a global internetwork.

The various protocols, including IP, TCP, DNS, POP, and SMTP, took shape over the years, and by the time the World Wide Web (HTML and HTTP) was created in the early 90's, this "Internet" had become a fully functional, fairly robust system of network communication, able to support this new pair of protocols which eventually turned the Internet into a household word.

While a large portion of users today confuse the Web with the Internet itself, it must be emphasized that the Web is only one type of Internet application, and one set of protocols among a great many which were in use for over a decade before the Web entered into the public awareness.

The Web is a subset of the Net. Email is not a part of the Web, and neither are newsgroups, although Web designers have developed web sites through which users, the world over, commonly access both of these much older forms of Internet media.

While the Net is a largely abstract phenomenon, it cannot (at least, not yet) be accurately equated with the concept of "cyberspace" as depicted in science fiction. If "judgement day" were to occur as depicted in the latest "Terminator" film, much of the Internet would survive it, but most of the electrical and data infrastructure by which we access the net would not. The line which currently demarcates the "digital divide" would shift dramatically to a point where it would leave only a small segment of humanity in virtual touch. This limitation, however, will slowly be overcome as wireless technologies continue to proliferate and wired technologies become increasingly cheaper.

In March 1972 ARPA became known as DARPA, the Defense Advanced Research Project Agency, and then went back to ARPA in February 1993 and back to DARPA in March 1996 and has been ever since. It was originally created as ARPA in 1958 in response to the launching of Sputnik. The launch of Sputnik made America realize that the Soviet Union could exploit military technology. DARPA has contributed to the creation of ARPANET as well as the Packet Radio Network, the Packet Satellite Network and the Internet. As well as research into the Artificial Intelligence field commonly referred to as AI. By the late 1970's the Department of Defense had adopted BSD UNIX as the primary operating system for DARPA.

References

Look up the term "Virtual Network"

The term "virtual" probably gets you thinking along the lines of virtual reality. Well, it's helpful for you to think: SOFTWARE when you're referring to Virtual networks. Virtual networks make use of software to divide devices on a LAN into smaller groups.

It's useful to remember that the whole LAN is still physically connected by cables, but the 'virtual network' of devices created through software are restricted from accessing any of the other computers on the LAN. Because of this they appear to be a completely separate network within the larger one.

The youtube video below may help a little with Virtual Networks


Devices on the finance office virtual network can see all of the files and folders they need and can easily share data with anyone else on their network. However, they cannot see teacher or student files stored in the blue and yellow virtual networks. Likewise, students on the yellow virtual network cannot see resources stored on the blue or red networks.

NOTE: in your exam, do not talk about coloured networks. We have used them here just to help you understand the concept.

SUMMARY DEFINITION: Local Area Networks are created using hardware (cables). Virtual networks are created using software.

Video - Summary of Networks so far

Tasks & Worksheets

Your teacher may ask you to do one or more of the following tasks

Past paper based worksheet

Mark scheme answers with solutions and illustrations in subscription only drive

Worksheet

#1 Worksheet 1: LAN/WAN/Factors affecting performance. Complete the following worksheet on Networks *Your teacher may set this as a test or assignment

#2 Worksheet 2: LAN Hardware, Types of Networks (Peer-to-Peer, Client-Server), Virtual Networks

Learning Poster

1. Complete a learning poster (a single slide) in which all of the following terms is explained

a) Types of Networks, Factors that affect the performance of networks, Different roles of computers in client-server and peer-to-peer networks, Hardware needed to connect stand-alone computers into a LAN, The internet as a worldwide collection of computer networks, The concept of virtual networks

Research Power Point

1. Complete a research powerpoint that provides two different case studies of networks that have been set up (you could chose a school and company or a network in a village in africa contrasted with the network in a home - you decide!

End of topic assessment

Well done on completing this topic!

Your teacher will direct you as to which task needs to be handed in

What to submit

-learning poster

-research powerpoint

-worksheet

-other

Ensure you revise and go over your learning for this topic yourself in order to retain this information for your exam and beyond!