1. Unit 2.4 Transfer of Data in ICT Systems (Networks)

2. You will cover… - Basic elements of a network –What is the difference between a LAN and a WAN? –What are the advantages of networks over stand- alone systems? –What do we mean by peer to peer and client / server networks? –The Internet and the World Wide Web –Extranet and intranet –Protocols –Standards (De facto and De jure) –Network topologies (star, bus and ring)

3. Basic elements of an ICT Network… There are 4 basic elements: –Communication devices (hardware needed to turn stand-alone computers into networked computers) Network Interface card (prepares and sends the data, controls flow of data) Hub (joins computers so they can share files and an internet connection) Switches (similar to a hub, but more intelligent – it inspects a data packet and sends it to the intended computer) Routers (act as gateways so that small home computers can connect to the internet) –Networking software (tells the connected devices how to communicate with each other) Network Operating software (e.g. UNIX, Linux, Novell Netware) Network Management software –How will this software help a network manager? –Data transfer media (material through which data travels from one computer to another) Metal wires – (offer high transmission but expensive to be installed) Fibre Optic Cable – (high speed, small, lack of electrical interference but are expensive) Wireless – (ideal for people who travel) –Standards and procedures (data sent can be understood)

4. What is an ICT Network? A computer network consists of two or more computers and peripherals that are linked together These links can be made through cables or wirelessly. A wireless network uses radio waves in the same way as TV’s, radios and mobile phones to make links. A wireless network following a common protocol is called Wi-Fi

5. Comment on the following… Where the data is stored? Back ups Installation and update of s/w Maintenance Security Administration (allocation of user names and passwords) Advantages & Disadvantages? Client – Server Vs Peer to Peer

6. Lack of access when file server fails –If a file server fails the entire network may fail, so users may not be able to access files and data Cost –Although a network may save money over time, there is the initial high cost of all the network equipment and training needed Technical knowledge needed –More IT knowledge is needed to run a network –Specialist staff are needed What are the disadvantages of networks?

7. Characteristics of Networks… The internet and the world wide web are DIFFERENT things! Write down the definition of: –Internet – A large group of interconnected computers around the world that allow the sending and retrieval of information from one computer to another. –World wide web – A collection of multimedia resources accessible via the internet Other than accessing webpages what other services can the Internet provide? –Email facilities –Instant messaging –Forums –FTP (exchanging of files between different computers) –P2P

8. Characteristics of Networks… The intranet and Extranet are DIFFERENT things! Write down the definition of: –Intranet – A private network used within an organisation that makes use of internet technology. Access is restricted to employees using passwords. –Extranet – A private network that restricts access to employees of an organisation and also external people / organisations. What security measures can be put in place to keep data secure in an extranet? –Gateways –Firewalls –Encryption –User authentication

9. Star Topology… A star topology has a central computer with each device connected directly to it. The central computer serves as a switch. Star topology requires extra cabling. If one device or cable is broken, the network can still operate. However, if the central computer fails, then the network fails.

10. Star topology Advantages Each node has its own cable and does not need to share the line with any other node. If the cable to a node is broken, then only that node is affected. The rest of the network can operate normally. New links to the central node can be easily added, or existing links removed, without affecting the rest of the network. It is easy to identify a faulty cable because it will only affect a single link.

11. Star topology Disadvantages If the central node fails then the entire network will cease to operate. More cabling is needed than for the other network topologies.

12. Ring Topology A ring topology is an arrangement where all devices are attached so that the path is in the shape of a continuous circle. Data flow is in one direction, moving from device to device until the data arrives at its destination. There is not necessarily a main computer acting as a server, if there is a server it is just 1 computer in the ring. Less secure – as all data passes through all computers. Need to close down network to add another computer

13. Ring topology… Advantages A single cable is used to connect all the nodes. Disadvantages The ring must be broken (and the network stopped) to add new nodes or remove existing ones. If the ring is broken, or the cable is faulty, then the entire network will cease to work.

14. Bus Topology A bus topology is where all the devices are attached to a direct line called the bus. Each device is considered to be connected to every other device A Bus Topology is one of the easiest to set up and can still operate if one node fails. Data is transferred in both directions and the receiving computer picks up the response. If main cable fails all computers are affected.

15. Bus topology Advantages They are easy and cheap to set up. Nodes can be easily added and removed. Disadvantages Because the one cable carries all the data, collisions (data traffic jams) become more common as more nodes are added. A fault in the cable can be difficult to locate because it will usually stop all the nodes from transmitting or receiving.

16. Standard & Procedures A standard is a common way of doing something, for example storing data in a particular format or transferring data in a pre-determined way There are hardware standards such as USB (universal serial bus) ports which can connect a wide range of peripherals like cameras, phones scanners, printers. You need to be aware of: –De Facto Standards –De Jure Standards Explain what each standard means with examples to support your explanation

17. De facto standard No formal agreement is in place Has become the most commonly used in practice Example GIF format used for pictures placed on the internet – widely used on the web by developers Example WINDOWS operating system used in PCs

18. De jure standard Legally binding industry standard Restrictions are in place, some people feel this stifles and slows creativity and development Example WI-FI – wireless standard

19. Benefits & Limitations of Standards BenefitLimitation Users not restricted to one manufacturers equipment Standards and protocols are difficult to change as getting universal agreement is time consuming Competitive markets better for consumers In fast changing areas, standards may not be able to keep up with technological developments. Can communicate with people / organisations using different hardware Having to follow standards may mean that in some cases the full power of a machine might not be available therefore there may be reduced functionality or performance

20. Protocols What are protocols? –Is a standard set of rules that define how communications take place between computers. –The use of protocols means that a network does not have to be restricted to one manufacturers equipment. It allows for the existence of OPEN SYSTEMS This means that several disparate pieces of equipment can be connected together and communicate effectively.

21. Protocols cont… Detail the features of FTP, WAP and HTTP –FTP Allows a file to be transferred from one computer to another; it is often used to upload files to the web –WAP Wireless Application Protocol Is a standard for wireless communication networks used by mobile phones to access the internet –HTTP HyperText Transfer Protocol Is a standard for transferring web pages to a client computer –POP Post Office Protocol Is a standard for transferring e-mail between computers –IP Internet Protocol A protocol that directs data from one computer to another –TCP Transmission Control Protocol A protocol to manage the assembly (and reassembly) of data into packets transmitted between computers over the internet no matter what hardware is used.

22. Use of Communication Technologies A high percentage of homes now have one or more computers which are used in a variety of ways not related to business. For example: –Keeping in contact with friends and family using email and VoIP (e.g. Skype) –Accessing the web for information and services –Online shopping and banking –Downloading, modifying and sharing photos –Accessing social networking sites such as Face book –Instant messaging and web blogs –Video conferencing –Forums

23. The Internet & Business Across the globe there are millions of people using the Internet. This technology offers new opportunities for many businesses. For example they can: –Market their products to a worldwide audience through a website –Carry out research –Sell products directly over the internet (e-commerce) –Use video conferencing for virtual meetings –Use EDI (electronic data interchange) to communicate with suppliers –Use email to communicate quickly –Use intranets and extranets to get up to the minute information

24. Virtual Learning Environments Many schools and colleges have a Virtual Learning Environment (VLE Software) This allows students and their teachers to interact online. Features include access to course materials and learning resources Students can work through the resources at their own pace Progress can be tracked through online assessments Communication between students can be conducted via discussion forums and chat rooms