Introduction to Networks 1 of 21 Boardworks Ltd

Introduction to Networks 1 of 21 © Boardworks Ltd 2010

This lesson will cover: The purpose and uses of networks. The key components of a computer network. The different types of network and the advantages and disadvantages of them. Icons key: For more detailed instructions, see the Getting Started presentation Flash activity. These activities are not editable. Teacher’s notes included in the Notes Page Student task accompanies this slide 2 of 21 Web addresses Functional Skills check Printable activity © Boardworks Ltd 2010

The importance of networks Networking is a way of connecting hardware together so that software, data, files and peripheral devices can be shared. Networks allow users to have access to lots of hardware devices from their personal terminal. What other advantages do networks have? 3 of 21 © Boardworks Ltd 2010

What is the Internet? The Internet is a network of networks that connects governments, people and companies all over the world. 10 Downing Street, London, England Koji Araki, Japan Sydney Opera House, Australia The Internet Patel’s Fine Silks, India 4 of 21 Jim’s Skateboards USA © Boardworks Ltd 2010

Where did it begin? The Internet began in the 1980 s to allow US universities to share computer resources. It grew so much that by the 1990 s it had become possible for people to use the Internet from home. The World Wide Web (www) was developed to make browsing (viewing) easier through http (Hypertext Transfer Protocol). http is a set of standards that allows web browsers and servers to communicate. 5 of 21 © Boardworks Ltd 2010

Network components – modems A modem stands for modulator–demodulator. They connect computers to the Internet or distant networks by converting the digital, binary signals into an analogue signal that can be transmitted down telephone lines. Old modems converted digital information to an audio signal. Press play to hear this. Modern modems are built into computers and use DSL or ADSL technology. These use much higher transmission frequencies which allows for faster data transfer. 6 of 21 © Boardworks Ltd 2010

Network components – network cards In order for a computer to function as part of a network, it has to have a special piece of equipment installed to give it this capability. This is called a Network Interface Card or NIC. It has a port for a network cable to be connected. NICs are still very common, but increasingly people are using wireless network cards or wireless USB adaptors. 7 of 21 © Boardworks Ltd 2010

Ethernet and alternatives Ethernet is the name given to the most common method of networking computers. Although other methods exist, Ethernet has been the standard since the 1990 s. Ethernet uses Cat 5 cables to connect computers together. What alternatives are there to Ethernet? 8 of 21 © Boardworks Ltd 2010

Cables There are many types of network cable. Twisted-pair cables are the most common. This cabling is often called ethernet cabling. Category 5 (Cat 5) twisted-pair cables can carry 100 Mb per second over distances of up to 100 metres. Coaxial cable is better at resisting interference and can be run for longer lengths, but it is not as flexible and is not used much now. Fibre optic cable can transfer data at higher speeds over longer distances, and can be used outside buildings, but it is much more expensive. It has a central core made of glass and transmits the signals using light. 9 of 21 © Boardworks Ltd 2010

Remember the terminology 10 of 21 © Boardworks Ltd 2010

Hubs, switches and routers 11 of 21 © Boardworks Ltd 2010

Wireless networks With improvements in radio technology, it has become possible to connect computers on a LAN network without using wires. A wireless network card is similar to a standard NIC, but has a transmitter/receiver for sending signals via radio waves. Wireless networks are popular as they allow the user more freedom, such as working outdoors. Are there any problems with wireless networks? 12 of 21 © Boardworks Ltd 2010

Wi-Fi hotspots Wi-Fi technology allows users to wirelessly connect to the Internet. Access points are set up at various locations from which users can connect to a wireless network and access the Internet. Many cafes and bars offer wireless hotspots, allowing users to work where they please. What benefits and drawbacks might establishments face when offering Wi-Fi access? 13 of 21 © Boardworks Ltd 2010

Benefits and drawbacks 14 of 21 © Boardworks Ltd 2010

Mobile networks It is now incredibly common to use mobile devices to access a network. Most modern mobiles allow Internet access via 3 G (third generation) networks. It’s not just mobiles though. Tablet computers, PDAs, E-readers and even gaming devices like the Nintendo DS are all being created with the ability to connect to local area networks (LANs) or wide area networks (WANs) without the need for cables. 15 of 21 © Boardworks Ltd 2010

Packets Each computer on a network has to have a network address so that the data knows where it is being sent. IP 192. 168. 10. 2 Computers break down data into small parts so they can find the quickest route to their destination. These small parts are called packets and will be reassembled when they arrive at the right destination. Computers connected to the Internet have their own IP address to allow data packets to arrive at the right location. 16 of 21 © Boardworks Ltd 2010

URLs The domain name system links the IP address (e. g. 217. 240. 45) with the text name or web address (e. g. http: //www. boardworks. co. uk). This means that users only have to remember a short name instead of lots of numbers. Most people still refer to this as a website address but its proper name is a URL or Uniform Resource Locator. 17 of 21 © Boardworks Ltd 2010

URLs are usually made up of these parts: www, standing for World Wide Web an organization name (. boardworks) a top level domain (. co) a country (. uk). There are many top level domains, for instance. com, . org (organization), . sch (school) and. ac (university). When you are deciding whether the information from a website is reliable, take a look at the URL. It will give you some idea about the source of the information. 18 of 21 © Boardworks Ltd 2010

Speaking the same language To allow different types of computers in different parts of the world to interact, there has to be some agreement about how they communicate. These standards are called protocols. http is the first part of many web addresses – it stands for hypertext transfer protocol, and states the protocol that the site will use to communicate. HTML stands for Hypertext Markup Language, and it is the standard language for writing web pages. What does HTTPS stand for? 19 of 21 © Boardworks Ltd 2010